PREDICTION OF FUTURE LAND USE LAND COVER (LULC) AND ASSESSMENT OF ITS IMPACT ON THE WATER SUPPLY AVAILABILITY OF BUTUAN CITY-TAGUIBO RIVER WATERSHED AND FOREST RESERVE (TRWFR), PHILIPPINES

Abstract. The Taguibo River Watershed and Forest Reserve (TRWFR) is the primary source of water supply in Butuan City. However, intermittent water supply became a problem for years now in Butuan especially in dry seasons. Hence, this study intended to assess the impacts of LULC change in the TRWFR by generating and predict temporal land covers and determine the impact of these land covers to the current and future water supply of the watershed. This study used Google Earth Engine (GEE) to generate LULC maps of TRWFR from year 2013–2021 which will be used as inputs for the LULC prediction. The QGIS MOLUSCE Plugin was used to predict a land cover for the year 2024. The generated and predicted LULC maps for the year 2021 and 2024, respectively, were then used to simulate streamflow using the Soil and Water Assessment Tool (SWAT) model. The analysis of the SWAT model of the watershed, with the generated temporal land covers from 2013–2024, showcased increase streamflow from 3225.53 liter per second (lps) in 2013, 3267.10 lps in 2021 and 3239.73 lps in 2024. With the results of the hydrologic modeling, there is an increase in the water flow from 2013 to 2021 which might be due to the increase in vegetation but there is a probable decrease in the year 2024. The results show that the change in vegetation has an effect in the water flow in a watershed and this could be assessed through hydrologic modeling.