The city of Bouaké, the second biggest city of Côte d’Ivoire, experienced a water shortage in 2018 that lasted four months due to the drying up of the Loka reservoir, which supplies two-thirds of the c...The city of Bouaké, the second biggest city of Côte d’Ivoire, experienced a water shortage in 2018 that lasted four months due to the drying up of the Loka reservoir, which supplies two-thirds of the city. The challenge of the Loka reservoir is that it is located in an ungauged basin where very few hydrological studies have been carried out, despite the recurrent problems of access to drinking water. In the purpose to better understand the phenomena that caused this temporary drying of the dam, the methodology implemented was based on agro-hydrological modeling with SWAT using a regionalization technique of a nearby watershed. The model performance was assessed using three statistical indices (the Nash-Sutcliffe coefficient (NS), the coefficient of determination (R<sup><span style="font-family:Verdana;">2</span></sup><span style="font-family:Verdana;">) and the percentage of bias (PBIAS)) and the visual appreciation of hydrographs for monthly series. The statistical indices appear satisfactory with a NS and R</span><sup><span style="font-family:Verdana;">2</span></sup><span style="font-family:Verdana;"> ≥ 0.6 both for calibration and validation, and a PBIAS of </span><span style="font-family:;" "=""><span style="font-family:Verdana;">-</span><span style="font-family:Verdana;">11.2 and </span><span style="font-family:Verdana;">-</span><span><span style="font-family:Verdana;">3.8 respectively for calibration and validation. The hydrological modeling of Loka basin has shown the impact of climate change already reported by some authors as well as anthropization. Thus, while the reservoir records a decrease in its water volume estimated at 384,604 m</span><sup><span style="font-family:Verdana;">3</span></sup><span style="font-family:Verdana;"> each year, the water demand undergoes an increase of 122,033 m</span><sup><span style="font-family:Verdana;">3</span></sup><span style="font-family:Verdana;"> per year.</span></span></span>展开更多
缺资料流域水文模型的参数率定是水文学科的一个研究重点.除传统的参数区域化方法以外,考虑到在部分缺资料流域可能存在少量短时间序列或零星不连续径流量观测数据的实际情况,近年来采用少量不连续径流量观测数据率定模型参数的方法逐...缺资料流域水文模型的参数率定是水文学科的一个研究重点.除传统的参数区域化方法以外,考虑到在部分缺资料流域可能存在少量短时间序列或零星不连续径流量观测数据的实际情况,近年来采用少量不连续径流量观测数据率定模型参数的方法逐渐引起关注.本研究以我国西北内陆的黑河流域上游为研究区域,选取分布式水文模型SWAT(Soil and Water Assessment Tool)为研究工具,使用SUFI-2方法作为参数自动率定与不确定性分析工具,分析不同径流量观测数据数量对模型参数率定结果的影响.研究结果显示,4组不同径流量数据在验证期的Nash效率系数均为0.67,表明使用1年的径流量数据进行参数率定时所获得的模拟效果可以达到使用多年径流数据率定参数的水平;比较各组模拟结果获得的P因子和R因子,表明使用1年径流量数据进行模型率定的不确定性会更大.展开更多
The semi-distributed SWAT (Soil and Water Assessment Tools) model was used in this study to model the sediment yield in the watershed of the Aghien lagoon with an area of 365 km<sup><span style="font-fam...The semi-distributed SWAT (Soil and Water Assessment Tools) model was used in this study to model the sediment yield in the watershed of the Aghien lagoon with an area of 365 km<sup><span style="font-family:Verdana;">2</span></sup><span style="font-family:Verdana;">, located in the north of the district of Abidjan (South-East from</span><span style="font-family:Verdana;"> C<span style="white-space:nowrap;">?</span>te d’Ivoire). A sensitivity and uncertainty analysis, as well as calibration of the SWAT model, was conducted using the Sequential Uncertainty Adjustment Procedure (SUFI-2) which is one of the programs interfaced with SWAT in the SWAT-Cup package (SWAT-Calibration-Uncertainty</span><span style="font-family:Verdana;"> Programs). Five parameters of the SWAT model were found to be more sensitive to sediment fluxes. These have been modified (calibration) sparingly in order to improve the reproduction of observed sediments data. Two measures were used to assess the uncertainty analysis of the model: P-factor and R-factor. The R</span><sup><span style="font-family:Verdana;">2</span></sup><span style="font-family:Verdana;"> and Nash-Sutcliffe (NS) coefficients of determination were used to assess the quality of the calibration. The P-factor obtained is 0.58 and the R-factor is 2.28. The NS and R</span><sup><span style="font-family:Verdana;">2</span></sup><span style="font-family:Verdana;"> coefficients in calibration over the period from June 2014 to January 2015 are 0.51 and 0.86 respectively. These values </span><span style="font-family:Verdana;">indicate correct consideration of uncertainties by the model and satisfactory calibration</span><span style="font-family:Verdana;"> of the SWAT model for solid fluxes. Then, the model was used to simulate the sediment fluxes at the horizons 2040 (2035-2056), 2060 (2057-2078</span><span style="font-family:Verdana;">)</span><span style="font-family:Verdana;"> and 2080 (2079-2100) in order to assess the impact of climate change on sediments in the watershed of the Aghien lagoon. The results indicate that sediment fluxes could increase in the future under the RCP 4.5 and RCP 8.5 scenarios. With RCP 4.5, sediment fluxes would increase on average by 14.42%. They could increase by 17.95% on average under RCP 8.5.</span>展开更多
文摘The city of Bouaké, the second biggest city of Côte d’Ivoire, experienced a water shortage in 2018 that lasted four months due to the drying up of the Loka reservoir, which supplies two-thirds of the city. The challenge of the Loka reservoir is that it is located in an ungauged basin where very few hydrological studies have been carried out, despite the recurrent problems of access to drinking water. In the purpose to better understand the phenomena that caused this temporary drying of the dam, the methodology implemented was based on agro-hydrological modeling with SWAT using a regionalization technique of a nearby watershed. The model performance was assessed using three statistical indices (the Nash-Sutcliffe coefficient (NS), the coefficient of determination (R<sup><span style="font-family:Verdana;">2</span></sup><span style="font-family:Verdana;">) and the percentage of bias (PBIAS)) and the visual appreciation of hydrographs for monthly series. The statistical indices appear satisfactory with a NS and R</span><sup><span style="font-family:Verdana;">2</span></sup><span style="font-family:Verdana;"> ≥ 0.6 both for calibration and validation, and a PBIAS of </span><span style="font-family:;" "=""><span style="font-family:Verdana;">-</span><span style="font-family:Verdana;">11.2 and </span><span style="font-family:Verdana;">-</span><span><span style="font-family:Verdana;">3.8 respectively for calibration and validation. The hydrological modeling of Loka basin has shown the impact of climate change already reported by some authors as well as anthropization. Thus, while the reservoir records a decrease in its water volume estimated at 384,604 m</span><sup><span style="font-family:Verdana;">3</span></sup><span style="font-family:Verdana;"> each year, the water demand undergoes an increase of 122,033 m</span><sup><span style="font-family:Verdana;">3</span></sup><span style="font-family:Verdana;"> per year.</span></span></span>
文摘缺资料流域水文模型的参数率定是水文学科的一个研究重点.除传统的参数区域化方法以外,考虑到在部分缺资料流域可能存在少量短时间序列或零星不连续径流量观测数据的实际情况,近年来采用少量不连续径流量观测数据率定模型参数的方法逐渐引起关注.本研究以我国西北内陆的黑河流域上游为研究区域,选取分布式水文模型SWAT(Soil and Water Assessment Tool)为研究工具,使用SUFI-2方法作为参数自动率定与不确定性分析工具,分析不同径流量观测数据数量对模型参数率定结果的影响.研究结果显示,4组不同径流量数据在验证期的Nash效率系数均为0.67,表明使用1年的径流量数据进行参数率定时所获得的模拟效果可以达到使用多年径流数据率定参数的水平;比较各组模拟结果获得的P因子和R因子,表明使用1年径流量数据进行模型率定的不确定性会更大.
文摘The semi-distributed SWAT (Soil and Water Assessment Tools) model was used in this study to model the sediment yield in the watershed of the Aghien lagoon with an area of 365 km<sup><span style="font-family:Verdana;">2</span></sup><span style="font-family:Verdana;">, located in the north of the district of Abidjan (South-East from</span><span style="font-family:Verdana;"> C<span style="white-space:nowrap;">?</span>te d’Ivoire). A sensitivity and uncertainty analysis, as well as calibration of the SWAT model, was conducted using the Sequential Uncertainty Adjustment Procedure (SUFI-2) which is one of the programs interfaced with SWAT in the SWAT-Cup package (SWAT-Calibration-Uncertainty</span><span style="font-family:Verdana;"> Programs). Five parameters of the SWAT model were found to be more sensitive to sediment fluxes. These have been modified (calibration) sparingly in order to improve the reproduction of observed sediments data. Two measures were used to assess the uncertainty analysis of the model: P-factor and R-factor. The R</span><sup><span style="font-family:Verdana;">2</span></sup><span style="font-family:Verdana;"> and Nash-Sutcliffe (NS) coefficients of determination were used to assess the quality of the calibration. The P-factor obtained is 0.58 and the R-factor is 2.28. The NS and R</span><sup><span style="font-family:Verdana;">2</span></sup><span style="font-family:Verdana;"> coefficients in calibration over the period from June 2014 to January 2015 are 0.51 and 0.86 respectively. These values </span><span style="font-family:Verdana;">indicate correct consideration of uncertainties by the model and satisfactory calibration</span><span style="font-family:Verdana;"> of the SWAT model for solid fluxes. Then, the model was used to simulate the sediment fluxes at the horizons 2040 (2035-2056), 2060 (2057-2078</span><span style="font-family:Verdana;">)</span><span style="font-family:Verdana;"> and 2080 (2079-2100) in order to assess the impact of climate change on sediments in the watershed of the Aghien lagoon. The results indicate that sediment fluxes could increase in the future under the RCP 4.5 and RCP 8.5 scenarios. With RCP 4.5, sediment fluxes would increase on average by 14.42%. They could increase by 17.95% on average under RCP 8.5.</span>