USGS Recreation
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Among the sycamores and rhododendrons bordering West Virginia’s rivers you occasionally see rustic-looking tool sheds and sleek stainless steel boxes. On the outside, sophisticated antennas point toward satellites flying 22,300 miles above the Earth; inside, advanced electronics hum with data. These U.S. Geological Survey (USGS) streamflow-gaging stations provide valuable information for river recreationists. Using the current USGS Web pages available at http://wv.usgs.gov/ recreationists can check the data from these stations to determine if a trip to a favorite river reach will result in a wasted trip to a bone-dry stream channel or a thrashing ride down some of West Virginia’s best white water. The USGS maintains 100 streamflow-gaging stations throughout West Virginia. Currently (2001), data from 87 of these stations appear on the World Wide Web, updated every 4 hours. Many of the stations report river stage and discharge. By using this information, river recreationists can better plan their trips and make efficient use of their time on the river. Streamflow information is usually presented in two ways—river stage and discharge. White water guidebooks often use river stage to evaluate rafting conditions. Many believe that by using stage you can quickly determine how much water is in the river and make an informed decision about whether or not to raft that day. But, by using only stage as a reference, paddlers can be mislead. To accurately see a river’s conditions on a particular day, paddlers and anglers should also note a river’s discharge. How does the combined use of these measurements help river recreationists avoid finding themselves in unexpected river conditions? First, lets look at river stage. River stage refers to the height of the water surface above an arbitrary reference point set at the river streamflow gage. Stage refers only to the specific pool where the streamflow gage is found and not to the entire river. And, most importantly, stage does not refer to water depth, because river depth and discharge can change without corresponding changes in stage. In short, a river can have more or less water flowing in it, but stage may not change. During periods of high flow, for example, a river bottom can scour or erode. If water erodes the rocks and sediment at the location where the river is gaged, the channel is now deeper and wider and the river has more flow, but the stage has not changed. The opposite can happen also. Stage can change without an increase in flow. For instance, during the summer of 1999, drought conditions on several rivers caused aquatic grasses to grow across the “control,” the downstream section or tail of a pool that controls the stage. These grasses caused a natural dam on the pool and forced the stage to rise by 2 feet, but flow did not increase. Now lets look at river discharge. Discharge, often measured in cubic feet per second (cfs), refers to the actual volume of water flowing through the river. By using discharge as their point of reference, river users will better understand conditions on the whole river, rather than on just the gaged pool. The USGS develops a mathematical relation between the river’s stage and the actual measurement of its discharge. This mathematical relation, used to determine discharges for all stages recorded at the streamflow gage, provides the real-time data provided on the USGS Web site http://wv.usgs.gov/. River users should also note on the Web site a river’s conditions over the 7-day period. By watching river fluctuations for several days, anglers can see if a river is falling and when it might be wadeable again after a high flow. Paddlers can note a river rising and better plan the time and location of their next outing. For instance, before running the lower New River from Cunard to Fayette Station, go to the USGS Web site and check discharge for the New River at Thurmond Station. There you’ll see real-time information about discharge and stage and better prepare yourself for the trip ahead. Recreationists may also want to keep their own log of river conditions. Look at the Web site before and after a trip to the river and jot down the discharge and stage. Once you have a personal history, you can make a more informed decision about your trips. Soon you may be able to notice the subtle differences in your favorite stretch of river at slightly different flow volumes. When using streamflow information of any kind, always keep in mind that rivers are dynamic systems. They change over time, often rapidly. You never see the same river twice. But by using the USGS Web site, you may see the changes as they take place. Remember also that any information presented on the USGS Web site is provisional and subject to significant change. Several times each year, the USGS measures discharge with current meters at the river streamflow gages. These measurements are then used to check the relationship between stage and discharge. The stage and discharge relationships may change and not be shown in the Web information until the flow measurements define the new relations. The USGS streamflow-gaging program in West Virginia began in 1879, the year the U.S. Geological Survey became an agency. At that time, the USGS started maintaining a streamflow gage on the Kanawha River at Kanawha Falls. Constructed by the U.S. Army Corps of Engineers in March 1877, this streamflow gage has recorded daily average flow every day for over 120 years. During the drought of 1999, the station recorded some daily flows lower than any corresponding day in that 120-year period. The USGS built many streamflow gages in West Virginia between 1895 and 1905. For most streamflow gages, the period of record (amount of time that data at a particular site have been recorded) dates back to 1895. Today, the USGS and other agencies use this data for many projects, such as estimating the magnitude and frequency of current and historic floods, studying a river’s water quality, and providing information to help water managers plan and design construction projects, such as reservoirs, levees, or highways. Funding for the USGS streamflow-gaging network in West Virginia comes from a cooperative program, with cooperators primarily from the USGS, the Army Corps of Engineers, and the State of West Virginia. Please contact the USGS, Charleston, W. Va, for further information about USGS streamflow data or other USGS activities in West Virginia (304 347-5130 or email dc_wv@usgs.gov. Written by Matt Cooke, USGS, Charleston, W. Va. |
U.S. Department of the Interior
U.S. Geological Survey
URL: http://recreation.usgs.gov/streamflow_information.html
Page Contact Information: Webmaster
Page Last Modified: Thursday, 11-Sep-2008 12:00:26 EDT
