Assessing the Link between Groundwater Depletion and Aquatic Habitat Loss

Groundwater, a vital but unappreciated component of aquatic systems, provides the temperature and steady base flows that sustain aquatic biodiversity. Despite being one of the most important, if not the most important, components of aquatic systems, widespread, ever-expanding agricultural and industrial withdrawal of groundwater is occurring extensively, with expanding, variable hydrological landscapes. Though declining groundwater levels are widely documented, direct cause-and-effect links between declining groundwater and loss of aquatic habitat are still under-investigated and under-quantified. The current work attempts to fill this gap using the Upper Guajira Basin of Northern Colombia as a case study, where significant piezometric decline and ecosystem degradation are evident. It combines multi-source hydro-geological data and remote sensing data from 2005-2025, using a geospatial correlation technique and GAMs to quantify the relationship between groundwater drawdown and habitat degradation. It finds that an average annual drawdown rate of 0.85 meters correlates with a 42% decrease in wetland surface area and
segmentation of perennial stream sections. It identifies a hydrological tipping point at the 5.5 m depth-to-groundwater, where habitat contraction rate accelerates non-linearly, resulting in ecological collapse and landscape homogenization. The findings highlighted the need for an integrated, ecosystem-based water resource management policy, such as establishing ecologically based pumping restrictions and a conjunctive management zone, for the conservation of groundwater.