Identification of Surface Runoff Source Areas as a Tool for Projections of NBS in Water Management

The location of surface runoff source areas is one of the most important information for the conservation of water resources, their sustainable management as well as mitigation of the frequency of extreme hydrological phenomena. The location of the surface runoff source areas in the landscape affects not only the hydrological and sediment regime of the watercourse itself, but also some physicochemical properties of the water. The exact parameters of the hydrological and sediment regime are the result of a number of variables – mostly soil properties, morphometric parameters of the terrain, and the level of anthropogenic influence, but also the type of surface cover. This research deals with the relationship between types of habitats (in terms of their qualitative properties – e.g. naturalness of the habitat, diversity of structures, sensitivity of the habitat to external interventions, etc.) and their impact on runoff processes in the landscape; i.e., the extent to which the habitat type can affect the soil water retention and infiltration capacity, and thus runoff processes. The creation of habitats with an identified positive effect on the hydrological regime (mitigation the frequency of drought and flash floods), or the creation of conditions suitable for the natural formation of these habitats, can be considered as a good example of nature-based solutions for water management. Within a study area in the Czech Republic, a medium-sized watercourse catchment with forest-agricultural landscape, a newly developed water retention model LOREP was applied. This model takes into account a multiple-flow regime, providing more accurate results than previous models. The analysis revealed that there are several types of natural or close-to-nature habitats able to retain a significant amount of rainwater, even in soils with limited retention capacity. A possible increase in the area of these habitats may indirectly contribute to the mitigation of hydrological extremes and the increase of surface water quality.