San Antonio River Improvements Project Glossary

Organizations:

  • SARIP: San Antonio River Improvements Project; a comprehensive, multi-year investment by the City of San Antonio, Bexar County, San Antonio River Authority, San Antonio River Foundation and the U.S. Army Corps of Engineers in flood control, amenities, ecosystem restoration and recreational improvements to the San Antonio River, both north and south of downtown San Antonio.
  • SAROC: San Antonio River Oversight Committee; a twenty-two member citizen committee appointed in 1998 to guide the planning and implementation of the San Antonio River Improvements Project.
  • SARA: San Antonio River Authority; SARA was created by the State of Texas to preserve, protect and manage the resources and environment to the San Antonio River and its tributaries. The district spans Bexar, Wilson, Karnes and Goliad counties. SARA serves as project manager for the San Antonio River Improvements Project and as local sponsor with the U.S. Army Corps of Engineers. SARA will also be responsible for the operations and maintenance of the San Antonio River Improvements Project upon completion of the project.
  • USACE: U.S. Army Corps of Engineers; The federal agency responsible for oversight, protection and maintenance of all U.S. waterways.
  • FEMA: Federal Emergency Management Agency; The federal agency responsible for dealing with emergency flood conditions and flood insurance.
  • HEC: Hydrologic Engineering Center; The part of the U.S. Army Corps of Engineers that produces hydrology models to study river dynamics.
  • TCEQ: Texas Commission on Environmental Quality.

Terms:

  • Acequia: irrigation channels constructed during the period of Spanish Colonial Mission settlement. An extensive network of acequias irrigated the agricultural lands surrounding the San Antonio area missions, some of which are still in existence and operation. The U.S. National Park Service protects the mission acequias, which still provide water to some private land owners in the area.
  • Base flow: the water that flows in a river during the dry periods between rainstorms. The San Antonio River had historic base flows fed by artesian springs, but because the Edwards Aquifer has been drawn down by urban well water use, the San Antonio River typically has very little and at many times no natural base flow water source. Today's base flow is provided primarily by recycled water that is pumped into the river in Brackenridge Park near the Witte Museum.
  • Big water: To avoid reducing channel capacity, the San Antonio River Improvements Project plan calls for these wider stretches of water to be excavated just upstream of a grade control structure where the overall main channel can be widened. Big Water might create a body of water that could vary from two to three times the width of the base flow channel to one to two hundred feet wide, depending on available land and the ability to widen the main channel at that point.
  • Chute: portion of the channel with homogeneous depths and velocity.
  • Chute below a Pool: portion of the channel below a natural or artificial pool (e.g. downstream from a weir).
  • Embayment: small, deep, backwater typically at the mouth of a temporary or intermittent stream.
  • Erosion: the wearing away of a riverbank caused by continuous movement of water and wind.
  • Floodplain: the area on either side of the bankfull channel that carries the flow greater than the bankfull flow, that is, all storms greater than the one-to-two year storm. In natural areas the floodplain might be miles wide; in urban areas communities usually try to confine the floodplain to as narrow an area as possible.
  • Fluvial geomorphology: the study of rivers and streams and the processes that form them.
  • Hydraulics: The physical forces that interact between the river and it’s surrounding landscape.
  • Hydrology: The properties, distribution, and effects of water on the earth's surface, below the earth’s surface, and in the atmosphere.
  • Meander: curves in the stream channel where the stream dissipates energy.
  • Peak flow: the maximum volume of water that is carried in the river over a certain period of time, expressed in cubic feet per second (cfs). Peak flows are described in terms of rainfall event frequencies. For example, the "100-year peak flow" has a 1% chance of occurring in any given year.
  • Pool: A river feature where above average depth and/or width and below average velocity create a calm river section.
  • Old River Bendway: meanders that were part of the historical channel but are now cut off from the river.
  • Riffles: A river feature where below average depth and above average velocity create small cresting waves.
  • Scour: process of water eroding material through high velocities in conjunction with moving sediment.
  • Scour Pool: deep pool forming below a plunge point, spillway, or waterfall.
  • Siltation: the deposition of soil particles moved by the river caused by an obstruction to the river's flow or lower flow velocity.
  • Tributary: small, permanent stream emptying into the main stem of the river.
  • Vegetated Channel: main channel with riparian canopy and/or emergent and submerged aquatic vegetation.
  • Watershed: the geographic area that drains into a particular river.