Jones Edmunds developed a Watershed Management Plan (WMP) for the Cross Bayou Watershed. The project consisted of selected elements from SWFWMD’s Watershed Management Plan Guidelines & Specifications. Primary tasks included creation of digital topographic information, development of a watershed evaluation report, identification of surveys to be performed and preliminary junction/reach coverage development, model simulations, BMP analysis, floodplain mapping and a surface water resource assessment. The watershed is approximately 13 square miles and connects across to both coasts of the Pinellas County peninsula.
We used existing stormwater asset inventory data from the County, the City of Seminole, and the City of Largo – all in different formats – to reduce field reconnaissance and survey requirements and to better define local drainage patterns.
The floodplain model was developed in ICPR and had to consider significant inflows from two canals outside of the watershed as well as other intermittent connections with surrounding watersheds. Development of the model schematic and model parameterization were expedited through extensive use of GIS-model automation tools and our standard operating procedures for applying the tools. The tools made extensive use of LiDAR data and other site plan information that superseded the LiDAR data in specific locations to develop a date-certain terrain, soils and land use layers, stormwater infrastructure geodatabases, and high-resolution multispectral imagery.
The model was calibrated and verified at two USGS gage locations as well as at other high water mark locations throughout the watershed for a recent very large storm event. NEXRAD data were used for the verification, and local rain gage data were used to corroborate the NEXRAD data.