Estimation of Unit Hydrograph Parameters and Development of Direct Surface Runoff Hydrograph
Puji Harsanto
Department of Civil Engineering, Universitas Muhammadiyah Yogyakarta
Abstract
Hydrograph is a diagram, curve, or graph that illustrates the relationship between discharge flow parameters and time. Estimating flood hydrograph is the main analysis on river constructions design. Synthetic unit hydrograph (SUH) is one of method to design a flood discharge when there is no dischrage series data in a long time. In fact, the SUH methods does not always provide an accurate result. In this research, flood hydrograph analysis using Nakayasu, ITB, GAMA-1, and Snyder methods are applied on the upper Progo River basin. Daily rainfall in January 2012 data is used and is divided into 3 conditions, namely Case 1 (dated on 1-7 January), Case 2 (dated on 8-13 January), and Case 3 (dated on 20-26 January). The streamflow data from Borobudur AWLR station is applied for model calibration. The Thiessen polygon is used for analyzing the average rainfall and ABM method for converting the daily to hourly data. The results show that the peak discharge using Nakayasu, Snyder and GAMA-1 method is 296.5% greater than observed data but the result using ITB method is 68.3% smaller than observed data. The parameter calibration is an important step fordesigning peak discharge in a practical work.
Keywords: hydrograph parameters, synthetic unit hydrograph, peak discharge, progo river
Topic: International Symposium of Civil, Environmental, and Infrastructure Engineering