Changes In Land Use/ Cover And Water Balance Components During 1964–2010 Period In The Mono River Basin, Togo-Benin

The Intergovernmental Panel on Climate Change has predicted that sub-tropical regions are more vulnerable to climate change’s negative effects (CC). Additionally, to CC, land use and land cover (LULC) changes and dam construction, often neglected, play an important role in the spatial and temporal distribution of water balance components (WBC) for agricultural production and socio-ecological equilibrium. This study aimed to analyze and compare the changes in LULC and WBC for the period before Nangbéto dam construction (1964–1986) and the period after its construction (1988–2010) in the Mono River Basin (MRB). To this end, the study used mainly WBC extracted from the validated Soil and Water Assessment Tool and LULC data of 1975–2000 in the MRB to explore their temporal distributions and the link in their changes. The results showed that mean actual monthly evapotranspiration, percolation, water yield, surface runoff, groundwater, and lateral flow represent 51%, 17.5%, 15.9%, 9.4%; 5.7% and 0.4%, respectively, of total water balance between 1964 and 1986. The same components represented 51%, 9.1%, 20.4%, 6.3%, 10.6% and 2.6%, respectively, between 1988 and 2010. The contribution of these WBC in the mean-annual (1964–1986) period was for actual evapotranspiration (31.3%), water yield (25.9%), percolation (17.7%), groundwater (14.71%), surface runoff (9.94%) and lateral flow (0.40%). Meanwhile, between 1988 and 2010, the contribution of actual evapotranspiration, water yield, percolation, groundwater, surface runoff and lateral flow is 49.8%,19.9%, 11.2%, 10.3%, 6.1%, and 2.5%, respectively. The results showed that the peaks of the actual evapotranspiration, surface runoff, percolation and water yield appeared in September, corresponding to a month after the maximum rainfall in August. However, our more detailed analysis showed that a significant decrease in forest and savanna and an increase in croplands led to a decrease in actual evapotranspiration and lateral flow over the second simulation period compared to the first period of simulation over the MRB scale. These findings showed that sustainable management and conservation of natural vegetation are crucial for integrated water resource management and conservation in MRB.