Wellhead protection areas

Capture zones for pumping wells are calculated to identify protection areas for drinking wells (Well Head Protection Areas, WHPA), where land-use restriction and safeguard measures must be adopted, and capture areas for hydraulic barriers in Pump & Treat systems.

Capture zones are usually determined by the calculation of the well capture zone and isochrones along the flow pathlines, using deterministic or probabilistic methods. Both of them are studied and applied by the Groundwater Engineering Group.

Capture zone calculated using a probability method

Capture zones calculated using the APA method

Deterministic methods consist in the calculation of flow paths in the aquifer (backward particle tracking), taking into account only advective phenomena, while the probable capture zones are studied using a backward probability model based on the adjoint of the classical transport equation of solutes in groundwater. Concerning deterministic capture zones, the group is working on the development of a methodology for an automatic delineation of time-related protection areas, the APA model. The algorithm is an improvement of the standard backward particle tracking and uses non-equally spaced particles around the pumping wells and includes a perimetration algorithm for automatic capture zone encirclement (Tosco et al, 2008).

 

Bibliography

TOSCO T., SETHI R. (2010), Comparison between backward probability and particle tracking methods for the delineation of well head protection areas, Environmental Fluid Mechanics, 10, pp 77-90, DOI: 10.1007/s10652-009-9139-2 pdf

TOSCO T., DI MOLFETTA A., SETHI R. (2010), Automatic delineation of capture zones for pump and treat systems: A case study in Piedmont, Italy, Ground Water Monitoring and Remediation, 30(2), pp 46-52, DOI: 10.1111/j.1745-6592.2010.01276.x pdf

TOSCO T., SETHI R., DI MOLFETTA A. (2008), An automatic, stagnation point based algorithm for Wellhead Protection Areas delineation, Water Resources Research, DOI: 10.1029/2007WR006508 pdf