Human well-being and livelihoods depend on natural ecosystem services(ESs).Following the increment of population,ESs have been deteriorated over time.Ultimately,land use/land cover(LULC)changes have a profound impact ...Human well-being and livelihoods depend on natural ecosystem services(ESs).Following the increment of population,ESs have been deteriorated over time.Ultimately,land use/land cover(LULC)changes have a profound impact on the change of ecosystem.The primary goal of this study is to determine the impacts of LULC changes on ecosystem service values(ESVs)in the upper Gilgel Abbay watershed,Ethiopia.Changes in LULC types were studied using three Landsat images representing 1986,2003,and 2021.The Landsat images were classified using a supervised image classification technique in Earth Resources Data Analysis System(ERDAS)Imagine 2014.We classified ESs in this study into four categories(including provisioning,regulating,supporting,and cultural services)based on global ES classification scheme.The adjusted ESV coefficient benefit approach was employed to measure the impacts of LULC changes on ESVs.Five LULC types were identified in this study,including cultivated land,forest,shrubland,grassland,and water body.The result revealed that the area of cultivated land accounted for 64.50%,71.50%,and 61.50%of the total area in 1986,2003,and 2021,respectively.The percentage of the total area covered by forest was 9.50%,5.90%,and 14.80%in 1986,2003,and 2021,respectively.Result revealed that the total ESV decreased from 7.42×10^(7) to 6.44×10^(7) USD between 1986 and 2003.This is due to the expansion of cultivated land at the expense of forest and shrubland.However,the total ESV increased from 6.44×10^(7) to 7.76×10^(7) USD during 2003-2021,because of the increment of forest and shrubland.The expansion of cultivated land and the reductions of forest and shrubland reduced most individual ESs during 1986-2003.Nevertheless,the increase in forest and shrubland at the expense of cultivated land enhanced many ESs during 2003-2021.Therefore,the findings suggest that appropriate land use practices should be scaled-up to sustainably maintain ESs.展开更多
Soil erosion in the Hare watershed led to significant land degradation,water pollution,and reduced agricultural productivity.Despite its effects,very few researchers have used combined morphometric and RUSLE model tec...Soil erosion in the Hare watershed led to significant land degradation,water pollution,and reduced agricultural productivity.Despite its effects,very few researchers have used combined morphometric and RUSLE model techniques to quantify soil erosion and thereby prioritize impacted areas.This work used an automated GIS-based tool(SWPT)to prioritize crucial areas based on topohydrological and morphometric factors and predict soil loss in sub-watersheds using the RUSLE model.Land use/cover data were obtained from Landsat imagery,while slope and morphometric information were extracted from digital elevation data with a resolution of 12.5 m.Soil erodibility was determined using Ethiopian soil maps,and rainfall erosivity was computed using meteorological data.An average annual soil loss of 49 t ha-1 yr-1 was observed in the Hare watershed.Sub-watershed 11 was found to be the most affected,with an average annual soil loss of 85.12 t ha-1 yr-1and a compound parameter value(CPV)of 0.059.Subwatershed 17 has the least amount of soil loss,with 3.67t ha-1 yr-1 and a CPV of 1.32.The study emphasizes the usefulness of integrating RUSLE and morphometric analysis for soil and water conservation planning,suggesting a variety of modeling tools in data-sparse locations to quantify and prioritize erosion-prone areas.展开更多
Understanding the active tectonic processes in the Nandakini Watershed is imperative for evaluating geological hazards and seismic risks,as well as for informing land-use planning and natural resource management strat...Understanding the active tectonic processes in the Nandakini Watershed is imperative for evaluating geological hazards and seismic risks,as well as for informing land-use planning and natural resource management strategies in the region.Tectonic geomorphology serves as a vital tool for characterizing recent tectonic movements.This research employs GIS techniques to elucidate tectonic activity and its influence on drainage patterns in the Nandakini Watershed,utilizing morphometric parameters derived from SRTM DEM data.Morphometric indices are employed to assess the tectonic movement within drainage basins,capturing both areal and linear factors such as drainage density,texture,circulatory and bifurcation ratios,and stream length ratios.The linear and areal morphometric indices are categorized into three classes representing varying degrees of active tectonic activity.These classifications are then utilized to compute the relative active tectonic index(IRAT).In addition,geomorphic parameters include hypsometric integral,stream length-gradient index,normalized steepness index,chi gradient index,and swath profiles.The majority of the studied region is in an extremely high to moderately active tectonic zone.Large-scale faults and thrusts within the basins are closely correlated with these zones that have been identified.The integrated methodology of GIS-based morphometric analysis and geomorphic study enables the identification of deformed landforms associated with ongoing tectonic activity.Furthermore,these results offer valuable insights for informing watershed management strategies and promoting sustainable land use planning initiatives.展开更多
The Wangdonggou Watershed on the Loess Plateau in China was selected as the study area to develop a model for soil erosion assessments. Using the data collected at 20 sampling sites all tentatively selected indicators...The Wangdonggou Watershed on the Loess Plateau in China was selected as the study area to develop a model for soil erosion assessments. Using the data collected at 20 sampling sites all tentatively selected indicators were assessed against their corresponding erosion intensity through a correlation analysis. Eight highly correlated indicators were then chosen for the soil erosion assessment. In addition, threshold limits to delineate the class size for these indicators and weights to rank them were determined. Next, a grading model incorporating the selected indicators class rating and their associated weights was developed and verified by an on site evaluation of the soil erosion intensity in the study area. Results of the verification showed that the overall accuracy of the indicator system for assessing soil erosion in the Loess Plateau gully regions could reach 85%.展开更多
Wetland systems in headstream watersheds are important to control the nonpoint source pollutant phosphorus. Experiments were conducted using intact sediment-water columns obtained from the multipond system in Liuchahe...Wetland systems in headstream watersheds are important to control the nonpoint source pollutant phosphorus. Experiments were conducted using intact sediment-water columns obtained from the multipond system in Liuchahe watershed of Chaohu Lake to determine its capacity to retain P. It was found that pond sediments had strong P retention ability. For the Hill pond, Village pond and Rice pond, their retention coefficient(A) were 288.3, 279.2 and 260.8 L/m2, respectively. The equilibrium P concentration(EPC_w) were 0.016, 0.028 and 0.018 mg/L, respectively. The Hill pond indicated the highest P retention ability. P retained in the pond sediments indicated high stable degree. P removal from the overlying water column into the pond sediments followed a first-order kinetic model. Under the experimental hydrological conditions, the retention time had a positive correlation with the P loading. The multipond system could provide enough retention time to retain P in drainage runoffs. At the P levels evaluated, the sediments of the multipond system are effective sinks to retain P from nonpoint source runoffs.展开更多
Physiography and soil in Mae Rim watershed, Chiang Mai Province, Thailand were investigated by using aerial photographs and satellite image in conjunction with field work, and soil infiltration rate and soil shear res...Physiography and soil in Mae Rim watershed, Chiang Mai Province, Thailand were investigated by using aerial photographs and satellite image in conjunction with field work, and soil infiltration rate and soil shear resistance were measured in field. Many factors affecting runoff were analyzed using the Integrated Land and Water Information System (ILWIS). As a result, a model determining flood hazard was set up. Three maps including runoff curve number map, runoff coefficient map, and flood inundation map were created. In addition, the time of concentration was predicted.展开更多
Under the guide of system theory, taking the oasis in the Sangong River watershed as a case study, this paper analyzes the oasis structure and function from 4 aspects including oasis spatial structure, water resources...Under the guide of system theory, taking the oasis in the Sangong River watershed as a case study, this paper analyzes the oasis structure and function from 4 aspects including oasis spatial structure, water resources structure, vegetation structure, economic structure and their corresponding functions. The results indicate that as a typical small-scale watershed, Sangong River watershed has the relatively complete mountain-basin structure, and ecological and productive function. Because of human drastic activity the utilization rate of water resources was as high as 98.7%, and the utilization of groundwater was not reasonable, which resulted in an average annual decline of 0.353m in the water table of alluvial-diluvial-fan oasis, and an average annual increase of 0.047m in the alluvial-plain. The layout of crop and shelter forest benefits to the utilization of water and land resources. The development of oasis economy is at low level, and its eco-economic function is weak.展开更多
This study proposes a Watershed-based Adaptive Knowledge System(WAKES) to consistently coordinate multiple stakeholders in developing sustainable partnerships for ecosystem management.WAKES is extended from the instit...This study proposes a Watershed-based Adaptive Knowledge System(WAKES) to consistently coordinate multiple stakeholders in developing sustainable partnerships for ecosystem management.WAKES is extended from the institutional mechanism of Payments for Improving Ecosystem Services at the Watershed-scale(PIES-W).PIES-W is designed relating to the governance of ecosystem services flows focused on a lake as a resource stock connecting its inflowing and outflowing rivers within its watershed.It explicitly realizes the values of conservation services provided by private land managers and incorporates their activities into the public organizing framework for ecosystem management.It implicitly extends the "upstream-to-downstream" organizing perspective to a broader vision of viewing the ecosystems as comprised of both "watershed landscapes" and "marine landscapes".Extended from PIES-W,WAKES specifies two corresponding feedback:Framework I and II.Framework I is a relationship matrix comprised of three input-output structures of primary governance factors intersecting three subsystems of a watershed with regard to ecosystem services and human stakeholders.Framework II is the Stakeholder-and-Information structure channeling five types of information among four stakeholder groups in order to enable the feedbacks mechanism of Framework I.WAKES identifies the rationales behind three fundamental information transformations,illustrated with the Transboundary Diagnostic Analysis and the Strategic Action Program of the Bermejo River Binational Basin.These include(1) translating scientific knowledge into public information within the Function-and-Service structure corresponding to the ecological subsystem,(2) incorporating public perceptions into political will within the Serviceand-Value structure corresponding to the economic subsystem,and(3) integrating scientific knowledge,public perceptions and political will into management options within the Value-and-Stakeholder structure corresponding to the social subsystem.This study seeks to share a vision of social adaptation for a global sustainable future through developing a network to adopt contributions from and forming partnerships among all ecosystem stakeholders.展开更多
Gully systems and watersheds are geomorphic units with clear boundaries that are relatively independent of basin landscapes and play an important role in natural geography. In order to explore the morphological charac...Gully systems and watersheds are geomorphic units with clear boundaries that are relatively independent of basin landscapes and play an important role in natural geography. In order to explore the morphological characteristics of gully systems and watersheds in the Dry-Hot Valley [South West(SW) China], gullies are interpreted from online Google images with high resolution and watersheds are extracted from digital elevation model at a scale of 1:50,000. The results show that:(1) There are17,382 gullies(with a total area of 1141.66 km2) and 42 watersheds in the study area.(2) The average gully density of the study area(D) is 4.29 km/km2, gully frequency(F) is 14.39 gullies/km2, the branching ratio(B) is 5.13, the length ratio(L) is 3.12, and the coefficient of the main and tributary gullies(M) is 0.06. The degree of gully erosion isstrong to extremely strong, the main development intensity of gully erosion ranges from intense to moderate, and the type of gully system is tributary.(3) The watershed areas(A) are between 0.39 and 96.43 km2, the relief ratio(R) is from 0.10 to 0.19, the circularity ratio(C) is from 0.30 to0.83, the texture ratio(T) is from 0.82 to 39.35, and the dominant geomorphological texture type is fine.(4) There is a quantitative relationship between F and D:F = 0.624 D2(R =0.84) and T is closely related to D, F, M(R2[ 0.7). A,R and C are related to M(R2[ 0.5). The development of gully systems is the result of coupling effects between multiple factors. In this area, the degree of erosion and the condition of the main and tributary gullies can be controlled by the degree of topographic breakage in the watershed, which provides some theoretical basis for the evaluation of gully erosion by the latter. In addition, the scale, relief, and shape have a significant impact on the locations of the main and tributary gullies. For tributary gullies, attention should be paid to the interception and control of runoff and sediment in the small confluence branches in order to prevent gully expansion and head advance. These features can inform the development of targeted measures for the control of soil erosion.展开更多
Sustainable management of groundwater resources has now become an obligation,especially in arid and semi-arid regions given the socio-economic importance of this resource.The optimization in zoning for groundwater exp...Sustainable management of groundwater resources has now become an obligation,especially in arid and semi-arid regions given the socio-economic importance of this resource.The optimization in zoning for groundwater exploitation helps in planning and managing groundwater supply works such as boreholes and wells in the catchment.The objective of this study is to use remote sensing and GIS-based Analytical Hierarchy Process(AHP)techniques to evaluate the groundwater potential of Wadi Saida Watershed.Spatial analysis such as geostatistics was also used to validate results and ensure more accuracy.Through the GIS tools and remote sensing technique,earth observation data were converted into thematic layers such as lineament density,geology,drainage density,slope,land use and rainfall,which were combined to delineate groundwater potential zones.Based on their respective impact on groundwater potential,the AHP approach was adopted to assign weights on multi-influencing factors.These results will enable decision-makers to optimize hydrogeological exploration in large-scale catchment areas and map areas.According to the results,the southern part of the Wadi Saida Watershed is characterized as a higher groundwater potential area,where 32%of the total surface area falls in the excellent and good class of groundwater potential.The validation process revealed a 71%agreement between the estimated and actual yield of the existing boreholes in the study area.展开更多
This paper introduces a general method of establishing Watershed Flooding Disaster Management Information System (WFDMIS). The functions, database, models, user interface, software and hardware are considered. An appl...This paper introduces a general method of establishing Watershed Flooding Disaster Management Information System (WFDMIS). The functions, database, models, user interface, software and hardware are considered. An application example in Poyang Lake Basin was given.展开更多
Hydrological monitoring and real-time access to data are valuable for hydrological research and water resources management. In the recent decades, rapid developments in digital technology, micro-electromechanical syst...Hydrological monitoring and real-time access to data are valuable for hydrological research and water resources management. In the recent decades, rapid developments in digital technology, micro-electromechanical systems, low power micro-sensing technologies and improved industrial manufacturing processes have resulted in retrieving real-time data through Wireless Sensor Networks (WSNs) systems. In this study, a remotely operated low-cost and robust WSN system was developed to monitor and collect real-time hydrologic data from a small agricultural watershed in harsh weather conditions and upland rolling topography of Southern Ontario, Canada. The WSN system was assembled using off-the-shelf hardware components, and an open source operating system was used to minimize the cost. The developed system was rigorously tested in the laboratory and the field and found to be accurate and reliable for monitoring climatic and hydrologic parameters. The soil moisture and runoff data for 7 springs, 19 summer, and 19 fall season rainfall events over the period of more than two years were successfully collected in a small experimental agricultural watershed situated near Elora, Ontario, Canada. The developed WSN system can be readily extended for the purpose of most hydrological monitoring applications, although it was explicitly tailored for a project focused on mapping the Variable Source Areas (VSAs) in a small agricultural watershed.展开更多
Human activities in a transborder watershed are complex under the influence of domestic policies,international relations,and global events.Understanding the forces driving human activity change is important for the de...Human activities in a transborder watershed are complex under the influence of domestic policies,international relations,and global events.Understanding the forces driving human activity change is important for the development of transborder watershed.In this study,we used global historical land cover data,the hemeroby index model,and synthesized major historical events to analyze how human activity intensity changed in the Heilongjiang River(Amur River in Russia)watershed(HLRW).The results showed that there was a strong spatial heterogeneity in the variation of human activity intensity in the HLRW over the past century(1900-2016).On the Chinese side,the human activity intensity change shifted from the plain areas for agricultural reclamation to the mountainous areas for timber extraction.On the Russian side,human activity intensity changes mostly concentrated along the Trans-Siberian Railway and the Baikal-Amur Mainline.Localized variation of human activity intensity tended to respond to regional events while regionalized variation tends to reflect national policy change or broad international events.The similarities and differences between China and Russia in policies and positions in international events resulted in synchronous and asynchronous changes in human activity intensity.Meanwhile,policy shifts were often confined by the natural features of the watershed.These results reveal the historical origins and fundamental connotations of watershed development and contribute to formulating regional management policies that coordinate population,eco-nomic,social,and environmental activities.展开更多
In developing countries, land productivity involves little market, where the agricultural land use is mainly determined by the food demands as well as the land suitability. The land use pattern will not ensure everywh...In developing countries, land productivity involves little market, where the agricultural land use is mainly determined by the food demands as well as the land suitability. The land use pattern will not ensure everywhere enough land for certain cropping if spatial allocation just according to land use suitability. To solve this problem, a subzone and a pre-allocation for each land use are added in spatial allocation module, and land use suitability and area optimi- zation module are incorporated to constitute a whole agricultural land use optimal allocation （ALUOA） system. The system is developed on the platform .Net 2005 using ArcGIS Engine （version 9.2） and C# language, and is tested and validated in Yili watershed of Xinjiang Region on the newly reclaimed area. In the case study, with the help of soil data obtained from 69 points sampled in the fieldwork in 2008, main river data supplied by the Department of Water Resources of Xinjiang Uygur Autonomous Region in China, and temperature data provided by Data Center for Resources and Environmental Sciences, Chinese Academy of Sciences, land use suitability on eight common crops are evaluated one by one using linear weighted summation method in the land use suitability model. The linear pro- gramming （LP） model in area optimization model succeeds to give out land area target of each crop under three scenarios. At last, the land use targets are allotted in space both with a six subzone file and without a subzone file. The resuits show that the land use maps with a subzone not only ensure every part has enough land for every crop, but also gives a more fragmental land use pattern, with about 87.99% and 135.92% more patches than the one without, while at the expense of loss between 15.30% and 19.53% in the overall suitability at the same time.展开更多
Human activities to improve the quality of life have accelerated the natural rate of soil erosion.In turn,these natural disasters have taken a great impact on humans.Human activities,particularly the conversion of veg...Human activities to improve the quality of life have accelerated the natural rate of soil erosion.In turn,these natural disasters have taken a great impact on humans.Human activities,particularly the conversion of vegetated land into agricultural land and built-up area,stand out as primary contributors to soil erosion.The present study investigated the risk of soil erosion in the Irga watershed located on the eastern fringe of the Chota Nagpur Plateau in Jharkhand,India,which is dominated by sandy loam and sandy clay loam soil with low soil organic carbon(SOC)content.The study used the Revised Universal Soil Loss Equation(RUSLE)and Geographical Information System(GIS)technique to determine the rate of soil erosion.The five parameters(rainfall-runoff erosivity(R)factor,soil erodibility(K)factor,slope length and steepness(LS)factor,cover-management(C)factor,and support practice(P)factor)of the RUSLE were applied to present a more accurate distribution characteristic of soil erosion in the Irga watershed.The result shows that the R factor is positively correlated with rainfall and follows the same distribution pattern as the rainfall.The K factor values in the northern part of the study area are relatively low,while they are relatively high in the southern part.The mean value of the LS factor is 2.74,which is low due to the flat terrain of the Irga watershed.There is a negative linear correlation between Normalized Difference Vegetation Index(NDVI)and the C factor,and the high values of the C factor are observed in places with low NDVI.The mean value of the P factor is 0.210,with a range from 0.000 to 1.000.After calculating all parameters,we obtained the average soil erosion rate of 1.43 t/(hm^(2)•a),with the highest rate reaching as high as 32.71 t/(hm^(2)•a).Therefore,the study area faces a low risk of soil erosion.However,preventative measures are essential to avoid future damage to productive and constructive activities caused by soil erosion.This study also identifies the spatial distribution of soil erosion rate,which will help policy-makers to implement targeted soil erosion control measures.展开更多
Classification of groundwater conditions at the watershed scale synthesizes landscape hydrology, provides a mapped summary of groundwater resources, and supports water management decisions. The application of a recent...Classification of groundwater conditions at the watershed scale synthesizes landscape hydrology, provides a mapped summary of groundwater resources, and supports water management decisions. The application of a recently developed watershed-scale groundwater classification methodology is applied and evaluated in the 100,000 hectare lower Ruby Valley watershed of southwestern Montana. The geologic setting, groundwater flow direction, aquifer productivity, water quality, anthropogenic impact to water levels, depth to groundwater, and the degree of connection between groundwater and surface water are key components of the classification scheme. This work describes the hydrogeology of the lower Ruby Valley watershed and illustrates how the classification system is applied to assemble, analyze, and summarize groundwater data. The classification process provides information in summary tables and maps of seamless digital overlays prepared using geographical information system (GIS) software. Groundwater conditions in the watershed are classified as low production bedrock aquifers in the mountainous uplands that recharge the moderate productivity basin-fill sediments. Groundwater levels approach the surface near the Ruby River resulting in sufficient groundwater discharge to maintain stream flow during dry, late summer conditions. The resulting classification data sets provide watershed managers with a standardized organizational tool that represents groundwater conditions at the watershed scale.展开更多
In the Ethiopian Highlands, research projects were often measuring soil attributes of spatially structured point data but soil variability at a watershed scale is not clearly defined. This study was conducted to asses...In the Ethiopian Highlands, research projects were often measuring soil attributes of spatially structured point data but soil variability at a watershed scale is not clearly defined. This study was conducted to assess the correlation among selected soil attributes and to illustrate the spatial pattern and dependence of neighboring observations. The 53.7 km2?study watershed was divided into a 500 m by 500 m square grid using arcgis and at the center of each grid soil samples from 0 to 25 cm depth were collected within 184 locations. The descriptive statistics revealed available phosphorous (AP) had the largest coefficient of variation (CV = 104) while pH was the least variable. There was a positive link between elevation and SOC whereas bulk density (ρd) and pH indicated an inverse relationship with elevation and SOC. The value for nugget/sill of ρd, pH and elevation are less than 0.25, and depicts that it has strong spatial autocorrelation. The value for nugget/?sill of SOC, and TN found between 0.25 and 0.75, and indicate that they have moderate spatial?autocorrelation. With regard to AP, the value for nugget/sill is more than 0.75, which displays a weak?spatial autocorrelation. Semivariograms of ρd, pH and elevation were best fitted to Gaussian model whereas SOC, TN and AP were best fitted to exponential function. Generally, the study verified that soil measurements taken at the given scale through regular sampling interval were adequate to capture the spatial dependence of numerous initial soil assessments in the study watershed.展开更多
In order to maintain a proper balance between development pressure and water resources protection, and also to improve public participation, efficient tools and techniques for soil and water conservation projects are ...In order to maintain a proper balance between development pressure and water resources protection, and also to improve public participation, efficient tools and techniques for soil and water conservation projects are needed. This paper describes the development and application of a web-based watershed management spatial decision support system, WebWMPI. The WebWMPI uses the Watershed Management Priority Indices (WMPI) approach which is a prioritizing method for watershed management planning and it integrates land use/cover, hydrological data, soils, slope, roads, and other spatial data. The land is divided into three categories: Conservation Priority Index (CPI) land, Restoration Priority Index (RPI) land, and Stormwater Management Priority Index (SMPI) land. Within each category, spatial factors are rated based on their influence on water resources and critical areas can be identified for soil conservation, water quality protection and improvement. The WebWMPI has user-friendly client side graphical interfaces which enable the public to interactively run the server side Geographic Information System to evaluate different scenarios for watershed planning and management. The system was applied for Dry Run Creek watershed (Cedar Falls, Iowa, US) as a demonstration and it can be easily used in other watersheds to prioritize crucial areas and to increase public participation for soil and water conservation projects.展开更多
The objective of this study was to assess the contribution of the spatial organization of cropping systems and the physicochemical properties of surface layers of the agricultural zones soils in tropical hydrosystems ...The objective of this study was to assess the contribution of the spatial organization of cropping systems and the physicochemical properties of surface layers of the agricultural zones soils in tropical hydrosystems to the spatial availability of nitrogen and pesticides during the wet season, such as the Béré watershed (BW) in C<span style="white-space:nowrap;">?</span>te d’Ivoire. For this purpose, after mapping the spatial distribution of the BW cropping systems based on the likelihood classification methodology of satellite images of the study area, 27 samples from the 0 - 20 cm horizon of the soil surface layers of the agricultural areas were taken during the wet and agricultural season of the year 2016. The Kjeldahl method has been used to evaluate the total nitrogen concentration and high-performance liquid chromatography (HPLC) chain made it possible for the analysis of pesticide residues in the soil solutions. Geostatistical analysis and processing of spatial data and physicochemical and agrochemical soil parameters revealed that two major agricultural areas stand out in the BW, namely the Béré upstream watershed (BUW) dominated at 32.65% by annual croppings (maize, cotton, rainfed or lowland rice, market gardening, etc.) and the Béré downstream watershed (BDW) by large areas of perennial croppings (cashew nuts, cocoa, etc.), <em>i.e.</em> 21.47%. Agricultural soils in BW are usually of the moderately desaturated ferralitic type with a low acid pH and a quite strong temperature, such as those of tropical soils’ characteristics. However, agricultural soils in the BUW are characterized by higher proportions of sand and coarse sand. The parameters such as total porosity, cation exchange capacity, clay, organic matter, silt, fine silt, coarse silt, and potassium ions, are higher in the soils of the agricultural area of the BDW. Moreover, soils in the agricultural areas of the BUW are less rich in total nitrogen (0.84 g<span style="white-space:nowrap;">·</span>kg<sup>-1</sup>) in contrast to those of the BDW (1.2 g<span style="white-space:nowrap;">·</span>kg<sup>-1</sup>). On the other hand, the median concentrations of total pesticides remain very high in the BUW (193.80 μg<span style="white-space:nowrap;">·</span>kg<sup>-1</sup>) in front of those of the BDW (94.81 μg<span style="white-space:nowrap;">·</span>kg<sup>-1</sup>). In addition, the biological family of herbicides was the most notable in BW. The chemical families of triazines (100% detection;79.37 μg<span style="white-space:nowrap;">·</span>kg<sup>-1</sup>) are the most important in the agricultural area of the BUW with the very significant presence of active molecules of pesticides such as simazine (92.86% detection;13.17 μg<span style="white-space:nowrap;">·</span>kg<sup>-1</sup>). However, in the BDW, urea substitute (100% detection;44.02 μg<span style="white-space:nowrap;">·</span>kg<sup>-1</sup>) dominate, including the active substance chlortoluron (84.62% detection;10.12 μg<span style="white-space:nowrap;">·</span>kg<sup>-1</sup>). The presence and abundance of nitrogen and pesticides in the soils of the agricultural areas of BW are strongly linked to the intensive use of these agrochemicals in cropping systems in recent decades in West African countries, even though most of the active molecules found are forbidden in several countries, especially in European countries. These are applied to tropical agricultural soils with physicochemical characteristics favorable to their retention in wet weather, as confirmed by the case of BW’s agricultural soils. Therefore, the BW’s water resources present worrying risks of contamination during rainy events that deserve to be assessed and monitored. Hence the need to take mitigating measures to this effect in order to preserve the quality of the environment.展开更多
Integrated management has become an essential approach for sustainable water resource management. However, if the concept seems relevant, its concrete application at the local scale has yet to be undertaken, with all ...Integrated management has become an essential approach for sustainable water resource management. However, if the concept seems relevant, its concrete application at the local scale has yet to be undertaken, with all the difficulties related to the complexity underlying the issue. The Rif is characterized by the multiplication and interdependence of uses, the overlapping responsibilities between public and private actors, the superposition of sectoral regulations, which raises the following question: Is the current management of water resources in the Rif mountains suitable for a future constraining on several aspects: socio-economic and climatic? The general objective of this work is to analyze the current management of water resources scientifically, politically, institutionally and legally, to identify the innovations needed for sustainable management and adaptation to climate change in the Rif Mountains. The systemic approach allowed us to highlight and prioritize the structuring elements of water management in the Nekor basin and their interactions. The crossing of hydrological data with socio-economic data allowed us to have a global and multidisciplinary vision of both uses and water resources, and of all the components of the system’s environment, the interdependencies influence the management system, despite the complexity accentuated by the lack of data. Indeed, it was difficult to identify the influence of each component. The current degradation of resources is only a reflection of a socio-cultural crisis that can only be remedied by a change in mentality, economic development, social equity and more solidarity between the city and rural communities.展开更多
文摘Human well-being and livelihoods depend on natural ecosystem services(ESs).Following the increment of population,ESs have been deteriorated over time.Ultimately,land use/land cover(LULC)changes have a profound impact on the change of ecosystem.The primary goal of this study is to determine the impacts of LULC changes on ecosystem service values(ESVs)in the upper Gilgel Abbay watershed,Ethiopia.Changes in LULC types were studied using three Landsat images representing 1986,2003,and 2021.The Landsat images were classified using a supervised image classification technique in Earth Resources Data Analysis System(ERDAS)Imagine 2014.We classified ESs in this study into four categories(including provisioning,regulating,supporting,and cultural services)based on global ES classification scheme.The adjusted ESV coefficient benefit approach was employed to measure the impacts of LULC changes on ESVs.Five LULC types were identified in this study,including cultivated land,forest,shrubland,grassland,and water body.The result revealed that the area of cultivated land accounted for 64.50%,71.50%,and 61.50%of the total area in 1986,2003,and 2021,respectively.The percentage of the total area covered by forest was 9.50%,5.90%,and 14.80%in 1986,2003,and 2021,respectively.Result revealed that the total ESV decreased from 7.42×10^(7) to 6.44×10^(7) USD between 1986 and 2003.This is due to the expansion of cultivated land at the expense of forest and shrubland.However,the total ESV increased from 6.44×10^(7) to 7.76×10^(7) USD during 2003-2021,because of the increment of forest and shrubland.The expansion of cultivated land and the reductions of forest and shrubland reduced most individual ESs during 1986-2003.Nevertheless,the increase in forest and shrubland at the expense of cultivated land enhanced many ESs during 2003-2021.Therefore,the findings suggest that appropriate land use practices should be scaled-up to sustainably maintain ESs.
文摘Soil erosion in the Hare watershed led to significant land degradation,water pollution,and reduced agricultural productivity.Despite its effects,very few researchers have used combined morphometric and RUSLE model techniques to quantify soil erosion and thereby prioritize impacted areas.This work used an automated GIS-based tool(SWPT)to prioritize crucial areas based on topohydrological and morphometric factors and predict soil loss in sub-watersheds using the RUSLE model.Land use/cover data were obtained from Landsat imagery,while slope and morphometric information were extracted from digital elevation data with a resolution of 12.5 m.Soil erodibility was determined using Ethiopian soil maps,and rainfall erosivity was computed using meteorological data.An average annual soil loss of 49 t ha-1 yr-1 was observed in the Hare watershed.Sub-watershed 11 was found to be the most affected,with an average annual soil loss of 85.12 t ha-1 yr-1and a compound parameter value(CPV)of 0.059.Subwatershed 17 has the least amount of soil loss,with 3.67t ha-1 yr-1 and a CPV of 1.32.The study emphasizes the usefulness of integrating RUSLE and morphometric analysis for soil and water conservation planning,suggesting a variety of modeling tools in data-sparse locations to quantify and prioritize erosion-prone areas.
文摘Understanding the active tectonic processes in the Nandakini Watershed is imperative for evaluating geological hazards and seismic risks,as well as for informing land-use planning and natural resource management strategies in the region.Tectonic geomorphology serves as a vital tool for characterizing recent tectonic movements.This research employs GIS techniques to elucidate tectonic activity and its influence on drainage patterns in the Nandakini Watershed,utilizing morphometric parameters derived from SRTM DEM data.Morphometric indices are employed to assess the tectonic movement within drainage basins,capturing both areal and linear factors such as drainage density,texture,circulatory and bifurcation ratios,and stream length ratios.The linear and areal morphometric indices are categorized into three classes representing varying degrees of active tectonic activity.These classifications are then utilized to compute the relative active tectonic index(IRAT).In addition,geomorphic parameters include hypsometric integral,stream length-gradient index,normalized steepness index,chi gradient index,and swath profiles.The majority of the studied region is in an extremely high to moderately active tectonic zone.Large-scale faults and thrusts within the basins are closely correlated with these zones that have been identified.The integrated methodology of GIS-based morphometric analysis and geomorphic study enables the identification of deformed landforms associated with ongoing tectonic activity.Furthermore,these results offer valuable insights for informing watershed management strategies and promoting sustainable land use planning initiatives.
基金supported by the State Key Laboratory of Soil Erosion and Dryland Farming on Loess Plateau, China (No. 10501-88) the National High Technology Research and Development Program of China (863 Program) (No. 2001AA245041).
文摘The Wangdonggou Watershed on the Loess Plateau in China was selected as the study area to develop a model for soil erosion assessments. Using the data collected at 20 sampling sites all tentatively selected indicators were assessed against their corresponding erosion intensity through a correlation analysis. Eight highly correlated indicators were then chosen for the soil erosion assessment. In addition, threshold limits to delineate the class size for these indicators and weights to rank them were determined. Next, a grading model incorporating the selected indicators class rating and their associated weights was developed and verified by an on site evaluation of the soil erosion intensity in the study area. Results of the verification showed that the overall accuracy of the indicator system for assessing soil erosion in the Loess Plateau gully regions could reach 85%.
基金Key Project of Knowledge Innovation Programme of CAS(No. KZCX1 SW 12) and the National Natural Science Foundation of China (No. 40171003)
文摘Wetland systems in headstream watersheds are important to control the nonpoint source pollutant phosphorus. Experiments were conducted using intact sediment-water columns obtained from the multipond system in Liuchahe watershed of Chaohu Lake to determine its capacity to retain P. It was found that pond sediments had strong P retention ability. For the Hill pond, Village pond and Rice pond, their retention coefficient(A) were 288.3, 279.2 and 260.8 L/m2, respectively. The equilibrium P concentration(EPC_w) were 0.016, 0.028 and 0.018 mg/L, respectively. The Hill pond indicated the highest P retention ability. P retained in the pond sediments indicated high stable degree. P removal from the overlying water column into the pond sediments followed a first-order kinetic model. Under the experimental hydrological conditions, the retention time had a positive correlation with the P loading. The multipond system could provide enough retention time to retain P in drainage runoffs. At the P levels evaluated, the sediments of the multipond system are effective sinks to retain P from nonpoint source runoffs.
文摘Physiography and soil in Mae Rim watershed, Chiang Mai Province, Thailand were investigated by using aerial photographs and satellite image in conjunction with field work, and soil infiltration rate and soil shear resistance were measured in field. Many factors affecting runoff were analyzed using the Integrated Land and Water Information System (ILWIS). As a result, a model determining flood hazard was set up. Three maps including runoff curve number map, runoff coefficient map, and flood inundation map were created. In addition, the time of concentration was predicted.
基金Under the auspices of Project of Western Light Related to Eastern Scholar, the National Natural Science Foundation of China (No. 40471134)
文摘Under the guide of system theory, taking the oasis in the Sangong River watershed as a case study, this paper analyzes the oasis structure and function from 4 aspects including oasis spatial structure, water resources structure, vegetation structure, economic structure and their corresponding functions. The results indicate that as a typical small-scale watershed, Sangong River watershed has the relatively complete mountain-basin structure, and ecological and productive function. Because of human drastic activity the utilization rate of water resources was as high as 98.7%, and the utilization of groundwater was not reasonable, which resulted in an average annual decline of 0.353m in the water table of alluvial-diluvial-fan oasis, and an average annual increase of 0.047m in the alluvial-plain. The layout of crop and shelter forest benefits to the utilization of water and land resources. The development of oasis economy is at low level, and its eco-economic function is weak.
基金financial support of the organizing committee of the International Conference on Salt Lake Research,held during 2014 in Beijing,China
文摘This study proposes a Watershed-based Adaptive Knowledge System(WAKES) to consistently coordinate multiple stakeholders in developing sustainable partnerships for ecosystem management.WAKES is extended from the institutional mechanism of Payments for Improving Ecosystem Services at the Watershed-scale(PIES-W).PIES-W is designed relating to the governance of ecosystem services flows focused on a lake as a resource stock connecting its inflowing and outflowing rivers within its watershed.It explicitly realizes the values of conservation services provided by private land managers and incorporates their activities into the public organizing framework for ecosystem management.It implicitly extends the "upstream-to-downstream" organizing perspective to a broader vision of viewing the ecosystems as comprised of both "watershed landscapes" and "marine landscapes".Extended from PIES-W,WAKES specifies two corresponding feedback:Framework I and II.Framework I is a relationship matrix comprised of three input-output structures of primary governance factors intersecting three subsystems of a watershed with regard to ecosystem services and human stakeholders.Framework II is the Stakeholder-and-Information structure channeling five types of information among four stakeholder groups in order to enable the feedbacks mechanism of Framework I.WAKES identifies the rationales behind three fundamental information transformations,illustrated with the Transboundary Diagnostic Analysis and the Strategic Action Program of the Bermejo River Binational Basin.These include(1) translating scientific knowledge into public information within the Function-and-Service structure corresponding to the ecological subsystem,(2) incorporating public perceptions into political will within the Serviceand-Value structure corresponding to the economic subsystem,and(3) integrating scientific knowledge,public perceptions and political will into management options within the Value-and-Stakeholder structure corresponding to the social subsystem.This study seeks to share a vision of social adaptation for a global sustainable future through developing a network to adopt contributions from and forming partnerships among all ecosystem stakeholders.
基金financial support from the Meritocracy Research Funds of China West Normal University (17YC134, 17YC105)Project of Sichuan Provincial Department of Education and Ecological Security Key Laboratory of Sichuan Province (ESP201301)+1 种基金the Project of Science & Technology Department of Sichuan Province (2018SZ0337, 2017JY0189)the Project of Sichuan Provincial Department of Education (16ZB0182, 18TD0025, 18ZA0465)
文摘Gully systems and watersheds are geomorphic units with clear boundaries that are relatively independent of basin landscapes and play an important role in natural geography. In order to explore the morphological characteristics of gully systems and watersheds in the Dry-Hot Valley [South West(SW) China], gullies are interpreted from online Google images with high resolution and watersheds are extracted from digital elevation model at a scale of 1:50,000. The results show that:(1) There are17,382 gullies(with a total area of 1141.66 km2) and 42 watersheds in the study area.(2) The average gully density of the study area(D) is 4.29 km/km2, gully frequency(F) is 14.39 gullies/km2, the branching ratio(B) is 5.13, the length ratio(L) is 3.12, and the coefficient of the main and tributary gullies(M) is 0.06. The degree of gully erosion isstrong to extremely strong, the main development intensity of gully erosion ranges from intense to moderate, and the type of gully system is tributary.(3) The watershed areas(A) are between 0.39 and 96.43 km2, the relief ratio(R) is from 0.10 to 0.19, the circularity ratio(C) is from 0.30 to0.83, the texture ratio(T) is from 0.82 to 39.35, and the dominant geomorphological texture type is fine.(4) There is a quantitative relationship between F and D:F = 0.624 D2(R =0.84) and T is closely related to D, F, M(R2[ 0.7). A,R and C are related to M(R2[ 0.5). The development of gully systems is the result of coupling effects between multiple factors. In this area, the degree of erosion and the condition of the main and tributary gullies can be controlled by the degree of topographic breakage in the watershed, which provides some theoretical basis for the evaluation of gully erosion by the latter. In addition, the scale, relief, and shape have a significant impact on the locations of the main and tributary gullies. For tributary gullies, attention should be paid to the interception and control of runoff and sediment in the small confluence branches in order to prevent gully expansion and head advance. These features can inform the development of targeted measures for the control of soil erosion.
文摘Sustainable management of groundwater resources has now become an obligation,especially in arid and semi-arid regions given the socio-economic importance of this resource.The optimization in zoning for groundwater exploitation helps in planning and managing groundwater supply works such as boreholes and wells in the catchment.The objective of this study is to use remote sensing and GIS-based Analytical Hierarchy Process(AHP)techniques to evaluate the groundwater potential of Wadi Saida Watershed.Spatial analysis such as geostatistics was also used to validate results and ensure more accuracy.Through the GIS tools and remote sensing technique,earth observation data were converted into thematic layers such as lineament density,geology,drainage density,slope,land use and rainfall,which were combined to delineate groundwater potential zones.Based on their respective impact on groundwater potential,the AHP approach was adopted to assign weights on multi-influencing factors.These results will enable decision-makers to optimize hydrogeological exploration in large-scale catchment areas and map areas.According to the results,the southern part of the Wadi Saida Watershed is characterized as a higher groundwater potential area,where 32%of the total surface area falls in the excellent and good class of groundwater potential.The validation process revealed a 71%agreement between the estimated and actual yield of the existing boreholes in the study area.
文摘This paper introduces a general method of establishing Watershed Flooding Disaster Management Information System (WFDMIS). The functions, database, models, user interface, software and hardware are considered. An application example in Poyang Lake Basin was given.
文摘Hydrological monitoring and real-time access to data are valuable for hydrological research and water resources management. In the recent decades, rapid developments in digital technology, micro-electromechanical systems, low power micro-sensing technologies and improved industrial manufacturing processes have resulted in retrieving real-time data through Wireless Sensor Networks (WSNs) systems. In this study, a remotely operated low-cost and robust WSN system was developed to monitor and collect real-time hydrologic data from a small agricultural watershed in harsh weather conditions and upland rolling topography of Southern Ontario, Canada. The WSN system was assembled using off-the-shelf hardware components, and an open source operating system was used to minimize the cost. The developed system was rigorously tested in the laboratory and the field and found to be accurate and reliable for monitoring climatic and hydrologic parameters. The soil moisture and runoff data for 7 springs, 19 summer, and 19 fall season rainfall events over the period of more than two years were successfully collected in a small experimental agricultural watershed situated near Elora, Ontario, Canada. The developed WSN system can be readily extended for the purpose of most hydrological monitoring applications, although it was explicitly tailored for a project focused on mapping the Variable Source Areas (VSAs) in a small agricultural watershed.
基金Under the auspices of National Key Research and Development Program of China(No.2017YFA0604403)National Natural Science Foundation of China(No.41801108)。
文摘Human activities in a transborder watershed are complex under the influence of domestic policies,international relations,and global events.Understanding the forces driving human activity change is important for the development of transborder watershed.In this study,we used global historical land cover data,the hemeroby index model,and synthesized major historical events to analyze how human activity intensity changed in the Heilongjiang River(Amur River in Russia)watershed(HLRW).The results showed that there was a strong spatial heterogeneity in the variation of human activity intensity in the HLRW over the past century(1900-2016).On the Chinese side,the human activity intensity change shifted from the plain areas for agricultural reclamation to the mountainous areas for timber extraction.On the Russian side,human activity intensity changes mostly concentrated along the Trans-Siberian Railway and the Baikal-Amur Mainline.Localized variation of human activity intensity tended to respond to regional events while regionalized variation tends to reflect national policy change or broad international events.The similarities and differences between China and Russia in policies and positions in international events resulted in synchronous and asynchronous changes in human activity intensity.Meanwhile,policy shifts were often confined by the natural features of the watershed.These results reveal the historical origins and fundamental connotations of watershed development and contribute to formulating regional management policies that coordinate population,eco-nomic,social,and environmental activities.
基金Under the auspices of National Natural Science Foundation of China (No. 41001108, 41071065)Beijing Municipal Natural Science Foundation (No. 9113029)
文摘In developing countries, land productivity involves little market, where the agricultural land use is mainly determined by the food demands as well as the land suitability. The land use pattern will not ensure everywhere enough land for certain cropping if spatial allocation just according to land use suitability. To solve this problem, a subzone and a pre-allocation for each land use are added in spatial allocation module, and land use suitability and area optimi- zation module are incorporated to constitute a whole agricultural land use optimal allocation （ALUOA） system. The system is developed on the platform .Net 2005 using ArcGIS Engine （version 9.2） and C# language, and is tested and validated in Yili watershed of Xinjiang Region on the newly reclaimed area. In the case study, with the help of soil data obtained from 69 points sampled in the fieldwork in 2008, main river data supplied by the Department of Water Resources of Xinjiang Uygur Autonomous Region in China, and temperature data provided by Data Center for Resources and Environmental Sciences, Chinese Academy of Sciences, land use suitability on eight common crops are evaluated one by one using linear weighted summation method in the land use suitability model. The linear pro- gramming （LP） model in area optimization model succeeds to give out land area target of each crop under three scenarios. At last, the land use targets are allotted in space both with a six subzone file and without a subzone file. The resuits show that the land use maps with a subzone not only ensure every part has enough land for every crop, but also gives a more fragmental land use pattern, with about 87.99% and 135.92% more patches than the one without, while at the expense of loss between 15.30% and 19.53% in the overall suitability at the same time.
基金the financial support received from the University Grants Commission (UGC) in the form of a Junior Research Fellowship (JRF)。
文摘Human activities to improve the quality of life have accelerated the natural rate of soil erosion.In turn,these natural disasters have taken a great impact on humans.Human activities,particularly the conversion of vegetated land into agricultural land and built-up area,stand out as primary contributors to soil erosion.The present study investigated the risk of soil erosion in the Irga watershed located on the eastern fringe of the Chota Nagpur Plateau in Jharkhand,India,which is dominated by sandy loam and sandy clay loam soil with low soil organic carbon(SOC)content.The study used the Revised Universal Soil Loss Equation(RUSLE)and Geographical Information System(GIS)technique to determine the rate of soil erosion.The five parameters(rainfall-runoff erosivity(R)factor,soil erodibility(K)factor,slope length and steepness(LS)factor,cover-management(C)factor,and support practice(P)factor)of the RUSLE were applied to present a more accurate distribution characteristic of soil erosion in the Irga watershed.The result shows that the R factor is positively correlated with rainfall and follows the same distribution pattern as the rainfall.The K factor values in the northern part of the study area are relatively low,while they are relatively high in the southern part.The mean value of the LS factor is 2.74,which is low due to the flat terrain of the Irga watershed.There is a negative linear correlation between Normalized Difference Vegetation Index(NDVI)and the C factor,and the high values of the C factor are observed in places with low NDVI.The mean value of the P factor is 0.210,with a range from 0.000 to 1.000.After calculating all parameters,we obtained the average soil erosion rate of 1.43 t/(hm^(2)•a),with the highest rate reaching as high as 32.71 t/(hm^(2)•a).Therefore,the study area faces a low risk of soil erosion.However,preventative measures are essential to avoid future damage to productive and constructive activities caused by soil erosion.This study also identifies the spatial distribution of soil erosion rate,which will help policy-makers to implement targeted soil erosion control measures.
文摘Classification of groundwater conditions at the watershed scale synthesizes landscape hydrology, provides a mapped summary of groundwater resources, and supports water management decisions. The application of a recently developed watershed-scale groundwater classification methodology is applied and evaluated in the 100,000 hectare lower Ruby Valley watershed of southwestern Montana. The geologic setting, groundwater flow direction, aquifer productivity, water quality, anthropogenic impact to water levels, depth to groundwater, and the degree of connection between groundwater and surface water are key components of the classification scheme. This work describes the hydrogeology of the lower Ruby Valley watershed and illustrates how the classification system is applied to assemble, analyze, and summarize groundwater data. The classification process provides information in summary tables and maps of seamless digital overlays prepared using geographical information system (GIS) software. Groundwater conditions in the watershed are classified as low production bedrock aquifers in the mountainous uplands that recharge the moderate productivity basin-fill sediments. Groundwater levels approach the surface near the Ruby River resulting in sufficient groundwater discharge to maintain stream flow during dry, late summer conditions. The resulting classification data sets provide watershed managers with a standardized organizational tool that represents groundwater conditions at the watershed scale.
文摘In the Ethiopian Highlands, research projects were often measuring soil attributes of spatially structured point data but soil variability at a watershed scale is not clearly defined. This study was conducted to assess the correlation among selected soil attributes and to illustrate the spatial pattern and dependence of neighboring observations. The 53.7 km2?study watershed was divided into a 500 m by 500 m square grid using arcgis and at the center of each grid soil samples from 0 to 25 cm depth were collected within 184 locations. The descriptive statistics revealed available phosphorous (AP) had the largest coefficient of variation (CV = 104) while pH was the least variable. There was a positive link between elevation and SOC whereas bulk density (ρd) and pH indicated an inverse relationship with elevation and SOC. The value for nugget/sill of ρd, pH and elevation are less than 0.25, and depicts that it has strong spatial autocorrelation. The value for nugget/?sill of SOC, and TN found between 0.25 and 0.75, and indicate that they have moderate spatial?autocorrelation. With regard to AP, the value for nugget/sill is more than 0.75, which displays a weak?spatial autocorrelation. Semivariograms of ρd, pH and elevation were best fitted to Gaussian model whereas SOC, TN and AP were best fitted to exponential function. Generally, the study verified that soil measurements taken at the given scale through regular sampling interval were adequate to capture the spatial dependence of numerous initial soil assessments in the study watershed.
文摘In order to maintain a proper balance between development pressure and water resources protection, and also to improve public participation, efficient tools and techniques for soil and water conservation projects are needed. This paper describes the development and application of a web-based watershed management spatial decision support system, WebWMPI. The WebWMPI uses the Watershed Management Priority Indices (WMPI) approach which is a prioritizing method for watershed management planning and it integrates land use/cover, hydrological data, soils, slope, roads, and other spatial data. The land is divided into three categories: Conservation Priority Index (CPI) land, Restoration Priority Index (RPI) land, and Stormwater Management Priority Index (SMPI) land. Within each category, spatial factors are rated based on their influence on water resources and critical areas can be identified for soil conservation, water quality protection and improvement. The WebWMPI has user-friendly client side graphical interfaces which enable the public to interactively run the server side Geographic Information System to evaluate different scenarios for watershed planning and management. The system was applied for Dry Run Creek watershed (Cedar Falls, Iowa, US) as a demonstration and it can be easily used in other watersheds to prioritize crucial areas and to increase public participation for soil and water conservation projects.
文摘The objective of this study was to assess the contribution of the spatial organization of cropping systems and the physicochemical properties of surface layers of the agricultural zones soils in tropical hydrosystems to the spatial availability of nitrogen and pesticides during the wet season, such as the Béré watershed (BW) in C<span style="white-space:nowrap;">?</span>te d’Ivoire. For this purpose, after mapping the spatial distribution of the BW cropping systems based on the likelihood classification methodology of satellite images of the study area, 27 samples from the 0 - 20 cm horizon of the soil surface layers of the agricultural areas were taken during the wet and agricultural season of the year 2016. The Kjeldahl method has been used to evaluate the total nitrogen concentration and high-performance liquid chromatography (HPLC) chain made it possible for the analysis of pesticide residues in the soil solutions. Geostatistical analysis and processing of spatial data and physicochemical and agrochemical soil parameters revealed that two major agricultural areas stand out in the BW, namely the Béré upstream watershed (BUW) dominated at 32.65% by annual croppings (maize, cotton, rainfed or lowland rice, market gardening, etc.) and the Béré downstream watershed (BDW) by large areas of perennial croppings (cashew nuts, cocoa, etc.), <em>i.e.</em> 21.47%. Agricultural soils in BW are usually of the moderately desaturated ferralitic type with a low acid pH and a quite strong temperature, such as those of tropical soils’ characteristics. However, agricultural soils in the BUW are characterized by higher proportions of sand and coarse sand. The parameters such as total porosity, cation exchange capacity, clay, organic matter, silt, fine silt, coarse silt, and potassium ions, are higher in the soils of the agricultural area of the BDW. Moreover, soils in the agricultural areas of the BUW are less rich in total nitrogen (0.84 g<span style="white-space:nowrap;">·</span>kg<sup>-1</sup>) in contrast to those of the BDW (1.2 g<span style="white-space:nowrap;">·</span>kg<sup>-1</sup>). On the other hand, the median concentrations of total pesticides remain very high in the BUW (193.80 μg<span style="white-space:nowrap;">·</span>kg<sup>-1</sup>) in front of those of the BDW (94.81 μg<span style="white-space:nowrap;">·</span>kg<sup>-1</sup>). In addition, the biological family of herbicides was the most notable in BW. The chemical families of triazines (100% detection;79.37 μg<span style="white-space:nowrap;">·</span>kg<sup>-1</sup>) are the most important in the agricultural area of the BUW with the very significant presence of active molecules of pesticides such as simazine (92.86% detection;13.17 μg<span style="white-space:nowrap;">·</span>kg<sup>-1</sup>). However, in the BDW, urea substitute (100% detection;44.02 μg<span style="white-space:nowrap;">·</span>kg<sup>-1</sup>) dominate, including the active substance chlortoluron (84.62% detection;10.12 μg<span style="white-space:nowrap;">·</span>kg<sup>-1</sup>). The presence and abundance of nitrogen and pesticides in the soils of the agricultural areas of BW are strongly linked to the intensive use of these agrochemicals in cropping systems in recent decades in West African countries, even though most of the active molecules found are forbidden in several countries, especially in European countries. These are applied to tropical agricultural soils with physicochemical characteristics favorable to their retention in wet weather, as confirmed by the case of BW’s agricultural soils. Therefore, the BW’s water resources present worrying risks of contamination during rainy events that deserve to be assessed and monitored. Hence the need to take mitigating measures to this effect in order to preserve the quality of the environment.
文摘Integrated management has become an essential approach for sustainable water resource management. However, if the concept seems relevant, its concrete application at the local scale has yet to be undertaken, with all the difficulties related to the complexity underlying the issue. The Rif is characterized by the multiplication and interdependence of uses, the overlapping responsibilities between public and private actors, the superposition of sectoral regulations, which raises the following question: Is the current management of water resources in the Rif mountains suitable for a future constraining on several aspects: socio-economic and climatic? The general objective of this work is to analyze the current management of water resources scientifically, politically, institutionally and legally, to identify the innovations needed for sustainable management and adaptation to climate change in the Rif Mountains. The systemic approach allowed us to highlight and prioritize the structuring elements of water management in the Nekor basin and their interactions. The crossing of hydrological data with socio-economic data allowed us to have a global and multidisciplinary vision of both uses and water resources, and of all the components of the system’s environment, the interdependencies influence the management system, despite the complexity accentuated by the lack of data. Indeed, it was difficult to identify the influence of each component. The current degradation of resources is only a reflection of a socio-cultural crisis that can only be remedied by a change in mentality, economic development, social equity and more solidarity between the city and rural communities.
