Rehabilitation Potential of the Drainage System in the Kosik Residential Area

Today there are many projects for rehabilitation of the residential areas in the Czech Republic. A typical example is Kosik residential area where a system of the storm sewer network with partly culverted Kosikovsky Creek flows to the cascade of two reservoirs with the permanent storage built up in order to reduce peak discharges in the creek to the natural level. At the present days the existence of the reservoirs was put into question due to the high land costs. Therefore, the main goal of the project was to examine the reservoirs function after 30 years of the operation by comparison of different development phases of the area (current state, current state without reservoirs and pre-urbanization state). The legitimacy of reservoirs was proved as their abolishment would lead to 300% increase of peak discharges during wet weather. On the other hand, the peak discharges are only one symptom of intensive urbanization. The volume of the surface runoff is increased and infiltration decreased in comparison to the natural state. Therefore, measures including sustainable urban drainage systems principles were recommended.