Impact of hydraulic and storage properties on river leakage estimates: A numerical groundwater flow model case study from southern Benin

Flow characterization and modelling of a South Benin artesian aquifer system : Effects of hydraulic and storage properties and recharge on simulated heads across the artesian zone

“…RCH, GWA, GWD are respectively groundwater recharge to the subsurface from rainfall, groundwater abstractions and groundwater discharge through the southern limits of the flow domain (See Figure 4.1). Estimates of the above different groundwater budget components are based on abstractions data from the national data base (BDI-DGEau), recharge calculation based on climatic data and groundwater modelling from previous studies (Kpegli et al, 2018b). The total groundwater input (from both rainfall and net rivers leakage is estimated to be in average 2×10 8 m 3 /year while the total output (through groundwater abstractions/outflows (from wells, boreholes, artesian wells), springs and groundwater discharge out of the system (through the southern limits)) is about 1.46×10 8 m 3 /year, representing about 73% of the total input.…”

“…According to M'Po et al ( 2016), the Adjusted Quantile Mapping method is the most effective method in correcting the bias in daily precipitations in the study area. After bias corrections, the projected rainfall data of RACMO8.5 were considered to estimate groundwater recharge applying a combination of the Penman (for potential evapotranspiration estimation) and the water balance method (see Kpegli et al, 2018b and Appendix A). The temperature is projected to slightly increase by 2050 (Jalloh et al, 2013) and therefore higher potential evapotranspiration is expected (Figure 4.5b).…”

“…The conceptual groundwater flow model (Kpegli et al, 2018a) of the study area was translated into a numerical MODFLOW (McDonald and Harbaugh, 1988) model which was constructed by Kpegli et al (2018b). The numerical model is a 3D-model with a total of five model layers.…”

“…Recharge is assumed to be zero for the outcropping clay areas due to the very low permeability of this clay layer and based on previous studies (Kpegli et al, 2018a). The subsurface layers properties (hydraulic and storage properties), obtained from previous studies (Bouzid, 1971;IGIP, 1984;BURGEAP-BRGM, 1994;Turkpak International-SCET-Tunisie, 1991) were implemented (see Table 4.3 for the properties values), the known groundwater abstractions (from wells) were applied and the model was calibrated (stationary and transient calibrations) by Kpegli et al (2018b). For further details about the numerical model, the reader is referred to Kpegli et al (2018b).…”

“…The subsurface layers properties (hydraulic and storage properties), obtained from previous studies (Bouzid, 1971;IGIP, 1984;BURGEAP-BRGM, 1994;Turkpak International-SCET-Tunisie, 1991) were implemented (see Table 4.3 for the properties values), the known groundwater abstractions (from wells) were applied and the model was calibrated (stationary and transient calibrations) by Kpegli et al (2018b). For further details about the numerical model, the reader is referred to Kpegli et al (2018b). The calibrated hydraulic and storage properties by Kpegli et al (2018b) were validated with additional set of observed heads available for only three locations.…”