Impact of LULC Change on Streamflow in a Mauritius Catchment using IHACRES and HEC-HMS Models

Abstract

Land use and land cover (LULC) play an important role in the catchment hydrology, regulating the transfer of water within the system. Mauritius is a tropical island in the Indian Ocean which is frequently affected by floods and the frequency of these floods have increased considerably over the last two decades. Due to rapid urbanization, the LULC of Mauritius has been altered drastically. In this study, the authors have tried to assess the relationship between streamflow volume and LULC changes using the IHACRES (Identification of Hydrographs and Component flows from Rainfall,Evaporation and Streamflow data)and the HEC-HMS(Hydrologic Modelling Centre-HydrologicModelling System) hydrological models. LULC and soil maps are generated for the catchment using ArcMap 10.1. The HEC-GeoHMS extension is used to simulate different hydrologic files that are to be exported in HEC-HMS for runoff simulation. Performance of the models during the calibration and validation period are compared and the output of HEC-HMS is found to be the more reliable. The comparison between the observed and simulated streamflow values for a period of ten years, leads us to conclude that runoff simulated by both models are reliable.Further,while observing the change in streamflow over the ten year speriod, it has been deduced that an increase in urban area results in an increase in streamflow volume.