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Journal Cover
Physics and Chemistry of the Earth, Parts A/B/C
Journal Prestige (SJR): 0.621
Citation Impact (citeScore): 2
Number of Followers: 8  
 
  Hybrid Journal Hybrid journal (It can contain Open Access articles)
ISSN (Print) 1474-7065
Published by Elsevier Homepage  [3163 journals]
  • Fertility status of cultivated floodplain soils in the Zambezi Valley,
           northern Zimbabwe
    • Authors: M. Chimweta; I.W. Nyakudya; L. Jimu
      Pages: 147 - 153
      Abstract: Publication date: June 2018
      Source:Physics and Chemistry of the Earth, Parts A/B/C, Volume 105
      Author(s): M. Chimweta, I.W. Nyakudya, L. Jimu
      Flood–recession cropping improves smallholder farmers' household food security. The objective of this study was to determine the fertility status of cultivated Zambezi Valley floodplain soils, in northern Zimbabwe. The study was conducted at three sites, along tributaries of Musengezi River. Soil samples were taken at 0.20 m depth increments to 0.60 m from hydromorphologically stratified fields, during the cropping season. Sampling points were replicated twice in each stratum at points equidistant from river edges. Relative elevations of sampling points were measured using levelling equipment. Soil was analysed using: core method for bulk density, hydrometer method for texture, loss on ignition for soil organic carbon (SOC), Kjeldahl procedure for total nitrogen (N), 0.01 M CaCl2 for pH, and Inductively Coupled Plasma (ICP) for Mehlich 3 extractable elements. Data from soil analyses were subjected to One Way Analysis of Variance and Pearson's correlation analysis. Bulk density ranged from 1.2 to 1.4 g cm−3 and it was negatively related to distance from river; and positively related to elevation at two sites. Highest values for SOC and total N were 2.04% and 0.36% respectively. Soil pH ranged from 7.70 to 8.60. Soil organic carbon and N were positively related to distance from river but negatively related to elevation. Threshold concentrations for deficiency: < 12 ppm for K, and <39 ppm for Mg, were exceeded. Calcium, Na, and micronutrients in most cases exceeded concentrations reported for floodplains. Practices that slow down flowing water and fertilizer microdosing are among possible fertility management options.

      PubDate: 2018-06-03T09:40:30Z
      DOI: 10.1016/j.pce.2017.12.005
      Issue No: Vol. 105 (2018)
       
  • A geomorphological characterisation of river systems in South Africa: A
           case study of the Sabie River
    • Authors: Peter N. Eze; Jasper Knight
      Pages: 196 - 205
      Abstract: Publication date: June 2018
      Source:Physics and Chemistry of the Earth, Parts A/B/C, Volume 105
      Author(s): Peter N. Eze, Jasper Knight
      Fluvial geomorphology affects river character, behaviour, evolution, trajectory of change and recovery potential, and as such affects biophysical interactions within a catchment. Water bodies in South Africa, in common with many other water-stressed parts of the world, are generally under threat due to increasing natural and anthropogenic influences including aridity, siltation and pollution, as well as climate and environmental change. This study reports on a case study to characterise the geomorphology of different river systems in South Africa, with the aim of better understanding their properties, controls, and implications for biophysical interactions including water quality, biodiversity (aquatic and riparian), and human activity within the catchment. The approach adopted is based on the River Styles® framework (RSF), a geomorphology-based approach developed for rivers in New Zealand and Australia, but applied here for the first time to South Africa. Based on analysis of remote sensing imagery, SRTM-2 digital topographic data and field observations on sites through the entire river system, six geomorphic elements were identified along the Sabie River, northeast South Africa (gorge, bedrock-forced meander, low-moderate sinuosity planform controlled sand bed, meandering sand bed, low sinuosity fine grained sand bed, and floodouts), using the RSF classification scheme and based on the RSF procedural tree of Brierley and Fryirs (2005). Previous geomorphological studies along the Sabie River have shown that different reaches respond differently to episodic floods; we use these data to link river geomorphological character (as defined by the RSF) to the hydrodynamic conditions and processes giving rise to such character. This RSF approach can be used to develop a new management approach for river systems that considers their functional biophysical behaviour within individual reaches, rather than considering them as homogeneous and uniform systems.

      PubDate: 2018-06-03T09:40:30Z
      DOI: 10.1016/j.pce.2018.01.001
      Issue No: Vol. 105 (2018)
       
  • Integrating environmental variables and geospatial technologies in
           landscape scale habitat modelling of edible stink bugs in Zimbabwe
    • Authors: Mhosisi Masocha; Timothy Dube; Tendai Maziva
      Pages: 206 - 211
      Abstract: Publication date: June 2018
      Source:Physics and Chemistry of the Earth, Parts A/B/C, Volume 105
      Author(s): Mhosisi Masocha, Timothy Dube, Tendai Maziva
      Encosternum delegorguei spinola (edible stink bugs) is renowned for its high protein and contribution to the local economies of the people in Africa. Although many studies have evaluated the economic and nutritional importance of E. delegorguei, little is known about its geographic distribution and habitat yet the insects are an important source of protein and money for many people in Southern Africa. In this study maximum entropy model was used to predict the probability of presence of E. delegorguei in southern Zimbabwe. The environmental factors governing its geographic distribution in Zimbabwe were also evaluated. Presence/absence data were selected along thirty-five randomly selected transects. The climatic and topographic variables used to predict the distribution of E. delegorguei were: maximum temperature of the warmest month; minimum temperature of the coldest month; the normalised difference vegetation index (NDVI); altitude; slope; and aspect. It was found that E. delegorguei is most likely to occur on steep slopes with high NDVI located at an altitude ranging of 856 and 1450 m above sea level. These suitable habitats are characterised by mild temperatures ranging from 17 °C to 28 °C. These results are in agreement with previous studies indicating that E. delegorguei is sensitive to temperature, as well as tree cover and may contribute towards conserving its habitat, which is being fragmented by anthropogenic disturbance.

      PubDate: 2018-06-03T09:40:30Z
      DOI: 10.1016/j.pce.2018.01.002
      Issue No: Vol. 105 (2018)
       
  • Perceptions on the use of bottled water in restaurants in Harare's Central
           Business District (CBD)
    • Authors: Olivia Sakhile Juba; Vincent Itai Tanyanyiwa
      Pages: 239 - 246
      Abstract: Publication date: June 2018
      Source:Physics and Chemistry of the Earth, Parts A/B/C, Volume 105
      Author(s): Olivia Sakhile Juba, Vincent Itai Tanyanyiwa
      Bottled water use continues to expand worldwide and in the last two decades, a significant number of consumers have shifted from tap water to bottled water due to Cryptosporidium outbreaks. Bottled water consumption has increased in Harare due to erratic tap water supplies. Since 2011, forty bottled water brands have been banned because of failure to meet safety and quality standards due to contamination, unsuitable packaging, and wrong labelling. Nevertheless, the bottled water industry continues to thrive as local authorities fail to adequately purify municipal water. The study assessed the perceptions on drinking bottled water in restaurants within Harare's CBD. Demographic and social factors associated with bottled water users were established and the role and influence of stakeholders in bottling and distribution of water documented. A field survey through the administration of questionnaires to fifty restaurant users was carried out to assess the perceptions of people on the use of bottled water in terms of its safety and potential health benefits. Key informant interviews were conducted using a semi-structured interview with ten local water bottling companies as well as representatives from the Environmental Management Agency (EMA) and Standards Association of Zimbabwe (SAZ). Data were analysed using descriptive statistics and logistic regression analysis. Standard descriptive statistics were generated, with 95% confidence intervals (95% CIs). Consumers used bottled water as their primary drinking water source when they perceived that tap water was not safe. Perceptions of purity of water, bottled water convenience, and tap water unavailability seemed to determine consumption patterns among users. Females in the 18–48 age groups were more likely to think that bottled water was cleaner, safer, tasted better and was more convenient than tap water. Consumers regularly purchased bottled water for drinking and used bottled water as their primary drinking water source regardless of cost implications. Government and local authorities need to ensure that pure and clean water is availed in Harare. In addition, the public must be engaged in recognizing the relationships that exist between water quality and the capacity of local authorities to maintain taste and safety standards.

      PubDate: 2018-06-03T09:40:30Z
      DOI: 10.1016/j.pce.2017.12.003
      Issue No: Vol. 105 (2018)
       
  • Validation and verification of lawful water use in South Africa: An
           overview of the process in the KwaZulu-Natal Province
    • Authors: E. Kapangaziwiri; J. Mwenge Kahinda; S. Dzikiti; A. Ramoelo; M. Cho; R. Mathieu; M. Naidoo; A. Seetal; H. Pienaar
      Pages: 274 - 282
      Abstract: Publication date: June 2018
      Source:Physics and Chemistry of the Earth, Parts A/B/C, Volume 105
      Author(s): E. Kapangaziwiri, J. Mwenge Kahinda, S. Dzikiti, A. Ramoelo, M. Cho, R. Mathieu, M. Naidoo, A. Seetal, H. Pienaar
      South Africa is a water-stressed country which has, over the years, strived to adopt a rational, just and equitable way to manage this limited resource. The National Water Act (Act No.36 of 1998) (NWA) provides the legal framework to achieve this objective. Since 2003, the government embarked on a national process to: validate (confirm the quantum of), and; verify (establish the lawfulness of) water uses that exceed domestic requirements. The objective of the process is to determine how much water is allocated for: (1) existing lawful use in accordance with specific requirements of the NWA, and; (2) current water uses. The process identified users with or without registered use entitlements, whether claims for registered uses were correct, under-estimated, over-estimated or false; and confirmed the lawfulness of each water use in accordance with water legislation that pre-dated the NWA. The process included identifying land and non-land based water uses (industrial, mining and bulk potable water supplies, irrigation, crop types and impoundments) using remote sensing (RS) techniques for both a qualifying (defined as two years before the enactment of the NWA) and the current periods. Using this as a basis, volumetric crop irrigation requirements were then estimated using the South African Procedure for estimating irrigation WATer requirements (SAPWAT), while the Gush curves were used to quantify Stream Flow Reduction Activities (SFRAs) for commercially afforested areas. The boundaries of farm reservoirs were delineated from RS and the volumes calculated using a regression approach. Estimates of the irrigation water requirements, SFRAs and reservoir volumes formed the basis for interaction between the Department of Water and Sanitation (DWS) and water users to confirm their uses; and subsequently, to update the DWS Water Authorisation and Registration Management System (WARMS), a database of water users. While WARMS initially indicated a total of approximately 16 000 registered users in the KwaZulu-Natal Province, following the RS analysis up to 6000 potential additional water users have been identified, mostly currently unregistered, who are expected to be registered in the updated database. Despite certain process methodology challenges and limitations, it forms a critical basis for all other aspects of water management, informs macro- and micro-water resource planning, water allocation reform, as well as water use compliance, monitoring and enforcement.

      PubDate: 2018-06-03T09:40:30Z
      DOI: 10.1016/j.pce.2017.12.002
      Issue No: Vol. 105 (2018)
       
  • Scenario planning for water resource management in semi arid zone
    • Authors: Rajiv Gupta; Gaurav Kumar
      Pages: 290 - 299
      Abstract: Publication date: June 2018
      Source:Physics and Chemistry of the Earth, Parts A/B/C, Volume 105
      Author(s): Rajiv Gupta, Gaurav Kumar
      Scenario planning for water resource management in semi arid zone is performed using systems Input-Output approach of time domain analysis. This approach derived the future weights of input variables of the hydrological system from their precedent weights. Input variables considered here are precipitation, evaporation, population and crop irrigation. Ingles & De Souza's method and Thornthwaite model have been used to estimate runoff and evaporation respectively. Difference between precipitation inflow and the sum of runoff and evaporation has been approximated as groundwater recharge. Population and crop irrigation derived the total water demand. Compensation of total water demand by groundwater recharge has been analyzed. Further compensation has been evaluated by proposing efficient methods of water conservation. The best measure to be adopted for water conservation is suggested based on the cost benefit analysis. A case study for nine villages in Chirawa region of district Jhunjhunu, Rajasthan (India) validates the model.

      PubDate: 2018-06-03T09:40:30Z
      DOI: 10.1016/j.pce.2017.12.004
      Issue No: Vol. 105 (2018)
       
  • Assessment of the quality of SOBO industrial wastewater and its impact on
           water quality in Nankhaka River
    • Abstract: Publication date: Available online 9 June 2018
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): L. Ngwira, D. Lakudzala
      An assessment of the quality of industrial (effluent) from soft drink manufacturer Southern Bottlers (SOBO) factory in Lilongwe was carried out to determine the impact of pollution in Nankhaka River. Both the effluents and the water samples at selected points in the river were analysed for pH, suspended solids (SS), total dissolved solids (TDS), phosphate, nitrates, dissolved oxygen (DO), biochemical oxygen demand (BOD), chemical oxygen demand (COD) and faecal coliform (FC) using standard methods. The levels of SS, TDS, phosphate, BOD and COD with mean values of 111, 803, 4.61, 186 and 570 mg/ℓ respectively, in the SOBO industrial wastewater were outside the Malawi Standard recommended limits for effluents discharged into inland waters. However, the levels of pH (8.29) and nitrates (0.031 mg/ℓ) were within the recommended limits whereas the levels of faecal coliform (42,900 counts /100 mℓ) and DO (2.50 mg/ℓ) were not specified in the standard. The variation in water quality between upstream and downstream parameters was statistically significant (p < 0.05) at 95% confidence level. The results suggest that SOBO effluent pollutes the water in the river rendering it unfit for human consumption. It is therefore recommended that the discharge of poor quality effluents should be discouraged. Authorities should enforce the laws governing the disposal of wastes to protect the lives of the people who use the water in Nankhaka River.

      PubDate: 2018-06-12T10:13:48Z
       
  • Influence of Paper Mill Wastewater on Reed Chlorophyll Content and Biomass
    • Authors: Fangli Su; Linlin Dong; Haifu Li; Tieliang Wang
      Abstract: Publication date: Available online 5 June 2018
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Fangli Su, Linlin Dong, Haifu Li, Tieliang Wang
      Studies on the influence of paper mill wastewater, which affects photosynthesis, on reed chlorophyll and biomass can provide a theoretical basis for the ecological restoration of wetland plants. The influence of different concentrations of wastewater (chemical oxygen demands (COD) of 300, 175 and 50 mg•L-1) and different irrigation times (germination, blade-expansion, rapid-growth, heading and maturity stages) on the contents of chlorophyll a, chlorophyll b, total chlorophyll and chlorophyll a/b in reeds were tested in experimental pools that simulated the wetland ecosystem of the Liaoning Shuangtai estuary. The contents of chlorophyll a, chlorophyll b, total chlorophyll and chlorophyll a/b all increased significantly with increasing concentrations of wastewater, and their contents all differed significantly from each other. The contents of chlorophyll a, chlorophyll b and total chlorophyll were maximal when irrigated at the beginning of all growth stages with COD) of 300 mg•L-1(C1O) at 2.253, 0.458 and 2.711 mg•g-1 fresh weight (FW), respectively, with irrigation at the rapid-growth stage and were minimal in the control plants at 0.142, 0.068 and 0.210 mg•g-1 FW, respectively, with irrigation at maturity. Chlorophyll a/b was maximal at C1O at 5.753 with irrigation at germination stage and was minimal in the control plants at 2.113 with irrigation at maturity. Reed biomass was maximal at C1O at 3.26 kg, which was 2.76 times higher than the control. Reed biomass was positively correlated with the content of chlorophyll and with COD in the wastewater. Paper mill wastewater generally increased the content of chlorophyll and the net photosynthesis rate and enhanced the growth of reeds.

      PubDate: 2018-06-06T09:54:52Z
      DOI: 10.1016/j.pce.2018.06.003
       
  • Modeling the luminous intensity of Beijing, China using DMSP-OLS
           night-time lights series data for estimating population density
    • Authors: Pavan Kumar; Haroon Sajjad P.K. Joshi Christopher Elvidge Sufia Rehman
      Abstract: Publication date: Available online 5 June 2018
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Pavan Kumar, Haroon Sajjad, P.K. Joshi, Christopher D. Elvidge, Sufia Rehman, B.S. Chaudhary, Bismay Ranjan Tripathy, Jyoti Singh, Gajendra Pipal
      Various scientific researches were conducted to monitor human activities and natural phenomena with the availability of various night time satellite data such as Defense Meteorological Satellite Program (DMPS). Population growth especially in a faster growing economy like China is an important indicator for assessing socio-economic development, urban planning and environmental management. Thus, spatial distribution of population is instrumental in assessing growth and developmental activities in Beijing city of China. The satellite observation data derived from Defense Meteorological Satellite Program (DMSP) was utilized to estimate population density through the measurement of light flux with radiometric recording. The data was calibrated using C0, C1, C2 parameters before processing. Population density of Beijing city was estimated using light volume of this calibrated data. Regression analysis between urban population and light volume revealed high correlation ( r 2 = 0.89 ) . Thus, population density can effectively be estimated using light intensity. The model used for estimating urban population density can effectively be utilized for other major cities of the world.
      Graphical abstract image

      PubDate: 2018-06-06T09:54:52Z
       
  • Understanding the impacts of human resettlement and projected land use
           dynamics in Chimanimani District of Zimbabwe
    • Authors: Charity Nyelele; Amon Murwira Timothy Dube
      Abstract: Publication date: Available online 30 May 2018
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Charity Nyelele, Amon Murwira, Timothy Dube
      Land cover change has been identified as a major driver of global environmental change. In agricultural landscapes that are undergoing land cover conversions, there is need to investigate the nature, extent and pattern of these conversions. This helps to assess the resultant forest cover changes and their consequences, as well as to help inform sustainable biodiversity conservation measures. This study tests whether and in what way agricultural expansion drives land cover change in resettled landscapes of Zimbabwe now and in the future. Classified Landsat Thematic Mapper images of 2000, 2009, and Landsat 8 image of 2013 were analyzed, using the widely used Markov modelling framework, to determine land use and land cover changes between the year 2000 and 2013, as well as future land cover dynamics in the area of interest. Specifically, land cover data was used to simulate land cover transitions up to 2050, using Markov chain model. Historic land cover modelling and future spatial predictions revealed increases in cropland accompanied by decreases in plantation and forests. This study concludes that agriculture is a major driver of land cover changes, especially forest cover changes in newly resettled agricultural landscapes.

      PubDate: 2018-05-31T10:32:02Z
       
  • A novel photodegradation approach for the efficient removal of natural
           organic matter (NOM) from water
    • Authors: Nqobile Ndlangamandla; Alex Kuvarega Titus A.M. Msagati Bhekie Mamba Thabo
      Abstract: Publication date: Available online 30 May 2018
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Nqobile G. Ndlangamandla, Alex T. Kuvarega, Titus A.M. Msagati, Bhekie B. Mamba, Thabo T.I. Nkambule
      The presence of natural organic matter (NOM) in water can negatively affect water quality if NOM is present in excessive amounts during certain stages of water treatment. It is known that NOM constituents serve as precursors for DBPs (disinfection by-products) during the disinfection step of the water treatment process. Removal of natural organic matter (NOM) before disinfection is therefore essential to control DBP formation; however, owing to the heterogeneity and complexity of NOM, most water treatment processes are unable to attain complete removal of NOM from water sources. There is therefore a great need to develop methods that can effectively degrade NOM into smaller and relatively harmless compounds that are easily removed during water treatment processes. In this study, multi-walled carbon nanotubes/nitrogen, palladium co-doped titanium dioxide (MWCNT/N, Pd co-doped TiO2) (0.5–5% MWCNTs) were fabricated for the enhancement of NOM degradation under visible-light illumination. Different MWCNT/N, Pd co-doped TiO2 (also referred to as CT) nanocomposites were synthesised via a modified sol-gel method and characterised using ultraviolet visible (UV-Vis), X-ray diffraction spectroscopy (XRD), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), Fourier transform infrared (FTIR) Spectroscopy and energy-dispersive X-ray spectroscopy (EDS) analysis. The UV-Vis results showed that introducing the MWCNTs on the nanocomposites was accompanied by a red shift, with CT (0.5% MWCNTs) occurring at a longer wavelength than the others. The efficiency and effectiveness of the synthesised nanocomposites was quantified through measuring the NOM degradation rate in raw water samples collected from two South African water treatment plants. These two drinking water treatment plants were selected as the raw water treated in these plants contains different NOM fractions: the raw water treated at Midvaal (MV) Water Company contains transphilic NOM fractions, while that treated at Plettenberg Bay (P) Water Treatment Plant contains high amounts of hydrophobic NOM. The changes in the amount of NOM in a sample were monitored by measuring the UV absorbance at 254 nm (UVA254) as there is a strong correlation between absorbance at this wavelength and the aromatic content. The highest photocatalytic activity was observed with CT (0.5% MWCNTs) which attained 69.4% UVA254 reduction for MV and 97.7% UVA254 reduction for P raw waters. Compared to conventional methods applied by the two water treatment plants of interest, NOM removal efficiency (in terms of UVA254 reduction) by CT (0.5% MWCNTs) increased by up to 9.4% and 11.5% for MV and P water treatment plants, respectively. The enhanced photocatalytic activity of this CT nanocomposite (0.5% MWCNTs) is attributable to the large surface area of the synthesised nanocomposites which allows huge amounts of NOM to be adsorbed onto the surface of the TiO2, thereby increasing their photodegradation. It is also due to the synergistic effect of N and Pd which enhanced the photoactivity of the TiO2 in the MWCNT/N, Pd co-doped TiO2 composite. Overall, it is clear that the use of the conventional processes is not effective in removing NOM from water. Findings obtained show that CT (0.5% MWCNTs) nanocomposite is a promising future NOM removal method that could complement the available water treatment processes in enhancing the removal of the aromatic component of NOM in water.

      PubDate: 2018-05-31T10:32:02Z
       
  • Constraints to smallholder agricultural production in the Western Cape,
           South Africa
    • Authors: Bongani Ncube
      Abstract: Publication date: Available online 29 May 2018
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Bongani Ncube
      Improving agricultural production remains a major challenge for smallholder farmers in South Africa. The enactment of the 1998 Water Act and subsequent water allocation reforms were meant to correct equity challenges of the past in water allocation and increase agricultural productivity in the rural sector. More than 20 years after the initiation of the processes smallholder farmers remain poor with limited agricultural productivity. With the advent of more frequent droughts and the ever increasing climate change threat, the need to find lasting solutions for smallholder agriculture remains a priority for the government. So far the emphasis has been placed on water allocation, but could this be the only challenge to smallholder farmer livelihoods' South Africa is currently experiencing one of the worst droughts in history. Smallholder farmers who are already faced with water shortages have been the worst hit. The research sought to untangle some of the complexities of improving smallholder farmer livelihoods in the Breede-Gouritz Catchment Management Area (BGCMA) in the Western Cape, one of the first two catchment management areas to be created in South Africa. The main aim of the study was to assess constraints in addition to water, to the success of smallholder farmers in improving livelihoods. The specific objectives were to determine how institutional policies limited smallholder farmers from accessing resources in the Western Cape; to identify constraints affecting smallholder farmer performance and participation in agricultural activities. Interviews with farmers and key informants in government and other relevant institutions were conducted to determine how institutional arrangements have influenced and impacted the success of smallholder farmers. Results indicated uncoordinated institutional processes to support smallholder farmers resulting in limited participation by smallholder farmers in policy and strategy formulation. Farmer livelihoods were constrained by lack of information, limited access to water and lack of funding. The results and recommendations of the study were shared with the BGCMA and other relevant institutions with the aim of influencing future policy formulation for smallholder farmer livelihoods. The institutions decided to address the information gap through collaborative effort. The process has resulted in the creation of better relationships and trust between the smallholder farmers and the institutions.

      PubDate: 2018-05-31T10:32:02Z
       
  • Innovative solutions for intractable water problems in the face of climate
           change in southern and East African sub regions
    • Authors: Benjamin Mapani; Hodson Makurira Lapologang Magole Maideyi Meck Theresa Mkandawire
      Abstract: Publication date: Available online 24 May 2018
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Benjamin Mapani, Hodson Makurira, Lapologang Magole, Maideyi Meck, Theresa Mkandawire, Marloes Mul, Cosmo Ngongondo


      PubDate: 2018-05-28T10:31:08Z
       
  • Estimating spatial catchment natural hydrological response characteristics
           in Swaziland
    • Authors: Coli Ndzabandzaba; Denis A. Hughes
      Abstract: Publication date: Available online 19 May 2018
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Coli Ndzabandzaba, Denis A. Hughes
      The aim of hydrological research has always been, and should still be to improve our understanding of hydrologic processes. Catchment hydrological response has the potential to enhance understanding of these processes. Regionalisation of hydrological response is important in identifying watersheds with similar catchment hydrological response, thus making predictions in ungauged and poorly gauged basins to be possible. This study establishes the hydrological response of 122 catchments in Swaziland's trans-boundary basins on the basis of validated WR90 hydro-meteorological time series data. The flow duration indices (FDIs: Q10, Q50, Q90) were determined and standardised by the mean monthly streamflow, and the runoff ratio was calculated as a method to determine how catchments respond to precipitation inputs. The runoff ratio and FDIs were then plotted against aridity indices, and the plot shows that the runoff ratio is consistent with the aridity index, except for a few suspected anomalies emanating from values of Q50 and Q90. The findings indicate that the hydrological response of the catchments is diverse and somewhat characterised by regions. The diversity and the regions are associated with climate regime and topography controls. It is anticipated that the potential of using hydrological response to gain more understanding of catchments behaviour will improve and further rigorous exploration may be required.

      PubDate: 2018-05-28T10:31:08Z
      DOI: 10.1016/j.pce.2018.05.007
       
  • Assessment of empirical and regression methods for infilling missing
           streamflow data in Little Ruaha catchment Tanzania
    • Authors: Stanislaus Kamwaga; Deogratias M.M. Mulungu; Patrick Valimba
      Abstract: Publication date: Available online 14 May 2018
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Stanislaus Kamwaga, Deogratias M.M. Mulungu, Patrick Valimba
      Water resources and engineering projects are of major importance due to great demand of water and power supplies, irrigation needs, drought mitigation and flood control. In order to plan and design these projects, complete and reliable hydrological datasets are required. Missing data can severely compromise data quality and utility. The Rufiji Water Basin Office has developed and kept a database of daily streamflow records from 1950s to-date for at least 87 gauging stations. While the majority of the records are complete, data checks revealed significant gaps. Some stations are experiencing large gaps of up to 19 consecutive years. There is no dedicated study that looked at assessment of suitable methods for infilling such gaps. This study therefore made a contribution by appraising empirical and regression rainfall runoff based methods in the Little Ruaha River catchment, a sub-catchment of the Great Ruaha River sub-basin both within the Rufiji River Basin. The methods employed included simple linear regression (with untransformed and log-transformed data), multiple linear regression (with untransformed and log-transformed data), rainfall-runoff relationship using double mass curve technique, flow duration matching and drainage-area ratio. In addition, rainfall runoff modeling using HBV-Light was done for further comparison. With exception to the rainfall-runoff relationship and HBV-Light model, all other methods relied upon data transfer from donor stations (upstream & downstream station(s)) for infilling a downstream/upstream station. Data quality and consistency checks were performed, and performances of infilling methods were evaluated based on three performance criteria namely Nash-Sutcliffe efficiency coefficient (NSE), Coefficient of determination (R2) and standard error of estimate (SE) during calibration and validation periods. Four gauging stations (2 each upstream and downstream) were separately used to infill artificially created gaps to the target station. Overall, the calibration and validation daily results at 1KA21A indicated that the flow duration matching technique and multiple linear regression methods performed better than other methods with NSE (71%; 93%) and NSE (55%; 75%) respectively. These results have a potential for wide application in other basins of Tanzania for hydrological analysis and water resource management, where missing data is very common.

      PubDate: 2018-05-28T10:31:08Z
      DOI: 10.1016/j.pce.2018.05.008
       
  • Impacts of hydropower dam operations in the Mana Pools National Park
           floodplains
    • Authors: M.N. Ekandjo; H. Makurira; E. Mwelwa; W. Gumindoga
      Abstract: Publication date: Available online 12 May 2018
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): M.N. Ekandjo, H. Makurira, E. Mwelwa, W. Gumindoga
      The Mana Pools flood plain along the Middle Zambezi River and part of the popular Mana Pools National Park of Zimbabwe has been experiencing both ecological and morphological changes since the construction of upstream hydropower reservoirs. This study investigated the hydro-dynamics from natural and human influenced flows, particularly at the Mana Pools floodplains which are downstream of Kariba and Kafue hydropower dams. Descriptive statistics were used to analyse the differences in flow regime upstream and downstream of the hydropower reservoirs. A standard t-test was done to compare the natural and modified mean annual flows. Results show that the presence of upstream reservoirs has reduced the high peak average monthly flows by 17% and increased the average monthly low flows by 5% at Mana Pools. However, the mean annual runoff has not significantly changed. Results also established that. In line with recent calls for ecological considerations in reservoir management, the study recommends that the reservoir operation in the Middle Zambezi River should mimic the pre-impoundment Middle Zambezi River flow regime at Mana Pools.

      PubDate: 2018-05-28T10:31:08Z
      DOI: 10.1016/j.pce.2018.05.009
       
  • Microwave assisted graft synthesis and characterization of
           poly(methacrylic acid)-grafted polyethersulfone for preparation
           hydrophilic and low-fouling membranes for water treatment
    • Authors: Lwazi Ndlwana; Keneiloe Sikhwivhilu; Richard Moutloali; Jane Catherine Ngila
      Abstract: Publication date: Available online 11 May 2018
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Lwazi Ndlwana, Keneiloe Sikhwivhilu, Richard Moutloali, Jane Catherine Ngila
      Herein, we report on powder composites of polymethacrylic acid (PMAA)-grafted polyethersulfone (PES) prepared via microwave (MW) assisted synthesis. The grafting was confirmed by Fourier transform infra-red spectroscopy (FTIR) after which ultrafiltration membranes were prepared from the powder composites by phase inversion. The effect of PMAA grafting on the morphology of the membranes was investigated by atomic force microscopy (AFM) and scanning electron microscopy (SEM); which showed enhanced surface roughness with increased degree of grafting. Contact angle measurements showed improved hydrophilicity. Water permeation, protein rejection, porosity and fouling studies were also carried out and these parameters presented significant enhancements with increased degree of grafting. The rapidity of the MW-assisted grafting method means more related composites can now be prepared and most conveniently over others. Potential use of these low fouling membranes exists in water treatment and protein separation.

      PubDate: 2018-05-28T10:31:08Z
      DOI: 10.1016/j.pce.2018.05.002
       
  • Hydrogeological conceptual model of large and complex sedimentary aquifer
           systems – Central Kalahari Basin (Botswana)
    • Authors: Moiteela Lekula; Maciek W. Lubczynski; Elisha M. Shemang
      Abstract: Publication date: Available online 9 May 2018
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Moiteela Lekula, Maciek W. Lubczynski, Elisha M. Shemang
      Successful groundwater resources evaluation and management is nowadays typically undertaken using distributed numerical groundwater flow models. Such models largely rely on hydrogeological conceptual models. The conceptual models summarize hydrogeological knowledge of an area to be modelled and thereby providing a framework for numerical model design. In this study, an efficient data integration method for developing hydrogeological conceptual model of the large and hydrogeologically-complex, Central Kalahari Basin (CKB) aquifer system, was undertaken. In that process, suitability of 3-D geological modelling with RockWorks code in iterative combination with standard GIS (ArcGIS) was tested. As a result, six hydrostratigraphic units were identified, their heads and related flow system interdependencies evaluated and hydraulic properties attached. A characteristic feature of the CKB is a thick unsaturated Kalahari Sand Unit (KSU), that restricts the erratic recharge input to <1 mm yr−1 in the centre to about 5–10 mm yr−1 in the eastern fringe. The analysis of the spatial distribution of topological surfaces of the hydrostratigraphic units and hydraulic heads of the aquifers, allowed to identify three flow systems of the three aquifers, Lebung, Ecca and Ghanzi, all three having similar radially-concentric regional groundwater flow patterns directed towards discharge area of Makgadikgadi Pans. That pattern similarity is likely due to various hydraulic interconnections, direct or through aquitard leakages, and also due to the presence of the overlying unconfined, surficial KSU, hydraulically connected with all the three aquifers, redistributing recharge into them. As a result of conceptual modelling, fully 3-D, 6-layer numerical model, with shallow, variably-saturated saturated, unconfined layer is finally recommended as transition from conceptual into numerical model of the CKB. The proposed 3-D geological modelling with RockWorks, turned to be vital and efficient in developing hydrogeological conceptual model of a large and complex multi-layered aquifer systems. Its strength is in simplicity of operation, in conjunctive, iterative use with other software such as standard GIS and in flexibility to interface with numerical groundwater model.

      PubDate: 2018-05-28T10:31:08Z
      DOI: 10.1016/j.pce.2018.05.006
       
  • Investigation of nutrients and faecal coliforms removal in wastewater
           using a hydroponic system
    • Authors: S.F. Ndulini; G.M. Sithole; M.S. Mthembu
      Abstract: Publication date: Available online 9 May 2018
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): S.F. Ndulini, G.M. Sithole, M.S. Mthembu
      Fresh water resources are diminishing rapidly through increased inadequately treated or untreated wastewater disposal in water bodies. Disposal of untreated wastewater in freshwater bodies threatens the environment, aquatic and human life. The primary objective of this study was to investigate the removal of contaminants using a simple cost effective hydroponic system in the treatment of raw wastewater to allowable discharge limits. After macrophytes were planted and water circulated in the hydroponic system the influent and effluent samples were collected at various time intervals between 24 and 244 h for the period of 3 months at varying concentrations. Ammonia, nitrite, nitrate and total phosphorus were measured using spectrophotometric methods and membrane filtration technique was used for faecal coliform counts. The removal of ammonia, nitrite, nitrate, total phosphorus and faecal coliforms reached 87%, 96%, 99%, 87% and 92% respectively. The paired t-test indicated the removal of these contaminants to be statistically significant (0.019 ≥ p ≥ 0.001). Irrespective of the change in wastewater composition the system efficiently treated water to allowable discharge limits. The system proved to be a cheaper method of wastewater treatment and its applications may offer an alternative to the problems of wastewater treatment in areas where modern systems are either unavailable or cost ineffective.

      PubDate: 2018-05-28T10:31:08Z
      DOI: 10.1016/j.pce.2018.05.004
       
  • Implementation of Community Based Management (CBM) in Zimbabwe: The
           dichotomy of theory and practice and its influence on sustainability of
           rural water supply systems
    • Authors: T. Kativhu; D. Mazvimavi; D. Tevera; I. Nhapi
      Abstract: Publication date: Available online 8 May 2018
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): T. Kativhu, D. Mazvimavi, D. Tevera, I. Nhapi
      In the quest to address sustainability challenges in the rural water sector the Community Based Management (CBM) approach was adopted by many developing countries including Zimbabwe as the model for managing rural water facilities. CBM having principles embedded on equity, empowerment and effectiveness was expected to promote sustainability, however field evidence has shown that the variance between theory and practice in its implementation has contributed to its failure to deliver expected results. This study was done to investigate how CBM is being implemented in Zimbabwe. The specific objectives were to analyze how practices of different stakeholders in the rural water sector differ from their roles as stipulated in the CBM framework and to analyze how discrepancies between theory and practice in CBM implementation are influencing sustainability of water supply systems. The study also sought to investigate how trainings which are stipulated in the CBM framework are being done. Data was collected using Focus Group Discussions (FGDs), Key Informant Interviews (KIIs) and a Water Point Committee questionnaire. Pearson Chi square test was used to analyze quantitative data while the thematic approach was used to analyze qualitative data. Results showed that most WPCs were not performing their roles as outlined in the CBM framework. Since most rural water projects were funded by Non Governmental Organizations (NGOs) their strategies and objectives were taking precedence over CBM guidelines which negatively impacted on technical, social and institutional factors of sustainability. The project nature of NGO programmes which are budget and time bound also resulted in CBM principles not being applied as outlined. Rural District Councils (RDCs) were depending on NGOs to fund water supply activities. WPCs were diverging from their stipulated roles due to incapacitation in technical and managerial skills which negatively impacted on financial and technical sustainability factors. Chi square test results show that there is a significant association between capacity building and sustainability ((χ2 = 3.20, df = 2, p < 0.02). It can be concluded that the discrepancies in the CBM theory and practice in the Zimbabwe's rural water sector is negatively influencing sustainability of water supply facilities.

      PubDate: 2018-05-28T10:31:08Z
      DOI: 10.1016/j.pce.2018.05.003
       
  • Assessment of seawater intrusion in an arid coastal aquifer, south-eastern
           Tunisia, using multivariate statistical analysis and chloride mass balance
           
    • Authors: Faten Telahigue; Belgacem Agoubi; Faiza Souid; Adel Kharroubi
      Abstract: Publication date: Available online 8 May 2018
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Faten Telahigue, Belgacem Agoubi, Faiza Souid, Adel Kharroubi
      Water availability is a fundamental concern for coastal areas in arid and semiarid regions such as Jerba Island, southeastern Tunisia. In these areas, the water demand is steadily increasing and putting pressure on water resources. These pressures are maintained by excessive pumping to meet the needs of various agricultural, domestic, industrial and tourism sectors. The effects on the groundwater are expressed by a quantitative and qualitative deterioration of the regional ecosystem. An assessment of groundwater salinization and seawater intrusion in Jerba aquifer are therefore needed. Physical parameters were measured in situ in one hundred and three boreholes and major ions were analyzed and several diagram were used to model groundwater mineralization. Geochemical analysis revealed that Cl-Na-Mg-Ca-SO4 was the dominant water type indicating rock-water interaction and saltwater intrusion. Na+/Cl−, Ca2+/Cl−, Br−/Cl−, Ca2+/Na+, Mg2+/Ca2+ and Cl−/HCO3 − ratios versus chloride confirms the double influence of mixing mechanisms of fresh and saline waters and the water-rock interactions. Computed seawater fraction for sampled water shows that the average mixing rate of seawater intrusion reached 10.5%, confirming the marine intrusion in the aquifer. The highest values were registered in coastal wells. The statistical analyses reveal that high groundwater mineralization is due to rock-water interaction associated with mixture of groundwater and seawater in many areas.

      PubDate: 2018-05-28T10:31:08Z
      DOI: 10.1016/j.pce.2018.05.001
       
  • Surface water bodies mapping in Zimbabwe using landsat 8 OLI multispectral
           imagery: A comparison of multiple water indices
    • Authors: Mhosisi Masocha; Timothy Dube; Mellisa Makore; Munyaradzi D. Shekede; Jacob Funani
      Abstract: Publication date: Available online 8 May 2018
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Mhosisi Masocha, Timothy Dube, Mellisa Makore, Munyaradzi D. Shekede, Jacob Funani
      Water is integral for the survival of humans, animals, as well as vegetation and information on its spatial distribution is important for water resources management. Various methods have been applied to detect and map land surface water, especially due to the availability of a large range of satellite sensors. The main methods involved are either general feature classification techniques or thematic water body information extraction. Thematic water body extraction methods make use of band information and in this study; spectral indices are used to delineate land surface water for Zimbabwe using Landsat 8 OLI images. Multiple algorithms i.e. spectral indices were used to extract surface water bodies from Landsat 8 imagery. Then overall accuracies and Kappa coefficients and average reliability were then applied to assess the performance of the seven applied models. The results have shown that the LSWI plus VI can map surface water bodies with an overall accuracy of 86%, kappa statistic of 0.70 and a reliability accuracy of 89%. Comparatively, the index produced good results followed by the mNDWI which had an overall classification accuracy of 84% and an average reliability of 87%. Following on the list in terms of performance was the AWEIsh, mMDWI plus VI, NDWI and NDWI plus VI. However, other indices had slightly lower results comparatively. The study noted that LSWI plus VI applied on Landsat 8 OLI data can reliably delineate land surface water in a subtropical environment.

      PubDate: 2018-05-28T10:31:08Z
      DOI: 10.1016/j.pce.2018.05.005
       
  • Access to water and sanitation facilities in primary schools: A neglected
           educational crisis in Ngamiland sub-district in Botswana
    • Authors: B.N. Ngwenya; O.T. Thakadu; N.A. Phaladze; B. Bolaane
      Abstract: Publication date: Available online 5 April 2018
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): B.N. Ngwenya, O.T. Thakadu, N.A. Phaladze, B. Bolaane
      In developing countries, the sanitation and hygiene provision often receives limited resources compared to the water supply. However, water supply benefits tend to diminish if improved sanitation and hygiene are neglected. This paper presents findings of a situational analysis of water supply, sanitation and hygiene infrastructure and their utilization in three primary schools in north-western Botswana. The overall objective of the paper is to determine access and functionality of water supply, sanitation and hygiene infrastructure in three primary schools. The specific objectives are: a) Learners' perspective of their water and sanitation facilities and b) gendered utilization of sanitation and hygiene facilities. Data were collected through a face-to-face administered social survey tool to 286 learners selected through proportionate stratified random sampling from three purposively selected villages in the middle and lower Okavango Delta. Findings indicate that standpipes provide 96% of potable water supply. However, the majority (65% of leaners) indicated that they ‘sometimes’ experienced water shortage due to dry/nonfunctioning taps/pumps and leaks/wastage. Overall, schools have relatively sufficient sanitation facilities consisting of both water borne toilets and VIP latrines. The major sanitation gap identified was that 80% flush toilets hardly work, while 77% of VIP toilets were in disrepair. Furthermore, poor water supply compromised hand washing with 65.7% learners “always” washing their hands if school standpipes had water, while the majority did not wash hands if standpipes were dry. The study concluded that availability of sanitation infrastructure does not necessarily translate into utilization in the study area due to multiple problems, such as lack of personal hygiene supplies (regular toilet paper and hand washing detergents), privacy issues and recurring water problems. The chronicity of inadequate water, sanitation and hygiene infrastructure in primary schools is critical and there is urgent need to address these challenges in order to create a conducive learning environment in primary schools in the district.

      PubDate: 2018-04-15T17:55:03Z
      DOI: 10.1016/j.pce.2018.03.006
       
  • A review of formal institutions affecting water supply and access in
           Botswana
    • Authors: Patricia K. Mogomotsi; Goemeone E.J. Mogomotsi; Dimpho M. Matlhola
      Abstract: Publication date: Available online 28 March 2018
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Patricia K. Mogomotsi, Goemeone E.J. Mogomotsi, Dimpho M. Matlhola
      Over the years, many countries across the world have increasingly experienced the collapse of their ecosystems, leading to an elevated increase on the demand for freshwater resources. Botswana is not an exception. The problem of disrupted potable water supply is widespread across the country. However, the physical shortage of water in the country is arguably coupled by lack of effective and efficient water supply and management institutions and water infrastructure. Most of the research on water scarcity in Botswana is mostly inclined towards physical water scarcity, while little is investigated on how the design of institutions for water management in developing countries leads to water scarcity. Furthermore, the premises of most research is neoclassical economics ideas, thereby offering solutions as developing and/or reforming water markets and water pricing mechanisms, among other findings. This paper analyses potable water supply and access in Botswana within a new institutional economics paradigm. The study examines key features of water institutions in Botswana on how they affect water supply and access, applying new institutional economics fundamentals. The study extensively uses various secondary data sources including weather and climate reports, policy documents, maps and charts and survey data, among others. The paper argues that to achieve effective water allocation in Botswana, there is a need to balance social and environmental water resource needs through water policies and other statutory enactments, as well as the crafting of practical management strategies. The country, therefore, requires not only a swift institutional transformation in the water sector, but also needs practical governance structure necessary for implementing integrated water resources management and driving water resources towards sustainability.

      PubDate: 2018-04-15T17:55:03Z
      DOI: 10.1016/j.pce.2018.03.010
       
  • Signature of present and projected climate change at an urban scale: The
           case of Addis Ababa
    • Authors: Bisrat Kifle Arsiso; Gizaw Mengistu Tsidu; Gerrit Hendrik Stoffberg
      Abstract: Publication date: Available online 27 March 2018
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Bisrat Kifle Arsiso, Gizaw Mengistu Tsidu, Gerrit Hendrik Stoffberg
      Understanding climate change and variability at an urban scale is essential for water resource management, land use planning, development of adaption plans, mitigation of air and water pollution. However, there are serious challenges to meet these goals due to unavailability of observed and/or simulated high resolution spatial and temporal climate data. The statistical downscaling of general circulation climate model, for instance, is usually driven by sparse observational data hindering the use of downscaled data to investigate urban scale climate variability and change in the past. Recently, these challenges are partly resolved by concerted international effort to produce global and high spatial resolution climate data. In this study, the 1 km2 high resolution NIMR-HadGEM2-AO simulations for future projections under Representative Concentration Pathways (RCP4.5 and RCP8.5) scenarios and gridded observations provided by Worldclim data center are used to assess changes in rainfall, minimum and maximum temperature expected under the two scenarios over Addis Ababa city. The gridded 1 km2 observational data set for the base period (1950–2000) is compared to observation from a meteorological station in the city in order to assess its quality for use as a reference (baseline) data. The comparison revealed that the data set has a very good quality. The rainfall anomalies under RCPs scenarios are wet in the 2030s (2020–2039), 2050s (2040–2069) and 2080s (2070–2099). Both minimum and maximum temperature anomalies under RCPs are successively getting warmer during these periods. Thus, the projected changes under RCPs scenarios show a general increase in rainfall and temperatures with strong variabilities in rainfall during rainy season implying level of difficulty in water resource use and management as well as land use planning and management.

      PubDate: 2018-04-15T17:55:03Z
      DOI: 10.1016/j.pce.2018.03.008
       
  • Effects of land use and land cover changes on water quality in the uMngeni
           river catchment, South Africa
    • Authors: Jean Nepomuscene Namugize; Graham Jewitt; Mark Graham
      Abstract: Publication date: Available online 27 March 2018
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Jean Nepomuscene Namugize, Graham Jewitt, Mark Graham
      Land use and land cover change are major drivers of water quality deterioration in watercourses and impoundments. However, understanding of the spatial and temporal variability of land use change characteristics and their link to water quality parameters in catchments is limited. As a contribution to address this limitation, the objective of this study is to assess the linkages between biophysico-chemical water quality parameters and land use and land cover (LULC) classes in the upper reaches of the uMngeni Catchment, a rapidly developing catchment in South Africa. These were assessed using Geographic Information Systems tools and statistical analyses for the years 1994, 2000, 2008 and 2011 based on changes over time of eight LULC classes and available water quality information. Natural vegetation, forest plantations and cultivated areas occupy 85% of the catchment. Cultivated, urban/built-up and degraded areas increased by 6%, 4.5% and 3%, respectively coinciding with a decrease in natural vegetation by 17%. Variability in the concentration of water quality parameters from 1994 to 2011 and an overall decline in water quality were observed. Escherichia coli (E. coli) levels exceeding the recommended guidelines for recreation and public health protection was noted as a major issue at seven of the nine sampling points. Overall, water supply reservoirs in the catchment retained over 20% of nutrients and over 85% of E. coli entering them. A relationship between land use types and water quality variables was found. However, the degree and magnitude of the associations varies between sub-catchments and is difficult to quantify. This highlights the complexity and the site-specific nature of relationships between land use types and water quality parameters in the catchment. Thus, this study provides useful findings on the general relationship between land use and land cover and water quality degradation, but highlights the risks of applying simple relationships or adding complex relationships in the management of the catchment.

      PubDate: 2018-04-15T17:55:03Z
      DOI: 10.1016/j.pce.2018.03.013
       
  • Effects of climate change on evapotranspiration over the Okavango Delta
           water resources
    • Authors: Oliver Moses; Wame L. Hambira
      Abstract: Publication date: Available online 27 March 2018
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Oliver Moses, Wame L. Hambira
      In semi-arid developing countries, most poor people depend on contaminated surface or groundwater resources since they do not have access to safe and centrally supplied water. These water resources are threatened by several factors that include high evapotranspiration rates. In the Okavango Delta region in the north-western Botswana, communities facing insufficient centrally supplied water rely mainly on the surface water resources of the Delta. The Delta loses about 98% of its water through evapotranspiration. However, the 2% remaining water rescues the communities facing insufficient water from the main stream water supply. To understand the effects of climate change on evapotranspiration over the Okavango Delta water resources, this study analysed trends in the main climatic parameters needed as input variables in evapotranspiration models. The Mann Kendall test was used in the analysis. Trend analysis is crucial since it reveals the direction of trends in the climatic parameters, which is helpful in determining the effects of climate change on evapotranspiration. The main climatic parameters required as input variables in evapotranspiration models that were of interest in this study were wind speeds, solar radiation and relative humidity. Very little research has been conducted on these climatic parameters in the Okavango Delta region. The conducted trend analysis was more on wind speeds, which had relatively longer data records than the other two climatic parameters of interest. Generally, statistically significant increasing trends have been found, which suggests that climate change is likely to further increase evapotranspiration over the Okavango Delta water resources.

      PubDate: 2018-04-15T17:55:03Z
      DOI: 10.1016/j.pce.2018.03.011
       
  • Estimating soil organic and aboveground woody carbon stock in a protected
           dry Miombo ecosystem, Zimbabwe: Landsat 8 OLI data applications
    • Authors: Timothy Dube; Richard Muchena; Mhosisi Masocha; Cletah Shoko
      Abstract: Publication date: Available online 26 March 2018
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Timothy Dube, Richard Muchena, Mhosisi Masocha, Cletah Shoko
      Accurate and reliable soil organic carbon stock estimation is critical in understanding forest role to regional carbon cycles. So far, the total carbon pool in dry Miombo ecosystems is often under-estimated. In that regard this study sought to model the relationship between the aboveground woody carbon pool and the soil carbon pool, using both ground-based and remote sensing methods. To achieve this objective, the Ratio Vegetation Index (RVI), Normalized Difference Vegetation Index (NDVI), and the Soil Adjusted Vegetation Index (SAVI) computed from the newly launched Landsat 8 OLI satellite data were used. Correlation and regression analysis were used to relate Soil Organic Carbon (S.O.C), aboveground woody carbon and remotely sensed vegetation indices. Results showed a soil organic carbon in the upper soil layer (0–15 cm) was positively correlated with aboveground woody carbon and this relationship was significant (r = 0.678; P < 0.05) aboveground carbon. However, there were no significant correlations (r = −0.11, P > 0.05) between SOC in the deeper soil layer (15–30 cm) and aboveground woody carbon. These findings imply that (relationship between aboveground woody carbon and S.O.C) aboveground woody carbon stocks can be used as a proxy to estimate S.O.C in the top soil layer (0–15 cm) in dry Miombo ecosystems. Overall, these findings underscore the potential and significance of remote sensing data in understanding savanna ecosystems contribution to the global carbon cycle.

      PubDate: 2018-04-15T17:55:03Z
      DOI: 10.1016/j.pce.2018.03.007
       
  • Modelling nitrogen transformation and removal in mara river basin wetlands
           upstream of lake Victoria
    • Authors: Aloyce W. Mayo; Marwa Muraza; Joel Norbert
      Abstract: Publication date: Available online 26 March 2018
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Aloyce W. Mayo, Marwa Muraza, Joel Norbert
      Lake Victoria, the largest lake in Africa, is a resource of social-economic potential in East Africa. This lake receives water from numerous tributaries including Mara River, which contributes about 4.8% of the total Lake water inflow. Unfortunately, Mara River basin faces environmental problems because of intensive settlement, agriculture, overgrazing in the basin and mining activities, which has lead to water pollution in the river, soil erosion and degradation, decreased soil fertility, loss of vegetation cover, decreased water infiltration capacity and increased sedimentation. One of the pollutants carried by the river includes nitrogen, which has contributed to ecological degradation of the Lake Victoria. Therefore this research work was intended to determine the effectiveness of Mara River wetland for removal of nitrogen and to establish nitrogen removal mechanisms in the wetland. To predict nitrogen removal in the wetland, the dynamics of nitrogen transformation was studied using a conceptual numerical model that takes into account of various processes in the system using STELLA II version 9.0®2006 software. Samples of model input from water, plants and sediments were taken for 45 days and were analyzed for pH, temperature, and DO in situ and chemical parameters such as NH3-N, Org-N, NO2-N, and NO3-N were analyzed in the laboratory in accordance with Standard methods. For plants, the density, dominance, biomass productivity and TN were determined and for sediments TN was analyzed. Inflow into the wetland was determined using stage-discharge relationship and was found to be 734,400 m3/day and the average wetland volume was 1,113,500 m3. Data collected by this study were used for model calibration of nitrogen transformation in this wetland while data from another wetland were used for model validation. It was found that about 37.8% of total nitrogen was removed by the wetland system largely through sedimentation (26.6%), plant uptake (6.6%) and denitrification (4.6%).

      PubDate: 2018-04-15T17:55:03Z
      DOI: 10.1016/j.pce.2018.03.005
       
  • Residual antibiotics, antibiotic resistant superbugs and antibiotic
           resistance genes in surface water catchments: Public health impact
    • Authors: Adegoke Anthony A; Faleye Adekunle C; Stenstrӧm Thor A
      Abstract: Publication date: Available online 26 March 2018
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Adegoke Anthony A, Faleye Adekunle C, Stenstrӧm Thor A
      Antibiotics are released to the surface water through different routes, like for example the wastewater treatment plants, from human and animal metabolic waste, agriculture run off, industrial antibiotic waste. The release of the antibiotics to the water catchment and/or the environments in sub-lethal concentrations for the microorganisms lead to the emergence of antibiotic resistance (AR) and selection for antibiotic resistance genes (ARGs). The bacteria utilize their quorum sensing to form biofilm within which ARGs are transferred from antibiotic resistant bacteria (ARB) to the susceptible strains, conferring resistance on them. This has contributed substantially to the growing trend of resistance from multiple antibiotic resistance to extended spectrum resistance, extreme resistance and recently to total antibiotic resistance. The antibiotics, ARB, ARGs are sometimes internalized into the crops irrigated with the surface water returning the bacteria to human in a difficult to control form. While quorum quenching strategy is being advocated during treatment of wastewater to disrupt biofilm as well as the spread of resistance, intermittent check for effectiveness of treatment of wastewater before release into receiving water bodies is hereby advocated. To achieve this, there is the need for better measurements, surveillance and follow-up and thereby the further needs to incorporate more integrative (multidisciplinary) approaches and state of the art tools, for appropriate detection and action. This presentation is to critically review the effect of antibiotic release, ARGs, ARB in water catchment on other water related applications in Southern African countries in relation to other part of the world.

      PubDate: 2018-04-15T17:55:03Z
      DOI: 10.1016/j.pce.2018.03.004
       
  • Analysis of potential future droughts limiting maize production, in the
           Luvuvhu River catchment area, South Africa
    • Authors: Teboho Elisa Masupha; Mokhele Edmond Moeletsi
      Abstract: Publication date: Available online 26 March 2018
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Teboho Elisa Masupha, Mokhele Edmond Moeletsi
      Recurring droughts associated with global warming have raised major concern for the agricultural sector, particularly vulnerable small-scale farmers who rely on rain-fed farming such as in the Luvuvhu River catchment. The Standardized Precipitation Evapotranspiration Index (SPEI) and Water Requirement Satisfaction Index (WRSI) were calculated to assess drought on a 120-day maturing maize crop based on outputs of the CSIRO-Mk3.6.0 under RCP 4.5 emission scenario, for the period 1980/81–2089/90. Results by SPEI show that 40–54% of the agricultural seasons during the base period experienced mild drought conditions (SPEI 0 to −0.99), equivalent to a recurrence of once in two seasons. However, WRSI results clearly indicated that stations in the drier regions (annual rainfall <600 mm) of the catchment experienced mild drought (WRSI 70 - 79) corresponding to satisfactory crop performance every season. Results further showed overall mild to moderate droughts in the beginning of the near-future climate period (2020/21–2036/37) with SPEI values not decreasing below −1.5. These conditions are then expected to change during the far-future climate period (2055/56–2089/90), whereby results on the expected crop performance predicted significantly drier conditions (p < 0.05). This study provided information on how farmers in the area can prepare for future agricultural seasons, while there is sufficient time to implement strategies to reduce drought risk potential. Thus, integrated interventions could provide best options for improving livelihoods and building the capability of farmers to manage climate change-related stresses.

      PubDate: 2018-04-15T17:55:03Z
      DOI: 10.1016/j.pce.2018.03.009
       
  • An assessment of groundwater potential and vulnerability in the Upper
           Manyame Sub-Catchment of Zimbabwe
    • Authors: Alfred Misi; Webster Gumindoga; Zvikomborero Hoko
      Abstract: Publication date: Available online 26 March 2018
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Alfred Misi, Webster Gumindoga, Zvikomborero Hoko
      Severe depletion and pollution of groundwater resources are of rising concern in the Upper Manyame Sub-Catchment (UMSC); Zimbabwe's most urbanised sub-catchment. Despite groundwater playing a pivotal role in the provision of potable water in the sub-catchment, it is under serious threat from anthropogenic stressors which include sewage effluents and leachates from landfills, among others. Inadequate scientific knowledge pertaining to the spatio-temporal variability of groundwater storage and vulnerability in the UMSC is further compromising its sustainability. Therefore, comprehensive assessments of UMSC's Groundwater Potential (GP) and vulnerability are crucial for its effective management. This study assessed GP and vulnerability in the UMSC using Geographic Information Systems and Remote Sensing techniques. Groundwater conditioning factors: geology, slope, land-use, drainage density, topographic index, altitude, recharge and rainfall were used to develop GP zones. Validation of the GP map was done by correlating estimated GP with historical borehole yields. An assessment of groundwater vulnerability was done at micro-catchment level (Marimba) using the GOD model; a three parameter Index Overlay Model. Marimba is the most urbanised and has the second highest borehole density. It also exhibits similar landuse characteristics as the UMSC. Furthermore, groundwater quality in Marimba was assessed from 15 sampling sites. Fifteen drinking water parameters were analysed based on the standard methods for Water and Wastewater Examination. The potability of groundwater was then assessed by comparing the measured water quality parameters with the Standards Association of Zimbabwe (SAZ) drinking water standards and/or WHO guidelines for drinking water. Repeated Measures ANOVA and Principal Component Analysis (PCA) were used to assess the spatio-temporal variations in groundwater quality and to identify key parameters, respectively. About 72% (2725.9 km2) of the UMSC was found to be of moderate GP, while 19% and 9% accounted for high and low GP, respectively. Marimba vulnerability status was dominantly moderate (77.3%). Parameters: EC, pH, coliforms, TDS, total hardness, Fe, NH4 + and turbidity exceeded SAZ and/or WHO drinking water limits on most sampling sites with DO, total and faecal coliforms showing significant variations (p < 0.05). Four Principal Components representing 84% of the cumulative variance were extracted; with PC1, PC2, PC3 and PC4 contributing 38%, 19.1%, 14.3% and 12.85%, respectively. PC1 was characterized by pH, TDS, EC and total hardness. PC2's variance was associated with elevated levels of Cl−, Zn and Cu. PC3 had high loadings of total and faecal coliforms, Fl− and turbidity while PC4 was characterized by high loadings of Pb, Fe, ammonia and turbidity. The variation in the nature of the parameters across PCs explains the complexity of pollutants within the micro-catchment. PC2 and PC4 were largely characterized by metallic compounds, suggesting pollution from mineral dissolution into the aquifers e.g. from industrial areas and dumpsites. PC3 indicate the contribution of domestic waste e.g. faecal waste from waste pipe leakages and poorly constructed pit latrines. The findings of this study are useful decision-making tools on groundwater utilisation and groundwater protection.

      PubDate: 2018-04-15T17:55:03Z
      DOI: 10.1016/j.pce.2018.03.003
       
  • Synthesized af-PFCl and GG-g-P(AN)/TEOS hydrogel composite used in
           hybridized technique applied for AMD treatment
    • Authors: Elvis Fosso-Kankeu
      Abstract: Publication date: Available online 6 March 2018
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Elvis Fosso-Kankeu
      In the present study af-PFCl, GL-g-P(AN) hydrogel and GL-g-P(AN)/TEOS hydrogel composite were synthesized. The hydrogels were characterized using the fourier transformed infra-red (FTIR) and the scanning electron microscope (SEM) techniques. The coagulant af-PFCl and the hydrogels were applied consecutively in flocculation and adsorption processes respectively for the treatment of acid mine drainage (AMD). It was observed that the grafting process increased the amount of binding groups on the hydrogels. The hybridization of the techniques assisted in the removal of anions; while the cations were mostly removed by the adsorption process. The adsorbents behaviour was fittingly expressed by the pseudo-second order model. The adsorption capacities of GL-g-P(AN)/TEOS hydrogel composite for the removal of Al, As and Zn were 3.89, 0.66 and 0.394 respectively; while the adsorption capacities of GL-g-P(AN) for the removal of Al and Mg were 3.47 and 9.66 mg/g respectively. The techniques applied in this study have shown good potential for the removal of specific pollutants from the AMD; it is however, important that the appropriate hybridization of techniques allows to remove all the pollutants and restore acceptable water quality.

      PubDate: 2018-04-15T17:55:03Z
      DOI: 10.1016/j.pce.2018.02.015
       
  • Investigating waste rock, tailings, slag and coal ash clinker as
           adsorbents for heavy metals: Batch and column studies
    • Authors: D. Letina; W.M. Letshwenyo
      Abstract: Publication date: Available online 5 March 2018
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): D. Letina, W.M. Letshwenyo
      Wastewater from the mining industry is a concern because most of the time it contains heavy metals with concentrations above permissible levels, posing a threat to terrestrial and aquatic life. The study was conducted to evaluate the effectiveness of locally available waste materials (waste rock, tailings, coal ash clinker, and slag) generated by BCL (Ltd) mine, a copper and nickel mining and smelting company in Botswana, for removal of nickel and copper from the real mining wastewater. Batch adsorption studies were conducted to establish the adsorptive efficiency and kinetics of each media with respect to nickel and copper ions. The best media was further evaluated through fixed bed column studies at 24 and 48 h empty bed contact time. The results indicate that the percentage removal for coal ash clinker, waste rock, smelter slag and tailings was 98%, 15%, 3% and −3% with respect to copper ions, and 46%, 9%, 7% and 2% with respect to nickel ions for each media respectively. Coal ash clinker followed pseudo first order kinetic model and Langmuir isotherm model with respect to nickel ions indicating the dominance of physisorption and mono layer coverage respectively. The Langmuir separation factor (RL) was 0.37 suggesting favourable adsorption onto the media. Fixed bed column studies revealed that copper was completely retained in the bed at both 24 and 48 h contact times. In the case of nickel, removal efficiency ranged between 83% and 99% when contact time was 48 h and between 68% and 99% when the contact time was reduced to 24 h. Breakthrough was not reached after 19 bed volumes. It can be concluded that coal ash clinker is a better candidate for the removal of copper and nickel ions from mining wastewater.

      PubDate: 2018-04-15T17:55:03Z
      DOI: 10.1016/j.pce.2018.02.013
       
  • Key attributes of agricultural innovations in semi-arid smallholder
           farming systems in south-west Zimbabwe
    • Authors: Eness P. Mutsvangwa-Sammie; Emmanuel Manzungu; Shephard Siziba
      Abstract: Publication date: Available online 2 March 2018
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Eness P. Mutsvangwa-Sammie, Emmanuel Manzungu, Shephard Siziba
      In Sub-Sahara Africa, which includes Zimbabwe, about 80% of the population depends on agriculture for subsistence, employment and income. Agricultural production and productivity are, however, low. This has been attributed to a lack of appropriate innovations despite the huge investments that have been made to promote ‘innovations’ as a means to safeguarding agriculture-based livelihoods, which raises the question of how innovations are conceptualized, designed and implemented. This paper explores the key attributes of agricultural innovations by assessing how innovations are conceptualized, designed and implemented in semi-arid smallholder farming systems in south-west Zimbabwe. The study gathered information from 13 key informants and a household survey of 239 farmer households from Gwanda and Insiza districts. Results showed a multiplicity of understandings of agricultural innovations among different stakeholders. However, novelty/newness, utility and adaptability were identified as the major attributes. In general, farmers characterized agricultural innovations as ‘something new and mostly introduced by NGOs’ but did not associate them with the key attributes of utility and adaptability. More crop-related innovations were identified despite the area being suitable for livestock production. The paper concludes that, rather than view the multiple and sometimes competing understandings of agricultural innovations as undesirable, this should be used to promote context specific innovations which stand a better chance of enhancing agriculture-based livelihoods.

      PubDate: 2018-04-15T17:55:03Z
      DOI: 10.1016/j.pce.2018.03.001
       
  • Assessment of quality of water provided for wildlife in the Central
           Kalahari Game Reserve, Botswana
    • Authors: Moses Selebatso; Glyn Maude; Richard W.S. Fynn
      Abstract: Publication date: Available online 1 March 2018
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Moses Selebatso, Glyn Maude, Richard W.S. Fynn
      Arid and semi-arid environments have low and unpredictable rainfall patterns resulting in limited availability of surface water for wildlife. In the Central Kalahari Game Reserve (CKGR) wildlife populations have lost access to natural surface water through cordon fences, livestock and human encroachment along the access routes. Artificial waterholes have been developed in the reserve to compensate for this loss. However, there have not been any assessments of the quality of water provided for wildlife and how that may be contributing to populations declines in the CKGR. We assessed water quality from 12 artificial waterholes against both Botswana and international livestock standards for drinking. Overall the quality of water provided is poor and poses a health risk to both animals and humans. Eight out of twelve boreholes tested exceeded the maximum acceptable Total Dissolved Solids (TDS) limits while three and four boreholes have toxic levels of lead and arsenic, respectively. Thus, pumping ground water could have more negative than positive impacts on wildlife thus defeating the intended management purpose. Failure to provide water of acceptable quality is a major concern for wildlife management in the CKGR and it may underlie some wildlife declines in the reserve. These findings confirm that restriction of populations from natural water sources create complex management challenges, especially where safe and sustainable alternative sources are scarce. Restriction of access of the population to natural water sources by fences and provision of poor quality water could compromise the overall fitness of wildlife populations and contribute to their decline.

      PubDate: 2018-04-15T17:55:03Z
      DOI: 10.1016/j.pce.2018.02.012
       
  • Determinants of farmers' participation in collective maintenance of
           irrigation infrastructure in KwaZulu-Natal
    • Authors: S. Sharaunga; M. Mudhara
      Abstract: Publication date: Available online 1 March 2018
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): S. Sharaunga, M. Mudhara
      The decentralization framework and the Dublin Principles on Integrated Water Resource Management (IWRM) emphasize the need for a participatory approach to irrigation water management. This study identifies the factors influencing farmers' decision to, and extent of participation in the maintenance of irrigation infrastructure in KwaZulu-Natal province, South Africa based on cross-section data collected from 320 randomly selected smallholder irrigating farmers. A two-step Heckman regression model was applied in the analysis. It was established that households whose heads were older, block committee members, with larger irrigation plots, good soil quality and experiencing severe irrigation water shortages are more likely to participate in maintenance of irrigation infrastructure. On the other hand, farmers with insecure land tenure and with no access to irrigation water were less likely to make the decision to participate. Farmers who were members of the farming cooperative as well as block committee members and those paying irrigation water costs were likely to intensively participate in maintaining irrigation infrastructure. Therefore, decentralization alone cannot lead to improved irrigation outcomes. Several factors are necessary for households to participate intensively in the maintenance of irrigation infrastructure. Governments should address these challenges before handing irrigation schemes to their beneficiaries.

      PubDate: 2018-04-15T17:55:03Z
      DOI: 10.1016/j.pce.2018.02.014
       
  • Influence of urbanization-driven land use/cover change on climate: The
           case of Addis Ababa, Ethiopia
    • Authors: Bisrat Kifle Arsiso; Gizaw Mengistu Tsidu; Gerrit Hendrik Stoffberg; Tsegaye Tadesse
      Abstract: Publication date: Available online 13 February 2018
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Bisrat Kifle Arsiso, Gizaw Mengistu Tsidu, Gerrit Hendrik Stoffberg, Tsegaye Tadesse
      Land use change is the second most important anthropogenic influence on climate beside the emission of greenhouse gases. Urbanization is leading to significant land use changes in Africa since the continent is undergoing rapid urbanization and population growth in recent decades. Addis Ababa is one of these fast growing cities in the continent. Therefore, detection of land use change is very important to identify its impact on climate and sustainable land use management of the city. The study used Landsat images to generate land use/land cover change map for the city. The normalized difference vegetation index (NDVI) is used to detect the major changes of vegetation cover occurred between 1986 and 2011 as a result of land use and land cover change. Downscaled HadCM3 simulations under A2 and B2 emission scenarios is used to investigate future urban heat island (UHI) over the city of Addis Ababa. In the city, the analysis of Landsat images has shown that the built-up areas have increased by 121.88 km2 within the last 25 years. This finding is consistent with NDVI images taken over the same period that reveal a decline in vegetation cover. The impact of the urbanization-driven land use/cover change has resulted in notable nocturnal urban heat island (UHI) as revealed from an average increase in minimum temperature of 1.5 ° C  at the centre of the city relative to rural site over the 1960–2001 period. The mean of the 2006–2010 spatial minimum temperature anomaly with respect to the base period mean of 1981–2005 is consistent with the observed UHI. The temperature in the central areas (both commercial and residential sectors) of Addis Ababa is warmer than the surrounding areas. The thermal gradient increase from about 1.44 ° C  at the centre (Arada, Addis Ketema, Lideta and Kirkos) to 0.21 ° C  at the peripheral parts of the city (Gulele, Bole, Nefasilk-Lafto, Kolfe Keranio and east of Yeka sub-cities) transecting across the hot (high-density urban) to moderately warm to cool (non-built-up) areas. However, the maximum temperature and rainfall exhibit variability that follows topographic differences. Future urban climate change projections of urban heat island formation under A2 and B2 emission scenarios show that the nocturnal UHI will be intense in winter or dry season episodes in the city. The highest urban warming is from October to December (2.5 ° C to 3.2 ° C ) during 2050s and 2080s.

      PubDate: 2018-02-26T15:49:38Z
      DOI: 10.1016/j.pce.2018.02.009
       
  • Validation of satellite-based rainfall in Kalahari
    • Authors: Moiteela Lekula; Maciek W. Lubczynski; Elisha M. Shemang; Wouter Verhoef
      Abstract: Publication date: Available online 9 February 2018
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Moiteela Lekula, Maciek W. Lubczynski, Elisha M. Shemang, Wouter Verhoef
      Water resources management in arid and semi-arid areas is hampered by insufficient rainfall data, typically obtained from sparsely distributed rain gauges. Satellite-based rainfall estimates (SREs) are alternative sources of such data in these areas. In this study, daily rainfall estimates from FEWS-RFE∼11 km, TRMM-3B42∼27 km, CMOPRH∼27 km and CMORPH∼8 km were evaluated against nine, daily rain gauge records in Central Kalahari Basin (CKB), over a five-year period, 01/01/2001-31/12/2005. The aims were to evaluate the daily rainfall detection capabilities of the four SRE algorithms, analyze the spatio-temporal variability of rainfall in the CKB and perform bias-correction of the four SREs. Evaluation methods included scatter plot analysis, descriptive statistics, categorical statistics and bias decomposition. The spatio-temporal variability of rainfall, was assessed using the SREs' mean annual rainfall, standard deviation, coefficient of variation and spatial correlation functions. Bias correction of the four SREs was conducted using a Time-Varying Space-Fixed bias-correction scheme. The results underlined the importance of validating daily SREs, as they had different rainfall detection capabilities in the CKB. The FEWS-RFE∼11 km performed best, providing better results of descriptive and categorical statistics than the other three SREs, although bias decomposition showed that all SREs underestimated rainfall. The analysis showed that the most reliable SREs performance analysis indicator were the frequency of “miss” rainfall events and the “miss-bias”, as they directly indicated SREs' sensitivity and bias of rainfall detection, respectively. The Time Varying and Space Fixed (TVSF) bias-correction scheme, improved some error measures but resulted in the reduction of the spatial correlation distance, thus increased, already high, spatial rainfall variability of all the four SREs. This study highlighted SREs as valuable source of daily rainfall data providing good spatio-temporal data coverage especially suitable for areas with limited rain gauges, such as the CKB, but also emphasized SREs' drawbacks, creating avenue for follow up research.

      PubDate: 2018-02-26T15:49:38Z
      DOI: 10.1016/j.pce.2018.02.010
       
  • Flood hazard vulnerability assessment in Kashmir Valley, India using
           geospatial approach
    • Authors: Tauseef Ahmad; Arvind Chandra Pandey; Amit Kumar
      Abstract: Publication date: Available online 9 February 2018
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Tauseef Ahmad, Arvind Chandra Pandey, Amit Kumar


      PubDate: 2018-02-26T15:49:38Z
      DOI: 10.1016/j.pce.2018.02.003
       
  • Urban flood simulation and prioritization of critical urban sub-catchments
           using SWMM model and PROMETHEE II approach
    • Authors: Sahar Babaei; Reza Ghazavi; Mahdi Erfanian
      Abstract: Publication date: Available online 9 February 2018
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Sahar Babaei, Reza Ghazavi, Mahdi Erfanian
      Urban runoff increased due to augment of impervious surfaces. In order to flood mitigation during rainy season, determination of critical urban sub-catchments is very important for urban planners. Due to lack of information, adopting a simulation approach is one of the practical ways to identify the surcharged junctions and critical sub-catchments. Occurrence of destructive floods in the rainy seasons indicates the inappropriateness of the urban drainage system in Urmia. The main aims of this study were to estimate the surface runoff of urban sub-catchments using SWMM, to evaluate the accuracy of the drainage system of the study urban area and to prioritize sub-catchments using PROMETHEE II approach and SWMM. In the present study, the occurrence of rainfall event of the Urmia city (West Azerbaijan province, Iran) used for estimation of runoff depth. The study area was divided into 22 sub-catchments. For calibration and validation of model parameters, 3 rainfall events and their related runoff were measured. According to sensitivity analysis CN was the most sensitive parameter for model calibration. Amount of surcharged conduits and junctions indicates that the drainage system of the study area has not enough capacity for converting of the runoff and. For 10 year return period, depth of channels should increase by 20% for prevention of flooding in these sub-catchments. Sub-catchments were prioritized using PROMETHEE II approach and its results were compared with SWMM simulation outcomes. Based on SWMM simulation, S11, S7, S18, S16 and S1 sub-catchments are more critical sub-catchments respectively, while according to PROMETHEE method, S1, S11, S16, S14 and S18 are determined as the critical areas.

      PubDate: 2018-02-26T15:49:38Z
      DOI: 10.1016/j.pce.2018.02.002
       
  • Quantification of water resources uncertainties in the Luvuvhu sub-basin
           of the Limpopo river basin
    • Authors: N. Oosthuizen; D. Hughes; E. Kapangaziwiri; J. Mwenge Kahinda; V. Mvandaba
      Abstract: Publication date: Available online 9 February 2018
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): N. Oosthuizen, D. Hughes, E. Kapangaziwiri, J. Mwenge Kahinda, V. Mvandaba
      In the absence of historical observed data, models are generally used to describe the different hydrological processes and generate data and information that will inform management and policy decision making. Ideally, any hydrological model should be based on a sound conceptual understanding of the processes in the basin and be backed by quantitative information for the parameterization of the model. However, these data are often inadequate in many sub-basins, necessitating the incorporation of the uncertainty related to the estimation process. This paper reports on the impact of the uncertainty related to the parameterization of the Pitman monthly model and water use data on the estimates of the water resources of the Luvuvhu, a sub-basin of the Limpopo river basin. The study reviews existing information sources associated with the quantification of water balance components and gives an update of water resources of the sub-basin. The flows generated by the model at the outlet of the basin were between 44.03 Mm3 and 45.48 Mm3 per month when incorporating +\-20% uncertainty to the main physical runoff generating parameters. The total predictive uncertainty of the model increased when water use data such as small farm and large reservoirs and irrigation were included. The dam capacity data was considered at an average of 62% uncertainty mainly as a result of the large differences between the available information in the national water resources database and that digitised from satellite imagery. Water used by irrigated crops was estimated with an average of about 50% uncertainty. The mean simulated monthly flows were between 38.57 Mm3 and 54.83 Mm3 after the water use uncertainty was added. However, it is expected that the uncertainty could be reduced by using higher resolution remote sensing imagery.

      PubDate: 2018-02-26T15:49:38Z
      DOI: 10.1016/j.pce.2018.02.008
       
  • Changes in streamflow contributions with increasing spatial scale in
           Thukela basin, South Africa
    • Authors: Macdex Mutema; Vincent Chaplot
      Abstract: Publication date: Available online 9 February 2018
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Macdex Mutema, Vincent Chaplot
      Sustainable management of river basins requires precise understanding of the origin and variability of water fluxes. Water samples were collected in Thukela Basin (30,000 km2), South Africa, over the 2012 rainy season, from fifteen 1 m2 runoff microplots (for OF), a 5-m deep piezometer (SW) and 20-m deep borehole (GW), in the basin headwater and nested catchment outlets (microcatchment, 0.23 km2; subcatchment, 1.20 km2; catchment, 9.75 km2; sub-basin, 253 km2). The water samples were analysed for Sodium (Na) and Silica (Si) concentrations using an inductively coupled-plasma emission spectrophotometry. End Member Mixing Analysis (EMMA), with Na and Si as tracers, was then used to quantify the water compartment contributions to river flow. The results showed a general decrease of unit-area runoff in downslope direction from 5.7 to 1.2 L m−2 day−1 at microplot and microcatchment level, respectively, to 1.4 L m−2 day−1 at the basin outlet. OF contributions averaged 61% at microcatchment, 79% at subcatchment, 40% at catchment, 78% at sub-basin and 67% at the basin outlet, which corresponded to 0.82, 0.26, 5 × 10−5, 2 × 10−3 and 9 × 10−5 L m−2 day−1, respectively. The respective SW contributions were 39% (0.38 L m−2 day−1), 18% (0.10 L m−2 day−1), 49% (5 × 10−5 L m−2 day−1), 15% (4 × 10−4 L m−2 day−1) and 33% (5 × 10−5 L m−2 day−1). GW contributions were much lower at all spatial scales, but showed a general increase with increasing contributing surface area from microcatchment to sub-basin outlet followed by a decrease to the basin outlet. The end-member contributions showed large spatial variations, hence longer-term research integrating more observation points is recommended to generate adequate data for development of prediction models for this important river basin. More research linking carbon, nutrient and pollutant fluxes to water dynamics is also recommended.

      PubDate: 2018-02-26T15:49:38Z
      DOI: 10.1016/j.pce.2018.02.007
       
  • Preparation and application of a tyre-based activated carbon solid phase
           extraction of heavy metals in wastewater samples
    • Authors: K. Mogolodi Dimpe; J.C. Ngila; Philiswa N. Nomngongo
      Abstract: Publication date: Available online 9 February 2018
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): K. Mogolodi Dimpe, J.C. Ngila, Philiswa N. Nomngongo
      In this paper, the tyre-based activated carbon solid phase extraction (SPE) method was successfully developed for simultaneous preconcentration of metal ions in the model and real water samples before their determination using flame atomic absorption spectrometry (FAAS). The activation of carbon was achieved by chemical activation and the tyre-based activated carbon was used as a sorbent for solid phase extraction. The prepared activated carbon was characterized using the scanning electron microscope (SEM), Brunauer-Emmett-Teller (BET), and Fourier Transform Infrared spectroscopy. Moreover, optimization of the proposed method was performed by the two-level full factorial design (FFD). The FFD was chosen in order to fully investigate the effect of the experimental variables (pH, eluent concentration and sample flow rate) that significantly influence the preconcentration procedure. In this model, individual factors are considered along with their interactions. In addition, modelling of the experiments allowed simultaneous variation of all experimental factors investigated, reduced the required time and number of experimental runs which consequently led to the reduction of the overall required costs. Under optimized conditions, the limits of detection and quantification (LOD and LOQ) ranged 0.66–2.12 μg L−1and 1.78–5.34 μg L−1, respectively and the enrichment factor of 25 was obtained. The developed SPE/FAAS method was validated using CWW-TM-A and CWW-TM-B wastewater standard reference materials (SRMs). The procedure showed to be accurate with satisfactory recoveries ranging from 92 to 99%. The precision (repeatability) was lower than 4% in terms of the relative standard deviation (%RSD). The developed method proved to have the capability to be used in routine analysis of heavy metals in domestic and industrial wastewater samples. In addition, the developed method can be used as a final step (before being discharged to the rivers) in wastewater treatment process in order to keep our water bodies free from toxic metals.

      PubDate: 2018-02-26T15:49:38Z
      DOI: 10.1016/j.pce.2018.02.005
       
  • Sanitation and hygiene practices among primary school learners in
           Ngamiland district, Botswana
    • Authors: Olekae T. Thakadu; Barbara N. Ngwenya; Nthabiseng A. Phaladze; Benjamin Bolaane
      Abstract: Publication date: Available online 9 February 2018
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Olekae T. Thakadu, Barbara N. Ngwenya, Nthabiseng A. Phaladze, Benjamin Bolaane
      Improved sanitation and personal hygienic practices are considered important towards reducing the risks of spreading communicable diseases and improving public health. Diarrheal related deaths amongst adolescents are reported to be amongst the top ten for the age groups 10–19 year olds and second among the age group 10–14 year olds globally. Primary school learners in developing countries are among the most vulnerable sub-population. These mortalities and illnesses can be reduced by addressing personal hygiene among school children and simultaneously promoting better school attendance and improved learning. In order to facilitate improved health and educational outcomes, it is necessary therefore to effectively address water, sanitation and hygiene matters within the school environment. This study explored hygiene education, personal hygiene practices among learners, environmental sanitation and hygiene within three primary schools in the Ngamiland district, Botswana. From the three schools, a total sample of 285 pupils was selected using proportionate stratified random sampling technique, and 15 teachers purposively selected as key informants. Data was collected using semi-structured questionnaires with key informants and social survey instrument for learners. Results show that very few learners linked poor hygiene to the following diseases; diarrhea/upset stomach (31.7%); malaria (23%); bilharzia (16.4%), and cholera (14.8%), demonstrating low hygiene knowledge. Hygiene education in schools is infused in the curriculum, and teacher training on hygiene education is only through in-service training workshops. Regarding personal hygiene practices, over 70% of the learners indicated that they ‘always’ wash their hands before and after eating, with slightly over one-fifth indicating ‘sometimes’. Overwhelming majority of learners dispose solid waste in dustbins (99.3%, n = 284), use refuse bags (80.8%, n = 231), open skips (64%, n = 183) and very few throw trash anywhere either on the school compound or classroom (9.1%, n = 26 and 8.7%, n = 25 respectively). The current low levels of hygiene knowledge among learners in the study area has potential to affect learners' performance at school as risky hygiene practices make them vulnerable to contracting infectious diseases and missing school. This prompts the need to think beyond the infusion approach used in schools. Extra-curricular clubs in schools should be established to promote pro-hygiene behaviors and to facilitate adolescence meaningful and sustained participation.

      PubDate: 2018-02-26T15:49:38Z
      DOI: 10.1016/j.pce.2018.02.006
       
 
 
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