Spatiotemporal Rainfall Projection in Majalaya basin, West Java, Indonesia under CMIP6 Scenarios

Abstract

In this study, a Coupled Model Intercomparison Project Phase 6 (CMIP6), from the newest set of General Circulation Models (GCMs), was used to assess the spatiotemporal variability in rainfall regimes over the Majalaya basin in West Java, Indonesia. Twenty grid points of the gridded-based daily rainfall from the Climate Hazards Group InfraRed Precipitation with Station data (CHIRPS) datasets spanning from 1981 to 2014 were extracted. For the future projection, a set of 23 GCMs from the Shared Socioeconomic Pathways (SSPs) with SSP1-2.6, SSP2-4.5, SSP3-7.0, and SSP5-8.5 common to historical period were selected. Initially, the performance of the GCMs in simulating the local rainfall at each grid point was assess by using seven relative importance metrics. Then, compromise programming index (CPI) and Jenks optimised classification (JOC) were used to aggregate the results from the ranking of GCMs to select the best GCMs in simulating the local rainfall. It was found that EC-Earth3-Veg-LR ranked the best as Class I, followed by EC-Earth3-Veg, INM-CM4-8, EC-Earth3, MPI-ESM1-2-HR and MRI-ESM2-0 as Class II. Subsequently, the linear scaling (LS) method was used in bias correcting the selected GCM, EC-Earth3-Veg-LR using CHIRPS as reference observed data. The spatiotemporal assessment of bias-corrected LS-EC-Earth3-Veg-LR for the different months over the mid-future period 2041–2070 and 2071–2100 was compared with those under SSPs 126, 245, 370 and 585. Our results show a generally wetter tendency over Majalaya under all SSPs toward the end of the 21st century, particularly under SSP370 and SSP585. For the mid-future period, the results suggest a worsening drier period for the month of June to October. Meanwhile, the usually high rainfall month of November is projected to receive lower rainfall than normal. For the far-future period, all SSPs in most of the cases projected more increasing rainfall months as the typically drier period become shorter. The changes in rainfall were observed to move toward a more homogeneous increase in rainfall for all rainfall months across the basin from the mid-future to the far-future period. It is projected that rainfall events will become more frequent, more intense, and happen consecutively for the rainy months of December and January and followed by another consecutive rainy month for March and April.

The Utilization of Satellite Data and Machine Learning for Predicting the Inundation Height in the Majalaya Watershed

“…Rapid urbanization, overpopulation, climate change, extreme precipitation events, aging infrastructure, and low standards of stormwater drainage networks can threaten people's lives, properties, and the environment [54]. Several studies have studied some of Majalaya's problems, such as microplastic problems in drainage [55], the distributions of unconfined aquifers [56], the changes in rainfall characteristics in the Majalaya Basin that cause climate change [14], and the modeling of the 2018 Majalaya, and the floods caused the most extensive losses [12].…”

“…The subdistricts are all parts of Bandung Regency of West Java Province. The area is known for the textile and agriculture industries that support West Java's economy [9,12,13]. Although the Majalaya area has an important economic function, it has experienced flooding nearly every year since the 1970s.…”

“…The MERIT DEM was chosen because it was developed by removing errors from past DEM data [29]. A river bathymetric survey was also used to fix the inaccuracies of MERIT DEM in the river area [12]. The HEC-RAS and ANN modeling covered the extent of the February 2018 Majalaya flood area [9,13].…”

Analyzing lead time for flood early warning system in the upstream Citarum River

“…Floods in Majalaya occur almost every year since 2008 [6]. Usually, floods occur in a relatively short period with depths ranging from ankle-high to 1 m [7]. A flood incident in Majalaya on 22 February 2018 inundated the Majalaya area of 5.35 km² with a peak discharge of 155.82 m³/s.…”

Flood Characteristics in the Lower Citarum River, Indonesia and Their Possible Management Practices

“…The study showed that most of the rivers in the UCR have more than one ratio, with some classified as severely damaged. Rohmat [3,10] also worked in the Majalaya region and studied areas vulnerable to yearly flooding. As Majalaya is a vital component of the economy of the Bandung Metropolitan Area, the study intended to recreate the devastating flood that occurred on February 22, 2018, damaging a significant amount of property and the surrounding area.…”