Water Velocity Mapping of the L-67C Canal in support of the Decompartmentalization Physical Model (DPM)

The primary goal of the Comprehensive Everglades Restoration Plan is to restore natural water flow through the Everglades. An approach known as decompartmentalization, which involves the removal of levees, canals, and other barriers to flow, has been suggested to aid in the restoration. In the region known as Water Conservation Area 3 (WCA-3), the L-67A and L-67C canals and levees, which bisect WCA-3 into WCA-3A to the north and WCA-3B to the south, are major barriers to natural flow. A test project for the decompartmentalization of WCA-3 has been initiated through the WCA-3 Decompartmentalization and Sheetflow Enhancement Physical Model (DPM). This flow-release test involves reconnecting WCA-3A and WCA-3B through the construction of S-152, a structure comprised of ten gated five-foot diameter culverts in the L-67A levee. In addition, 3,000 feet of the “downstream” L-67C levee were removed to provide a pathway for flow; backfilling of the adjacent canal ranged in extent from no fill to partial fill to complete backfilling. Data collected during the DPM flow-release test will allow researchers to evaluate the effects of decompartmentalization on the hydrology and landscape within a small section of WCA-3 prior to implementing larger scale restoration efforts. Velocity mapping surveys were performed within the L67C canal in the region where the adjacent levee was removed to improve understanding of the movement of water across the connection. Data collection along the flooded canal edge and within the partial and complete backfill sections of the canal used a point-velocity acoustic Doppler velocimeter (ADV) within a protective wire-mesh cage to permit data collection within the heavily vegetated environment. Measuring locations were referenced to a differential global positioning system (DGPS) and the ADV was aligned relative to the canal to allow conversion into velocity vectors with heading and magnitude. The downstream component of velocity was also used in conjunction with the depth and section width to provide discharge. Data collection within the unmodified and no fill section of the canal used an acoustic Doppler current profiler (ADCP) interfaced with a DGPS to measure the three-dimensional flow fields and discharge. The data were processed using the USGS Velocity Mapping Toolbox (VMT) software package to provide detailed geo-referenced velocity contour images.