FLOOD CONTROL STRATEGY IN SAMPANG CITY, EAST JAVA, INDONESIA

Abstract

Flood always hits Sampang City every year and it causes the transportation disruption in Madura Island.The flood in Sampang City is caused by four main factors: the watershed (DAS) quality, the drainage system, the river capacity, and the tide. The flood control strategies that have been done are: the reduction of flood discharge peakand increasing the river capacity. However,these strategies have not achieved the significant results yet. Thus a new strategy is needed to solve the problem. The result of hydrography analysis shows that the discharge is dominated by the surface runoff, thus it indicates that the quality of DAS is very poor.Further, the land usage in DAS is dominated by the agricultural land such as thefarms and the rice fields. Based on these observations, a new flood control strategy by controllingthe surface runoff on agricultural land is proposed. The strategy isdescribed as the technical activities in the form of utilization of the farmland partition as the temporary storage facilities. To achieve the maximum result, it should be followed by the following activities: a) increasing the capacity of interception and infiltration by the land conservation; b) increasing the capacity of the water reservoir on the land by raising the embankment design from 30 cm to 50 cm; c) shortening the water puddle time by constructing the absorption wells. The result of the hydrological analysis shows that the new strategy is able to reduce the flood discharge peak of 20% to 67%.