Water School

The rate of the river flow is measured in cubic feet per second (cfs), which is the measure of the volume of water passing any given point in a river in one second. One cubic foot of water is about the size of a beachball. These levels are measured by the United States Geological Survey (USGS) along the course of the waterflow at different points, or subsections, along a marked line. A river will typically be measured approximately 25 to 30 times at regularly spaced locations. USGS gage loc...

A drought is generally considered to be a prolonged period of less-than-normal precipitation such that the lack of water causes below-average streamflow or lake levels, lowered soil moisture, crop damage, or economic losses.  Droughts are globally the second-most costly weather event behind hurricanes, according to National Geographic. In Texas, during the 2011 drought, an estimated $7.62 billion was lost by farmers and ranchers, according to Texas AgriLife. Not only are droughts one o...

The Brazos River is the longest river contained entirely in Texas, with its watershed stretching from New Mexico to the Gulf of Mexico. The Brazos River draw lies approximately 50 miles west of the Texas-New Mexico border, beginning a watershed that stretches 1,050 miles and comprises 44,620 square miles, 42,000 of which are in Texas.The Brazos River proper is formed at the confluence of the upper forks of the river, the Salt and Double Mountain, in Stonewall County. The Clear Fork joins th...

A floodplain is any ordinarily dry land area susceptible to inundation by water. This area is usually low, flat, and next to a stream or other body of water. Living on a floodplain can be especially dangerous in the circumstance that flooding does occur. There is always some risk for those on a floodplain, whether it’s people, businesses, or agriculture. Some floodplains are clearly defined by natural features, by infrastructure made by people, or not clearly outlined.Some floodplains are ...

The measurement cubic foot per second (cfs or ft3/s) is the rate of water movement representing a volume of 1 cubic foot passing a given point during 1 second.  This measurement is equivalent to approximately 7.48 gallons per second or 448.8 gallons per minute.

The headwater is the upper reaches of a stream or reservoir. It can also include the merging of streams that come together to form a river.The Brazos River’s headwater begins at the confluence of its Salt Fork and Double Mountain Fork near the eastern boundary of Stonewall County. The river stretches a total of 938 miles across the state of Texas.Knowledge surrounding a stream or river’s headwater can provide important information about the sources or causes of pollution and nutrient...

The Clear Fork is one of the longest tributaries of the Brazos River. It originates as a draw in Scurry County and runs for about 307 river miles through  Fisher, Jones, Shackelford, Haskell, Stephens, and Throckmorton counties before joining the river’s main stem in Young County north of Possum Kingdom Lake.For a full-sized map, click here.

The United States Geological Survey (USGS) is a federal scientific agency that works in biology, geography, geology and hydrology. USGS is the nation’s primary civilian mapping agency. The agency also monitors streams and other bodies of water across the country for flow and depth. Among its other activities, USGS also monitors earthquakes and volcanic activity.The USGS web site may be found by clicking here.

A river basin is the area drained by a river and its tributaries. A river basin is synonymous with the term “watershed.”  For example, the Brazos River basin refers to the same area as the Brazos River watershed.  photo courtesy Texas Parks and Wildlife

A 500-year flood is a high streamflow that overflows the natural or artificial banks of a waterway and has a two-tenths of 1% chance of occurring in any given year.

A 50-year flood is a high streamflow that overflows the natural or artificial banks of a waterway and has a two percent chance of occurring in any given year.

The height above mean sea level that water in a reservoir has reached. Brazos River Authority and U.S. Army Corps of Engineers lakes are actually reservoirs, or parts of the Brazos River basin impounded by dams. (A free-flowing river is measured in stages, that is, by depth from the river bed to the surface.)

Datum is the basis for relating a river's stage to mean sea level. (datum + stage = elevation in feet above mean sea level)

A river's bank is the sloping ground that borders the watercourse and confines the water in the natural channel when the water level, or flow, is normal.

A drought of record is the worst recorded drought since compilation of meteorologic and hydrologic data began.  In terms of severity and duration, the devastating drought of the 1950s is considered the drought of record for many areas in the Brazos River basin. This drought lasted a decade in many places and covered much of the nation, including all of Texas.  In 2008-2009, some parts of the state recorded a new drought of record.