Grasping water availability at regional scale: development of exploratory methods

Climate change and socio-economic development are putting water resources under increasing pressure, even in what are so far seen as ‘water-rich’ countries. At a regional scale, the water resources present in groundwater, soil water and surface water are often used for various functions, including nature, agriculture and drinking water production. Local changes in water management or land cover can potentially affect all these functions. Therefore, ensuring a sustainable water availability requires an integrated understanding of the interactions in the water system. However, regional water systems, that often include a wide range of water pathways and functions, can be complex to grasp and time-intensive to study in detail. There is therefore a need for exploratory methods that provide a fast and comprehensive overview of the interactions in regional water systems. This provides a valuable first step to direct research and management efforts.  

In this study, we have developed an exploratory water system analysis method using a case study in the south of the Netherlands. The case study area supports groundwater-dependent nature areas, agriculture, drinking water production and urban land use, which may face increasing pressure in the future. Several adaptation measures have been proposed, including restoration of natural brook systems, enhancing groundwater recharge and changing extraction regimes. As a first step, we developed quantitative visual overviews of the water system under both average and dry conditions, using a combination of a groundwater model and field data. Next, we used simplified analytical functions to assess the potential effects of several proposed measures on water stores and fluxes in the water system. Together, these analyses provide an overview of the main system drivers and potential threats to water availability. In addition, they help to identify which potential solutions are promising for further exploration. The results can be used to guide further research and cooperation in the area towards a sustainable water system. In addition, the methods can be easily applied to other regions and scales.