Modelling water scarcity across Europe in terms of water quantity and quality

The need for integrated and sustainable water resources management has become an important
driver behind large-scale gridded modelling. Such modelling has traditionally focused on water
quantity. However, reduced water quality can also limit water resources, particularly for drinking
water. The water availability model GWAVA has been further developed to include a water quality
module. This module will initially focus on biochemical oxygen demand (BOD). The module
considers drivers of BOD loading from land, such as agriculture and urban runoff, and transport
and loss of BOD through sewage treatment and river networks. In an exploratory assessment,
GWAVA was used to produce maps of water scarcity across Europe. The new module enhanced
those maps with effects of BOD on water resources. This enhancement increased the modelled
proportion of Europe experiencing water scarcity, which indicates that it is important to include
both water quantity and quality in model estimates of water scarcity.