Regional Flow Duration Model for the Salawin River Basin of Thailand

Pannathat Rojanamon,* Taweep Chaisomphob and Winyu Rattanapitikon

ABSTRACT: This study presents a simple model for determination of a monthly flow duration curve for a small ungauged watershed in the Salawin river basin, which is located in the northwestern part of Thailand, to develop a small hydropower project. Flow data from twenty stream gauging stations were used to develop the model. The flow duration curves from all gauging stations were fitted with five distributions equations, i.e. logarithmic, quadratic, cubic, power and exponential equations. The results showed that the logarithmic and exponential equations were very good fits. For regionalization, to make the model simple, the variations of coefficients in the models are expressed in terms of drainage area only. Although the model is simple, reasonable agreements are obtained between measured and computed flow duration curves.

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Civil Engineering Program, Sirindhorn International Institute of Technology, Thammasat University, P.O. Box 22 Thammasat Rangsit Post Office, Pathumthani 12121, Thailand.

* Corresponding author, E-mail: pannathat@siit.tu.ac.th

Received 9 Aug 2006, Accepted 6 Jun 2007