Investigator: Eric Swain Proposal Abstracts Metadata Publication

Summary

The objective of this study is to determine discharge ratings for 16 coastal hydraulic control structures in eastern Dade County.

A system of canals and levees (see map of study area) has been constructed over the last century for the purpose of drainage, flood control, and aquifer recharge. Strategically placed control structures allow the water management officials to move water from inland areas during high-rainfall periods and retain water in the dry periods. Freshwater discharged to tide through coastal structures not only affects the amount of water available for water supply in the lower east coast and the Everglades, but also affects the biota in the Intracoastal Waterways and Biscayne Bay. Therefore, it is imperative that there be accurate ratings for these structures to predict the effects of various restoration alternatives. Although these coastal structures are a pivotal part of the man-made system, the discharge through most of them are computed only from theoretical ratings. Actual field measurements are needed in order to determine if the theoretical ratings are adequate, and to develop more accurate ratings.

Stage measurements are currently made by SFWMD or USGS at the east coast structures. The flows through the coastal control structures in Dade, Broward, and Palm Beach Counties can be computed by developing stage-discharge ratings from field measurements of flow, stage, and structure operations. Although theoretical ratings exist for the structures, no check as to the accuracy of these ratings has been made. In order to develop ratings from field measurements, discharge measurements must be made at the structure simultaneously with water level and structure operation measurements. Difficulties in making accurate discharge measurements arise from the slow flows and non-standard velocity profiles in south Florida canals. The Acoustic Doppler Current Profiler (ADCP), a new state-of-the art device for measuring flows, will be used to make these discharge measurements. The ADCP uses the Doppler shift in acoustic signals to determine water velocity and compute discharge. It is ideal for measurements in slow and spatially varying velocity fields. Statistical techniques will be used to determine the best-fit ratings for the structures and error analysis of the ratings.

Proposal