Water Footprint Assessment to support water resources management in the regulatory context: a case study in the Thames River Basin, UK

Abstract:

The economy and environment of the Hertfordshire and North London Area (H&NL Area) within Thames River Basin rely on the limited water resources in the region, especially groundwater. The water resources in the area are managed, amongst other mechanisms, through water abstraction licences and discharge permits. Current management practice is not responsive or flexible enough to address future pressures. To support improving current water management in the area, a Water Footprint Assessment (WFA) study was conducted.

This is a pioneering work in the field of WFA applied in a regulatory context. The study deals with a high level of complexity in a number of aspects: 1) high spatial and temporal resolution (sub-catchment level and monthly time scale); 2) multiple water use sectors (industry, domestic and agriculture); 3) different sources of water for human use (surface and groundwater); 4) different types of human pressure on water resources (consumption and pollution); 5) integrated assessment of water use sustainability (water scarcity and water pollution level); and 6) projected water footprint (WF) with water demand and climate change scenarios.

The green, blue and grey WF on surface water, the blue and grey WF on groundwater of the 35 sub-catchments within the H&NL Area have been estimated for the domestic, industrial and agricultural sectors on a monthly basis. Blue water scarcity (BWS) and water pollution level (WPL) were evaluated to assess the sustainability of the blue and grey WF respectively, distinguishing between ground and surface water. A “wet” and “dry” climate change scenario for 2060 was used to project the WF components and BWS. This study identifies sub-catchments in the area facing moderate to severe BWS and/or WPLs and illustrates the relation between the two.

The results demonstrate that WFA and in particular BWS and WPLs can and should form a basis for regulatory reform for water resources management. Levels of BWS in sub-catchments can inform decisions on issuing and putting conditions on water abstraction licenses. Data on sub-catchment grey WF and WPLs can help review of the current effluent discharge consenting scheme. Abstraction licensing should be linked to effluent discharge consenting. The study proposes an approach to this regulatory reform based on the BWS and WPLs within the area.