Land use change is a very important issue considering global dynamics and their response to hydrologic characteristics of soil and water management in a catchment.A significant land use change has been observed in the...Land use change is a very important issue considering global dynamics and their response to hydrologic characteristics of soil and water management in a catchment.A significant land use change has been observed in the Tekeze dam catchment.The main objective of this study was to estimate the potential impacts of the land use land cover(LULC)dynamics on hydrological response(stream flow and sediment yield).This was done by integrating SWAT model with GIS.The simulation and sensitivity analysis for each land use was done by dividing the catchment in to 47 sub-catchments and assigning HRUs based on multiple HRU definition.After a sensitivity analysis,calibration and validation of SWAT model,the impact of LULC dynamics on hydrological response were evaluated with three scenarios(climate of 2000s&2008 LULC,climate of 2000s&1986 LULC and climate of 1980s&1986 LULC).In the Tekeze dam watershed,land cover change had a beneficial impact on modeled watershed response due to the transition from grass and shrub land to agricultural land.Simulation results for the Tekeze dam watershed indicates that increasing bare land and agricultural areas resulted in increased annual and seasonal stream flow and sediment yield in volumes.The mean annual stream flow was increased by 6.02%(129.20-137.74 m^(3)/s)and the impact on sediment yield amounts to an increase of 17.39%(12.54-15.18 t/ha/yr)due to LULC dynamics.The hydrological response was more sensitive to LULC dynamics for the months of August to October than others in the year.These results demonstrate the usefulness of integrating remote sensing and distributed hydrologic models through the use of GIS for assessing watershed conditions and the relative impacts of land cover transitions on hydrologic response in a continuous manner.展开更多
The availability of satellite and reanalysis climate datasets and their applicability have been greatly promoted in hydro-climatic studies.However,such climatic products are still subject to considerable uncertainties...The availability of satellite and reanalysis climate datasets and their applicability have been greatly promoted in hydro-climatic studies.However,such climatic products are still subject to considerable uncertainties and an evaluation of the products is necessary for applications in specific regions.This study aims to evaluate the reliability of nine gridded precipitation and temperature datasets against ground-based observations in the upper Tekeze River basin(UTB)of Ethiopia from 1982 to 2016.Precipitation,maximum temperature(Tmax),minimum temperature(Tmin),and mean temperature(Tmean)were evaluated at daily and monthly timescales.The results show that the best estimates of precipitation are from the Eart H2 Observe,WFDEI,and ERA-Interim reanalysis data Merged and Bias-corrected for the Inter-Sectoral Impact Model Intercomparison Project(EWEMBI),and the Climate Hazards Group Infra Red Precipitation with Station data(CHIRPS)datasets.The percentage biases and correlation coefficients(CCs)are within±15%and>0.5,respectively,for both EWEMBI and CHIRPS at the two timescales.All products underestimate the drought conditions indicated by the standardized precipitation index(SPI),while the EWEMBI and CHIRPS datasets show higher agreement with the observations than other datasets.The Tmean estimates produced by the ECMWF ReAnalysis version 5(ERA5)and the Climate Hazards Group Infra Red Temperature with Station data(CHIRTS)are the closest to the observations,with CCs of 0.65 and 0.55,respectively,at the daily timescale.The CHIRTS and EWEMBI datasets show better representations of Tmax(T_(min)),with CCs of 0.69(0.72)and 0.62(0.68),respectively,at the monthly timescale.The temperature extremes are better captured by the ERA5(T_(mean)),CHIRTS(T_(max)),and EWEMBI(T_(min))datasets.The findings of this study provide useful information to select the most appropriate dataset for hydrometeorological studies in the UTB and could help to improve the regional representation of global datasets.展开更多
Sedimentation and/or soil erosion are huge problems that have threatened many reservoirs in the Northern Ethiopian highlands,particularly in the Tekeze dam watershed.This study has been conducted to identify and prior...Sedimentation and/or soil erosion are huge problems that have threatened many reservoirs in the Northern Ethiopian highlands,particularly in the Tekeze dam watershed.This study has been conducted to identify and prioritize the most sensitive subwatersheds with the help of a semi-distributed watershed model(SWAT 2009)for improved management of reservoir sedimentation mitigating strategies at the watershed level.SWAT 2009 was chosen for this study due to its ability to produce routed sediment yield and identify principal sediment source areas at the selected point of interest.Based on a digital elevation model(DEM)the catchment was divided in to 47 subwatersheds using the dam axis as the main outlet.By overlaying land use,soil and slope of the study area,the subwatersheds were further divided in to 690 hydrological response units(HRUs).Model calibration(for the period of January 1996 to December 2002)and validation(for the period of January 2003 to December 2006)were carried out for stream flow rate and sediment yield data observed at Emba madre gage station.The results of model performance evaluation statistics for both stream flow and sediment yield shows that the model has a high potential in estimation of stream flow and sediment yield.Tekeze dam watershed has mean annual stream flow of 137.74 m^(3)/s and annual sediment yield of 15.17 t/ha/year.Out of the 47 subwatersheds,13 subwatersheds(mostly located in the north eastern and north western part of the catchment)were prioritized.The maximum sediment outflow of these 13 subwatersheds,ranges from 18.49 to 32.57 t/ha/year and are characterized dominantly by cultivated land,shrub land&bare land with average land slope ranging from 7.9 to15.2%and with the dominant soil type of Eutric cambisols.These results can help to formulate and implement effective,appropriate and sustainable watershed management which in turn can help in sustaining the reservoir storage capacity of the dam.展开更多
文摘Land use change is a very important issue considering global dynamics and their response to hydrologic characteristics of soil and water management in a catchment.A significant land use change has been observed in the Tekeze dam catchment.The main objective of this study was to estimate the potential impacts of the land use land cover(LULC)dynamics on hydrological response(stream flow and sediment yield).This was done by integrating SWAT model with GIS.The simulation and sensitivity analysis for each land use was done by dividing the catchment in to 47 sub-catchments and assigning HRUs based on multiple HRU definition.After a sensitivity analysis,calibration and validation of SWAT model,the impact of LULC dynamics on hydrological response were evaluated with three scenarios(climate of 2000s&2008 LULC,climate of 2000s&1986 LULC and climate of 1980s&1986 LULC).In the Tekeze dam watershed,land cover change had a beneficial impact on modeled watershed response due to the transition from grass and shrub land to agricultural land.Simulation results for the Tekeze dam watershed indicates that increasing bare land and agricultural areas resulted in increased annual and seasonal stream flow and sediment yield in volumes.The mean annual stream flow was increased by 6.02%(129.20-137.74 m^(3)/s)and the impact on sediment yield amounts to an increase of 17.39%(12.54-15.18 t/ha/yr)due to LULC dynamics.The hydrological response was more sensitive to LULC dynamics for the months of August to October than others in the year.These results demonstrate the usefulness of integrating remote sensing and distributed hydrologic models through the use of GIS for assessing watershed conditions and the relative impacts of land cover transitions on hydrologic response in a continuous manner.
基金Supported by the National Natural Science Foundation of China(41790424,41730645,and 41877164)Strategic Priority Research Program of the Chinese Academy of Sciences(XDA20060402)International Partnership Program of the Chinese Academy of Sciences(131A11KYSB20170113)。
文摘The availability of satellite and reanalysis climate datasets and their applicability have been greatly promoted in hydro-climatic studies.However,such climatic products are still subject to considerable uncertainties and an evaluation of the products is necessary for applications in specific regions.This study aims to evaluate the reliability of nine gridded precipitation and temperature datasets against ground-based observations in the upper Tekeze River basin(UTB)of Ethiopia from 1982 to 2016.Precipitation,maximum temperature(Tmax),minimum temperature(Tmin),and mean temperature(Tmean)were evaluated at daily and monthly timescales.The results show that the best estimates of precipitation are from the Eart H2 Observe,WFDEI,and ERA-Interim reanalysis data Merged and Bias-corrected for the Inter-Sectoral Impact Model Intercomparison Project(EWEMBI),and the Climate Hazards Group Infra Red Precipitation with Station data(CHIRPS)datasets.The percentage biases and correlation coefficients(CCs)are within±15%and>0.5,respectively,for both EWEMBI and CHIRPS at the two timescales.All products underestimate the drought conditions indicated by the standardized precipitation index(SPI),while the EWEMBI and CHIRPS datasets show higher agreement with the observations than other datasets.The Tmean estimates produced by the ECMWF ReAnalysis version 5(ERA5)and the Climate Hazards Group Infra Red Temperature with Station data(CHIRTS)are the closest to the observations,with CCs of 0.65 and 0.55,respectively,at the daily timescale.The CHIRTS and EWEMBI datasets show better representations of Tmax(T_(min)),with CCs of 0.69(0.72)and 0.62(0.68),respectively,at the monthly timescale.The temperature extremes are better captured by the ERA5(T_(mean)),CHIRTS(T_(max)),and EWEMBI(T_(min))datasets.The findings of this study provide useful information to select the most appropriate dataset for hydrometeorological studies in the UTB and could help to improve the regional representation of global datasets.
文摘Sedimentation and/or soil erosion are huge problems that have threatened many reservoirs in the Northern Ethiopian highlands,particularly in the Tekeze dam watershed.This study has been conducted to identify and prioritize the most sensitive subwatersheds with the help of a semi-distributed watershed model(SWAT 2009)for improved management of reservoir sedimentation mitigating strategies at the watershed level.SWAT 2009 was chosen for this study due to its ability to produce routed sediment yield and identify principal sediment source areas at the selected point of interest.Based on a digital elevation model(DEM)the catchment was divided in to 47 subwatersheds using the dam axis as the main outlet.By overlaying land use,soil and slope of the study area,the subwatersheds were further divided in to 690 hydrological response units(HRUs).Model calibration(for the period of January 1996 to December 2002)and validation(for the period of January 2003 to December 2006)were carried out for stream flow rate and sediment yield data observed at Emba madre gage station.The results of model performance evaluation statistics for both stream flow and sediment yield shows that the model has a high potential in estimation of stream flow and sediment yield.Tekeze dam watershed has mean annual stream flow of 137.74 m^(3)/s and annual sediment yield of 15.17 t/ha/year.Out of the 47 subwatersheds,13 subwatersheds(mostly located in the north eastern and north western part of the catchment)were prioritized.The maximum sediment outflow of these 13 subwatersheds,ranges from 18.49 to 32.57 t/ha/year and are characterized dominantly by cultivated land,shrub land&bare land with average land slope ranging from 7.9 to15.2%and with the dominant soil type of Eutric cambisols.These results can help to formulate and implement effective,appropriate and sustainable watershed management which in turn can help in sustaining the reservoir storage capacity of the dam.
