Groundwater Level Analysis Using Regional Kendall Test for Trend with Spatial Autocorrelation.

Area of Science:

• Hydrology and Hydrogeology
• Environmental Science
• Spatial Statistics

Background:

• Understanding historical groundwater level changes is crucial for assessing human impact on water resources and informing policy.
• Anthropogenic activities significantly influence groundwater exploitation patterns and sustainability.
• Developing effective response policies requires accurate assessment of groundwater dynamics.

Purpose of the Study:

• To assess the regional groundwater level trends and annual decline rates in Beijing, Tianjin, and Hebei.
• To analyze the evolution of groundwater exploitation and its relationship with water resource management strategies.
• To apply a novel method for analyzing correlated spatial data in trend assessment.

Main Methods:

• Application of the regional Kendall test for analyzing spatial correlated data.
• Development of an exponential relation to approximate covariances based on spatial distances.
• Analysis of county-level groundwater data from 1959, 1984, 2005, and 2013.

Main Results:

• A consistent declining trend in regional groundwater levels was observed across the study area.
• Groundwater recharge rates were generally higher than withdrawal rates, despite the declining trend.
• Annual groundwater decline rates exhibited an initial increase followed by a decrease, mirroring the environmental Kuznets curve.

Conclusions:

• Groundwater levels in the study region are declining, influenced by historical water management practices.
• The observed trend in decline rates suggests a shift from supply-driven management to more sustainable water stress relief measures.
• The applied methodology effectively assesses groundwater level evolution in regions with spatially correlated data.