Study of rainfall - runoff relationship for Langat river watershed by using HEC-HMS

摘要

In this era, we always heard about a flood problems occurrence in Malaysia. Malaysia is audcountry that subjected to flood problems because it was surrounded by South China Sea. InudMalaysia, there are some places that have serious flood problems which is a state near withudSouth China Sea such as in Terengganu, Johor and Selangor. Langat River was located nearudwith Selangor and it is connected to the South China Sea. The places near with LangatudRiver always had a flood problem in every year. The thesis is conducted to stimulate theudprecipitation-runoff processes of dendritic watershed systems. The thesis also preparedudvalidation and verification of HEC- HMS (hydrological model) to recorded data. Afterudthese two objectives of study were completed, the appropriate model for flood hydrographudprediction is produce. From the model, hopefully it will help to make a decision to preventuda flood problem. HEC-HMS is a tool to produce a number of hydrologic modeling inputs. Itudalso can be used to recognize the rainfall- runoff relationship of Langat River in a certainudperiod. From the rainfall data, a hydrograph of Langat River can be obtained by usingudanalysis of relationship between rainfall and runoff. This hydrograph are used for studies ofudurban drainage and flow forecasting. So, it can be guidance to people along Langat Riverudaware about flood problems and also can be flood control management in Langat River. Byudreferring to Root Mean Square Error (RMSE), as the value is near to zero, it is consideredudas the best fit. The RMSE value obtained forudFigure 4.2, Figure 4.13, Figure 4.14 and udFigure 4.25udare 0.256 mud3ud/s, 0.346 mud3/s, 1.121udM3 ud/s and 0.319udM3 ud/s respectively. As forudconclusion, SCS Unit Hydrograph method can be used for simulation in Langat River udbasin.