River Improvements Project Glossary

ORGANIZATIONS:

• SARIP: San Antonio River Improvements Project; a comprehensive, multi-year investment by the City of San Antonio, Bexar County 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 citizen committee appointed in 1998 to guide the planning and implementation of the 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, Goliad, Karnes and Wilson counties. SARA serves as project manager for the SARIP and local sponsor with the U.S. Army Corps of Engineers
  
  
• 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 currently has no natural base flow water source. Today's base flow is provided primarily recycled water that is pumped into the river in Brackenridge Park near the Witte Museum.
  
  
• Big water: To avoid reducing channel capacity, the 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 urban rivers and streams and the processes that form them
  
  
• Hydraulics: the affects of the river based upon geologic factors
  
  
• Hydrology: the affects of the river based upon climactic factors
  
  
• 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 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: portion of the channel that abruptly widens and/or deepens, with reduction in water velocity and smooth water
  
  
• Old River Bendway: meanders that were part of the historical channel but are now cut off from the river.
  
  
• Riffles: steeper portions of stream channels, typically where water flows quickly and shallow
  
  
• 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