Drought Detection of Regional Nonparametric Standardized Groundwater Index

Groundwater drought index characterizes hydrological drought, aquifer characteristics and human disturbance in the hydrological system. For drought management, the values of standardized groundwater index (SGI) at local and regional scales are usually determined in a specific site and regional area. The SGI in the studied area is influenced mainly by precipitation, hydrogeology, and human disturbance occurring in the high-usage pumping area. The underlying signals of SGI at local and regional scales can therefore be identified using data clustering and decomposition analysis e.g. empirical orthogonal functions (EOFs). Using cluster analysis, the three primary SGI clusters of the investigated aquifer are identified to be situated at the proximal fan, mid-fan, and distal fan areas. With EOF, the meteorological drought pattern and the trend of long-term pumping in the aquifer are also identified. Specifically, the meteorological drought pattern is mainly from the proximal fan, while the over-pumping signal is from the coastal area of the distal fan. The regional SGI integrated with EOF is a useful and direct way for detecting and quantifying groundwater drought. The proposed method for identifying drought signals and sustainable zone for water supply is a substantial step toward an effective regional groundwater resource planning.