Nutrients spreading with cloudburst modeling

Abstract: Climate change and environmental disasters are strongly dependent. Humanity is facing considerable changes in environmental adaptions and remediation of contaminated sites. Water is a valuable resource that should be protected and prevented from hazardous influences. One of the main water quality problems is the excess of nutrients causing algae blooming. Many surface-and groundwaters have lost the ability to be used as anthropogenic water sources and other purposes (recreation, water supply, irrigation, etc.). Both nutrients and other substances impact water quality and climate change, making it challenging for modern society to maintain good water quality. Moreover, extreme rainfalls become more common, temporarily increasing surface runoff and exceeding infiltration capacity during high-intensity rainfall events. Water that is not capable of infiltration in the soil will run on the watershed into depressions and be infiltrated or spread to downstream catchments. This water might contain hazardous substances, e.g., nutrients, thereby enhancing water contamination in nearby waters. The investigation is made in how nutrients (P – phosphorus and N – nitrogen) spread depending on surface runoff from cloudburst in Hörby municipality in southern Sweden, Skåne-region. The land-use of the site is investigated, where pervious-and impervious areas are defined and further classified in more specific sub-groups. Different rain returns periods used to provide clear explanation of how the nutrient spreading is taking place and how rain intensity is impacting spreading of N and P. Furthermore, the sources of nutrient load are detected and investigated with a hydraulic model. The results show that the hydrodynamic model can be used to visualize the spread and determine the accumulated concentration in the flood area. Furthermore, rainfall mapping has been carried out to identify vulnerable areas in the landscape and determine critical parameters such as distribution and maximum water depth. The method's application area has been discussed in the industry's interest in studying cloudburst more simply and cost- effectively in parallel with nutritional load problems.