Rapid 2D Flood Risk Assessment for Radnor Township, Pennsylvania, USA

摘要

Flood models were developed using a rapid 2D simplified-hydraulics solver for four watersheds located within Radnor Township. These urban watersheds vary in size from 6.1 to 77.2 km~2. A range of design events were simulated in the four watershed models in order to understand the variations in extent and severity of flooding for different storm magnitudes and durations. The design events and their corresponding rainfall depths, which were based on point precipitation frequency estimates at Villanova, PA, range from 1.19 in. for the 1-year/1-h event to 7.61 in. for the 100-year/24-h event. Use of the Flood Modeller FAST simplified-hydraulics solver enabled a quick representation of the location, extent and severity (depth grid) of known flood locations and identification of additional areas that may be prone to further flooding. High flood risk areas were ultimately chosen based on the streets and parcels that contained the most significant flooding based on the modeled flood depth grid results. The simulated flood extents corresponded with the majority of the Township's known flooding areas. Several of the additional areas identified to be prone to flooding based on model results were also confirmed by the Township. The high flood risk areas determined by the modeling are currently being investigated in the field. Concept designs, ranging from increased conveyance capacity to implementation of green infrastructure, will be developed to alleviate flood risk in these areas.