Your search found 2 records
1 Siavashani, N. S.; Jimenez-Martinez, J.; Vaquero, G.; Elorza, F. J.; Sheffield, J.; Candela, L.; Serrat-Capdevila, A. 2021. Assessment of CHADFDM satellite-based input dataset for the groundwater recharge estimation in arid and data scarce regions. Hydrological Processes, 35(6):e14250. [doi: https://doi.org/10.1002/hyp.14250]
Groundwater recharge ; Satellites ; Datasets ; Weather data ; Semiarid zones ; Precipitation ; Drought ; Rain ; Evapotranspiration ; Irrigated land ; Soil water balance ; Water resources ; Aquifers ; Air temperature ; Remote sensing ; Sensitivity analysis ; Uncertainty ; Models / Chad / Niger / Nigeria / Lake Chad Basin
(Location: IWMI HQ Call no: e-copy only Record No: H050431)
https://onlinelibrary.wiley.com/doi/epdf/10.1002/hyp.14250
https://vlibrary.iwmi.org/pdf/H050431.pdf
https://vlibrary.iwmi.org/pdf/H050431.pdf
(3.85 MB) (3.85 MB)
Aquifer natural recharge estimations are a prerequisite for understanding hydrologic systems and sustainable water resources management. As meteorological data series collection is difficult in arid and semiarid areas, satellite products have recently become an alternative for water resources studies. A daily groundwater recharge estimation in the NW part of the Lake Chad Basin, using a soil–plant-atmosphere model (VisualBALAN), from ground- and satellite-based meteorological input dataset for non-irrigated and irrigated land and for the 2005–2014 period is presented. Average annual values were 284 mm and 30°C for precipitation and temperature in ground-based gauge stations. For the satellite-model-based Lake Chad Basin Flood and Drought Monitor System platform (CHADFDM), average annual precipitation and temperature were 417 mm and 29°C, respectively. Uncertainties derived from satellite data measurement could account for the rainfall difference. The estimated mean annual aquifer recharge was always higher from satellite- than ground-based data, with differences up to 46% for dryland and 23% in irrigated areas. Recharge response to rainfall events was very variable and results were very sensitive to: wilting point, field capacity and curve number for runoff estimation. Obtained results provide plausible recharge values beyond the uncertainty related to data input and modelling approach. This work prevents on the important deviations in recharge estimation from weighted-ensemble satellite-based data, informing in decision making to both stakeholders and policy makers.
2 Vaquero, G.; Siavashani, N. S.; García-Martinez, D.; Elorza, F. J.; Bila, M.; Candela, L.; Serrat-Capdevila, A. 2021. The Lake Chad Transboundary Aquifer. Estimation of groundwater fluxes through international borders from regional numerical modeling. Journal of Hydrology: Regional Studies, 38:100935. [doi: https://doi.org/10.1016/j.ejrh.2021.100935]
International waters ; Aquifers ; Groundwater recharge ; Modelling ; Hydrology ; Water levels ; Water balance ; Evapotranspiration ; Sensitivity analysis / Africa / Central African Republic / Niger / Chad / Nigeria / Cameroon / Lake Chad Transboundary Aquifer
(Location: IWMI HQ Call no: e-copy only Record No: H050770)
https://www.sciencedirect.com/science/article/pii/S2214581821001646/pdfft?md5=44d6bb1914f193381a3ed98bbaccb76b&pid=1-s2.0-S2214581821001646-main.pdf
https://vlibrary.iwmi.org/pdf/H050770.pdf
https://vlibrary.iwmi.org/pdf/H050770.pdf
(14.30 MB) (14.3 MB)
Study Region: Africa. The Lake Chad transboundary aquifer
Study Focus: To understand transboundary groundwater hydrodynamics and estimate quantitative groundwater fluxes values between aquifer-sharing countries. To enable estimations, we developed an updated 3D ‘quasi steady-state’ regional groundwater flow model of the Chad Formation based on integrating extensive available information and reflecting the best current conceptual understanding to date. The conceptual model was tentatively assessed by a steady-state numerical model based on MODFLOW.
New Hydrological Insights for the Region: This model simulates lateral groundwater flows between neighboring countries, and also provides insights into the large-scale flow pattern and flows among hydroestratigraphic units. Modeling indicated that groundwater fluxes through international borders exist between Basin-sharing countries, except between Central African Republic and Cameroon, where a buffer area was considered for modeling purposes, leading to more uncertain results. From 14ºN parallel to further north, data are scanty and outcomes should be carefully considered. Forecasting transboundary impacts indicated that changes in recharge rates were more sensitive that changes in groundwater abstraction. To date, abstraction represents a small part of the water balance, but if it increases, it can become a driving factor in the future. Land use change and water use in the source areas (southern area) will have the strongest impact on transboundary groundwater flows due to changes in recharge, which will lead to quantitative changes in groundwater levels, artesian conditions, or even water quality.
Study Focus: To understand transboundary groundwater hydrodynamics and estimate quantitative groundwater fluxes values between aquifer-sharing countries. To enable estimations, we developed an updated 3D ‘quasi steady-state’ regional groundwater flow model of the Chad Formation based on integrating extensive available information and reflecting the best current conceptual understanding to date. The conceptual model was tentatively assessed by a steady-state numerical model based on MODFLOW.
New Hydrological Insights for the Region: This model simulates lateral groundwater flows between neighboring countries, and also provides insights into the large-scale flow pattern and flows among hydroestratigraphic units. Modeling indicated that groundwater fluxes through international borders exist between Basin-sharing countries, except between Central African Republic and Cameroon, where a buffer area was considered for modeling purposes, leading to more uncertain results. From 14ºN parallel to further north, data are scanty and outcomes should be carefully considered. Forecasting transboundary impacts indicated that changes in recharge rates were more sensitive that changes in groundwater abstraction. To date, abstraction represents a small part of the water balance, but if it increases, it can become a driving factor in the future. Land use change and water use in the source areas (southern area) will have the strongest impact on transboundary groundwater flows due to changes in recharge, which will lead to quantitative changes in groundwater levels, artesian conditions, or even water quality.
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