A study of using GRAPH model to simulate watershed discharge hydrograph for the ungaged sites-A case study of the Wu-xi watershed

• Main Authors: Cheng-Jen Shun, 孫振哲
• Other Authors: Chao-Yuan Lin
• Format: Others
• Language: zh-TW
• Published: 2007
• Online Access: http://ndltd.ncl.edu.tw/handle/61214330044775189228

碩士 === 中興大學 === 水土保持學系所 === 95 === The discharge data and related information derived from hydrologic stations are usually used in hydrology study and/or river structure design. But there are only few stations set up at the proper sites in a watershed. Although area ratio method is usually adopted to calculate the peak flow of the ungaged sites by using the adjacent station, for more parameters considered to have better results in river discharge estimation, the GRAPH (Grid Rational Algorithm for Predicting Hydrograph) model is employed in this study to simulate watershed runoff hydrograph. The Wu-xi watershed was used in this study. The correction coefficients were derived from the model calculation for each typhoon event, coupled with watershed topographic and hydrological factors for multivariate analysis to have better hydrograph predicting. The results show that the correction coefficients can be affected by the factors such as 24 hours accumulated precipitation, maximum rainfall intensity, slope, river frequency and time of concentration of an analyzed watershed. From the test and verify result, found that GRAPH better than area ratio method in single-peak hydrograph. Beside that, GRAPH can estimated error time in peak discharge accurately in single-peak and high discharge hydrograph. But the watershed upstream area was too steep and full of fragmentary landslides, so that model could not simulation hydrograph accurately.