This study focuses on peak flow reduction from a small agricultural catchment in Norway by applying detention ponds as a land use measure. For this study, an event based hydrological and soil erosion model (LISEM) has been used. Surface runoff generated by two selected storm events has been simulated with and without detention ponds to determine the effect of detention pond in flood controlling.
Modeling detention pond as a flood reduction measure; an example case of Skuterud Hydrological Catchment, Norway
Large rainfall events generate large surface runoff with increased flow rate and risks downstream flooding and erosion. Detention ponds are manmade basins designed for temporary storage of storm water runoff volume. Their goal is to reduce the peak discharge of and limit downstream flooding. The main objective of this study is to study the effectiveness of detention pond on flood reduction in a small agricultural catchment by using LISEM model and assess the applicability of LISEM in such study.
Two heavy storm events, one for a summer event and the other for a winter event in the catchment were selected from the rainfall data of 1995 to 2011. These two storm events were simulated in an event based hydrological and soil erosion model (LISEM). Basic run of the model was made without the use of detention ponds whereas ponds of varying size and number (location) were applied to see the effect of the ponds. Sensitivity analysis of model parameters showed that LISEM was highly sensitive to hydraulic conductivity, water content and surface roughness coefficient with respect to discharge. The amount of peak reduction was found to be depended both to the pond size and their placement in the catchment, which in turn were very much dependent to the type of storm event under consideration. The use of 90° V-notch weir as outflow control in two selected ponds showed that the peak reduction of an individual pond can be increased even with smaller pond area. Sensitivity analysis also suggested that pond size and weir angle can be adjusted to regulate the outflow of the pond.