Application of hydrometeorological data to analyze water balance conditions in Bengkulu watershed

Abstract

Abstrak Water balance serves to determine hydrological conditions in a watershed, one of which is by analyzing the surplus (excess water) and deficit (water shortage) that occurs. Extreme surpluses or deficits can cause hydrometeorological disasters, such as floods or droughts. This study aims to calculate the monthly water balance using the Thornthwaite-Mather method to determine variations in the incidence of surplus and deficit months in all three sub-watersheds in Bengkulu Watershed, namely Rindu Hati, Susup, and Bengkulu Hilir sub-watershed. The data used are monthly hydrometeorological data for 2009-2018 (10 years) were divided into two periods of water balance based on land use data. Water balance period 1 (2009-2013) uses 2009 land use data, while period 2 (2014-2018) uses 2014 land use data. The results show that the surplus, deficit, runoff, and discharge in the three sub-watersheds in the Bengkulu watershed are affected by rainfall. In general, the deficit incidents in all three sub-watersheds occur almost every three years. The Rindu Hati and Susup sub-watersheds have the same variations of surplus and deficit month incidents, while the Bengkulu Hilir sub-watershed is different, both in periods 1 and 2. It is not only the rainfall that affects the variation in the events of surplus and deficit in all three sub-watersheds of the Bengkulu watershed, but also the amount of water holding capacity (WHC). Therefore, the application of hydrometeorological data to analyze the water balance conditions in the Bengkulu watershed provides information on climate impact on water resources and environmental impact on flows in the watershed.