A dynamic and spatially distributed rainfall runoff model - Developing a model for overland flow in GIS, based on a multiple flow direction algorithm

Sammanfattning: Climate change is expected to cause 20-25% heavier rainfall in Sweden which, in combination with the ongoing urbanization, increases the probability of flooding in urban areas. These floods may cause large infrastructural damage and economical costs. Therefore, adequate models for overland flow are needed to identify high-risk areas where mitigating actions should be performed. In this thesis a new model of intermediate complexity is developed. It is the first known dynamic model which uses the triangular form-based multiple flow algorithm by Pilesjö and Hasan (2014). The model only includes some basic hydrological processes and is therefore less complex than the fully physically based models. Meanwhile, the model still resembles the nature of flow to a larger extent than simpler static models. It includes temporally dynamic and spatially distributed precipitation as well as spatially distributed infiltration and surface roughness. The model is implemented as Matlab code which derives results at different modelling times. By using a geographical information system, the results are visualized as maps of water depths at different stages during and after a precipitation event. Modelling results for Swedish urban and rural conditions are presented together with some initial investigations on how resolution, area and runtime are related.