Disasters due to floods, sediment runoff and beach erosion

开展这项联合研究是为了开发预测降雨径流、产沙量和径流、河流变化和海岸侵蚀的方法，以及为印度尼西亚减少水和沉积物危害发展科学基础。主要结果如下：采用长期和短期降雨营养模型对苏塔米水库流域的水平衡和雨丘径流进行了评价。结果表明，即使在热带流域，该模型也能利用变入渗能力模型再现日降雨径流。利用遥感影像和地理信息系统（GIS）建立了布兰塔斯河支流普提利河（Putili river）的分布式水沙径流水文模型，该模型再现了1990年克希德火山喷发后7年的产沙量，并估算了影响产沙量的有效入流深度。通过对盆地内约30个点的土壤取样，对土壤性质和粒度进行了研究。采用一维和二维床层变化模型对布兰塔斯河中游进行了研究。l-D模型研究了河道宽度对河床变化的影响和悬移荷载的影响，发现河道宽度的快速变化导致了更大的河床变化。二维模型表明，河流分叉发生在河段变宽的河段，悬移荷载加剧了弯曲河段内岸泥沙的粗化。在面向印度洋的Pangandaran海岸（南爪哇）进行了海岸监测和数值预报，那里正在修建河流捷径。采用考虑波浪影响的三维水动力模型，对受东、西季风影响的爪哇海潮汐风驱动环流进行了为期一年的模拟。采用第三代海浪预报模型WAM计算了波浪场和与波浪相关的海面和海底阻力系数。ECMLWF全球气候再分析数据给出的海面以上10°的6小时风场作为代表风。模拟了流体示踪剂的运动轨迹，以了解物质在海面和海底的运输。本项目建立了由钻孔型破碎波模型、三维近岸环流模型和输沙模型组成的三维滩涂变化预测模型。在日本和印度尼西亚海岸继续对其进行核查。少

This joint research has been conducted to develop methods for predicting rainfall runoff, sediment yield and runoff, river changes and coastal erosion, as well as to develop scientific basis for water and sediment hazards mitigation in Indonesia. The principal results are swninarized as follows :A long- and short-term rainfall-nuioif model was tested to evaluate the water balance and rainfhll a runoff disehaige in the Sutami reservoir basin. The results show this model can reproduce daily rainfall-runoff using the variable infiltration capacity model, even in tropical drainage basins.Remote sensing images and geographic information systems (GIS) were used for establishing a distributed hydrological model for flood and sediment runoff The model applied to the Putili river, a tributary of the Brantas, reproduced the sediment yield during the seven years following the 1990 eruption of Mt. Kehid and estimated the effective infiltration depth that contributes to sediment yield.Based on samp … More led bed materials at about thirty points in the basin, soil property and particle size were investigated. One- and two- dimensional bed variation models were applied to the middle reach of the Brantas. The l-D model investigated the effect of channel width on bed variation and the effect of suspended load, and revealed that the rapid change in channel width causes greater river bed variation. The 2-D model showed that the stream bifurcation took place in broadening reaches and suspended load accentuated the coarsening of sediment at the inner bank of curved sections of the river.Coastal monitoring and numerical prediction have been conducted in Pangandaran coast (South Java), facing the Indian Ocean, were river short-cut works are under construction.One-year simulation of tide- and wind-driven circulation in Java Sea, wiuich is influenced by the west- and east- monsoons, was carried out using a three-dimensional hydrodynamic model incorporating the influence of waves. A third-generation ocean wave prediction model, WAM, was employed to calculate the wave fields and the wave-dependent sea surface and bottom drag coefficients.Six-hourly wind fields at 10 in above the sea surface ware given by ECMLWF's global climate reanalysis data as a representative wind. The trajectory of munnerical tracers was simulated to understand transport of materials at both the sea surface and bottom. A 3-D beach change prediction model which consists of a bore type breaking wave model, 3-D near-shore circulation model and sediment transport model, has been developed in this project. Its verification has been continued on coasts both in Japan and Indonesia. Less