It is hypothesized that the 2010 flood in the Hupsel Brook catchment is caused by an increasing discharge, above the design discharge of the culverts, leading to backwater feedbacks and extensive flooding of fields upstream of the culverts. In this colloquium the effect of a culvert on the runoff response during this flood is investigated.
Hydrologic and hydraulic modeling of the 2010 flood in the Hupsel Brook catchment using SOBEK
The incentive of this research project is a heavy rainfall event (160 mm in 24 hours) on 26 August 2010 in the Hupsel Brook catchment in the east of the Netherlands. Consequently, the discharge at the catchment outlet rose from 4.4 × 10-3 to nearly 5 m3s-1, which was the highest discharge ever measured there. The aim of this research is to investigate the effect of a culvert in the Hupsel Brook on the runoff response during this heavy rainfall event by means of a computer model. In this thesis the programming environment Sobek is used. A one-dimensional hydrodynamical model (Sobek-1DFLOW) is coupled with a one-dimensional physically-based rainfall-runoff model (Sobek-RR). A stepwise build procedure was followed. First a fairly Sobek- RR model is created. Second, this model is adjusted to match the Hupsel Brook catchment. Third, this model is extended with a Sobek-1DFLOW model, to match the main reach of the Hupsel Brook, including a culvert and the Q-h relationship of the weir as a downstream boundary condition. It is concluded that the culvert had an influence on the runoff response by lowering the discharge peak from 6.5 – 6.9 m3s-1 to 4.2 – 5 m3s-1. Also a backwater curve upstream of the culvert is simulated with a water depth ranging between ~9 – 10 m, 143 m upstream of the culvert. This is unrealistically high due to lack of two-dimensional processes (flooding) and due to the fact that the connection between Sobek-RR and Sobek-1DFLOW is too far upstream of the culvert.