Little Manatee River Data Collection / Monitoring Plan

SURFACE WATER MONITORING PLAN

This plan summarizes surface water monitoring performed to supplement existing hydrologic data used  for the Little Manatee River Watershed Management Study.  The monitoring plan was developed following review of existing data collected under Task II of the Scope of Services and the identification of additional data needs.  The intent of monitoring in the basin is to gather data to complete information requirements for most of the major tributaries within the watershed. This data is required to calibrate and verify hydrologic and hydraulic models used in the study.

The study team has identified existing and historic surface water monitoring sites throughout the basin.  Figure 1 shows the location of hydrologic monitoring sites in and around the Little Manatee River watershed, including rainfall, stage and discharge gages.  Table 1 summarizes information for ten (10) historic and two (2) active USGS gages in the watershed.  Table 2 contains a description of active SWFWMD daily rainfall gages located in the watershed.  Records for these gages were collected and reviewed for suitability in calibration and verification of the hydraulic model. The review resulted in identifying four potential storm events, three of which may be used for these purposes.

Although historic information is available for a large portion of the watershed, a need for additional hydrologic information exists.  Monitoring has been initiated to supplement the existing gage data.  Stream flow gages have been installed at three (3) new sites in the watershed, including Cypress Creek, Dug Creek and the main channel of the Little Manatee River. In addition, precipitation gages have also been installed in the watershed. Information about these stations, as well as up-to-date data are available via the internet at http://cmhas.eng.usf.edu/projects/lilman/.

Monitoring Details

The three additional data collection stations: Cypress Creek, Dug Creek and the main channel of the Little Manatee River were equipped with recording stage gages and recording doppler velocity meters.  A flow rating table for each cross section is being developed using manual periodic flow measurements taken when the gages are serviced and during high flow periods.  The stage gages are standard float and pulley type with electronic shaft encoder connected to an electronic data logger.  The stage is recorded as the average stage every 10 minutes.  The insitu velocity meter is a vertical profiling ultrasonic doppler type.  The average velocity is recorded every 10 minutes.  Manual flow measurements taken at all stations will be used to correlate recorded stage and velocity to flow at approximately weekly intervals in the beginning followed by only large events later.  Differences in channel velocity across the cross-section especially at flood stages will require further correction.  These flow measurements will be performed using standard partitioning techniques using a Marsh McBirney hand-held velocity meter.  Rain data is collected with a standard tipping bucket rain gage (NWS type).  The data is summed and stored in 5 minute intervals.  The logger can store 277 days using the 5 minute interval.  All gages and equipment will be maintained on an approximately weekly schedule.

Center for Modeling Hydrologic and Aquatic Systems

Last modified on Monday, September 7, 1999