Abstract. Land use change are become issues for many river basin in the world, including Cikapundung River Basin in West Java. Cikapundung River is one of the main water sources of Bandung City water supply system. In the other hand, as one of the tributaries of Citarum River, Cikapundung also contributes to flooding in the Southern part of Bandung. Therefore, it is important to analyze the effect of land use change on Cikapundung river discharge, to maintain the reliability of water supply system and to minimize flooding in Bandung Basin. Land use map of Cikapundung River in 2009 shows that residential area (49.7%) and mixed farming (42.6%), are the most dominant land use type, while dry agriculture (19.4%) and forest (21.8%) cover the rest. The effect of land use change in Cikapundung River Basin is simulated by using Hydrological Simulation Program FORTRAN (HSPF) through 3 land use change scenarios: extreme, optimum, and existing. By using the calibrated parameters, simulation of the extreme land use change scenario with the decrease of forest area by 77.7% and increase of developed area by 57.0% from the existing condition resulted in increase of Qmax/Qmin ratio from 5.24 to 6.10. Meanwhile, simulation of the optimum land use change scenario with the expansion of forest area by 75.26% from the existing condition resulted in decrease of Qmax/Qmin ratio from 5.24 to 4.14. Although Qmax/Qmin ratio of Cikapundung is still relatively small, but the simulation shows the important of water resources analysis in providing river health indicator, as input for land use planning.

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The Upper Citarum River Basin is the main catchment area of the Saguling Dam, the most upstream of three cascade dams in the Citarum River Basin. During the last 30 years, rapid economic development has led to an increase of water extraction and land conversion from green area to developed area. Also, evidence of climate change can clearly be seen from the climatological records of a number of climatology stations in this basin over the last few decades. In this study, the effect of anthropogenic and climate change in the Upper Citarum River Basin river discharge was simulated using the Sacramento Catchment Model. Historical river discharge, rainfall, climatology, and land cover from 1995 to 2009 were used for model calibration and verification. The multi-model mean monthly rainfall and the temperature projection taken from Coupled Model Intercomparison Project 5 (CMIP5) for the RCP6 and RCP8.5 climate change scenarios were statistically downscaled and used as input for a simulation of future river discharge from 2030 to 2050. The result showed that the combination of anthropogenic and climate change may result in a significant decrease of low flow in the Upper Citarum River Basin. This study underlines the importance of land cover and climate change factors for future infrastructure planning and management in the Upper Citarum River Basin.

Over the last few decades, prolonged drought in Indonesia has led to a catastrophic wildfire hazard, including on Kalimantan Island. The Barito River basin is one of the major river basins on the island, located in South and Central Kalimantan Provinces. According to The Indonesian National Board for Disaster Management (BNPB), the drought hazard index in the southern part of Kalimantan is mostly at the medium to high-risk level. In terms of Integrated Water Resources (IWRM), more detailed drought risk analysis needs to be conducted at the river basin level, so that drought adaptation and mitigation strategies can be integrated into long-term river basin management plans. In this study, a drought projection of the Barito River basin was simulated by using the Coupled Model Intercomparison Project 5 (CMIP5). A coarse grid of CMIP5 data was statistically downscaled to a smaller grid over the basin area. Data from climatology observation stations and Climate Forecast System Reanalysis (CFSR) were used to calibrate the bias correction function of the CMIP5 data. This function for rainfall data was developed based on the rainfall probability curve, while the bias correction function for temperature data was developed based on the elevation-temperature relation. The bias-corrected rainfall and temperature data were used as input for the Keetch-Byram Drought Index (KBDI) analysis. The study shows that the potential for drought hazard may increase in the future. Drought projection in the Barito basin for 2050 using KBDI shows that the potential areas with medium and high drought risk may cover around 50% and 2%, respectively, or about 35,000km 2 and 1,400km 2 . The occurrence of wildfires also has a strong correlation with the drought index. A comparison between 1998 and 2015 fire hotspot data shows that most hotspots were located in areas in the medium and high drought risk categories. The study shows the importance of climate change impact analysis to prevent more catastrophic hazards in the future, especially in the Barito River basin, Kalimantan Island.

On September 28, 2018, Palu Earthquake caused tremendous damage to the coastal area of Palu, Central Sulawesi, Indonesia. The epicenter was located at 27[Formula: see text]km northeast from Donggala Beach with a 10[Formula: see text]km depth. The magnitude of the earthquake was recorded at 7.4. This study assessed the tsunami overland characteristics and its outcome on the coastal area of Palu. The analysis was conducted based on satellite images and video recordings. The satellite images taken prior and post the event, were analyzed to evaluate the morphological change along the coast. The shoreline retreated up to 158[Formula: see text]m in some places. The tsunami damaged infrastructures along the affected coastal area. Video recordings were collected and analyzed to assess the tsunami overland propagation. The data were verified by field survey. The arrival time and celerity of the wave propagation overland on open area and the urban area were studied. It was found that buildings in the urban area have a significant impact on celerity. The wave propagates faster in the open area than inside the building.

Flood is a natural disaster that can occur at any time and anywhere. The flood disaster causes material and non-material loss, then in order to increase the resilience to disaster, an early warning system is needed. The data is indispensable as a reference to make an early warning system. Unfortunately, flood assessment in purpose to record the data is often conducted much later after the event occurs. Therefore, this research was conducted to do modelling of flood hazard map is quantitatively and validated with observation data as a form of rapid flood assessment. The location of this study is in the Upper Citarum River Basin, around Bandung basin. The model is well done if the result shows the location of the flood as illustrated as the observational data. The result shows fair agreement with observed data where some points of inundated areas are captured and the location of inundated areas from modelling result looks similar to the inundated area from observation data.

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