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PHYSICS (576 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  [3118 journals]
  • Changes in ecosystem services associated with planting structures of
           cropland: A case study in Minle County in China
    • Authors: Yaqun Liu; Wei Song; Fengyun Mu
      Pages: 10 - 20
      Abstract: Publication date: December 2017
      Source:Physics and Chemistry of the Earth, Parts A/B/C, Volume 102
      Author(s): Yaqun Liu, Wei Song, Fengyun Mu
      The cropland ecosystem provides essential direct and indirect products and services to mankind such as food, fiber, biodiversity and soil conservation. A change of crop planting structure can change the ecosystem services of cropland by affecting land use type. In recent years, under the influence of regional comparative advantage and consumer demand changes, the crop planting structure in China has changed rapidly. However, there is still a lack of deep understanding on the effect of such a change in planting structure on the ecosystem services of cropland. Therefore, this research selected Minle County in the Heihe River Basin, which has small scattered croplands and a complex planting structure, as a study area. Based on the key time phase and optimal threshold of the normalized difference vegetation index (NDVI) data of the Thematic Mapper and Enhanced Thematic Mapper Plus (TM/ETM+) images, this study used the decision tree algorithm to classify and extract the crop planting structure in Minle County in 2007 and 2012 and to analyze the changes in its temporal and spatial patterns. Then, the market value method was adopted to estimate the effect of the change in crop planting structure on the ecosystem services of the cropland. From 2007 to 2012, the planting area of corn and rapeseed in Minle County increased by 5.86 × 103 ha and 5.10 × 103 ha, respectively. Conversely, the planting area of wheat and barley was reduced by 3.26 × 103 ha and 6.34 × 103 ha, respectively. These changes directly caused the increase of the ecosystem services value of corn and rapeseed by 1062.82 × 104 USD and 842.54 × 104 USD, respectively. The resulting reduction in the ecosystem services value of wheat and barley was 488.24 × 104 USD and 828.29 × 104 USD, respectively. Besides, the total ecosystem services value of cropland increased by 1564.98 × 104 USD. Further analysis found that the change in the crop planting structure caused an increase in the ecosystem services value of cropland of 359.44 × 104 USD, with a contribution rate of 22.97% to the total increase. The expansion of corn caused the increase of the ecosystem services value of cropland by 151.65 × 104 USD, with a contribution rate of 9.69% to the total increase. The change in crop planting structure in Minle County increased not only the economic benefits of crop planting, but also the ecosystem services of cropland.

      PubDate: 2017-11-17T15:31:14Z
      DOI: 10.1016/j.pce.2016.09.003
      Issue No: Vol. 102 (2017)
       
  • The potential vulnerability of the Namib and Nama Aquifers due to low
           recharge levels in the area surrounding the Naukluft Mountains, SW Namibia
           
    • Authors: Winnie N. Kambinda; Benjamin Mapani
      Pages: 31 - 39
      Abstract: Publication date: December 2017
      Source:Physics and Chemistry of the Earth, Parts A/B/C, Volume 102
      Author(s): Winnie N. Kambinda, Benjamin Mapani
      The Naukluft Mountains in the Namib Desert are a high rainfall-high discharge area. It sees increased stream-, spring-flow as well as waterfalls during the rainy season. The mountains are a major resource for additional recharge to the Namib and Nama aquifers that are adjacent to the mountains. This paper aimed to highlight the potential vulnerability of the aquifers that surround the Naukluft Mountain area; if the strategic importance of the Naukluft Karst Aquifer (NKA) for bulk water supply becomes necessary. Chloride Mass Balance Method (CMBM) was applied to estimate rainfall available for recharge as well as actual recharge thereof. This was applied using chloride concentration in precipitation, borehole and spring samples collected from the study area. Groundwater flow patterns were mapped from hydraulic head values. A 2D digital elevation model was developed using Arc-GIS. Results highlighted the influence of the NKA on regional groundwater flow. This paper found that groundwater flow was controlled by structural dip and elevation. Groundwater was observed to flow predominantly from the NKA to the south west towards the Namib Aquifer in two distinct flow patterns that separate at the center of the NKA. A distinct groundwater divide was defined between the two flow patterns. A minor flow pattern from the northern parts of the NKA to the north east towards the Nama Aquifer was validated. Due to the substantial water losses, the NKA is not a typical karst aquifer. While the project area receives an average rainfall of 170.36 mm/a, it was estimated that 1–14.24% (maximum 24.43 mm/a) rainfall was available for recharge to the NKA. Actual recharge to the NKA was estimated to be less than 1–18.21% (maximum 4.45 mm/a) reflecting the vast losses incurred by the NKA via discharge. This paper concluded that groundwater resources of the NKA were potentially finite. The possibility of developing the aquifer for bulk water supply would therefore drastically lower recharge to surrounding aquifers that sustain local populations because all received rainfall will be utilized to maximise recharge to the NKA instead of surrounding aquifers.

      PubDate: 2017-11-17T15:31:14Z
      DOI: 10.1016/j.pce.2016.12.002
      Issue No: Vol. 102 (2017)
       
  • Climate change induced by Southern Hemisphere desertification
    • Authors: Ye Wang; Xiaodong Yan
      Pages: 40 - 47
      Abstract: Publication date: December 2017
      Source:Physics and Chemistry of the Earth, Parts A/B/C, Volume 102
      Author(s): Ye Wang, Xiaodong Yan
      Some 10–20% of global dry-lands are already degraded, and the ongoing desertification threatens the world's poorest populations. Studies on desertification effects are essential for humans to adapt to the environmental challenges posed by desertification. Given the importance of the much larger southern ocean to the global climate and the Southern Hemisphere (SH) climate changes in phase with those in the north, the biogeophysical effects of the SH desertification on climate are assessed using an Earth system model of intermediate complexity, MPM-2. This analysis focuses on differences in climate among the averages of simulations with desert expansion in different latitude bands by year 2000. The localized desertification causes significant global changes in temperature and precipitation as well as surface albedo. On the global scale, cooling dominates the SH desertification effects. However, the biogeophysical effects are most significant in regions with desertification, and the cooling is also prominent in northern mid-latitudes. Desert expansion in 15°–30°S reveals statistically most significant cooling and increased precipitation over the forcing regions during spring. The global and regional scale responses from desertification imply the climate teleconnection and address the importance of the effects from the SH which are contingent on the location of the forcing. Our study indicates that biogeophysical mechanisms of land cover changes in the SH need to be accounted for in the assessment of land management options especially for latitude band over 15°-30°S.

      PubDate: 2017-11-17T15:31:14Z
      DOI: 10.1016/j.pce.2016.03.009
      Issue No: Vol. 102 (2017)
       
  • Timescale differences between SC-PDSI and SPEI for drought monitoring in
           China
    • Authors: Haiyan Zhao; Ge Gao; Wei An; Xukai Zou; Haitao Li; Meiting Hou
      Pages: 48 - 58
      Abstract: Publication date: December 2017
      Source:Physics and Chemistry of the Earth, Parts A/B/C, Volume 102
      Author(s): Haiyan Zhao, Ge Gao, Wei An, Xukai Zou, Haitao Li, Meiting Hou
      The Palmer Drought Severity Index (PDSI) has been widely used to monitor drought. Its characteristics are more suitable for measuring droughts of longer timescales, and this fact has not received much attention. The Standardized Precipitation Evapotranspiration Index (SPEI) can better reflect the climatic water balance, owing to its combination of precipitation and potential evapotranspiration. In this study, we selected monthly average air temperature and precipitation data from 589 meteorological stations of China's National Meteorological Information Center, to compare the effects of applying a self-calibrating PDSI (SC-PDSI) and SPEI to monitor drought events in the station regions, with a special focus on differences of event timescale. The results show the following. 1) Comparative analysis using SC-PDSI and SPEI for drought years and characters of three dry periods from 1961 to 2011 in the Beijing region showed that durations of SC-PDSI-based dry spells were longer than those of 3-month and 6-month SPEIs, but equal to those of 12-month or longer timescale SPEIs. 2) For monitoring evolution of the fall 2009 to spring 2010 Southwest China drought and spring 2000 Huang-Huai drought, 3-month SPEI could better monitor the initiation, aggravation, alleviation and relief of drought in the two regions, whereas the SC-PDSI was insensitive to drought recovery because of its long-term memory of previous climate conditions. 3) Analysis of the relationship between SC-PDSI for different regions and SPEI for different timescales showed that correlation of the two indexes changed with region, and SC-PDSI was maximally correlated with SPEI of 9–19 months in China. Therefore, SC-PDSI is only suitable for monitoring mid- and long-term droughts, owing to the strong lagged autocorrelation such as 0.4786 for 12-month lagged ones in Beijing, whereas SPEI is suitable for both short- and long-term drought-monitoring and should have greater application prospects in China.

      PubDate: 2017-11-17T15:31:14Z
      DOI: 10.1016/j.pce.2015.10.022
      Issue No: Vol. 102 (2017)
       
  • Reception conditions of low frequency (LF) transmitter signals onboard
           DEMETER micro-satellite
    • Authors: M.Y. Boudjada; P.F. Biagi; E. Al-Haddad; P.H.M. Galopeau; B. Besser; D. Wolbang; G. Prattes; H. Eichelberger; G. Stangl; M. Parrot; K. Schwingenschuh
      Pages: 70 - 79
      Abstract: Publication date: December 2017
      Source:Physics and Chemistry of the Earth, Parts A/B/C, Volume 102
      Author(s): M.Y. Boudjada, P.F. Biagi, E. Al-Haddad, P.H.M. Galopeau, B. Besser, D. Wolbang, G. Prattes, H. Eichelberger, G. Stangl, M. Parrot, K. Schwingenschuh
      We analyse the flux density variation associated to low frequency (LF) broadcasting transmitters observed by the ICE electric field experiment onboard DEMETER micro-satellite, observed from 01st Jan. to 09th Dec. 2010. We select five stations localized around the Mediterranean and the Black seas: Tipaza (252 kHz, 02°28′E, 36°33′N, Algeria), Roumoules (216 kHz, 06°08′E, 43°47′N, Monte Carlo), Polatli (180 kHz, 32°25′E, 39°45′N, Turkey), Nadour (171 kHz, 02°55′W, 35°02′N, Morocco) and Brasov (153 kHz, 25°36′E, 45°40′, Romania). The detection of the LF transmitter signals by DEMETER micro-satellite is found to depend on the radiated power, the emitted frequency, and the orbit paths with regard to the location of the stations. This leads us to characterize the reception condition of the LF signals and to define time intervals where the detection probability is high. We show that LF signal are regularly recorded, each 12 days, when the satellite is above the broadcasting station. The signal intensity levels are principally significant during the solar activity. Hence we find that the solar and the geomagnetic activities are slightly correlated to the maxima of LF signal as recorded by DEMETER. Also we note a drop of the intensity level several days before the occurrence of earthquakes in/around the Mediterranean and Black seas.

      PubDate: 2017-11-17T15:31:14Z
      DOI: 10.1016/j.pce.2016.07.006
      Issue No: Vol. 102 (2017)
       
  • Physical and Economic Processes of Ecosystem Services Flows
    • Authors: Hongbo Su; Sudhagar Nagarajan; Jinwei Dong
      Pages: 1 - 2
      Abstract: Publication date: October 2017
      Source:Physics and Chemistry of the Earth, Parts A/B/C, Volume 101
      Author(s): Hongbo Su, Sudhagar Nagarajan, Jinwei Dong


      PubDate: 2017-12-18T09:34:48Z
      DOI: 10.1016/j.pce.2017.10.001
      Issue No: Vol. 101 (2017)
       
  • Measuring environmental performance of industrial sub-sectors in China: A
           stochastic metafrontier approach
    • Authors: Yuping Bai; Xiangzheng Deng; Qian Zhang; Zhan Wang
      Pages: 3 - 12
      Abstract: Publication date: October 2017
      Source:Physics and Chemistry of the Earth, Parts A/B/C, Volume 101
      Author(s): Yuping Bai, Xiangzheng Deng, Qian Zhang, Zhan Wang
      In this paper, we quantitatively measure the environmental performance and potential capacities of carbon emission mitigation of 39 industrial sectors in China during 2005–2011 by adopting a stochastic metafrontier approach. We also analyze the differences of environmental performance and technology gap ratios (TGRs) across three categorized industrial groups. Cluster analysis of carbon intensity provides the categorized groups. The results show that due to neglect of technology gaps among the categorized groups, the environmental performance measured by a stochastic frontier approach (SFA) is underestimated. Comparison analysis infers that, relative to the metafrontier, the industrial sectors in Group 1 achieve the highest environmental performance and TGRs, while environmental performance and TGRs of industrial sectors in Group 3 is still at a low level for lack of advanced production technology. Industrial sectors also perform significant differences on potential capacities of carbon emission mitigation. We suggest that policies and regulations on industrial technology innovation and control of carbon emissions should be strengthened for eco-efficient and sustainable development.

      PubDate: 2017-12-18T09:34:48Z
      DOI: 10.1016/j.pce.2016.12.007
      Issue No: Vol. 101 (2017)
       
  • Land-use-change induced dynamics of carbon stocks of the terrestrial
           ecosystem in Pakistan
    • Authors: Dongdong Chen; Xiangzheng Deng; Gui Jin; Abdus Samie; Zhaohua Li
      Pages: 13 - 20
      Abstract: Publication date: October 2017
      Source:Physics and Chemistry of the Earth, Parts A/B/C, Volume 101
      Author(s): Dongdong Chen, Xiangzheng Deng, Gui Jin, Abdus Samie, Zhaohua Li
      In recent years, dramatic decline of ecosystem service due to large scale human induced land use change activities, which has received much attention of researchers as diminishing of ecosystem function affects the sustainability of human society, economy and environmental protection. The study aims to analyze the impact of land use change on ecosystem service of carbon sequestration in Pakistan. This study, based on Dynamics of Land System (DLS) model, simulating the future land use changes, combing with Integrated Valuation of Environmental Services and Trade-offs (InVEST) model, has analyzed the changes in quantity and distribution of carbon stock in Pakistan under alternative land use scenarios for 2020 using historical land use data from 2006 to 2009. The results indicate that comparing the carbon stocks in 2009, only the Business-as-usual scenario of carbon stocks continue to decrease; the other two scenarios of carbon stocks show the increasing trend. Moreover, the Ecological protection scenario has the highest carbon storage, but it is not feasible to the current conditions of Pakistan, whereas Investment priority oriented scenario could be ideal one. The advances in research underpin scientific efforts to connect dynamic land use change with ecosystem service of carbon storage in Pakistan.

      PubDate: 2017-12-18T09:34:48Z
      DOI: 10.1016/j.pce.2017.01.018
      Issue No: Vol. 101 (2017)
       
  • Effect of particulate air pollution on coronary heart disease in China:
           Evidence from threshold GAM and Bayesian hierarchical model
    • Authors: Xiaoyu Chen
      Pages: 35 - 42
      Abstract: Publication date: October 2017
      Source:Physics and Chemistry of the Earth, Parts A/B/C, Volume 101
      Author(s): Xiaoyu Chen
      There are few multicity studies to address the effect of short-term effect of particulate matter air pollution on daily Coronary Heart Disease (CHD) mortality in developing countries, much fewer to further discuss its threshold and seasonal effect. This study investigates the season-varying association between particulate matter less than or equal to 10 μm in aerodynamic diameter (PM10) and daily CHD mortality in seven cities of China. Time series threshold Poisson regression model is specified to estimate the health effect for four cities with the threshold effect, and conventional linear Poisson model is used to analyze the effect for three cities without threshold. We apply the Bayesian hierarchical model to pool the city-specific estimates into overall level. On average, a 10 μg/m3 increase of the moving average concentrations of current-day and previous-day PM10 is associated with an increase of 0.81% (95% Posterior Interval, PI: −0.04%, 1.67%) in daily CHD mortality for all the cities as a whole. The associations are smaller than reported in developed countries or regions with lower polluted level, which is consistent to the findings in the literature. The hazardous effect are higher in hot summer and cold winter (1.15% and 0.89%) but lower in relative warm spring and fall (0.85% and 0.69%). In summary, we found significant associations between short-term exposure to PM10 and CHD mortality in China. The sensitivity analyses in the study support the robustness of our results.

      PubDate: 2017-12-18T09:34:48Z
      DOI: 10.1016/j.pce.2017.01.013
      Issue No: Vol. 101 (2017)
       
  • Ecological security assessment based on ecological footprint approach in
           Beijing-Tianjin-Hebei region, China
    • Authors: Xi Chu; Xiangzheng Deng; Gui Jin; Zhan Wang; Zhaohua Li
      Pages: 43 - 51
      Abstract: Publication date: October 2017
      Source:Physics and Chemistry of the Earth, Parts A/B/C, Volume 101
      Author(s): Xi Chu, Xiangzheng Deng, Gui Jin, Zhan Wang, Zhaohua Li
      Recently, researcher have been extensively using ecological footprint to quantitatively measure human pressure on ecosystems. This paper put forward ecological tension index (ETI), ecological occupancy index (EOI) and ecological economic coordination index (EECI) to evaluate ecological security of the Beijing-Tianjin-Hebei (BTH) region between 1995 and 2010. The results came as follows. (1) The ecological footprint of BTH region was increased, while the carrying capacity (biocapacity) of the terrestrial ecosystem was decreased. This led the region to a serious ecological deficit that was increased by 1.77 times. (2) ETI level of the region was found very risky. EOI level fluctuated from poor to moderately poor, indicating that rapid economic development has pressurized the ecosystem. EECI level indicated a very poor coordination between economic development and ecosystem conservation. (3) As to the indices results for sub-regions, ETI level in Tianjin was evaluated very risky, in Beijing it was changed from risky to very risky, while in Hebei it was changed from very risky to risky. EOI level in Beijing was changed from moderately poor to poor, keeping poor for long time. However, the EOI level in Tianjin and Hebei was found opposite to Beijing. It was changed from poor to moderately poor. While EECI level of Beijing, Tianjin and Hebei was found very poor, meaning economic development and ecosystem conservation are maintained imbalanced. This study finally concludes that whether the whole region or the sub-regions, their existing development patterns were unsustainable, and ecological security situation was serious.

      PubDate: 2017-12-18T09:34:48Z
      DOI: 10.1016/j.pce.2017.05.001
      Issue No: Vol. 101 (2017)
       
  • Can Potamonautids be used as umbrella invertebrate species for
           conservation: Identifying opportunities and challenges related to
           community sustainable livelihoods
    • Authors: Mwazvita T.B. Dalu; Ryan J. Wasserman; Tatenda Dalu
      Pages: 52 - 58
      Abstract: Publication date: October 2017
      Source:Physics and Chemistry of the Earth, Parts A/B/C, Volume 101
      Author(s): Mwazvita T.B. 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: 2017-12-18T09:34:48Z
      DOI: 10.1016/j.pce.2017.06.007
      Issue No: Vol. 101 (2017)
       
  • The urbanization efficiency in Chengdu City: An estimation based on a
           three-stage DEA model
    • Authors: Siqi Jia; Chengxin Wang; Yifan Li; Fan Zhang; Wei Liu
      Pages: 59 - 69
      Abstract: Publication date: October 2017
      Source:Physics and Chemistry of the Earth, Parts A/B/C, Volume 101
      Author(s): Siqi Jia, Chengxin Wang, Yifan Li, Fan Zhang, Wei Liu
      With economic development and population growth occurring throughout China, there has been increasing conflicts between resources, environmental protection and economic development in many regions, especially in the developed regions. Therefore, it is important to correctly evaluate the pressure of human activities on the natural environment and the ecosystem carrying capacity at a regional scale. This paper evaluated the urbanization efficiency based on the three-stage Data Envelopment Analysis (DEA) model, which takes the impacts of exogenous factors on the urbanization rate into consideration. From the perspectives of governmental management and urban growth and scale, this paper indicated the current urbanization mode and features in Chengdu based on land use data, socioeconomic and natural data in each district and county. The results show that Jinjiang, Longquanyi, Qingbaijiang, Qingyang districts, Pujiang, Xinjin counties and Dujiangyan county-level city are always with the balanced urbanization efficiency; while the efficiency in Dayi, Pi counties, Chongzhou, Pengzhou, Qionglai county-level cities and Jinniu, Chenghua districts still needs to be improved; and Shuangliu and Jintang counties keep the lowest urbanization level. Overall, the average reduction rate in built-up area in highest at 29.57% among the three input indicators (land, capital and labor), which means that the superfluous area of built-up land hinders the balanced development of urbanization in Chengdu. It also suggests that three-stage DEA model is effective to reflect the realistic level of urbanization efficiency by eliminating environmental impact. Finally, this paper further provides improved directions and policy suggestions for the sustainable and well-rounded urban development.

      PubDate: 2017-12-18T09:34:48Z
      DOI: 10.1016/j.pce.2017.05.003
      Issue No: Vol. 101 (2017)
       
  • Optimization of land-use management for ecosystem service improvement: A
           review
    • Authors: Gui Jin; Xiangzheng Deng; Xi Chu; Zhihui Li; Yuan Wang
      Pages: 70 - 77
      Abstract: Publication date: October 2017
      Source:Physics and Chemistry of the Earth, Parts A/B/C, Volume 101
      Author(s): Gui Jin, Xiangzheng Deng, Xi Chu, Zhihui Li, Yuan Wang
      Land use is closely related to human activity, which affect ecosystem services by changing the types, patterns and ecological processes of ecosystem, and consequently impact the human well-being. Scientific simulation is needed to analyze the land use policy impacts on ecosystem services and socioeconomic development. Based on the reviews, the Computable General Equilibrium (CGE) model plays an important role in building simulation framework for land-use management optimization for ecosystem services improvement, which can be used to systematically analyze changes of ecosystem service driven by land use change as well as the consequent impacts on socioeconomic development. In addition, the similarities and differences between the CGE model and System Dynamics (SD) model are identified. CGE and SD models have their advantages and disadvantages, a suitable model can be select in the practice of policy simulation. In this sense, these simulation models are of great significance to decision-making on land-use management measures for ecosystem service conservation and socioeconomic development.

      PubDate: 2017-12-18T09:34:48Z
      DOI: 10.1016/j.pce.2017.03.003
      Issue No: Vol. 101 (2017)
       
  • Scenario simulation of land exploitation and risk assessment of soil
           erosion in the low-slope hilly area of the Erhai basin
    • Authors: Gui Jin; Xiangzheng Deng; Yongwei Yuan; Sai Ma; Zhaohua Li; Saiya Shi
      Pages: 78 - 85
      Abstract: Publication date: October 2017
      Source:Physics and Chemistry of the Earth, Parts A/B/C, Volume 101
      Author(s): Gui Jin, Xiangzheng Deng, Yongwei Yuan, Sai Ma, Zhaohua Li, Saiya Shi
      Risk assessment of soil erosion is an important prerequisite to develop the low-slope hilly in basin-scale. Using Dynamics of Land System model (DLS), we design the scenario simulation of land exploitation of Dali city which is located in the Erhai basin and typical as low-slope hilly area. Then we bring in Universal Soil Loss Equation (USLE) to assess the risks of soil erosion under different scenarios. In two simulating scenarios, baseline scenario and planning scenario respectively, the spatial distribution pattern of land use of the study area in 2020 shows an overall consistency and a partial difference. The cultivated resources of Dali has been protected since the cultivated land located in dam area has not changed, while construction land has expanded more or less on the basis of existing built-up areas. Specifically, the expansion of construction land in planning scenario is concentrated on Haidong town and Fengyi town where there are rich in low-slope hilly resources. In two scenarios mentioned above, both the value-at-risk of soil erosion and its risk level have no significant rise or drop from 2008 to 2020. As the risk index of soil erosion in baseline scenario is 0.003 taller than in planning scenario, one conclusion can be drawn that the planning scenario will lower the overall risk of soil erosion and should be used to develop gentle hillside area in Erhai basin. The risk evaluation of soil erosion under different scenarios is valuable for land management decisions because the results provide fundamental information for optimal utilization of land use and prevention of ecological risks in the low-slope hilly regions.

      PubDate: 2017-12-18T09:34:48Z
      DOI: 10.1016/j.pce.2017.01.020
      Issue No: Vol. 101 (2017)
       
  • Responses of the water-yield ecosystem service to climate and land use
           change in Sancha River Basin, China
    • Authors: Yanqing Lang; Wei Song; Ying Zhang
      Pages: 102 - 111
      Abstract: Publication date: October 2017
      Source:Physics and Chemistry of the Earth, Parts A/B/C, Volume 101
      Author(s): Yanqing Lang, Wei Song, Ying Zhang
      Water supply is a key ecosystem service, directly influencing sustainable development of the social economy and ecological systems. Climate and land use change are two important factors that affect water supply. Since the 1990s, China has implemented a series of land use policies, such as the grain-for-green program, which have significantly changed land use patterns. However, the effect of global climate change on water resources in China is growing, resulting in water shortages and deterioration of the aqueous environment. In this context, China's land use change, concurrent with the impacts of climate change on regional water resources, has become an issue worthy of discussion. This work analyzed the effect of land use and climate change on water yield in 1990 and 2010 using the Sancha River Basin as a case study. The variations in water yield in Sancha River Basin were simulated using the water-yield module in the InVEST (Integrated Valuation of Ecosystem Services and Tradeoffs) model for three scenarios. The first scenario incorporated land use and climate change into the model in accordance with actual conditions. The second scenario was a simulation without climate change, and the third was without land use change. Water yield in Sancha River Basin increased by 17% between the two time periods in the actual scenario. In the scenario without climate change, land use conversions led to a 0.46% reduction in water yield. In the scenario without land use change, climate change led to a 17.50% increase in regional water yield due to precipitation. The impact of rainfall change on the Sancha River Basin water yield was as high as 97.44% while that of land use change was only 2.56%. This study shows that the grain-for-green program has negatively impacted water yield. Furthermore, to improve the ecological environment of the river basin, a comprehensive scheme for controlling water and soil erosion should be implemented according to the actual variation in water yield. This would give full consideration to the utility of water resources.

      PubDate: 2017-12-18T09:34:48Z
      DOI: 10.1016/j.pce.2017.06.003
      Issue No: Vol. 101 (2017)
       
  • Scenario analysis of land use change in Kabul River Basin – A river
           basin with rapid socio-economic changes in Afghanistan
    • Authors: Omaid Najmuddin; Xiangzheng Deng; Jia Siqi
      Pages: 121 - 136
      Abstract: Publication date: October 2017
      Source:Physics and Chemistry of the Earth, Parts A/B/C, Volume 101
      Author(s): Omaid Najmuddin, Xiangzheng Deng, Jia Siqi
      Land use management has a great importance in socio-economic development of countries and regions. Recently, Afghanistan has, at one hand, experienced significant socio-economic changes through political and economic transformation and, on the other hand it is considered amongst vulnerable countries to climate and other natural changes. For this, understanding the interactions between socio-economic and natural changes with land use change under different development scenarios is crucial for sustainable land use management. Present research took Kabul River Basin (KRB) as a case study area and used Dynamic of Land System (DLS) model to simulate land use/cover for the years of 2020 and 2030. For this purpose, various socio-economic and bio-physical datasets were prepared and then integrated into the model under three different scenarios i.e. baseline, economic development, and environmental protection. The results indicated a significant land use change under all three scenarios. Cultivated land, grassland and built-up area will significantly increase under all three scenarios; while forest area, water area and unused land will significantly decrease under the economic development and baseline scenarios. While in the environmental protections scenario, the forest area will considerably increase, however, water area still showed a decreasing trend but it will be lesser as compared to the other two scenarios. By considering the above degradations, particularly under baseline and economic scenarios, it is suggested that the government needs to develop overall land use planning in KRB to achieve a rational exploitation of land resources and we hoped that the results of this study will help to target management decisions on rational land uses and effective environment protections of KRB.

      PubDate: 2017-12-18T09:34:48Z
      DOI: 10.1016/j.pce.2017.06.002
      Issue No: Vol. 101 (2017)
       
  • Field assessment of surface runoff, sediment yield and soil erosion in the
           opencast mines in Chirimiri area, Chhattisgarh, India
    • Authors: G.K. Nigam; R.K. Sahu; M.K. Sinha; X. Deng; R.B. Singh; P. Kumar
      Pages: 137 - 148
      Abstract: Publication date: October 2017
      Source:Physics and Chemistry of the Earth, Parts A/B/C, Volume 101
      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 in soil sediment deposition from the overburdened dump. Dwindling resources has compelled the policy makers to search for alternatives such as waste lands and mined areas to improve soil and water resources for use in agriculture and allied sectors while maintaining the local ecology and hydrology. Most Opencast mines release huge amount of mining wastes in the form of overburden dump (OBD) materials that are prone to soil erosion and also create problems of sedimentation and deteriorating 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 byRevised Universal Soil Loss Equation (RUSLE) method and was compared with direct field measurements by placing plastic sheets in downstream portion of OBD. As a result monsoon rainfall constitutes 91.6 percent of the annual rainfall and surface runoff constitutes 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 Electrical Conductivity (EC), Organic Content (OC), Water Holding Capacities (WHC), and Available Nitrogen (N), Phosphorus (P) and Potassium (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. This can be eventually used for leguminous fodder/grass production.

      PubDate: 2017-12-18T09:34:48Z
      DOI: 10.1016/j.pce.2017.07.001
      Issue No: Vol. 101 (2017)
       
  • Set pair analysis method for coordination evaluation in water resources
           utilizing conflict
    • Authors: Zhengwei Pan; Yanhua Wang; Juliang Jin; Xiaowei Liu
      Pages: 149 - 156
      Abstract: Publication date: October 2017
      Source:Physics and Chemistry of the Earth, Parts A/B/C, Volume 101
      Author(s): Zhengwei Pan, Yanhua Wang, Juliang Jin, Xiaowei Liu
      In order to describe management problems of water resource system conflicts quantitatively, six elements were proposed in the management of water resources conflicts, which are coordination participator, coordination goal, coordination index, behavioral strategies, coordination situation and coordination rule. In the coordination management of conflicts in water resource systems a coordination index has a lower limiting value meeting the coordination participator interests, and has an upper limiting value for ensuring the interests of the overall system and other coordination participators. When the coordination index value exceeds the limiting range, the interests of the overall system and other coordination participators cannot be guaranteed. The coordination indexes of water resources conflict are interval numbers. According to the characteristics of interval pattern indexes, the bidirectional connection number was proposed to describe the coordination degree. Based on the bidirectional connection number, the coordination evaluation method was developed, and was used in the coordination evaluation of water resource conflicts in the Yellow River basin. The results showed that the coordination status of water resources utilization was generally acceptable. However, with increasing water consumption in some provinces in the Yellow River basin in recent years, the available water supply cannot meet the allocation plan for water resource supply. The coordination degree of water resources utilization has, therefore, been declining.

      PubDate: 2017-12-18T09:34:48Z
      DOI: 10.1016/j.pce.2017.05.009
      Issue No: Vol. 101 (2017)
       
  • Diffused impact of grassland degradation over space: A case study in
           Qinghai province
    • Authors: Pei Wang; Xiangzheng Deng; Sijian Jiang
      Pages: 166 - 171
      Abstract: Publication date: October 2017
      Source:Physics and Chemistry of the Earth, Parts A/B/C, Volume 101
      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: 2017-12-18T09:34:48Z
      DOI: 10.1016/j.pce.2017.06.006
      Issue No: Vol. 101 (2017)
       
  • Exploration of the causality between area changes of green spaces and
           waterlogging frequency in Beijing
    • Authors: Guofeng Wang; Jiancheng Chen; Chunhong Zhao; Xiaoxue Zhou; Xiangzheng Deng
      Pages: 172 - 177
      Abstract: Publication date: October 2017
      Source:Physics and Chemistry of the Earth, Parts A/B/C, Volume 101
      Author(s): Guofeng Wang, Jiancheng Chen, Chunhong Zhao, Xiaoxue Zhou, Xiangzheng Deng


      PubDate: 2017-12-18T09:34:48Z
      DOI: 10.1016/j.pce.2017.03.001
      Issue No: Vol. 101 (2017)
       
  • Balancing water demand for the Heihe River Basin in Northwest China
    • Authors: Feng Wu; Yuping Bai; Yali Zhang; Zhihui Li
      Pages: 178 - 184
      Abstract: Publication date: October 2017
      Source:Physics and Chemistry of the Earth, Parts A/B/C, Volume 101
      Author(s): Feng Wu, Yuping Bai, Yali Zhang, Zhihui Li
      Water 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: 2017-12-18T09:34:48Z
      DOI: 10.1016/j.pce.2017.07.002
      Issue No: Vol. 101 (2017)
       
  • Impacts of land use/cover change on terrestrial carbon stocks in Uganda
    • Authors: Fan Zhang; Jinyan Zhan; Qian Zhang; Lina Yao; Wei Liu
      Pages: 195 - 203
      Abstract: Publication date: October 2017
      Source:Physics and Chemistry of the Earth, Parts A/B/C, Volume 101
      Author(s): Fan Zhang, Jinyan Zhan, Qian Zhang, Lina Yao, Wei Liu
      Land use/cover change, especially conversion and degradation of forest land, is the key factor causing terrestrial carbon stocks declines in Uganda. How local ecological assemblages are responding is less clear—a concern given their importance for many ecosystem functions and services. The main objectives are to assess status and variation in carbon stocks across land covers and quantify spatial distribution and dynamic variation of terrestrial carbon stocks in response to land use/cover change. This paper presents a methodology for quantifying and assessing changes in carbon stocks as a result of land use change using the Integrated Valuation of Ecosystem Services and Tradeoffs (InVEST) model. The model was used to map and quantify carbon stocks for Uganda for 2006 and 2010 land use conditions. Our result showed that the total carbon stocks have a sharp decline from 2.42 billion Tg C in 2006 to 1.72 billion Tg C in 2010 in aboveground, belowground and soil. During 2006 to 2010, losses in carbon stocks from land use and land cover were 705.59 million Tg C. To be more specific, estimated carbon stocks in Uganda decreased 849.94 million Tg C because forest land changed to other land use and covers. Cultivated land change, which is from other types of land, resulting in carbon stocks decreased 71.11 million Tg C, and estimated carbon stocks increased 177.34 million Tg C with grassland changed to other land use and covers. Finally, we suggested potential policy measures to mitigate negative effects of land use and cover change on carbon stocks in Uganda.

      PubDate: 2017-12-18T09:34:48Z
      DOI: 10.1016/j.pce.2017.03.005
      Issue No: Vol. 101 (2017)
       
  • Impacts of water scarcity on socio-economic development: A case study of
           Gaotai County, China
    • Authors: Qing Zhou; Xiangzheng Deng; Feng Wu
      Pages: 204 - 213
      Abstract: Publication date: October 2017
      Source:Physics and Chemistry of the Earth, Parts A/B/C, Volume 101
      Author(s): Qing Zhou, Xiangzheng Deng, Feng Wu
      Provisioning services for socio-economic development are important hydrological ecosystem services that humans obtain from freshwater. The conflict between water scarcity and economic development in arid regions affects water utilization among different sectors. A water resource embedded social accounting matrix (SAM) can help to analyze the relationship between water resource utilization and socio-economic development. In this paper, a water resource embedded SAM was constructed in Gaotai County, northwestern China and the SAM multiplier model was applied to explore the economic structure, feedback mechanisms, and water flows among different sectors. Furthermore, scenario analyses were conducted to simulate the impacts of different policies on regional economic development and water resource utilization patterns. Through the multiplier analysis, we found that agriculture is less productive than the secondary industries because of its low development stage and lack of deep processing chains. However, the influence of agricultural sectors on the whole economic system outweighs the influence of the secondary and tertiary industries. Results also indicated that expanding agricultural exports can promote rural employment and improve rural household welfare, but will also lead to water resources outflow and aggravate water conflicts among different water users. At last, the simulation results of price reform showed that agriculture water price increase will cause a chain effects among different sectors. Water price increases by one unit will lead to the price of agricultural products, industrial products, and labor increase by 0.03, 0.018, and 0.005 units, respectively and the Consumer Price Index increases by 0.005 units.

      PubDate: 2017-12-18T09:34:48Z
      DOI: 10.1016/j.pce.2017.03.009
      Issue No: Vol. 101 (2017)
       
  • Impact assessment of climate change on poverty reduction: A global
           perspective
    • Authors: Xiaoxue Zhou; Jiancheng Chen; Zhihui Li; Guofeng Wang; Fan Zhang
      Pages: 214 - 223
      Abstract: Publication date: October 2017
      Source:Physics and Chemistry of the Earth, Parts A/B/C, Volume 101
      Author(s): Xiaoxue Zhou, Jiancheng Chen, Zhihui Li, Guofeng Wang, Fan Zhang
      Climate change and its impacts are the biggest environmental problems 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 affects poverty reduction is of great significance to the comprehensive assessment of climate change impacts on social economy and mitigation of its 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 that 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 when analyze climate changes’ impacts most concentrated on coastal urban areas, this paper is focused more on the rural poor areas and conduct a contrastive analysis of different income groups of countries. 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 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: 2017-12-18T09:34:48Z
      DOI: 10.1016/j.pce.2017.06.011
      Issue No: Vol. 101 (2017)
       
  • 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)
       
  • Evaluation of ecosystem service based on scenario simulation of land use
           in Yunnan Province
    • Authors: Hong Zhang; Xiaoli Liao; Tianlin Zhai
      Abstract: Publication date: Available online 26 December 2017
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Hong Zhang, Xiaoli Liao, Tianlin Zhai
      Climate change and rapid urbanization are important factors restricting future land use. Situational analysis, as an important foundation for the optimization of land use, needs to focus on the impact of climate factors and socio-economic factors. In this paper, the Markov model and the DLS (Simulation of Land System Dynamics) model are combined for the first time, and the land use pattern in 2020 is simulated based on the data of land use in 2000 and 2010 as well as the climate, soil, topography and socio-economic factors of Yunnan Province. In his paper, we took Yunnan Province as the case study area, and selected 12 driving factors by logistic regression method, then the land use demands and layout of Yunnan Province in 2020 has been forecasted and simulated under business as usual (BAU) scenario and farmland protection (FP) scenario and the changes in ecosystem service value has been calculated. The result shows that: (1) after the regression analysis and ROC (Relative Operating Characteristics) test, the 12 factors selected in this paper have a strong ability to explain the land use change in Yunnan Province. (2) Under the two scenarios, the significant reduction of arable land area is a common feature of land use change in Yunnan Province in the future, and its main land use type will be construction land. However, under FP scenario, the current situation where construction land encroach on arable land will be improved. Compared with the change from 2000 to 2010, the trend of arable land, forest land, water area, construction land and unused land will be the same under the two scenarios, whereas the change trend of grassland was opposite. (3) From 2000 to 2020, the value of ecosystem services in Yunnan Province is on the rise, but the ecosystem service value under FP scenario is higher than that of the ecosystem services under BAU scenario. In general, land use in 2020 in Yunnan Province continues the pattern of 2010, but there are also significant spatial differences. Under the BAU scenario, the construction land is mainly in the south of Lijiang City and the northeastern part of Kunming. Under the FP scenario, the new construction land is concentrated near the Lashi dam in northern Yunnan Province, and the high-quality arable land in the valley will be better protected. The research results can provide reference for the optimization of land use pattern in Yunnan Province, and provide scientific basis for land use management and planning. Based on the value of ecosystem services, we should implement the policy of strict protection of arable land, both to ensure food supply and promote the healthy development of ecological environment.

      PubDate: 2017-12-26T19:21:10Z
      DOI: 10.1016/j.pce.2017.12.001
       
  • 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
      Abstract: Publication date: Available online 25 December 2017
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      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: 2017-12-26T19:21:10Z
      DOI: 10.1016/j.pce.2017.12.002
       
  • When good practices by water committees are not relevant: Sustainability
           of small water infrastructures in semi-arid mozambique
    • Authors: Ducrot
      Abstract: Publication date: December 2017
      Source:Physics and Chemistry of the Earth, Parts A/B/C, Volume 102
      Author(s): Raphaëlle Ducrot
      This paper explores the contradiction between the need for large scale interventions in rural water supplies and the need for flexibility when providing support for community institutions, by investigating the implementation of the Mozambique - National Rural Water Supply and Sanitation Program in a semi-arid district of the Limpopo Basin. Our results showed that coordinated leadership by key committee members, and the level of village governance was more important for borehole sustainability than the normative functioning of the committee. In a context in which the centrality of leadership prevails over collective action the sustainability of rural water infrastructure derives from the ability of leaders to motivate the community to provide supplementary funding. This, in turn, depends on the added value to the community of the water points and on village politics. Any interventions that increased community conflicts, for example because of lack of transparency or unequitable access to the benefit of the intervention, weakened the coordination and the collective action capacity of the community and hence the sustainability of the infrastructures even if the intervention was not directly related to water access. These results stress the importance of the project/program implementation pathway.

      PubDate: 2017-11-17T15:31:14Z
       
  • Projected land use changes impacts on water yields in the karst mountain
           areas of China
    • Authors: Yanqing Lang; Wei Song; Xiangzheng Deng
      Abstract: Publication date: Available online 6 November 2017
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Yanqing Lang, Wei Song, Xiangzheng Deng
      Human-induced land use changes over short time scales have significant impacts on water yield, especially in China because of the rapid social economic development. As the biggest developing country of the world, China's economy is expected to continuously grow with a high speed in the next few decades. Therefore, what kind of land use changes will occur in the future in China' How these changes will influence the water yields' To address this issue, we assessed the water yields in the karst mountain area of China during the periods of 1990–2010 and 2010–2030 by coupling an Integrated Valuation of Ecosystem Services and Tradeoffs (InVEST) model and a Conversion of Land Use and its Effects (CLUE) model. Three different land use scenarios i.e. natural growth, economic development, and ecological protection, were developed in 2030 using the CLUE model. It was concluded that, given land use changes between 1990 and 2010, total water yields in the karst mountain area are characterized by a trend towards fluctuating reduction. However, total water yields of 2030 in the economic development scenario revealed an increase of 1.25% compared to the actual water yields in 2010. The economy development in karst mountain areas of China in the future has a slight positive influence on water yields.

      PubDate: 2017-11-17T15:31:14Z
      DOI: 10.1016/j.pce.2017.11.001
       
  • Association between forestry ecological engineering and dust weather in
           Inner Mongolia: A panel study
    • Authors: Huang Jixia; Zhang Qibin; Tan Jing; Yue Depeng; Ge Quansheng
      Abstract: Publication date: Available online 2 November 2017
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Huang Jixia, Zhang Qibin, Tan Jing, Yue Depeng, Ge Quansheng
      Forestry ecological engineering projects in Western China include the Three-North Shelter Forest Project (TNSFP), the Natural Forest Protection Project (NFPP), the Grain for Green Project (GGP) and the Beijing-Tianjin Sandstorm Source Project (BTSSP). Such projects play an important role in the control of dust weather in Western China. In this research, data on the frequency of sandstorms, sand-blowing and dust-floating weather, the area of four forestry ecological engineering projects, wind, rainfall and vegetation coverage from 2000 to 2010 were collected based on the unit of prefecture-level cities in Inner Mongolia. The panel-data model was used to analyze the quantitative association between forestry ecological engineering and dust weather. The results indicate that wind has a strong promotional effect on dust weather, while forestry ecological engineering and rainfall have a containment effect. In addition, the impacts of the four studied forestry ecological engineering projects on dust weather differ. For every increase of 1000 km2 in the Three-North Shelter Forest Project, the annual number of days of sandstorm weather decreased by 4 days. Similarly, for every increase of 1000 km2 in the Beijing-Tianjin Sandstorm Source Project, the sand-blowing weather decreased by 4.4 days annually. In addition, NFPP and GGP have a more obvious inhibitory effect on the dust-floating weather.

      PubDate: 2017-11-17T15:31:14Z
      DOI: 10.1016/j.pce.2017.10.003
       
  • Seasonal variations in the water quality of a tropical wetland dominated
           by floating meadows and its implication for conservation of Ramsar
           wetlands
    • Authors: Chongpi Tuboi; Michelle Irengbam; Syed Ainul Hussain
      Abstract: Publication date: Available online 6 October 2017
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Chongpi Tuboi, Michelle Irengbam, Syed Ainul Hussain
      The Loktak Lake is a palustrine wetland located in the Barak-Chindwin river basin of Northeast India. The Lake is characterized by floating meadows of various thickness which support severely depleted endangered Eld's deer (Rucervus eldii) and sympatric hog deer (Axis porcinus). The southern part of the Lake is protected as Keibul Lamjao National Park as the last remaining habitat of the Eld's deer in India. The Loktak Lake has been included in the Montreux record as it is changing its ecological character due to anthropogenic pressures especially due to water pollution. We examined the seasonal pattern of water quality of Loktak Lake and compared it with the Keibul Lamjao National Park with a view to suggest measures for removal of this wetland from the Montreux record and for improved conservation. The evaluation of spatio-temporal variations in the water quality parameters over two years was carried out using multivariate statistical analysis. Hierarchical cluster analysis grouped the 11 sampling sites into four groups, less polluted, medium polluted, highly polluted and most polluted and the 12 months into three time periods. Principal Component Analysis identified three factors in the data structure which explained 92.9% of the total variance of the data set which was used to group the selected parameters according to common features and to evaluate the influence of each group on the overall variation in water quality. Significant difference in terms of water quality parameters were observed across different parts of the lake and seasons (ANOVA, p < 0.05). Our study revealed that the Loktak Lake is hypereutrophic leading to decreased water quality that has adverse impacts on ecosystem level processes. Restoration of the Lake requires an integrated approach in reduction of nutrient inputs, enhanced flushing mechanism and restoration of environmental flow which has been disrupted due to damming.

      PubDate: 2017-10-12T07:57:35Z
      DOI: 10.1016/j.pce.2017.09.001
       
  • 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
       
  • 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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