University of Central Florida Civil and Environmental Engineering CWR4101 Hydrology - Laboratory 2A Streamflow and Probability Distributions

I. OBJECTIVE

To demonstrate the use of probability distributions in developing a flood prediction.

II. EQUIPMENT

• Library
• Internet Connection
• Distribution Analysis Software
• Regression Analysis Software
• Spreadsheet

III. PROCEDURE

• A. Using the Water Resources Data for the State of Florida (United States Geological Survey), available in the Library or on the internet, select two gaging sites along a river reach on any Florida river. Select a river and sites where at least 15 years of data exist. Record at least 15 yearly maximum flow and gage height values at each site along with information concerning location of gaging stations including contributing area at each gage.
• B. Using the data collected and the DISTRIB for Windows program predict the 10, 25, and 100 year return period maximum flows for the two stations.
• C. Develop a relationship (or use any reported relationship) between flow and gage height for the two stations. Be sure to investigate exponential and power relationships between flow and gage height. Using this relationship and the predictions from part B, also predict the maximum gage stage at each of the gaging stations. (This portion of the laboratory assignment will require the use of REGRESS or some other regression analysis software)

IV. DISCUSSION

The procedure followed in this lab has an ultimate outcome of predicting the water stage (elevation) due to an extreme event (50 Year or 100 Year storm). The distribution analysis is the portion which provides the prediction of the actual flowrate for this event. the prediction is based on historical data. The regression analysis between stage and flowrate allows the engineer to use the flow prediction to determine what the stage will be for this flow. This stage will be used to determine the flood plain elevation.

Your report should include the following;

1. Locator map including the general area of the gaging stations. (HINT: Using the Maps in the library make a xerox copy of the location of the gages)
2. A tabulation of the year, maximum stage, and maximum flow used in developing the distribution.
3. A tabulation (for each station) of the return period and the predicted stage and flow for that return period.
4. The results of the curve fit between maximum stage and flow, including a plot of actual and predicted data.

You will need to locate water resources data for your site. This data is available in the library under U.S.G.S. Water Resources Data. You may also find this data on the world-wide web. The researching of this data is left as an exercise to the student (hint: the USGS main computer address is www.usgs.gov and the water resources data will be in government documents in the library).