The objective of this study was to propose a mathematical regression model to estimate the exploitation flow rate of a water borehole from geophysical parameters in the midst of a fissured basement in the central-east...The objective of this study was to propose a mathematical regression model to estimate the exploitation flow rate of a water borehole from geophysical parameters in the midst of a fissured basement in the central-eastern part of C<span style="white-space:nowrap;">?</span>te d’Ivoire. The data of the study are both hydrogeological and geophysical parameters from one hundred and eleven (111) data sheets of (111) water and geophysical boreholes. Two methods were used. The Normal Principal Component Analysis (NPCA) method applied to the data made it possible to select the explanatory variables (geophysical parameters) for borehole productivity. The multiple linear regression method subsequently made it possible to propose a mathematical model capable of estimating the exploitation rate from the geophysical parameters. The results indicate a very strong correlation (0.87) between longitudinal conductivity and flow rate, with flow rate and apparent resistivity negatively correlated. The multiple linear regression method highlighted two relevant explanatory variables, longitudinal conductivity and apparent resistivity. These two geophysical parameters contributed to a mathematical model in the form <span style="white-space:nowrap;"><em>Q</em> = <em>C</em><sub>1</sub><em>X</em><sub>1</sub> + <em>C</em><sub>2</sub><em>X</em><sub>2</sub> + ... + <em>C</em><sub>n</sub><em>X</em><sub>n</sub> + <em>C</em><sub>0</sub></span>. the real model obtained in this work is <span style="white-space:nowrap;"><em>Q</em> = 0.82<em>Cl</em> - 0.12<em>Rho.app</em> + 2.5</span>. The resulting model is efficient with a correlation of 86% in calibration and 95% in validation. A bias of 0.37 in calibration and 0.82 in validation is observed. Finally, the square root mean square error (RMSE) is 3.10 to 3.38 respectively in calibration and validation.展开更多
The process by which rainfall reaches the aquifer in a sedimentary area is infiltration. This process could be affected quantitatively or qualitatively by the changes in the land use land cover (LULC) as a result of a...The process by which rainfall reaches the aquifer in a sedimentary area is infiltration. This process could be affected quantitatively or qualitatively by the changes in the land use land cover (LULC) as a result of anthropogenic activities which could affect groundwater reserves. This study focuses on the influence of LULC change on groundwater recharge in the context of urbanization and population growth. Four weather stations data and satellite image data were used in order to evaluate water infiltration which is the amount of water that reaches the piezometric surface from 1990 to 2016. The spatial-temporal LULC change in relation to urbanization sprawl was assessed based on a series of Landsat images for 1990, 2000 and 2016. The maximum likelihood pixel-based on classification method was used to analyze the spatial-temporal LULC dynamics. The Thiessen polygon method was used for the mean area precipitation computation. The recharge was determined using water balance method after determining the runoff based on the Soil Conservation Service curve number method. The results show an increase in built-up and agricultural land, while the forest and shrub areas declined with water body remaining unchanged over the period 1990-2016. The decline in forest could be imputed to the demographic and socio-economic growth as expressed by the expansion of agriculture and urbanization. Groundwater recharge and runoff results are respectively 34%, 20% in 1999;21%, 46% in 2000 and 26%, 14% in 2016 of rainfall and show their strong dependence on precipitation and LULC change.展开更多
文摘The objective of this study was to propose a mathematical regression model to estimate the exploitation flow rate of a water borehole from geophysical parameters in the midst of a fissured basement in the central-eastern part of C<span style="white-space:nowrap;">?</span>te d’Ivoire. The data of the study are both hydrogeological and geophysical parameters from one hundred and eleven (111) data sheets of (111) water and geophysical boreholes. Two methods were used. The Normal Principal Component Analysis (NPCA) method applied to the data made it possible to select the explanatory variables (geophysical parameters) for borehole productivity. The multiple linear regression method subsequently made it possible to propose a mathematical model capable of estimating the exploitation rate from the geophysical parameters. The results indicate a very strong correlation (0.87) between longitudinal conductivity and flow rate, with flow rate and apparent resistivity negatively correlated. The multiple linear regression method highlighted two relevant explanatory variables, longitudinal conductivity and apparent resistivity. These two geophysical parameters contributed to a mathematical model in the form <span style="white-space:nowrap;"><em>Q</em> = <em>C</em><sub>1</sub><em>X</em><sub>1</sub> + <em>C</em><sub>2</sub><em>X</em><sub>2</sub> + ... + <em>C</em><sub>n</sub><em>X</em><sub>n</sub> + <em>C</em><sub>0</sub></span>. the real model obtained in this work is <span style="white-space:nowrap;"><em>Q</em> = 0.82<em>Cl</em> - 0.12<em>Rho.app</em> + 2.5</span>. The resulting model is efficient with a correlation of 86% in calibration and 95% in validation. A bias of 0.37 in calibration and 0.82 in validation is observed. Finally, the square root mean square error (RMSE) is 3.10 to 3.38 respectively in calibration and validation.
基金the Federal Ministry of Education and Research(BMBF)and West African Science Centre on Climate Change and Adapted Land Use(WASCAL,www.wascal.org)for providing the scholarship and financial support for this programme.
文摘The process by which rainfall reaches the aquifer in a sedimentary area is infiltration. This process could be affected quantitatively or qualitatively by the changes in the land use land cover (LULC) as a result of anthropogenic activities which could affect groundwater reserves. This study focuses on the influence of LULC change on groundwater recharge in the context of urbanization and population growth. Four weather stations data and satellite image data were used in order to evaluate water infiltration which is the amount of water that reaches the piezometric surface from 1990 to 2016. The spatial-temporal LULC change in relation to urbanization sprawl was assessed based on a series of Landsat images for 1990, 2000 and 2016. The maximum likelihood pixel-based on classification method was used to analyze the spatial-temporal LULC dynamics. The Thiessen polygon method was used for the mean area precipitation computation. The recharge was determined using water balance method after determining the runoff based on the Soil Conservation Service curve number method. The results show an increase in built-up and agricultural land, while the forest and shrub areas declined with water body remaining unchanged over the period 1990-2016. The decline in forest could be imputed to the demographic and socio-economic growth as expressed by the expansion of agriculture and urbanization. Groundwater recharge and runoff results are respectively 34%, 20% in 1999;21%, 46% in 2000 and 26%, 14% in 2016 of rainfall and show their strong dependence on precipitation and LULC change.
