Failure of inland valleys development: a hydrological diagnosis of the Bankandi valley in Burkina Faso

摘要

Several developed inland valleys for rice production were abandoned due to poor design or implementation. The Bankandi inland valley (BIV) is a contour bunds system developed in 2006 by a development project, currently experiencing a systematic waterlogging. This study assessed: (1) the waterlogging vs. changing hydro-climatic conditions relationship; (2) the hydrological design and implementation of water control infrastructures; and (3) how digital elevation models (DEMs) data could be used for inland valleys development. To investigate the waterlogging vs. changing hydro-climatic conditions (precipitation and discharge), the conceptual HBV model was applied; coupled with break and trend detections tests. To evaluate the accuracy of the location of drainage flume and contour bunds, a topographic survey using a D-GPS was performed. To explore free DEMs as support tool in the development of inland valley, the Shuttle Radar Topography Mission 1 and the Advanced Spaceborne Thermal Emission and Reflection Radiometer 1, were used. The results show that: (1) the waterlogging was not related to changing environmental conditions; (2) major flaws including bunds not implemented on contour lines contribute to the waterlogging; (3) free DEMs were not accurate enough for valley development. The overall diagnostic of BIV entails conducting basic hydrological investigations prior to implementation.