In general, the problem of a water resources infrastructure, especially the raw water transmission system, is that the actual discharge is not in accordance with design discharge because of water losses along the transmission system.To restore the capacity to the design discharge, a comprehensive strategy is required. Various strategy methods have been developed especially the strategy of managing a system. This paper discusses how to analyze the comprehensive strategy with system component approach for water transmission system. The research used Klambu-Kudu Water Transmission System in Semarang, Central Java, Indonesia as a case study. Strategy analysis of Klambu-Kudu Water Transmission System utilized the modified Strength, Weakness, Opportunity, and Threats (SWOT) with Likert scale and Quantitative Strategic Planning Matrix (QSPM) method. SWOT analysis is was carried out to obtain a comprehensive strategy on each component of the water transmission system (intake, mud pouch, siphon, gutter, bridge, culvert, regulator doors, suppletion, drain pipe, and / or excavation), while the QSPM method is required to analyze the strategic priorities of component of Klambu Kudu Water Transmission System. Key factors of water transmission system performance were obtained from the discussion of experts, the management of Klambu Kudu Water Transmission System and the community. The results are a priority of strategies which are dominated by the opportunity factors to solve the problem of weakness (operation and maintenance, sedimentation, damage) and threats (water theft, destruction of buildings, flood) as well as maximizing the strengths (condition of the component, function, accessibility).

Hydrologic and hydraulic modeling are important to be conducted to examine the watershed response based on a rainfall input, especially over disaster-prone watershed such as Putih River watershed in Magelang, Central Java Province. A GIS-based grid-based distributed rainfall-runoff model was used to simulate the rainfall-runoff transformation. A two-dimensional hydrodynamic flow modeling was then carried out to simulate the flood processes on the stream and floodplain area. A sensitivity analysis was conducted on infiltration rate, Manning's n value, and rainfall intensity. Infiltration rate, Manning's n value, and rainfall intensity give considerable effects to the resulted flow hydrographs. The modeling results show that the results of hydrologic-hydraulic modeling is in good agreement with the observed results.

Flood disasters in Indonesia have shown an increase, both in magnitude and frequency. In fact, the area, depth, and duration of inundation tend to increase. Current flood control focuses on increasing river capacity: widening and/or deepening the cross-section of the river and controlling surface runoff by building storage upstream of the watershed. The storage requirement depends on the surface runoff rate in the upstream watershed. This study aimed to find the formulation of the most optimal watershed storage volume requirement through the correlation of flood discharge and surface runoff in the upstream watershed area. The results of the study found the optimum watershed storage volume capacity and produced 2 (two) representative equations to calculate the upstream watershed storage volume (WSVO) based on 2 (two) river slopes (slope 0.1, slope 0.01). WSVO is intended to facilitate the determination of the storage volume capacity in the upstream area if complete data, both primary and secondary data are not available.

Changes in land use in the upstream of Jatigede watershed cause discharge and sedimentation problems in the Jatigede Reservoir. The objective of this study is to analyse the affect of land use changes in the Jatigede Reservoir watershed to the inflow and sediment to the reservoir. SCS Curve Number method and HEC-HMS modeling system are used to discharge analysis. Flood discharges in the reach of Cimanuk River close to the reservoir using data of 2009 are Q2=1,751.5 m3/sec, Q5=2,280 m3/sec, Q25=3,064.5 m3/sec, Q50=3,589 m3/sec. Flood discharges in the reach of Cimanuk River close to the reservoir using data of 2018 are Q2=2,053.8 m3/sec, Q5= 2,616.7 m3/sec, Q25 = 3,439.2 m3/sec, Q50=3,984.9 m3/sec. Discharges increase in 10 years (based on 2009 data and 2018 data). For example discharge increment for Q25 is 375 m3/sec. The increment is due to the increment of CN number as the consequences of land use changes. In other words along with the time, flood discharge in the rainy season increases, however discharge in the drought season decreases.

No abstract