Assessing sub-regional water scarcity using the groundwater footprint

The groundwater footprint (GF) is an innovative concept that is used to evaluate groundwater sustainability, and it can be defined as the area required to sustain groundwater use and groundwater-dependent ecosystem services in a region. In this study, we evaluated water scarcity on a sub-regional scale using a water stress indicator defined as the ratio of groundwater footprint to aquifer area GF/A that indicates the sustainability of the aquifers. The higher the stress indicator is, the less sustainable the aquifer is. This study was conducted in the northern part of Colombia; it involves 19 municipalities located in the Sucre department and six main aquifers. Through the use of 5000 interviews, the study calculates water abstractions in the study area, such as cattle, commerce, industry, homes, agro-industry and agriculture; however, only domestic demand associated with groundwater fed aqueducts and groundwater wells was considered because it represents almost 80% of the total abstractions. In addition, the study considered climate change and population growth and how they may affect the GF. The analysis shows that the water stress indicator for the Morroa aquifer has the highest groundwater stress among the six aquifers subject to investigation. GF is considerably higher than many of the world aquifers. Using the same indicator, we compared different mitigation alternatives to increase the sustainability of the Morroa aquifer. Results show that a combination of artificial recharge measures with an alternative source able to supply at least 50% of the domestic consumption appears to be the best choice to make the aquifer more sustainable. GF is a simplified yet robust way to support decision-makers and stakeholders so as they can evaluate water management policies and strategies.