A Multi-scale Groundwater Modellling Tool to Understand Regional an Local Groundwater Processes in the Valle del Cauca Aquifer, Colombia

Groundwater management in highly intervened aquifers is a challenge for environmental authorities that seek the medium and long-term sustainability of the resource. Climate change and socio-economic developments exacerbate the situation and provide water authorities with increasingly complex problematics.

This study is focused on the Valle del Cauca aquifer, Colombia, which is of great importance for the region since groundwater is intensively used for agriculture, industry and also as an option to supply drinking water to the inhabitants of Santiago de Cali, the third largest city of Colombia, and to other municipalities located in the valley.

A multi-scale groundwater numerical modelling tool has been developed to study the processes occurring in the aquifer, through the use of numerical models at various scales. The tool supports the development of the aquifer management plans, which are formulated by the regional environmental authorities: CVC for the regional aquifer and DAGMA for the urban area of Santiago de Cali. The objective of the management plans is to update the knowledge on the groundwater system and to formulate strategies to address problematics and conflicts on the use of groundwater resources.

The regional processes were studied at the largest scale (resolution of 100 by 100 meters), through a regional numerical model that covers the area of interest in Valle del Cauca. This model was developed in three phases, in which sub-regional models were developed, and boundary conditions were defined to allow coupling of the models. A detailed model was developed for Santiago de Cali, with a resolution of 25 by 25 meters. This model includes specific processes associated with the urban area, such as effects of urbanisation on groundwater recharge, drainage and artificial recharge through water supply sewage pipes, intense shallow groundwater pumping for infrastructure drainage, etc. The regional model was used to define the boundary conditions of the detailed urban model.

The tool was developed with the active participation of CVC and DAGMA, thus ensuring that it responds to the particular needs of the environmental authorities.