Analysis of Climate Change & Land Use Effect on the Availability and Water Quality of Raw Water (Case Study: Cibangoak Intake of Spam Ciparay at Tirta Raharja Local Public Water Supply Company, Bandung Regency)

Abstract

Climate change and land use change have significantly impacted the hydrological cycle, particularly affecting the availability and quality of raw water. This study aims to identify changes in rainfall patterns, temperature, and land use, as well as to examine their effects on the availability and quality of raw water for the Tirta Raharj a Local Public Water Company . The research focuses on the Cibangoak Intake located in the Cirasea Sub-watershed. The methodology uses three climate model outputs (MPI-ESM1.2-HR, MPI-ESM1-2-LR, and GFDL-ESM4) under different emission scenarios. Additionally, historical data on rainfall, water quality, discharge, and land use. The coarse-resolution global climate data were downscaled using the statistical downscaling method Bias Correction Quantile Mapping to generate localized rainfall and temperature projections for the study area. The Mann-Kendall and Spearman Rank tests, were conducted to detect any trends in rainfall and temperature at the study site. To assess the impact of climate and land use  on the discharge and raw water quality, a correlation analysis was performed. Trend test results indicate an increase in rainfall during the wet season, which significantly correlates with discharge levels. Correlation test results show a positive correlation between rainfall and the parameters of BOD (Biochemical Oxygen Demand) and Fecal coliforms during the wet season, a negative correlation between maximum temperature and minimum discharge, and a negative correlation between minimum temperature and TSS (Total Suspended Solids) in the wet season. Projections of rainfall and temperature indicate an increase in 2025-2045 compared to the 2010-2020, coupled with land use changes, may significantly affect both the quantity and quality of raw water at the Cibangoak Intake, Tirta Raharja Public Water Supply Company.

Keywords: climate change, discharge, Public Water Supply Company, rainfall, temperature, water quality