Assessment of the Impact of Changing Land Use and land Cover on the Peak Discharges of a Tropical Watershed: A Study of the Davao River Basin

Abstract

Urbanization has spread throughout the globe. Accompanied by rapid population growth, urbanization has resulted in the change of land use/land cover manifested by conversion of forests to impervious areas and subsequent alteration of the hydrology in the area. This study sheds light on the impacts of such land cover changes to peak discharges in the Davao River Basin as a result of the watershed alterations. Land cover from 2010 and 2018 were used to represent two (2) levels of urbanization (increasing with year). These were generated from spatial analysis of MODIS imagery data in ArcGIS. This was used in the hydrologic simulation in HEC-HMS to gather the peak discharges for the two events. An increase in peak discharge is observed along with an increase in urbanization. Furthermore, the additional 1.12% of land converted to an impervious area of the basin lead to an increase in peak discharge of 105.85% in the simulations. Moreover, the conversion of areas to impermeable surfaces led to a 52.23% decrease in the infiltration capacity of the sub basins.