Evaluation and application of the SPDI-JDI for droughts in Texas, USA

Abstract

The lack of a system/model for integration of drought-related information has been an important obstacle in efforts for accurate and reliable drought monitoring and prediction. This study proposes an integrated multivariate standardized drought index (i.e. standardized Palmer drought index-based joint drought index, SPDI-JDI), where the Palmer scheme/model is accepted as a multivariate multi-index conceptual framework that integrates multiple drought-related indicators for characterizing drought. Using the meteorological data of ten climate divisions from Texas, the computed SPDI-JDI index is first compared to various ground observations (e.g. streamflow, lake/reservoir water level, soil moisture content and groundwater level) for the reflection of drought/wetness conditions. Moreover, the SPDI-JDI is also evaluated against Palmer drought indices and US Drought Monitor for drought detection. Results indicate that the SPDI-JDI is in good/acceptable agreements with surface and subsurface water anomalies and performs well with respect to the integrated use of Palmer drought severity index, Palmer modified drought index, Palmer hydrologic drought index and Palmer Z index as well as to the US Drought Monitor observations. Potential implications are that the SPDI-JDI allows for insights into different impacts of drought and leads to high probability of drought detection versus multi-source drought information, implying attractive properties originating from its physically inclusive and multivariate joint probabilistic combined nature.