Hydrologic process simulation of a semiarid, endoreic catchment in Sahelian West Niger. 1. Model-aided data analysis and screening

• Published in: Journal of hydrology (Amsterdam) Vol. 279; no. 1; pp. 224 - 243
• Main Authors: Peugeot, Christophe, Cappelaere, Bernard, Vieux, Baxter E., Séguis, Luc, Maia, Ana
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 25.08.2003; Elsevier Science; Elsevier
• Subjects: Africa, West, Sahel Region; Distributed hydrologic modeling; Earth Sciences; Earth, ocean, space; Exact sciences and technology; Hortonian runoff; Hydrogeology; Hydrology; Hydrology. Hydrogeology; Niger, Niamey; Outliers; Rainfall–runoff; Sahel; Sample construction; Sciences of the Universe; Uncalibrated model; Water resources; Niger; West Africa; Sahel; Distributed hydrologic modeling; Outliers; Uncalibrated model; Sample construction; Rainfall–runoff; Hortonian runoff; Sahel; ground water; ground-water recharge; geographic information systems; drainage patterns; digital simulation; drainage basins; hydraulic conductivity; water resources; land use; aquifers; wells; calibration; landscapes; rainfall; soil moisture; Africa; runoff; vulnerability; hydrological modeling; drought; water resource management; Rainfall-runoff; unconfined aquifers; semi-arid environment; BILAN HYDROLOGIQUE; CHANGEMENT CLIMATIQUE; MODELE HYDROLOGIQUE; ANALYSE STATISTIQUE; NIAMEY; ETAT DE SURFACE DU SOL; ANALYSE DISCRIMINANTE; SIMULATION; HUMIDITE DU SOL; COEFFICIENT D'ECOULEMENT; ZONE SEMIARIDE; WANKAMA BASSIN VERSANT; LOI DE HORTON; ETUDE D'IMPACT; ENDOREISME; NIGER; MODELE DISTRIBUE; SECHERESSE; BASSIN VERSANT; ZONE SAHELIENNE; PLUIE
• ISSN: 0022-1694; 1879-2707
• DOI: 10.1016/S0022-1694(03)00181-1

The drought in the African Sahel, persisting since 1968, emphasizes the vulnerability of local water resources to climatic variations and land use changes in this semiarid environment. Following the Hapex–Sahel experiment (1992–1994), research aims at understanding and modeling the impact on the hydrological cycle of these changing climatic and environmental conditions over a 1500-km 2 area east of Niamey, Niger. The hydrological landscape consists of a myriad of small endoreic catchments feeding temporary or permanent pools from which water percolates to an unconfined aquifer. As the first step in a local-to-regional scale approach to the water resource recharge in the area, a physically based rainfall–runoff model is developed for a typical, 1.9-km 2 endoreic system named Wankama, which is monitored continuously since 1992. This first of two companion papers describes the key elements of the hydrological landscape, the experimental setup with which the Wankama catchment and pool are monitored, the r.water.fea distributed hydrological model and its application to the construction of the Wankama catchment model. Because of the difficulties of long-term field experimentation in the region, not all observed events can be considered equally well recorded; in particular, detection of exogenous water inflow occurrences that may alter Wankama runoff estimates is needed. The paper describes the careful, model-aided data analysis performed in order to select the observation set with which the model can most reliably be tuned and operated. In this rainfall–runoff data analysis phase, the model is used prior to any calibration. Model calibration and verification, including output uncertainty, are the subject of the second paper [J. Hydrol. (2003)]. All steps of analysis and modeling were performed on the 1992–1998 data only, before the 1999–2000 data became available, and are tested a posteriori against the latter.