Tri Wahyu Hadi

Majalaya Flood Early Warning System: A Community Based Approach

Majalaya, a small city to the south-east of Bandung, was hit by flood almost every year. From January to June 2016, up to 5 severe floods and 4 moderate floods have hit this city. Although it usually not last for long, but the flood stream could be very rapid, thus have a high potential to bring damage to the city. Starting from 2012, ITB through Weather and Climate Prediction Laboratory (WCPL) has support Garda Caah (flood watcher society in Majalaya) with weather prediction system. In the late 2015, ITB also enhancing Garda Caah observation system by installing several Automatic Weather Station (AWS) and Automatic Water Level Recorder (AWLR) throughout Majalaya upstream area. The instruments itself was supported by a re-insurance company MAIPARK and some was built in house by WCPL. The collaboration between ITB, Garda Caah, and Majalaya citizens has been proved to be mutually beneficial. Garda Caah could get more accurate and faster observation and enhanced knowledge, thus could provide a better flood warning for Majalaya citizens. On the other hand, ITB could get data from observation network, with more efficient way to maintain observation instruments as it done by Garda Caah and other Majalaya citizens.

A preliminary comparison of hydrodynamic approaches for flood inundation modeling of urban areas in Jakarta Ciliwung river basin

This paper addresses on the numerical modeling approaches for flood inundation in urban areas. Decisive strategy to choose between 1D, 2D or even a hybrid 1D-2D model is more than important to optimize flood inundation analyses. To find cost effective yet robust and accurate model has been our priority and motivation in the absence of available High Performance Computing facilities. The application of 1D, 1D/2D and full 2D modeling approach to river flood study in Jakarta Ciliwung river basin, and a comparison of approaches benchmarked for the inundation study are presented. This study demonstrate the successful use of 1D/2D and 2D system to model Jakarta Ciliwung river basin in terms of inundation results and computational aspect. The findings of the study provide an interesting comparison between modeling approaches, HEC-RAS 1D, 1D-2D, 2D, and ANUGA when benchmarked to the Manggarai water level measurement.

Tropical cyclone rainfall structure affecting indochina peninsula and lower mekong river basin (LMB)

Indochina Peninsula is located in between Bay of Bengal (BoB) and South-China Sea (SCS). This region is affected frequently from Tropical Cyclones (TCs) formed in North Indian Ocean (NIO), South-China Sea (SCS), and North West Pacific Ocean (NWP). This research analyzed the structure of the rainfall over Indochina Peninsula and its relationships with TCs from the aforementioned sources. Principle Component Analysis (PCA) was performed to investigate the dominant rainfall area produced from those TCs. Spatial and Temporal structures of rainfall from the TCs is analyzed to understand their propagation. The results show that the dominant TC rainfall area covers Central Vietnam which contributed around 25% to total rainfall in the region. However, the contribution of this TC rainfall over LMB is likely less than 20% where Laoss territory receives highest contribution (20%). Furthermore, from the three source areas, TCs formed in SCS produce the highest rain rate when they develop into typhoon intensity stage of Joint Typhoon Warning Center (JTWC)s scale. The average duration of TC rainfall over Indochina Peninsula is 81.28 hours, and over LMB is 66.22 hours. Thus, same as other regions in the Indochina Peninsula, LMB is affected by TC rainfall with considerable scales both spatially and temporally that may lead to significant hydrometeorological hazards.