Influence of flood-control reservoir Brezje on flood waters of the river Horjulščica

The aim of this assignment is to determine how flood-control reservoir Brezje influences the flood wave on the river Horjulščica. Because of growing urban environment around the city of Ljubljana there is less and less natural environment for natural river flow. One example of this problem is the river Gradaščica. It flows through an area which is very much endangered by floods. This was already shown in the past when the flooded river Gradaščica caused extensive damage. Lately, there are lots of different flood-control projects in developing – they would lower the risk of floods in this area. One of these projects – the influence of flood- control reservoir Brezje – is studied in this diploma work. During this assignment hydrological and hydraulic models were made. The hydrological model computes hydrographs based on data of precipitation and composition of terrain. The hydrographs are then used in hydraulic model that is created for the area of flood-control reservoir Brezje. As a result of this model hydrographs for area of flood-control reservoir Brezje are given. The changes of output hydrographs are based on different manoeuvres of sluice gates which are halting the free discharge of the water and thus affect the flood wave of the river Horjulščica. The results of these models tell us that flood-control reservoir Brezje has a positive influence on 100-years flood waters and because of that floods are less likely to occur in downstream areas