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PHYSICS (573 journals)

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Journal Cover Physics and Chemistry of the Earth, Parts A/B/C
  [SJR: 0.611]   [H-I: 26]   [8 followers]  Follow
    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 1474-7065
   Published by Elsevier Homepage  [3044 journals]
  • Integrated water resources management and infrastructure planning for
           water security in Southern Africa
    • Authors: Benjamin Mapani; Lapologang Magole; Hodson Makurira; Maideyi Meck; Theresa Mkandawire; Marloes Mul; Cosmo Ngongondo
      Pages: 1 - 2
      Abstract: Publication date: August 2017
      Source:Physics and Chemistry of the Earth, Parts A/B/C, Volume 100
      Author(s): Benjamin Mapani, Lapologang Magole, Hodson Makurira, Maideyi Meck, Theresa Mkandawire, Marloes Mul, Cosmo Ngongondo


      PubDate: 2017-09-09T08:38:02Z
      DOI: 10.1016/j.pce.2017.08.001
      Issue No: Vol. 100 (2017)
       
  • Providing peak river flow statistics and forecasting in the Niger River
           basin
    • Authors: Jafet C.M. Andersson; Abdou Ali; Berit Arheimer; David Gustafsson; Bernard Minoungou
      Pages: 3 - 12
      Abstract: Publication date: August 2017
      Source:Physics and Chemistry of the Earth, Parts A/B/C, Volume 100
      Author(s): Jafet C.M. Andersson, Abdou Ali, Berit Arheimer, David Gustafsson, Bernard Minoungou
      Flooding is a growing concern in West Africa. Improved quantification of discharge extremes and associated uncertainties is needed to improve infrastructure design, and operational forecasting is needed to provide timely warnings. In this study, we use discharge observations, a hydrological model (Niger-HYPE) and extreme value analysis to estimate peak river flow statistics (e.g. the discharge magnitude with a 100-year return period) across the Niger River basin. To test the model's capacity of predicting peak flows, we compared 30-year maximum discharge and peak flow statistics derived from the model vs. derived from nine observation stations. The results indicate that the model simulates peak discharge reasonably well (on average + 20%). However, the peak flow statistics have a large uncertainty range, which ought to be considered in infrastructure design. We then applied the methodology to derive basin-wide maps of peak flow statistics and their associated uncertainty. The results indicate that the method is applicable across the hydrologically active part of the river basin, and that the uncertainty varies substantially depending on location. Subsequently, we used the most recent bias-corrected climate projections to analyze potential changes in peak flow statistics in a changed climate. The results are generally ambiguous, with consistent changes only in very few areas. To test the forecasting capacity, we ran Niger-HYPE with a combination of meteorological data sets for the 2008 high-flow season and compared with observations. The results indicate reasonable forecasting capacity (on average 17% deviation), but additional years should also be evaluated. We finish by presenting a strategy and pilot project which will develop an operational flood monitoring and forecasting system based in-situ data, earth observations, modelling, and extreme statistics. In this way we aim to build capacity to ultimately improve resilience toward floods, protecting lives and infrastructure in the region.

      PubDate: 2017-09-09T08:38:02Z
      DOI: 10.1016/j.pce.2017.02.010
      Issue No: Vol. 100 (2017)
       
  • Remote sensing of surface water quality in relation to catchment condition
           in Zimbabwe
    • Authors: Mhosisi Masocha; Amon Murwira; Christopher H.D. Magadza; Rafik Hirji; Timothy Dube
      Pages: 13 - 18
      Abstract: Publication date: August 2017
      Source:Physics and Chemistry of the Earth, Parts A/B/C, Volume 100
      Author(s): Mhosisi Masocha, Amon Murwira, Christopher H.D. Magadza, Rafik Hirji, Timothy Dube
      The degradation of river catchments is one of the most important contemporary environmental problems affecting water quality in tropical countries. In this study, we used remotely sensed Normalised Difference Vegetation Index (NDVI) to assess how catchment condition varies within and across river catchments in Zimbabwe. We then used non-linear regression to test whether catchment condition assessed using the NDVI is significantly (α = 0.05) related with levels of Total Suspended Solids (TSS) measured at different sampling points in thirty-two sub-catchments in Zimbabwe. The results showed a consistent negative curvilinear relationship between Landsat 8 derived NDVI and TSS measured across the catchments under study. In the drier catchments of the country, 98% of the variation in TSS is explained by NDVI, while in wetter catchments, 64% of the variation in TSS is explained by NDVI. Our results suggest that NDVI derived from free and readily available multispectral Landsat series data (Landsat 8) is a potential valuable tool for the rapid assessment of physical water quality in data poor catchments. Overall, the finding of this study underscores the usefulness of readily available satellite data for near-real time monitoring of the physical water quality at river catchment scale, especially in resource-constrained areas, such as the sub-Saharan Africa.

      PubDate: 2017-09-09T08:38:02Z
      DOI: 10.1016/j.pce.2017.02.013
      Issue No: Vol. 100 (2017)
       
  • Evaluation of satellite and simulated rainfall products for hydrological
           applications in the Notwane catchment, Botswana
    • Authors: P.K. Kenabatho; B.P. Parida; D.B. Moalafhi
      Pages: 19 - 30
      Abstract: Publication date: August 2017
      Source:Physics and Chemistry of the Earth, Parts A/B/C, Volume 100
      Author(s): P.K. Kenabatho, B.P. Parida, D.B. Moalafhi
      In semi-arid catchments, hydrological modeling, water resources planning and management are hampered by insufficient spatial rainfall data which is usually derived from limited rain gauge networks. Satellite products are potential candidates to augment the limited spatial rainfall data in these areas. In this paper, the utility of the Tropical Rainfall Measuring Mission (TRMM) product (3B42 v7) is evaluated using data from the Notwane catchment in Botswana. In addition, rainfall simulations obtained from a multi-site stochastic rainfall model based on the generalised linear models (GLMs) were used as additional spatial rainfall estimates. These rainfall products were compared to the observed rainfall data obtained from six (6) rainfall stations available in the catchment for the period 1998–2012. The results show that in general the two approaches produce reasonable spatial rainfall estimates. However, the TRMM products provided better spatial rainfall estimates compared to the GLM rainfall outputs on an average, as more than 90% of the monthly rainfall variations were explained by the TRMM compared to 80% from the GLMs. However, there is still uncertainty associated mainly with limited rainfall stations, and the inability of the two products to capture unusually high rainfall values in the data sets. Despite this observation, rainfall indices computed to further assess the daily rainfall products (i.e. rainfall occurrence and amounts, length of dry spells) were adequately represented by the TRMM data compared to the GLMs. Performance from the GLMs is expected to improve with addition of further rainfall predictors. A combination of these rainfall products allows for reasonable spatial rainfall estimates and temporal (short term future) rainfall simulations from the TRMM and GLMs, respectively. The results have significant implications on water resources planning and management in the catchment which has, for the past three years, been experiencing prolonged droughts as shown by the drying of Gaborone dam (currently at a record low of 1.6% full), which is the main source of water supply to the city of Gaborone and neighbouring townships in Botswana.

      PubDate: 2017-09-09T08:38:02Z
      DOI: 10.1016/j.pce.2017.02.009
      Issue No: Vol. 100 (2017)
       
  • Evaluation of drought using SPEI drought class transitions and log-linear
           models for different agro-ecological regions of India
    • Authors: N.M. Alam; G.C. Sharma; Elsa Moreira; C. Jana; P.K. Mishra; N.K. Sharma; D. Mandal
      Pages: 31 - 43
      Abstract: Publication date: August 2017
      Source:Physics and Chemistry of the Earth, Parts A/B/C, Volume 100
      Author(s): N.M. Alam, G.C. Sharma, Elsa Moreira, C. Jana, P.K. Mishra, N.K. Sharma, D. Mandal
      Markov chain and 3-dimensional log-linear models were attempted to model drought class transitions derived from the newly developed drought index the Standardized Precipitation Evapotranspiration Index (SPEI) at a 12 month time scale for six major drought prone areas of India. Log-linear modelling approach has been used to investigate differences relative to drought class transitions using SPEI-12 time series derived form 48 yeas monthly rainfall and temperature data. In this study, the probabilities of drought class transition, the mean residence time, the 1, 2 or 3 months ahead prediction of average transition time between drought classes and the drought severity class have been derived. Seasonality of precipitation has been derived for non-homogeneous Markov chains which could be used to explain the effect of the potential retreat of drought. Quasi-association and Quasi-symmetry log-linear models have been fitted to the drought class transitions derived from SPEI-12 time series. The estimates of odds along with their confidence intervals were obtained to explain the progression of drought and estimation of drought class transition probabilities. For initial months as the drought severity increases the calculated odds shows lower value and the odds decreases for the succeeding months. This indicates that the ratio of expected frequencies of occurrence of transition from drought class to the non-drought class decreases as compared to transition to any drought class when the drought severity of the present class increases. From 3-dimensional log-linear model it is clear that during the last 24 years the drought probability has increased for almost all the six regions. The findings from the present study will immensely help to assess the impact of drought on the gross primary production and to develop future contingent planning in similar regions worldwide.

      PubDate: 2017-09-09T08:38:02Z
      DOI: 10.1016/j.pce.2017.02.008
      Issue No: Vol. 100 (2017)
       
  • Effect of monthly areal rainfall uncertainty on streamflow simulation
    • Authors: J.G. Ndiritu; N. Mkhize
      Pages: 51 - 61
      Abstract: Publication date: August 2017
      Source:Physics and Chemistry of the Earth, Parts A/B/C, Volume 100
      Author(s): J.G. Ndiritu, N. Mkhize
      Areal rainfall is mostly obtained from point rainfall measurements that are sparsely located and several studies have shown that this results in large areal rainfall uncertainties at the daily time step. However, water resources assessment is often carried out a monthly time step and streamflow simulation is usually an essential component of this assessment. This study set out to quantify monthly areal rainfall uncertainties and assess their effect on streamflow simulation. This was achieved by; i) quantifying areal rainfall uncertainties and using these to generate stochastic monthly areal rainfalls, and ii) finding out how the quality of monthly streamflow simulation and streamflow variability change if stochastic areal rainfalls are used instead of historic areal rainfalls. Tests on monthly rainfall uncertainty were carried out using data from two South African catchments while streamflow simulation was confined to one of them. A non-parametric model that had been applied at a daily time step was used for stochastic areal rainfall generation and the Pitman catchment model calibrated using the SCE-UA optimizer was used for streamflow simulation. 100 randomly-initialised calibration-validation runs using 100 stochastic areal rainfalls were compared with 100 runs obtained using the single historic areal rainfall series. By using 4 rain gauges alternately to obtain areal rainfall, the resulting differences in areal rainfall averaged to 20% of the mean monthly areal rainfall and rainfall uncertainty was therefore highly significant. Pitman model simulations obtained coefficient of efficiencies averaging 0.66 and 0.64 in calibration and validation using historic rainfalls while the respective values using stochastic areal rainfalls were 0.59 and 0.57. Average bias was less than 5% in all cases. The streamflow ranges using historic rainfalls averaged to 29% of the mean naturalised flow in calibration and validation and the respective average ranges using stochastic monthly rainfalls were 86 and 90% of the mean naturalised streamflow. In calibration, 33% of the naturalised flow located within the streamflow ranges with historic rainfall simulations and using stochastic rainfalls increased this to 66%. In validation the respective percentages of naturalised flows located within the simulated streamflow ranges were 32 and 72% respectively. The analysis reveals that monthly areal rainfall uncertainty is significant and incorporating it into streamflow simulation would add validity to the results.

      PubDate: 2017-09-09T08:38:02Z
      DOI: 10.1016/j.pce.2016.10.005
      Issue No: Vol. 100 (2017)
       
  • Generation of climate change scenarios for precipitation and temperature
           at local scales using SDSM in Wami-Ruvu River Basin Tanzania
    • Authors: Metekiya M. Gulacha; Deogratias M.M. Mulungu
      Pages: 62 - 72
      Abstract: Publication date: August 2017
      Source:Physics and Chemistry of the Earth, Parts A/B/C, Volume 100
      Author(s): Metekiya M. Gulacha, Deogratias M.M. Mulungu
      The Wami-Ruvu River Basin is important for socio-economic activities in country such as water supply for Dar es Salaam and Morogoro cities, and major agricultural activities such as sugarcane irrigation at Mtibwa and Bagamoyo. Due to projected climate change and its impacts at global scale, it is important to understand future climate change impacts on water resources of Wami-Ruvu River basin. Rainfall and temperature are key variables for analysis of water resources and were used in this study. The statistical downscaling model (SDSM) was used to downscale the coarse global circulation model (GCM) to local scales by involving predictor predictand relationship. The predictor variables were selected based on partial correlation value (partial r) and significance value (p-value). For assessment of climate change, the baseline period was 30 years during 1961–1990. The baseline period was partitioned into two periods for SDSM calibration and validation: 1961–1975 and 1976–1990 respectively. In this case, ground stations and the U.S. National Center for Environmental Prediction (NCEP) reanalysis atmospheric data were used. During validation, the inbuilt scenario generator was used to generate simulated time series for five stations: Morogoro Maji, Ulaya, Ukaguru, Morogoro Airport, Dodoma Airport and Ruvu at Morogoro Rd. Brd. For precipitation, the SDSM's R2 (−) for the two periods ranged 0.07–0.20 and 0.21–0.63 respectively. The respective coefficient of correlation, r (−) ranged 0.03–0.05 and 0.46–0.80, indicating low to high performance of the SDSM. The respective R2 (−) values for temperature ranged: 0.42–0.5 and 0.6–0.98 respectively. The calibrated SDSM model was then used to downscale Global Circulation Model (GCM) scenario data to the local scales. The GCM used was HadCM3 where A2 and B2 scenarios were used. The climate change scenarios were determined using change factors. Results showed that for Wami-Ruvu basin the mean rainfall will change by −44–107%, −69–328% and 68–648% during 2020s, 2050s and 2080s for A2 scenario while by −37–117%, −56–199 and −76–346% respectively for B2 scenario as compared to the baseline period. In all cases, Ulaya and Morogoro Maji stations presented the lowest and highest extremes in the ranges. The downscaled and projected average monthly maximum temperature indicated increasing trend from 0.2 to 7.5 °C in 2020s–2080s time period. The minimum temperature showed decreasing trend from −0.4 to −1.5 °C during the same periods. These results indicate potential for floods or droughts occurrence in the basin, accordingly adaptation measures will be necessary.

      PubDate: 2017-09-09T08:38:02Z
      DOI: 10.1016/j.pce.2016.10.003
      Issue No: Vol. 100 (2017)
       
  • Evaluating the influence of the Red Edge band from RapidEye sensor in
           quantifying leaf area index for hydrological applications specifically
           focussing on plant canopy interception
    • Authors: Timothy Dube; Onisimo Mutanga; Mbulisi Sibanda; Cletah Shoko; Abel Chemura
      Pages: 73 - 80
      Abstract: Publication date: August 2017
      Source:Physics and Chemistry of the Earth, Parts A/B/C, Volume 100
      Author(s): Timothy Dube, Onisimo Mutanga, Mbulisi Sibanda, Cletah Shoko, Abel Chemura
      Reliable and accurate quantification of plant Leaf Area Index (LAI) is critical in understanding its role in reducing runoff. The main aim of the present study was to evaluate the ability of the Red Edge (RE) band derived from RapidEye in estimating LAI for applications in quantifying canopy interception at landscape scale. To achieve this objective, the study also compares the predictive power of two machine learning algorithms (Random Forest-RF and Stochastic Gradient Boosting-SGB) in estimating LAI. Comparatively, the results of the study have demonstrated that the inclusion of spectral information derived from the Red Edge band yields high accurate LAI estimates, when compared to the use of traditional traditional Red, Green, Blue and Near Infra-Red (traditional RGBNIR) spectral information. The results indicate that the use of the four traditional RGBNIR bands yielded comparatively lower R2 values and high Root Mean Squares, Mean Absolute Error (Pinus taeda: R2 of 0.60; the lowest RMSE (0.35 m2/m2) and MAE of 28); whereas the use of integration of traditional RGBNIR + RE in more accurate LAI estimates (Pinus taeda: R2 = 0.65; RMSE = 0.30 m2/m2) and the lowest MAE of 0.23). These findings therefore underscores the importance of new generation multispectral sensors with strategically-position bands and machine learning algorithms in estimating LAI for quantifying canopy interception, especially in resource-poor areas.

      PubDate: 2017-09-09T08:38:02Z
      DOI: 10.1016/j.pce.2017.02.016
      Issue No: Vol. 100 (2017)
       
  • Evaluating the performance of the newly-launched Landsat 8 sensor in
           detecting and mapping the spatial configuration of water hyacinth
           (Eichhornia crassipes) in inland lakes, Zimbabwe
    • Authors: Timothy Dube; Onisimo Mutanga; Mbulisi Sibanda; Victor Bangamwabo; Cletah Shoko
      Pages: 101 - 111
      Abstract: Publication date: August 2017
      Source:Physics and Chemistry of the Earth, Parts A/B/C, Volume 100
      Author(s): Timothy Dube, Onisimo Mutanga, Mbulisi Sibanda, Victor Bangamwabo, Cletah Shoko
      The remote sensing of freshwater resources is increasingly becoming important, due to increased patterns of water use and the current or projected impacts of climate change and the rapid invasion by lethal water weeds. This study therefore sought to explore the potential of the recently-launched Landsat 8 OLI/TIRS sensor in mapping invasive species in inland lakes. Specifically, the study compares the performance of the newly-launched Landsat 8 sensor, with more advanced sensor design and image acquisition approach to the traditional Landsat-7 ETM+ in detecting and mapping the water hyacinth (Eichhornia crassipes) invasive species across Lake Chivero, in Zimbabwe. The analysis of variance test was used to identify windows of spectral separability between water hyacinth and other land cover types. The results showed that portions of the visible (B3), NIR (B4), as well as the shortwave bands (Band 8, 9 and 10) of both Landsat 8 OLI and Landsat 7 ETM, exhibited windows of separability between water hyacinth and other land cover types. It was also observed that on the use of Landsat 8 OLI produced high overall classification accuracy of 72%, when compared Landsat 7 ETM, which yielded lower accuracy of 57%. Water hyacinth had optimal accuracies (i.e. 92%), when compared to other land cover types, based on Landsat 8 OLI data. However, when using Landsat 7 ETM data, classification accuracies of water hyacinth were relatively lower (i.e. 67%), when compared to other land cover types (i.e. water with accuracy of 100%). Spectral curves of the old, intermediate and the young water hyacinth in Lake Chivero based on: (a) Landsat 8 OLI, and (b) Landsat 7 ETM were derived. Overall, the findings of this study underscores the relevance of the new generation multispectral sensors in providing primary data-source required for mapping the spatial distribution, and even configuration of water weeds at lower or no cost over time and space.

      PubDate: 2017-09-09T08:38:02Z
      DOI: 10.1016/j.pce.2017.02.015
      Issue No: Vol. 100 (2017)
       
  • Use of Landsat series data to analyse the spatial and temporal variations
           of land degradation in a dispersive soil environment: A case of King
           Sabata Dalindyebo local municipality in the Eastern Cape Province, South
           Africa
    • Authors: Timothy Dube; Onisimo Mutanga; Mbulisi Sibanda; Khoboso Seutloali; Cletah Shoko
      Pages: 112 - 120
      Abstract: Publication date: August 2017
      Source:Physics and Chemistry of the Earth, Parts A/B/C, Volume 100
      Author(s): Timothy Dube, Onisimo Mutanga, Mbulisi Sibanda, Khoboso Seutloali, Cletah Shoko
      Land degradation as a result of inappropriate land use practices, such as overgrazing and cultivation on steep slopes, etc. is one of the major global environmental challenges. Specifically, land degradation threatens the productivity and sustainability of the natural environment, agriculture, and most importantly rural economies in most developing countries, particularly the sub-Saharan region. The main aim of this study was therefore, to assess the potential and strength of using the free or readily available Landsat series data in mapping degraded land areas at the King Sabata Dalindyebo local municipality in the Eastern Cape, South Africa (1984–2010). Data analysis was done using a robust non-parametric classification ensemble; Discriminant Analysis (DA). The results show that degraded areas vary over the years. For example, the results show that the year 1994 and 2004 incurred high degradation levels, when compared to the year 1984 and 2010. Moreover, the observed degradation significantly (α = 0.05) varies with soil type. The chromic acrisols have the highest levels of erosion (approx. 80% in 1984), when compared to humic-umbric acrisols (less than 10% for the entire period under study). It can also be observed that considerable part of degradation occurred in the northern part of the municipal district. Overall, the findings of this research underlines the importance and efficacy of multispectral Landsat series data-set in mapping and monitoring levels of land degradation in data-scarce catchments.

      PubDate: 2017-09-09T08:38:02Z
      DOI: 10.1016/j.pce.2017.01.023
      Issue No: Vol. 100 (2017)
       
  • Potential application of synthesized ferrocenylimines compounds for the
           elimination of bacteria in water
    • Authors: M.I. Ikhile; T.G. Barnard; J.C. Ngila
      Pages: 121 - 125
      Abstract: Publication date: August 2017
      Source:Physics and Chemistry of the Earth, Parts A/B/C, Volume 100
      Author(s): M.I. Ikhile, T.G. Barnard, J.C. Ngila
      This work reports a study towards a search for environmentally friendly water disinfectant. The most common method for water treatment is based on chlorine which had a wide application over the years as a water disinfectant, but suffer the disadvantage of reacting with natural organic matter to form disinfection by products. In this study, the potential application of novel ferrocenylimines compounds, namely 4-ferrocenylaniline (1), N-(3-bromo-2-hydroxylbenzylidene)-4-ferrocenylimine (2) and N-(3-bromo-5-chlorosalicyl)-4-ferrocenylimine (3) for the elimination of bacteria in water was investigated by evaluating their antibacterial properties against twelve different bacterial strains using microdilution method in sterile 96 well micro titer plates. The in vitro antibacterial activity revealed that the ferrocenylimines compound exhibit higher antibacterial activity than ferrocene, which is one of the starting materials towards the synthesis of this novel ferrocenylimines compounds. The most active ferrocenylimines compound was compound 3 with a minimal inhibitory concentration (MIC) value of 0.30 mg/ml against S. sonnei. In addition, all the ferrocenylimines compounds possessed excellent antibacterial activity against B. cereus with the same MIC value of 0.31 mg/ml. The results obtained so far show great potential in the three tested ferrocenylimines compounds for use in water treatment in killing bacteria in water.

      PubDate: 2017-09-09T08:38:02Z
      DOI: 10.1016/j.pce.2017.01.022
      Issue No: Vol. 100 (2017)
       
  • Effect of incorporating graphene oxide and surface imprinting on
           polysulfone membranes on flux, hydrophilicity and rejection of salt and
           polycyclic aromatic hydrocarbons from water
    • Authors: Rose Waithiegeni Kibechu; Derek Tantoh Ndinteh; Titus Alfred Makudali Msagati; Bhekie Briliance Mamba; S. Sampath
      Pages: 126 - 134
      Abstract: Publication date: August 2017
      Source:Physics and Chemistry of the Earth, Parts A/B/C, Volume 100
      Author(s): Rose Waithiegeni Kibechu, Derek Tantoh Ndinteh, Titus Alfred Makudali Msagati, Bhekie Briliance Mamba, S. Sampath
      We report a significant enhancement of hydrophillity of polysulfone (Psf) membranes after modification with graphene oxide (GO) as a filler followed by surface imprinting on the surface of GO/Psf composite imprinted membranes (CIMs). The surface imprinting on the GO-Psf membrane was employed in order to enhance its selectivity towards polycyclic aromatic hydrocarbons (PAHs) in water. The CIMs were prepared through a process of phase inversion of a mixture of graphene oxide and polysulfone (Psf) in N-methylpyrrolidone (NMP). Fourier-transform spectroscopy (FT-IR) of the imprinted showed new peaks at 935 cm−1 and 1638 cm−1 indicating success in surface imprinting on the GO-Psf membrane. The CIM also showed improvement in flux from 8.56 LM−2 h−1 of unmodified polysulfone membrane to 15.3 LM−2 h−1 in the CIM, salt rejection increased from 57.2 ± 4.2% of polysulfone membrane to 76 ± 4.5%. The results obtained from the contact angle measurements showed a decrease with increase in GO content from 72 ± 2.7% of neat polysulfone membrane to 62.3 ± 2.1% of CIM indicating an improvement in surface hydrophilicity. The results from this study shows that, it is possible to improve the hydrophilicity of the membranes without affecting the performance of the membranes.

      PubDate: 2017-09-09T08:38:02Z
      DOI: 10.1016/j.pce.2017.01.021
      Issue No: Vol. 100 (2017)
       
  • Carbon nanotube embedded PVDF membranes: Effect of solvent composition on
           the structural morphology for membrane distillation
    • Authors: Edgar C. Mapunda; Bhekie B. Mamba; Titus A.M. Msagati
      Pages: 135 - 142
      Abstract: Publication date: August 2017
      Source:Physics and Chemistry of the Earth, Parts A/B/C, Volume 100
      Author(s): Edgar C. Mapunda, Bhekie B. Mamba, Titus A.M. Msagati
      Rapid population increase, growth in industrial and agricultural sectors and global climate change have added significant pressure on conventional freshwater resources. Tapping freshwater from non-conventional water sources such as desalination and wastewater recycling is considered as sustainable alternative to the fundamental challenges of water scarcity. However, affordable and sustainable technologies need to be applied for the communities to benefit from the treatment of non-conventional water source. Membrane distillation is a potential desalination technology which can be used sustainably for this purpose. In this work multi-walled carbon nanotube embedded polyvinylidene fluoride membranes for application in membrane distillation desalination were prepared via non-solvent induced phase separation method. The casting solution was prepared using mixed solvents (N, N-dimethylacetamide and triethyl phosphate) at varying ratios to study the effect of solvent composition on membrane morphological structures. Membrane morphological features were studied using a number of techniques including scanning electron microscope, atomic force microscope, SAXSpace tensile strength analysis, membrane thickness, porosity and contact angle measurements. It was revealed that membrane hydrophobicity, thickness, tensile strength and surface roughness were increasing as the composition of N, N-dimethylacetamide in the solvent was increasing with maximum values obtained between 40 and 60% N, N-dimethylacetamide. Internal morphological structures were changing from cellular structures to short finger-like and sponge-like pores and finally to large macro void type of pores when the amount of N, N-dimethylacetamide in the solvent was changed from low to high respectively. Multi-walled carbon nanotube embedded polyvinylidene fluoride membranes of desired morphological structures and physical properties can be synthesized by regulating the composition of solvents used to prepare the casting solution.

      PubDate: 2017-09-09T08:38:02Z
      DOI: 10.1016/j.pce.2017.01.003
      Issue No: Vol. 100 (2017)
       
  • Detrimental effects of commercial zinc oxide and silver nanomaterials on
           bacterial populations and performance of wastewater systems
    • Authors: Anza-vhudziki Mboyi; Ilunga Kamika; MaggyN.B. Momba
      Pages: 158 - 169
      Abstract: Publication date: August 2017
      Source:Physics and Chemistry of the Earth, Parts A/B/C, Volume 100
      Author(s): Anza-vhudziki Mboyi, Ilunga Kamika, MaggyN.B. Momba
      The widespread use of commercial nanomaterials (NMs) in consumer products has raised environmental concerns as they can enter and affect the efficiency of the wastewater treatment plants. In this study the effect of various concentrations of zinc oxide NMs (nZnO) and silver NMs (nAg) on the selected wastewater bacterial species (Bacillus licheniformis, Brevibacillus laterosporus and Pseudomonas putida) was ascertained at different pH levels (pH 2, 7 and 10). Lethal concentrations (LC) of NMs and parameters such as chemical oxygen demand (COD) and dissolved oxygen (DO) were taken into consideration to assess the performance of a wastewater batch reactor. Bacterial isolates were susceptible to varying concentrations of both nZnO and nAg at pH 2, 7 and 10. It was found that a change in pH did not significantly affect the toxicity of test NMs towards target bacterial isolates. All bacterial species were significantly inhibited (p < 0.05) in the presence of 0.65 g/L of nZnO and nAg. In contrast, there was no significant difference (p > 0.05) in COD removal in the presence of increasing concentrations of NMs, which resulted in increasing releases of COD. Noticeably, there was no significant difference (p > 0.05) in the decrease in DO uptake in the presence of increasing NM concentrations for all bacterial isolates. The toxic effects of the target NMs on bacterial populations in wastewater may negatively impact the performance of biological treatment processes and may thus affect the efficiency of wastewater treatment plants in producing effluent of high quality.

      PubDate: 2017-09-09T08:38:02Z
      DOI: 10.1016/j.pce.2016.12.003
      Issue No: Vol. 100 (2017)
       
  • Modeling phytoremediation of nitrogen-polluted water using water hyacinth
           (Eichhornia crassipes)
    • Authors: Aloyce W. Mayo; Emmanuel E. Hanai
      Pages: 170 - 180
      Abstract: Publication date: August 2017
      Source:Physics and Chemistry of the Earth, Parts A/B/C, Volume 100
      Author(s): Aloyce W. Mayo, Emmanuel E. Hanai
      Water hyacinth (Eichhornia crassipes) has a great potential for purification of wastewater through physical, chemical and biological mechanisms. In an attempt to improve the quality of effluents discharged from waste stabilization ponds at the University of Dar es Salaam, a pilot plant was constructed to experiment the effectiveness of this plants for transformation and removal of nitrogen. Samples of wastewater were collected and examined for water quality parameters, including pH, temperature, dissolved oxygen, and various forms of nitrogen, which were used as input parameters in a kinetic mathematical model. A conceptual model was then developed to model various processes in the system using STELLA 6.0.1 software. The results show that total nitrogen was removed by 63.9%. Denitrification contributed 73.8% of the removed nitrogen. Other dominant nitrogen removal mechanisms are net sedimentation and uptake by water hyacinth, which contributed 16.7% and 9.5% of the removed nitrogen, respectively. The model indicated that in presence of water hyacinth biofilm about 1.26 g Nm−2day−1 of nitrogen was removed. However, in the absence of biofilm in water hyacinth pond, the permanent nitrogen removal was only 0.89 g Nm−2day−1. This suggests that in absence of water hyacinth, the efficiency of nitrogen removal would decrease by 29.4%.

      PubDate: 2017-09-09T08:38:02Z
      DOI: 10.1016/j.pce.2016.10.016
      Issue No: Vol. 100 (2017)
       
  • The effects of material loading and flow rate on the disinfection of
           pathogenic microorganisms using cation resin-silver nanoparticle filter
           system
    • Authors: L. Mpenyana-Monyatsi; N.H. Mthombeni; M.S. Onyango; M.N.B. Momba
      Pages: 181 - 188
      Abstract: Publication date: August 2017
      Source:Physics and Chemistry of the Earth, Parts A/B/C, Volume 100
      Author(s): L. Mpenyana-Monyatsi, N.H. Mthombeni, M.S. Onyango, M.N.B. Momba
      Waterborne diseases have a negative impact on public health in instances where the available drinking water is of a poor quality. Decentralised systems are needed to provide safe drinking water to rural communities. Therefore, the present study aimed to develop and investigate the point-of-use (POU) water treatment filter packed with resin-coated silver nanoparticles. The filter performance was evaluated by investigating the effects of various bed masses (10 g, 15 g, 20 g) and flow rates (2 mL/min, 5 mL/min, 10 mL/min) by means of breakthrough curves for the removal efficiency of presumptive Escherichia coli, Shigella dysenteriae, Salmonella typhimurium and Vibrio cholerae from spiked groundwater samples. The results revealed that, as the bed mass increases the breakthrough time also increases with regards to all targeted microorganisms. However, when the flow rate increases the breakthrough time decreased. These tests demonstrated that resin-coated silver nanoparticle can be an effective material in removing all targeted microorganisms at 100% removal efficiency before breakthrough points are achieved. Moreover the filter system demonstrated that it is capable of producing 15 L/day of treated water at an operating condition of 10 mL/min flow rate and 15 g bed mass, which is sufficient to provide for seven individuals in the household if they consume 2 L/person/day for drinking purpose. Therefore, the bed mass of the filter system should be increased in order for it to produce sufficient water that will conform to the daily needs of an individual.

      PubDate: 2017-09-09T08:38:02Z
      DOI: 10.1016/j.pce.2016.10.012
      Issue No: Vol. 100 (2017)
       
  • Development of a silicone-membrane passive sampler for monitoring
           cylindrospermopsin and microcystin LR-YR-RR in natural waters
    • Authors: Hlengilizwe Nyoni; Bhekie B. Mamba; Titus A.M. Msagati
      Pages: 189 - 200
      Abstract: Publication date: August 2017
      Source:Physics and Chemistry of the Earth, Parts A/B/C, Volume 100
      Author(s): Hlengilizwe Nyoni, Bhekie B. Mamba, Titus A.M. Msagati
      Silicone membrane tubes were functionalised by filling them with synthesised γ-Fe2O3 nanoparticles and used as a passive sampling device for monitoring microcystins and cylindrospermopsin in aquatic environments. This novel device was calibrated for the measurement of microcystin and cylindrospermopsin concentrations in water. The effect of temperature and hydrodynamics on the sampler performance was studied in a flow-through system under controlled conditions. The chemical uptake of microcystins (MCs) and cylindrospermopsin (CYN) into the passive sampler remained linear and integrative throughout the exposure period. The rate of accumulation of most of the MC compounds tested was dependent on temperature and flow velocity. The use of 13C labelled polychlorinated biphenyls as performance reference compounds (PRCs) in silicone membrane/γ-Fe2O3 nanoparticle passive sampler, Chemcatcher and polar organic chemical integrative sampler (POCIS) was evaluated. The majority of PRCs improved the semi quantitative nature of water concentration estimated by the three samplers. The corrected sampling rate values of model biotoxin compounds were used to estimate the time-weighted average concentrations in natural cyanobacterial water blooms of the Hartbeespoort dam. The corrected sampling rates R Scorr values varied from 0.1140 to 0.5628 Ld−1 between samplers with silicone membrane having the least R Scorr values compared to the Chemcatcher and POCIS. The three passive sampling devises provided a more relevant picture of the biotoxin concentration in the Hartbeespoort dam. The results suggested that the three sampling devices are suitable for use in monitoring microcystins and cylindrospermopsin concentrations in aquatic environments.

      PubDate: 2017-09-09T08:38:02Z
      DOI: 10.1016/j.pce.2016.10.010
      Issue No: Vol. 100 (2017)
       
  • Electrospun polyacrylonitrile nanofibers functionalized with EDTA for
           adsorption of ionic dyes
    • Authors: Eutilério F.C. Chaúque; Langelihle N. Dlamini; Adedeji A. Adelodun; Corinne J. Greyling; J. Catherine Ngila
      Pages: 201 - 211
      Abstract: Publication date: August 2017
      Source:Physics and Chemistry of the Earth, Parts A/B/C, Volume 100
      Author(s): Eutilério F.C. Chaúque, Langelihle N. Dlamini, Adedeji A. Adelodun, Corinne J. Greyling, J. Catherine Ngila
      The manipulation of nanofibers’ surface chemistry could enhance their potential application toward the removal of ionic dyes in wastewater. For this purpose, surface modification of electrospun polyacrylonitrile (PAN) nanofibers with ethylenediaminetetraacetic acid (EDTA) and ethylenediamine (EDA) crosslinker was experimented. The functionalized EDTA-EDA-PAN nanofibers were characterized using Fourier transform infrared (FT-IR) spectroscopy, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and Brunauer-Emmett-Teller (BET) technique. The impregnation of EDA and EDTA chelating agents on the surface of PAN changed the distribution of nanofibers as proximity is increased (accompanied by reduced softness), but the nanofibrous structure of the pristine PAN nanofibers was not substantially altered. Adsorption equilibrium studies were performed with Freundlich, Langmuir and Temkin isotherm models with the former providing better correlation to the experimental data. The modified PAN nanofibers showed efficient sorption of methyl orange (MO) and reactive red (RR) from aqueous synthetic samples, evinced by the maximum adsorption capacities (at 25 °C) of 99.15 and 110.0 mg g−1, respectively. The fabricated nanofibers showed appreciable removal efficiency of the target dye sorptives from wastewater. However, the presence of high metal ions content affected the overall extraction of dyes from wastewater due to the depletion of the adsorbent's active adsorptive sites.

      PubDate: 2017-09-09T08:38:02Z
      DOI: 10.1016/j.pce.2016.10.008
      Issue No: Vol. 100 (2017)
       
  • Electrospun and functionalized PVDF/PAN composite for the removal of trace
           metals in contaminated water
    • Authors: R.M. Nthumbi; A.A. Adelodun; J.C. Ngila
      Pages: 225 - 235
      Abstract: Publication date: August 2017
      Source:Physics and Chemistry of the Earth, Parts A/B/C, Volume 100
      Author(s): R.M. Nthumbi, A.A. Adelodun, J.C. Ngila
      The electrospinning of a nanofiber composite of polyvinylidene fluoride (PVDF) and polyacrylonitrile (PAN) in a dimethylformamide (DMF) solvent was carried out prior to functionalization by free radical grafting of acrylic acid (AA) brushes. Subsequent application for the removal of Pb2+ and Cd2+ from contaminated water is reported. Free radicals were initiated on the polymeric nanofiber composite using 5% 2,2′-Azobis(2-methylpropionitrile) (AIBN) in acetone. Upon solvent removal by air-drying, AA was added and grafting (in a methanol-water solvent system) was carried out in an oil bath at 70 °C for 5 h under nitrogen atmosphere. Structural and chemical characterization of the composite was done using scanning electron microscope (SEM), nitrogen sorption at 77 K (BET method), goniometer and Fourier transform infrared spectrometer (FTIR), while changes in metal ion concentration during batch adsorption were monitored using inductively coupled plasma optical emission spectrometer (ICP-OES). Through isotherm study, the adsorption was confirmed to follow both Langmuir and Freundlich models whilst adsorption kinetic studies showed that the adsorption rate is of pseudo-second order. In furtherance, the respective values for adsorption capacity and estimated removal efficiency for Pb2+ and Cd2+ were 1.585 and 0.164 mg g−1, 90% and 80% respectively, while a 5% loss in regeneration efficiency after 10 cycles was also observed. Consequently, the nanocomposite was found efficient when applied to the removal of Pb2+ and Cd2+ from contaminated water.

      PubDate: 2017-09-09T08:38:02Z
      DOI: 10.1016/j.pce.2016.08.007
      Issue No: Vol. 100 (2017)
       
  • Polyethyleneimine-carbon nanotube polymeric nanocomposite adsorbents for
           the removal of Cr6+ from water
    • Authors: Shepherd S. Sambaza; Monaheng L. Masheane; Soraya P. Malinga; Edward N. Nxumalo; Sabelo D. Mhlanga
      Pages: 236 - 246
      Abstract: Publication date: August 2017
      Source:Physics and Chemistry of the Earth, Parts A/B/C, Volume 100
      Author(s): Shepherd S. Sambaza, Monaheng L. Masheane, Soraya P. Malinga, Edward N. Nxumalo, Sabelo D. Mhlanga
      This work reports on the synthesis of multi-walled carbon nanotubes (MWCNTs) and their use in branched polyethyleneimine-multiwalled carbon nanotube (PEI-MWCNT) polymeric nanocomposite adsorbents for the removal of Cr6+ from contaminated water. The nanostructured materials were characterized using TEM, Raman, FTIR, BET surface area and zeta potential measurements. TEM confirmed the average diameter of the MWCNTs to be 25 nm. The point of zero-charge of PEI was at pH 8 and that of PEI-MWCNTs was at pH 7.7. FTIR analysis confirmed the formation of a new bond (–CO at 1716 cm−1) between the functional groups on the MWCNTs and PEI. Batch adsorption and kinetic studies showed that the PEI-MWCNT nanocomposite materials were more efficient in the removal of Cr6+ solution from water samples. The optimum conditions for adsorption were pH ≤ 4, contact time of 60 min. When the PEI-MWCNT dosage was increased the adsorption capacity increased. The kinetic adsorption data obtained for Cr6+ solution followed pseudo-second order model. The adsorption of Cr6+ solution reached equilibrium within 60 min of contact time with a removal of 99%. The adsorbents were effective even after 5 cycles of use.

      PubDate: 2017-09-09T08:38:02Z
      DOI: 10.1016/j.pce.2016.08.002
      Issue No: Vol. 100 (2017)
       
  • Articulating the history and major departure points evident in
           post-apartheid South African national water policy and law
    • Authors: C. Chikozho; L. Danga; D. Saruchera
      Pages: 270 - 277
      Abstract: Publication date: August 2017
      Source:Physics and Chemistry of the Earth, Parts A/B/C, Volume 100
      Author(s): C. Chikozho, L. Danga, D. Saruchera
      Governance of the water sector in South Africa has reflected the political changes taking place in society. For instance, due to apartheid policies of segregation, inequality of access to water resources marks South Africa's history in a very profound way and redistribution of rights to water to redress the results of past discrimination became an explicit purpose of the post-apartheid water governance policy and legislative regime. In this paper, we articulate the history and major departure points evident in post-apartheid South African national water policy and law. This includes documenting and reflecting on most of the available information that shows how the new water policy and law were developed. Findings from the study show that the key players active in the water law review process deliberately took into account the political goals and dynamics of power asymmetry within which the law was being articulated. Therefore, the water law as it stands today and in the past must be understood within the context of the socio-economic and political landscape that has prevailed in South Africa at different historical junctures. We contend that a detailed examination and articulation of the history and major departure points evident in post-apartheid South African national water policy and law enables practitioners and scholars to better understand the main motivations behind the water sector reforms and the then prevailing thinking behind the policy and legislation eventually promulgated. The present water law must be understood in the context of these reforms and the objectives they sought to achieve.

      PubDate: 2017-09-09T08:38:02Z
      DOI: 10.1016/j.pce.2017.01.006
      Issue No: Vol. 100 (2017)
       
  • Assessing and mapping the severity of soil erosion using the 30-m Landsat
           multispectral satellite data in the former South African homelands of
           Transkei
    • Authors: Khoboso E. Seutloali; Timothy Dube; Onisimo Mutanga
      Pages: 296 - 304
      Abstract: Publication date: August 2017
      Source:Physics and Chemistry of the Earth, Parts A/B/C, Volume 100
      Author(s): Khoboso E. Seutloali, Timothy Dube, Onisimo Mutanga
      Soil erosion is increasingly recognised as the principal cause of land degradation, loss of agricultural land area and siltation of surrounding water waterbodies. Accurate and up-to-date soil erosion mapping is key in understanding its severity if these negative impacts are to be minimised and affected areas rehabilitated. The aim of this work was to map the severity of soil erosion, based on the 30-m Landsat series multispectral satellite data in the former South African homelands of Transkei between the year 1994 and 2010. Further, the study assessed if the observed soil erosion trends and morphology that existed in this area could be explained by biophysical factors (i.e. slope, stream erosivity, topographic wetness index) retrieved from the 30-m ASTER Digital Elevation Model (DEM). The results of this study indicate that the Transkei region experiences varying erosion levels from moderate to very severe. The large portion of the land area under the former homelands was largely affected by rill erosion with approximately 74% occurring in the year 1984 and 54% in 2010. The results also revealed specific thresholds of soil erosion drivers. These include steeper areas (≥30°), high stream power index greater than 2.0 (stream erosivity), relatively lower vegetation cover (≤15%) and low topographic wetness index (≤5%). The results of this work demonstrate the severity of soil erosion in the Southern African former homelands of Transkei for the year 1984 and 2010. Additionally, this work has demonstrated the significance of the 30-m Landsat multispectral sensor in examining soil erosion occurrence at a regional scale where in-depth field work still remains a challenging task.

      PubDate: 2017-09-09T08:38:02Z
      DOI: 10.1016/j.pce.2016.10.001
      Issue No: Vol. 100 (2017)
       
  • Remote sensing leaf water stress in coffee (Coffea arabica) using
           secondary effects of water absorption and random forests
    • Authors: Abel Chemura; Onisimo Mutanga; Timothy Dube
      Pages: 317 - 324
      Abstract: Publication date: August 2017
      Source:Physics and Chemistry of the Earth, Parts A/B/C, Volume 100
      Author(s): Abel Chemura, Onisimo Mutanga, Timothy Dube
      Water management is an important component in agriculture, particularly for perennial tree crops such as coffee. Proper detection and monitoring of water stress therefore plays an important role not only in mitigating the associated adverse impacts on crop growth and productivity but also in reducing expensive and environmentally unsustainable irrigation practices. Current methods for water stress detection in coffee production mainly involve monitoring plant physiological characteristics and soil conditions. In this study, we tested the ability of selected wavebands in the VIS/NIR range to predict plant water content (PWC) in coffee using the random forest algorithm. An experiment was set up such that coffee plants were exposed to different levels of water stress and reflectance and plant water content measured. In selecting appropriate parameters, cross-correlation identified 11 wavebands, reflectance difference identified 16 and reflectance sensitivity identified 22 variables related to PWC. Only three wavebands (485 nm, 670 nm and 885 nm) were identified by at least two methods as significant. The selected wavebands were trained (n = 36) and tested on independent data (n = 24) after being integrated into the random forest algorithm to predict coffee PWC. The results showed that the reflectance sensitivity selected bands performed the best in water stress detection (r = 0.87, RMSE = 4.91% and pBias = 0.9%), when compared to reflectance difference (r = 0.79, RMSE = 6.19 and pBias = 2.5%) and cross-correlation selected wavebands (r = 0.75, RMSE = 6.52 and pBias = 1.6). These results indicate that it is possible to reliably predict PWC using wavebands in the VIS/NIR range that correspond with many of the available multispectral scanners using random forests and further research at field and landscape scale is required to operationalize these findings.

      PubDate: 2017-09-09T08:38:02Z
      DOI: 10.1016/j.pce.2017.02.011
      Issue No: Vol. 100 (2017)
       
  • Designing local solutions for emptying pit latrines in low-income urban
           settlements (Malawi)
    • Authors: W.C. Chipeta; R.H. Holm; J.F. Kamanula; W.E. Mtonga; F.L. de los Reyes
      Pages: 336 - 342
      Abstract: Publication date: August 2017
      Source:Physics and Chemistry of the Earth, Parts A/B/C, Volume 100
      Author(s): W.C. Chipeta, R.H. Holm, J.F. Kamanula, W.E. Mtonga, F.L. de los Reyes
      A lack of effective options in local technology poses challenges when onsite household sanitation facilities are eventually filled to capacity in unplanned settlement areas within Mzuzu City, located in northern Malawi. Vacuum trucks currently dominate the market but focus on emptying septic tanks in the more easily accessible planned settlement areas, rather than servicing the pit latrines common in unplanned settlement areas. As a result, households in the unplanned settlement areas within Mzuzu rely primarily on manual pit emptying (i.e., shoveling by hand) or digging a new pit latrine. These practices have associated health risks and are limited by space constraints. This research focused on filling the technological gap through the design, development, and testing of a pedal powered modified Gulper pump using locally available materials and fabrication. A modified pedal powered Gulper technology was developed and demonstrated to be capable of lifting fecal sludge from a depth of 1.5 m with a mean flow rate of 0.00058 m3/s. If the trash content was low, a typical pit latrine with a volume of 1–4 m3 could be emptied within 1–2 h. Based on the findings in our research Phase IV, the pedal powered Gulper modification is promising as a potential emptying technology for lined pit latrines in unplanned settlement areas. The success rate of the technology is about 17% (5 out 30 sampled lined pit latrines were successful) and reflects the difficulty in finding a single technology that can work well in all types of pit latrines with varying contents. We note that cost should not be the only design criteria and acknowledge the challenge of handling trash in pit latrines.

      PubDate: 2017-09-09T08:38:02Z
      DOI: 10.1016/j.pce.2017.02.012
      Issue No: Vol. 100 (2017)
       
  • Development of probabilistic operating rules for Hluhluwe Dam, South
           Africa
    • Authors: J. Ndiritu; J. Odiyo; R. Makungo; B. Mwaka; N. Mthethwa; C. Ntuli; A. Andanje
      Pages: 343 - 352
      Abstract: Publication date: August 2017
      Source:Physics and Chemistry of the Earth, Parts A/B/C, Volume 100
      Author(s): J. Ndiritu, J. Odiyo, R. Makungo, B. Mwaka, N. Mthethwa, C. Ntuli, A. Andanje
      Hluhluwe Dam, with a 30 million m3 reservoir that supplies water for irrigation and Hluhluwe municipality in Kwa-Zulu Natal Province, South Africa, was consistently experiencing low storage levels over several non-drought years since 2001. The dam was operated by rules of thumb and there were no records of water releases for irrigation - the main user of the dam. This paper describes an assessment of the historic behaviour of the reservoir since its completion in 1964 and the development of operating rules that accounted for: i) the multiple and different levels of reliability at which municipal and irrigation demands need to be supplied, and ii) inter-annual and inter-decadal variability of climate and inflows into the dam. The assessment of the behaviour of the reservoir was done by simulation assuming trigonometric rule curves that were optimized to maximize both yield and storage state using the SCE-UA method. The resulting reservoir behaviour matched the observed historic trajectory reasonably well and indicated that the dam has mainly been operated at a demand of 10 million m3/year until 2000 when the demand suddenly rose to 25 million m3/year. Operating rules were developed from a statistical analysis of the base yields from 500 simulations of the reservoir each using 5 year-long stochastically generated sequences of inflows, rainfall and evaporation. After the implementation of the operating rules in 2009, the storage state of the dam improved and matched those of other reservoirs in the region that had established operating rules.

      PubDate: 2017-09-09T08:38:02Z
      DOI: 10.1016/j.pce.2016.10.017
      Issue No: Vol. 100 (2017)
       
  • Assessment of drinking water quality and rural household water treatment
           in Balaka District, Malawi
    • Authors: Raphael C. Mkwate; Russel C.G. Chidya; Elijah M.M. Wanda
      Pages: 353 - 362
      Abstract: Publication date: August 2017
      Source:Physics and Chemistry of the Earth, Parts A/B/C, Volume 100
      Author(s): Raphael C. Mkwate, Russel C.G. Chidya, Elijah M.M. Wanda
      Access to drinking water from unsafe sources is widespread amongst communities in rural areas such as Balaka District in Malawi. This situation puts many individuals and communities at risk of waterborne diseases despite some households adopting household water treatment to improve the quality of the water. However, there still remains data gaps regarding the quality of drinking water from such sources and the household water treatment methods used to improve public health. This study was, therefore, conducted to help bridge the knowledge gap by evaluating drinking water quality and adoption rate of household water treatment and storage (HWTS) practices in Nkaya, Balaka District. Water samples were collected from eleven systematically selected sites and analyzed for physico-chemical and microbiological parameters: pH, TDS, electrical conductivity (EC), turbidity, F−, Cl−, NO3 −, Na, K, Fe, Faecal Coliform (FC) and Faecal Streptococcus (FS) bacteria using standard methods. The mean results were compared to the World Health Organization (WHO) and Malawi Bureau of Standards (MBS) (MS 733:2005) to ascertain the water quality for drinking purposes. A total of 204 randomly selected households were interviewed to determine their access to drinking water, water quality perception and HWTS among others. The majority of households (72%, n = 83) in Njerenje accessed water from shallow wells and rivers whilst in Phimbi boreholes were commonly used. Several households (>95%, n = 204) were observed to be practicing HWST techniques by boiling or chlorination and water storage in closed containers. The levels of pH (7.10–7.64), F− (0.89–1.46 mg/L), Cl− (5.45–89.84 mg/L), NO3 − (0–0.16 mg/L), Na (20–490 mg/L), K (2.40–14 mg/L) and Fe (0.10–0.40 mg/L) for most sites were within the standard limits. The EC (358–2220 μS/cm), turbidity (0.54–14.60 NTU), FC (0–56 cfu/100 mL) and FS (0–120 cfu/100 mL) - mainly in shallow wells, were found to be above the WHO and MBS water quality specifications. The majority of the water samples (73%, n = 11) were classified as of “Intermediate risk” (FC 11–100 cfu/100 mL), hence not suitable for human consumption without prior treatment. This calls for large scale adoption of HWTS and continued monitoring of the water sources used in the study areas.

      PubDate: 2017-09-09T08:38:02Z
      DOI: 10.1016/j.pce.2016.10.006
      Issue No: Vol. 100 (2017)
       
  • Managing water supply systems using free-market economy approaches: A
           detailed review of the implications for developing countries
    • Authors: C. Chikozho; K. Kujinga
      Pages: 363 - 370
      Abstract: Publication date: August 2017
      Source:Physics and Chemistry of the Earth, Parts A/B/C, Volume 100
      Author(s): C. Chikozho, K. Kujinga
      Decision makers in developing countries are often confronted by difficult choices regarding the selection and deployment of appropriate water supply governance regimes that sufficiently take into account national socio-economic and political realities. Indeed, scholars and practitioners alike continue to grapple with the need to create the optimum water supply and allocation decision-making space applicable to specific developing countries. In this paper, we review documented case studies from various parts of the world to explore the utility of free-market economics approaches in water supply governance. This is one of the major paradigms that have emerged in the face of enduring questions regarding how best to govern water supply systems in developing countries. In the paper, we postulate that increasing pressure on available natural resources may have already rendered obsolete some of the water supply governance regimes that have served human societies very well for many decades. Our main findings show that national and municipal water supply governance paradigms tend to change in tandem with emerging national development frameworks and priorities. While many developing countries have adopted water management and governance policy prescriptions from the international arena, national and local socio-economic and political realities ultimately determine what works and what does not work on the ground. We thus, conclude that the choice of what constitutes an appropriate water supply governance regime in context is never simple. Indeed, the majority of case studies reviewed in the paper tend to rely on a mix of market economics and developmental statism to make their water governance regimes more realistic and workable on the ground.

      PubDate: 2017-09-09T08:38:02Z
      DOI: 10.1016/j.pce.2016.10.002
      Issue No: Vol. 100 (2017)
       
  • Ungauged runoff simulation in Upper Manyame Catchment, Zimbabwe:
           Application of the HEC-HMS model
    • Authors: Webster Gumindoga; Donald T. Rwasoka; Innocent Nhapi; Timothy Dube
      Pages: 371 - 382
      Abstract: Publication date: August 2017
      Source:Physics and Chemistry of the Earth, Parts A/B/C, Volume 100
      Author(s): Webster Gumindoga, Donald T. Rwasoka, Innocent Nhapi, Timothy Dube
      The Hydrologic Engineering Center Hydrologic Modelling System (HEC-HMS) model was applied to simulate runoff in the ten gauged and ungauged Upper Manyame subcatchments in Zimbabwe. Remote sensing and Geographic Information System techniques were used to determine the geometric and hydrologic parameters required for estimating model parameters. The Snyder Unit Hydrograph method was used for ungauged subcatchment simulations based on parameter transfer from gauged subcatchments. The Marimba and Mukuvisi subcatchments were considered as the gauged subcatchments based on data completeness for the simulation period (2004–2010). Before extrapolating the calibrated model setup to eight ungauged subcatchments, the feasibility of model parameter transferability was tested, using the proxy – catchment approach and evaluated using the Nash Sutcliffe (NSE) and Relative Volume Error (RVE) criterion. Results showed that the model successfully predicted gauged catchment runoff and peakflows for the calibration (Marimba NSE = 68%, RVE = 5.8%; Mukuvisi NSE = 64%, RVE = −8.9%) and validation (Marimba NSE = 61%, RVE = 8.1%; Mukuvisi NSE = 57%, RVE = 9.9%) periods. The study demonstrates the suitability of HEC-HMS for continuous runoff simulation in a complex watershed with numerous subcatchments and channel reaches. The ungauged subcatchments contribute to 51% of Upper Manyame Catchment's runoff. Ruwa and Lake Chivero subcatchments had the highest ungauged subcatchment contribution to Upper Manyame Catchment runoff (19% and 15% respectively). This work will have a significant contribution for the future development of water resources programs in Upper Manyame Catchment in particular and in other data-scarce catchments.

      PubDate: 2017-09-09T08:38:02Z
      DOI: 10.1016/j.pce.2016.05.002
      Issue No: Vol. 100 (2017)
       
  • Is small-scale irrigation an efficient pro-poor strategy in the upper
           Limpopo Basin in Mozambique'
    • Authors: Raphaelle Ducrot
      Pages: 383 - 392
      Abstract: Publication date: August 2017
      Source:Physics and Chemistry of the Earth, Parts A/B/C, Volume 100
      Author(s): Raphaelle Ducrot
      In Sub-Saharan Africa, there is evidence that households with access to small-scale irrigation are significantly less poor than households that do not have access to irrigation. However, private motopumps tend to be distributed inequitably. This paper investigates the success of explicit pro-poor interventions with emphasis on small-scale irrigation in the semi-arid Limpopo Basin in Mozambique. It reveals that high irrigation costs are progressively excluding the poor, who are unable to generate a cash income from other activities they need to fund irrigation. In addition, the operation of collective schemes involving the poor is being jeopardized by the development of private irrigation schemes, which benefit from hidden subsidies appropriated by local elites. This results in unequal access to irrigation, which can cause resentment at community level. This weakens community cohesiveness, as well as communities' capacities for collective action and coordination, which are crucial for collective irrigation.

      PubDate: 2017-09-09T08:38:02Z
      DOI: 10.1016/j.pce.2016.06.001
      Issue No: Vol. 100 (2017)
       
  • Chitosan-based nanocomposites for de-nitrification of water
    • Authors: Monaheng Masheane; Lebea Nthunya Soraya Malinga Edward Nxumalo Sabelo Mhlanga
      Abstract: Publication date: August 2017
      Source:Physics and Chemistry of the Earth, Parts A/B/C, Volume 100
      Author(s): Monaheng L. Masheane, Lebea N. Nthunya, Soraya P. Malinga, Edward N. Nxumalo, Sabelo D. Mhlanga
      Novel chitosan (CTs) nanocomposite beads containing alumina (Al2O3, denoted as Al in the nanocomposites) and functionalized multiwalled carbon nanotubes (f-MWCNTs) (CTsAl/f-MWCNTs) were prepared using an environmentally benign phase inversion method and subsequently used for the removal of nitrates (NO3 −) in water. The ellipsoidal beads with an average size of 3 mm were readily formed at room temperature and contained a small amount of Al (20 wt%) and f-MWCNTs (5%). The beads were found to adsorb nitrates effectively over a wide range of pH (pH 2 – pH 6) and showed maximum nitrates removal of 96.8% from a 50 mg/L nitrate water solution. Pure CTs beads on the other hand removed only 23% at pH 4. Kinetic studies suggested that the particle diffusion was rate controlling step for the adsorption of nitrates on CTsAl/f-MWCNT nanocomposite beads. Langmuir-Freundlich isotherms revealed that the adsorption of nitrates was on the heterogeneous surface of CTsAl/f-MWCNT beads. The Dubinin–Radushkevich (D-R) isotherm further revealed that the adsorption of nitrates was by electrostatic interaction. Thermodynamic studies suggested that the adsorption was spontaneous and exothermic. More than 70% recovery was achieved for 5 cycles of desorption-degeneration studies. Al and f-MWCNTs have shown to improve swelling and solubility of CTs.

      PubDate: 2017-09-09T08:38:02Z
       
  • Field assessment of surface runoff, sediment yield and soil erosion in
           opencast mines in Chirimiri area, Chhattisgarh, India
    • Authors: G.K. Nigam; R.K. Sahu; M.K. Sinha; X. Deng; R.B. Singh; P. Kumar
      Abstract: Publication date: Available online 18 July 2017
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): G.K. Nigam, R.K. Sahu, M.K. Sinha, X. Deng, R.B. Singh, P. Kumar
      Chirimiri Coal field is located in the Koriya district of Chhattisgarh state of India. It lies in the valley of the Hasdeo River and is spread over 125 km2 area. Ever increasing problem of declining forest resources and water quality is a cause of concern particularly due to excessive soil erosion resulting into soil debris deposition from the overburdened dump. Dwindling resources has compelled the policy makers to search for alternative such as waste lands and mined areas to augment/improve soil and water resources for use in agriculture and allied sectors while maintaining the local ecology and hydrology. Most Opencast mines releases huge amount of mining wastes as overburden dump (OBD) materials that are prone to soil erosion and create problems of sedimentation and water quality, affecting agriculture. Historical daily rainfall data for 21 years and daily surface runoff as estimated by SCS-Curve Number method were analysed. Sediment yield was estimated at lower end of erosion face of OBD and near drainage outlet of opencast mine. Assessment of soil erosion from OBD materials was made by RUSLE (Revised Universal Soil Loss Equation) method and was compared with direct field measurements by placing plastic sheets in downstream portion of OBD. As results monsoon rainfall constitutes 91.6 percent of the annual rainfall and surface runoff 31.7 percent of monsoon rainfall. The surface runoff was found to be 4133 m3/ha while the sediment yield of drainage effluent was negligible. The soil loss from OBD as estimated by the RUSLE method (62.7 t ha−1 yr−1) was quite close (+13.2 percent) to the direct field measurement 54.44 t ha−1. The sediment samples from OBD were found acidic in nature and exhibited low values of EC, OC, WHC, N, P, and K. For controlling soil erosion of OBD, mechanical and vegetative measures have been suggested along with installation of sediment traps inside and outside the mines. There is good scope to backfill the mines with the OBD in the form of well laid out terraces to support plantation and later on used for leguminous fodder/grass production.

      PubDate: 2017-07-24T07:34:44Z
      DOI: 10.1016/j.pce.2017.07.001
       
  • Balancing water demand for the Heihe River Basin in Northwest China
    • Authors: Feng Wu; Yuping Bai; Yali Zhang; Zhihui Li
      Abstract: Publication date: Available online 11 July 2017
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Feng Wu, Yuping Bai, Yali Zhang, Zhihui Li
      Water resource crisis becomes the most serious threat to global economic sustainable development. Balancing water demand under the pressure of economic development is a new challenge faced by water resource managers. In this study, we investigated the mutual feedback mechanism between economic systems and eco-hydrological processes in the Heihe River Basin of China with a Water Economic Model (WEM). The WEM is built based on input-output table that embeds water-land resource factors and focuses on the interactive route between water resource and economic elements. On one hand, we investigated the routes and patterns of how eco-hydrological processes acted on economic systems in the upstream of Heihe River Basin, and analyzed how climate change disturbed the economic systems through its impacts on water yield. On the other hand, we explored the feedback of economic systems on eco-hydrological processes through land use interface. We determined the key parameters of simulation and designed the economic development scenarios for the Heihe River Basin. Based on the WEM, we simulated the change of water demand under urbanization and industrial transformation scenarios, supporting scientific basis for the water resource management and policy.

      PubDate: 2017-07-12T07:26:26Z
      DOI: 10.1016/j.pce.2017.07.002
       
  • Impact Assessment of Climate Change on Poverty Reduction: A Global
           Perspective
    • Authors: Xiaoxue Zhou; Jiancheng Chen; Zhihui Li; Guofeng Wang; Fan Zhang
      Abstract: Publication date: Available online 23 June 2017
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Xiaoxue Zhou, Jiancheng Chen, Zhihui Li, Guofeng Wang, Fan Zhang
      Climate change and its impacts are the biggest environmental problems that the world is facing in recent decades. Climate-sensitive events have already been critical obstacles of poverty reduction and sustainable economic development. Assessing how climate change impacts on poverty reduction is of great significance to the comprehensive assessment of climate change impacts on social economy and the mitigation of the negative impacts. With geo-spatially referenced malnutrition and infant mortality data as a proxy for poverty, focusing on the aspects of agriculture and human well-being consist of physical health and personal autonomy. This study selects three countries, China, India and Senegal, to investigate the impacts of climate change on poverty reduction. Contrast to previous work what analyze climate changes’ impacts most concentrated on coastal urban areas, this paper is concentrating on the rural poor areas in different income group countries and on a contrastive analysis. The correlation analysis results show the same is that the indicators of climate change are in significant correlations with indicators of poverty and that of agriculture and human well-being in China, India and Senegal. However, China performs poorly in terms of personal autonomy, while the Senegal performs well, the correlations of forest area percentage (one indicator of climate change) with other variables in Senegal are absolutely opposite to that in China and India. We find the same influence factors have different effects on poverty reduction in these countries, the anti-poverty policies should be made according to local conditions.

      PubDate: 2017-07-03T07:20:23Z
      DOI: 10.1016/j.pce.2017.06.011
       
  • Characterization of soil salinization in typical estuarine area of the
           Jiaozhou Bay, China
    • Authors: Qifei Li; Min Xi; Qinggai Wang; Fanlong Kong; Yue Li
      Abstract: Publication date: Available online 23 June 2017
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Qifei Li, Min Xi, Qinggai Wang, Fanlong Kong, Yue Li
      In this study, the characteristics of soil salinization and the effects of main land use/land cover and other factors in typical estuarine area of the Jiaozhou Bay are investigated. Soil samples were collected in the parallel coastal zone, vertical coastal zone and longitudinal profile depth in the area to determine the soil salt content. The correlation analysis and principal component analysis are used to address the general characteristics of soil salinization in the study area. In the horizontal direction, there are moderate salinization, severe salinization and saline soil state. The farther from the sea (within 1.1 km), the lower the soil salinization degree. In the direction of longitudinal profile depth, there are severe salinization and saline soil state, and the soil salt content is accumulated in the surface and bottom. The Na+ and Cl- are the dominant cation and anion, respectively, the distributions of which are consistent with that of salt content. All the salinization indexes, except for soil pH, are of moderate/strong variability. The invasion of Spartina alterniflora results in the increase of soil salt content and salinization degree, the effects of which are mainly determined by the physiological characteristics and the growth years. The degree of soil salinization increased significantly in the aquaculture ponds, which is mainly caused by the use of chemicals. The correlation between soil salt content and Na+, Cl- is significant. From the results of principal component analysis, Na+, Cl-, Ca2+, Mg2+ and SO4 2- could be used as main diagnostic factors for salinization in typical estuarine area of the Jiaozhou Bay. The effects of NaCl and sulfate on salt content further affect the degree of salinization in the estuarine area.

      PubDate: 2017-07-03T07:20:23Z
      DOI: 10.1016/j.pce.2017.06.010
       
  • Sensitivity of the mayfly Adenophlebia auriculata (Ephemeroptera:
           Leptophlebiidae) to MgSO4 and Na2SO4
    • Authors: E.C. Vellemu; P.K. Mensah; N.J. Griffin; O.N. Odume
      Abstract: Publication date: Available online 22 June 2017
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): E.C. Vellemu, P.K. Mensah, N.J. Griffin, O.N. Odume
      Acid mine drainage (AMD) continues to deteriorate water quality in freshwater ecosystems. Sulphates, a major salt component in AMD, can exacerbate AMD effects in freshwater because salts are toxic to aquatic life in high concentrations. Sulphates are predominant in South African AMD impacted freshwater ecosystems. In this study, the sensitivity of nymphs of the mayfly Adenophlebia auriculata (Ephemeroptera: Leptophlebiidae) was investigated by exposing the organisms to magnesium sulphate (MgSO4) and sodium sulphate (Na2SO4) as models of mining salinisation in short-term (96 h) and long-term (240 h) in static system tests. Short-term and long-term lethal concentrations of each salt were estimated using regression analyses. The results indicated that A. auriculata was more sensitive to MgSO4 (LC50 = 3.81 g/L) than Na2SO4 (LC50 = 8.78 g/L) after short-term exposures. However, this species became sensitive to Na2SO4 (LC10 = 0.19 g/L) but tolerant to MgSO4 (LC10 = 0.35 g/L) after long-term exposures. These results suggest that the 0.25 g/L sulphate compliance limit for South Africa is inadequate to protect A. auriculata from Na2SO4 toxicity in the long-term, yet it overprotects this species from MgSO4 exposures in the short-term. The findings of this study are an important major step in understanding the ecological effects of AMD to aquatic life.

      PubDate: 2017-07-03T07:20:23Z
      DOI: 10.1016/j.pce.2017.06.009
       
  • Dynamic characteristics of soil respiration in Yellow River Delta
           wetlands, China
    • Authors: Xiao Wang; Xianxiang Luo Hongli Jia Hao Zheng
      Abstract: Publication date: Available online 21 June 2017
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Xiao Wang, Xianxiang Luo, Hongli Jia, Hao Zheng
      The stable soil carbon (C) pool in coastal wetlands, referred to as ‘‘blue C’’, which has been extensively damaged by climate change and soil degradation, is of importance to maintain global C cycle. Therefore, to investigate the dynamic characteristics of soil respiration rate and evaluate C budgets in coastal wetlands are urgently. In this study, the diurnal and seasonal variation of soil respiration rate in the reed wetland land (RL) and the bare wetland land (BL) was measured in situ with the dynamic gas-infrared CO2 method in for seasons, and the factors impacted on the dynamic characteristics of soil respiration were investigated. The results showed that the diurnal variation of soil respiration rate consistently presented a “U” curve pattern in April, July, and September, with the maximum values at 12:00 AM and the minimum values at 6:00 AM. In the same season, the diurnal soil respiration rate in RL was significantly greater than those in BL (P < 0.05). In April, July, and September, the mean diurnal soil respiration rate was 0.14, 0.42, and 0.39 umol m-2 s-1 in RL, 0.05, 0.22, 0.13, and 0.01 umol m-2 s-1 in BL, respectively. Soil surface temperature was the primary factor that influenced soil respiration, which was confirmed by the exponential positive correlation between the soil respiration rate and soil surface temperature in BL and RL (P < 0.05). In addition, the high salinity of soils suppressed soil respiration, confirming by the significantly negative correlation between soil respiration rate and the content of soluble salt (S). These results will be useful for understanding the mechanisms underlying soil respiration and elevating C sequestration potential in the coastal wetlands.

      PubDate: 2017-06-22T07:11:36Z
       
  • Can Potamonautids be used as umbrella invertebrate species for
           conservation: identifying opportunities and challenges related to
           community sustainable livelihoods
    • Authors: Mwazvita TB. Dalu; Ryan J. Wasserman; Tatenda Dalu
      Abstract: Publication date: Available online 20 June 2017
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Mwazvita TB. Dalu, Ryan J. Wasserman, Tatenda Dalu
      In this study, we assessed direct or indirect community livelihoods impacts on the preservation of Potamonautes spp., in the Eastern Highlands region of Zimbabwe and attempted to identify opportunities and constraints to conservation of crabs within the pre-existing livelihoods of community households. Random and snowball sampling methods were used to select households for informal open-ended interviews and participants for the focus group discussions. We found that increasing human populations, poverty, crab consumption, and illegal mining (i.e. resulting in water pollution, degradation of habitats) are threatening freshwater crabs in the Eastern Highlands. The combined and interacting influences of the above highlighted anthropogenic factors have resulted in Potamonautes crab population declines in populated areas. Potamonautes spp. crabs were, therefore, found to be largely restricted to upstream mountainous sites where human populations were less dense. Patterns of spatial overlap of rural population, higher poverty prevalence and crab abundance revealed in this study indicate priority areas of possible conflicts of interest, but also areas where benefits to both conservation and livelihoods can potentially be realised.
      Graphical abstract image

      PubDate: 2017-06-22T07:11:36Z
      DOI: 10.1016/j.pce.2017.06.007
       
  • Diffused impact of grassland degradation over space: A case study in
           Qinghai province
    • Authors: Pei Wang; Xiangzheng Deng Sijian Jiang
      Abstract: Publication date: Available online 16 June 2017
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Pei Wang, Xiangzheng Deng, Sijian Jiang
      Our study aims to simulate and detect the interregional association of livestock production induced by grassland degradation in Qinghai province by TERM (The Enormous Regional Model). The shock variable, grassland degradation, is set and calculated by using its proxy, change of grassland area. We conclude that grassland area is decreasing during 1990-2008 in Qinghai province, and the average reduction rate is 1.591%. And grassland degradation in Qinghai province has a marginal effect on the other regions in China. Livestock production of the other 30 provinces expands in the case of the exogenous shock, and this impact is greater with a variation above 0.05% in Inner Mongolia, Tibet, Ningxia province and so on than the other regions. Thus, construction of ecological projects like natural reserves in Qinghai province for ecosystem conservation and livestock grazing benefits interregional equity and shrink their differences.

      PubDate: 2017-06-17T07:08:10Z
       
  • Factors influencing sustainability of communally-managed water facilities
           in rural areas of Zimbabwe
    • Authors: T. Kativhu; D. Mazvimavi; D. Tevera; I. Nhapi
      Abstract: Publication date: Available online 29 April 2017
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): T. Kativhu, D. Mazvimavi, D. Tevera, I. Nhapi
      Sustainability of point water facilities is a major development challenge in many rural settings of developing countries not sparing those in the Sub-Saharan Africa region. This study was done in Zimbabwe to investigate the factors influencing sustainability of rural water supply systems. A total of 399 water points were studied in Nyanga, Chivi and Gwanda districts. Data was collected using a questionnaire, observation checklist and key informant interview guide. Multi-Criteria analysis was used to assess the sustainability of water points and inferential statistical analysis such as Chi square tests and Analysis of Variance (ANOVA) were used to determine if there were significant differences on selected variables across districts and types of lifting devices used in the study area. The thematic approach was used to analyze qualitative data. Results show that most water points were not functional and only 17% across the districts were found to be sustainable. A fusion of social, technical, financial, environmental and institutional factors was found to be influencing sustainability. On technical factors the ANOVA results show that the type of lifting device fitted at a water point significantly influences sustainability (F=37.4, p< 0.01). Availability of spare parts at community level was found to be determining the downtime period of different lifting devices in the studied wards. Absence of user committees was found to be central in influencing sustainability as water points that did not have user committees were not sustainable and most of them were not functional during the time of the survey. Active participation by communities at the planning stage of water projects was also found to be critical for sustainability although field results showed passive participation by communities at this critical project stage. Financial factors of adequacy of financial contributions and establishment of operation and maintenance funds were also found to be of great importance in sustaining water supply systems. It is recommended that all factors should be considered when assessing sustainability since they are interrelated.

      PubDate: 2017-05-02T04:14:40Z
      DOI: 10.1016/j.pce.2017.04.009
       
  • Dispersion of inorganic contaminants in surface water in the vicinity of
           Potchefstroom
    • Authors: A. Manyatshe; E. Fosso-Kankeu; D. van der Berg; N. Lemmer; F. Waanders; H. Tutu
      Abstract: Publication date: Available online 27 April 2017
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): A. Manyatshe, E. Fosso-Kankeu, D. van der Berg, N. Lemmer, F. Waanders, H. Tutu
      Potchefstroom and the neighbouring cities rely mostly on the Mooi River and Vaal River for their water needs. These rivers flow through the gold mining areas and farms, and are therefore likely to be contaminated with substantial amounts of inorganic pollutants. Water was collected along the rivers network, streams, canals and dams in Potchefstroom and the vicinity. The samples were characterized for geochemical parameters, metals and anions concentrations. The results showed high concentrations of potentially toxic elements such as As (4.53 mg/L – 5.74 mg/L), Cd (0.25 mg/L – 0.7 mg/L), Pb (1.14 mg/L – 5.13 mg/L) and U (0.04 mg/L – 0.11 mg/L) which were predominantly found around the mining areas. Elevated concentrations of anions such SO4 2- and CN- were detected around mining areas while NO3 - was dominant near farms. The relatively high levels of anions and metals in the surface water made it unfit for domestic or agricultural use. The study showed that contaminants in mining and agricultural facilities were potentially mobilised, thus impacting the nearby water systems.

      PubDate: 2017-05-02T04:14:40Z
      DOI: 10.1016/j.pce.2017.04.008
       
 
 
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