San Juan Creek Watershed & Fluvial Studies

Orange County, CA

PACE is currently providing consulting services in a number of areas related to San Juan Creek including watershed, fluvial studies and impacts mitigation for the 175 square mile San Juan Creek basin located in Southern Orange County. The project objective is to generate comprehensive hydrology which reflects the County of Orange Hydrology Manual procedures for use in flood control design, floodplain mapping and sediment transport.  The analysis includes a comprehensive study of watershed divided into three different components which included (1) regional watershed hydrology, (2) floodplain hydraulics / mapping, and (3) sediment transport fluvial study.

Advanced Elements:

  • Watershed Hydrology required detailed creation of model using the County procedures which included (1) complete GIS mapping of hydrologic soils, land uses, and impervious values, (2) delineation of watershed into subareas not larger than 40 acres resulting in over 1,000 subareas for use in both a rational method analysis and unit hydrograph, (3) creation of ARC info programming to link the GIS hydraulics mapping to the AES County software which would automatically populate and create the model.
  • Floodplain Hydraulics creation of GeoRAS floodplain using digital topographic data and mapped roughness values.
  • Sediment Transport modeling using both HEC-6T and FLUVIAL-12 for the entire length of the modeled floodplain which included new field sampling of sediment and comparison to previous fluvial model