Hydrodynamic Modeling Approaches for Agricultural Storm Water Impoundments

Abstract

Hydrologic modeling of storm water impoundments is an effective tool in evaluating different water management options for addressing regional water issues in Florida. However, modeling impoundment water dynamics could be challenging because of the difference in scale between canals and the entire impoundment. Water pumped into the impoundments is first discharged into canals inside the impoundments, which distributes the water. The canal eventually overflows and water floods all the impoundment. Two modeling approaches to simulate this process were tested on two impoundments using the integrated MIKE-SHE and MIKE 11 model. The first approach simulates the one-dimensional flow in the canal in a link-node model; and once water floods, it is modeled as two-dimensional flow. The second approach simulates the entire impoundment as a canal. In both impoundments, Modeling Approach 1 resulted in overestimation of peaks and poor results. Modeling Approach 2 showed considerable improvements in the results and a satisfactory match between observed and simulated water levels. The difference is attributed to the difficulty in representing the canal flooding process in hydrodynamic models.