InTheMED D2.3 Report on Regional Groundwater Trends and Their Controlling Factors

This is the Deliverable 2.3, which summarises the work of Task 2.3: “Regional Groundwater Trends and Trajectories Analysis and Their Controlling Factors". This report analyses the quantitative status of groundwater bodies in the Mediterranean region to identify variations and significant changes. The study utilises historical groundwater level data to identify trends and significant changes, with a focus on detecting trends in groundwater levels. The study uses a statistical method called Mann-Kendall (MK) to identify trends and applies three different versions of the MK test. The study found that 40% of wells showed significant trends, with 63% of those showing declining and 37% showing rising levels. Most piezometers did not have a significant trend, ranging from 60% of the piezometers in the different countries. Nine clusters of piezometers were grouped based on their trend results in each decade in the 1985-2014 period, and then classified based on their evolution in stable, declining and rising. Stable clusters were related to highly productive aquifers, temperate climate with year-round precipitation, higher average precipitation and further away from irrigation areas than the others. Declining wells were more related to arid climates, moderately productive aquifers and proximity to irrigation areas. Rising wells were related mostly to higher rates of precipitation increase across the three decades and distant from cities.