Regionalization of Drought Characteristics Using an Entropy Approach

Abstract

Assessment and understanding of past climate is an important step for drought mitigation and water resources planning. In this study, streamflow simulated using the variable infiltration capacity (VIC) model was used for drought characterization for a time span of 1950–2000, and subsequently, regionalization was done for the state of Texas based on the annual drought severity level and drought duration. Droughts are regional in nature, and hence, identification of homogenous drought regions is important for investigating the drought characteristics within each of these regions. The concept of entropy was used for identification of homogenous regions based on drought severity and duration. A standardized version of mutual information, known as directional information transfer, was used for station grouping. The homogeneity of regions obtained was checked using L-moments. A total of eight regions were formed based on drought severity, and nine based on drought duration. Regions in west Texas were found to be critical in terms of severity, whereas east Texas showed the least severity. The longest drought duration was experienced in south Texas and lower valley zones, whereas the least drought duration was experienced in east Texas and the upper coast. Severely dry and extremely dry droughts were found to be restricted to the western and central parts of Texas.