Hydrological drought frequency analysis of the Yom River, Thailand

Abstract

The Yom River is subjected to flood and drought annually each for half a year. Several works suggested storing water during the surplus season for use in the dry season. None of them, however, quantified the precise amounts of suggested storage along the river with acceptable risk. In an attempt to quantify storage, we performed frequency analyses to find out severity of streamflow droughts along the river. A deficit volume, the amount of flow being less than a selected threshold level, was used to characterize a drought event. The Weibull distribution model was chosen for analysis after comparison with lognormal and Pareto models to the empirical distribution. Results show a more severe drought condition toward the downstream section of the river where paddy fields get larger. A large deep groundwater irrigation project located about the mid-section of the river mitigates drought along this section. Drought is more severe further downstream from the project, one reason being the baseflow is cut off by the groundwater abstraction. This presented method can help to quantify severity of hydrological drought along any river therefore its drought management can be undertaken.

Keywords

• Hydrological drought
• Frequency analysis
• Deficit volume
• Weibull distribution
• Yom River