No abstract

This study is intended to simulate the river discharges in major watersheds of northwestern Java, Indonesia. The five largest watersheds are considered: Ciujung, Cisadane, Ciliwung, Citarum, and Cimanuk. The simulation period covers the 20th century and early 21st century, from January 1901 to June 2006, at a monthly time step. Discharge simulation was carried out using STREAM (Spatial Tools for River Basins and Environmental and Analysis of Management Option). The input data for the simulation are climate (precipitation and temperature), land cover and topographic data. Setup and analysis of input data are also part of this study. The Mann-Kendall test and linear regression were used to detect trends. Temperature datasets show statistically significant increasing trends for all periods and areas. Significant increasing trends of precipitation occurred in the latest 16-year period (1990-2006) in hilly and middle areas. A positive trend of simulated discharge is seen in all watersheds and periods. They are only significant for Ciujung (periods of 1950-2006 and 1975-2006), Cisadane (periods of 1950-2006 and 1990-2006), and Ciliwung (periods of 1950-2006, 1975-2006, and 1990- 2006). The most noteworthy trend is seen in the 1990-2006 period. Over the course of the 20th and early decade of the 21st century, monthly discharges have increased by 3% to 9%.

This paper discusses a study of application of global spatio-temporal climate data sets and a hydrological model operated in Spatial Tools for River Basin Environmental Analysis and Management (STREAM). The study investigates reconstruction of monthly hydrographs across several selected points of the western part of Java, Indonesia for the period 1983-2002. Prior to the reconstruction, set up and calibration are carried out. The set up includes preparation of monthly precipitation and temperature data set, digital elevation model of the domain being studied and their compilation with land cover map. Discharge observations from six stations located mostly at the upper parts of major watersheds in the domain are used to calibrate the model. It is found that the model performs results with acceptable agreement. Comparison between computed and observed monthly average discharges correlate quite well with coefficient ranging from 0.72 to 0.93. The accuracy of computed total annual average discharge in five out of six observation stations is within the range of 7%. Optimum setting of calibration parameters is discovered. This study offers scheme for reconstructing historical discharge in paleo-climate perspective and future scenario for predicting local effect of global climate change, given the predicted climate data sets and geographic setting (i.e. topography and land cover).

Abstract. Regarding the acceleration of renewable energy diffusion in Indonesia as well as achieving the national energy mix target, renewable energy map is essential to provide useful information to build renewable energy system. This work aims at updating the renewable energy potential map, i.e. hydro and solar energy potential, with a revised model based on the global climate data. The renewable energy map is intended to assist the design off-grid system by hydropower plant or photovoltaic system, particularly for rural electrification. Specifically, the hydro energy map enables the stakeholders to determine the suitable on-site hydro energy technology (from pico-hydro, micro-hydro, mini-hydro to large hydropower plant). Meanwhile, the solar energy map depicts not only seasonal solar energy potential but also estimated energy output from photovoltaic system.