Analysis of Precipitation and Streamflow Data for Drought Assessment in an Unregulated Watershed

• Main Authors: Worapong Lohpaisankrit, Jessada Techamahasaranont
• Format: Article
• Language: English
• Published: Mahidol University 2021-02-01
• Series: Environment and Natural Resources Journal
• Subjects: drought index; cross-correlation; hydrological drought; trend analysis; standardized precipitation index (spi); upper lam pao watershed
• Online Access: https://ph02.tci-thaijo.org/index.php/ennrj/article/view/241779
• ISSN: 1686-5456; 2408-2384

Predicting drought occurrence accurately still remains a challenging task. To fill research gaps, this study identified and analysed meteorological and hydrological droughts using the Standardized Precipitation Index (SPI) and Streamflow Drought Index (SDI), respectively, in the upper Lam Pao watershed in Thailand. The study also focused on investigating the relationships between both droughts. The SPI and SDI were computed based on observed long-term precipitation and streamflow data during the period of 1988-2017. The drought analysis was carried out by using the R packages. The location, period and severity level of drought events were graphically presented. On the basis of trend analysis, the SPI series showed slightly increasing trends, whereas no trend was found for the SDI series. This implied that the hydrological drought was influenced by not only precipitation but also other factors. The key findings indicated that there was a positive relationship between meteorological and hydrological droughts. In addition, there was a specific lag time, which may depend on physical characteristics of a basin, in drought propagating from meteorological drought to hydrological drought. Overall, the drought indices can help to predict hydrological drought events, which could be valuable information for drought monitoring and early warning systems.