FLOODtool – mapping water storage potential and evaluating institutional barriers

Recent extreme drought and floods demonstrates society’s immediate need for climate adaptation and increased water storage capacity higher up in the landscape through the use of natural flood retention measures. Here, we present FLOODtool, a mapping tool that helps landowners, managers and catchment officers to estimate above and below ground water storage potential in the landscape. With the tool, we are able to investigate if detention ponds and restored wetlands in upstream forest areas can protect downstream arable fields (ensure food production), cities and waterways (improve water quality). In FLOODtool, we use soil distribution maps, high-resolution digital elevation data, land use maps and distributed modelling to quantify water storage potential and possible phosphorus reductions. We have applied the new tool in multiple watersheds with different land cover and water holding potential. In collaboration with different stakeholders, we have used FLOODtool modelling results to find cost-effective locations to rewet or implement new water retention measures depending on their criteria. Our modelling is complemented by empirical work in which we will use high-frequency sensors to quantify the ability of detention ponds ability to store water, prevent flooding, reduce erosion and phosphorus losses and study the drought mitigation potential. In co-creation with stakeholders, we followed the implementation process to evaluate possible barriers and goal conflicts. For example, if farmers and landowners can be compensated to protect downstream areas (prevent economic losses linked to infrastructure/housing) this would promote uptake of upstream flood retention measures. However, there may be obstacles in current legislation.