Evaluating the Impact of Water Policies on Groundwater Resources in Major Water Scarcity Hotspots

Effective water governance is critical for steering water scarcity hotspots toward sustainable water use, yet a systematic meta-analysis of water policy effectiveness across such regions is lacking. Here, we assess the effectiveness of water management policies in six major water scarcity hotspots: California, Central Chile, the Ganges–Brahmaputra Basin, the Murray–Darling Basin, Spain, and the U.S. High Plains.

We combine qualitative and quantitative evidence to evaluate policy effectiveness on groundwater levels. First, we reviewed 102 peer-reviewed case studies to compile a database of implemented water management policies and their reported effectiveness. Second, we analysed long-term groundwater level observations using ARX modelling (autoregressive models with exogenous inputs) to remove climate variability. We then applied multiple breakpoint detection methods on the ARX model residuals to identify systematic changes potentially associated with policy interventions.

Across hotspots, the qualitative literature is generally more critical of policy effectiveness than suggested by observed groundwater responses. According to the literature, regulations on groundwater abstraction and the expansion of unconventional water resources are policy categories that are most frequently associated with positive outcomes, while integrated water management approaches are reported as least effective. Consistently, our quantitative analysis most strongly associates groundwater regulation, unconventional water resources, and measures to improve water use efficiency with groundwater stabilization or recovery. The effectiveness of policy categories, however, varies considerably across regions, emphasizing the need for localized and context-specific solutions.