Floods in central Texas, August 1-4, 1978

Abstract

Acre-foot (acre-ft). The volume of water required to cover 1 acreto a depth of 1 foot. It equals 43,560 cubic feet, 325,851 gallons, or 1,233 cubic meters. Contents. The volume of water in a reservoir or lake. Content is computed on the basis of a level pool or reservoir backwater profile and does not include bank storage. Convection cloud. A cloud which owes its vertical development, and possibly its origin, to convection. Cubic foot per second (ft3/s). A rate of discharge. One cubic foot per second is equal to the discharge of a stream of rectangular cross section, 1 foot wide and 1 foot deep, flowing at an average velocity of 1 foot per second. It equals 28.32 liters per second or 0.02832 cubic meters per second. Cubic foot per second per square mile [(ft3/s)/mi2]. The average number of cubic feet per second flowing from each square mile of area drained by a stream, assuming that the runoff is distributed uniformly in time and area. One cubic foot per second per square mile is equivalent to 0.01093 cubic meter per second per square kilometer. Dew point (or dew temperature). The temperature to which a given parcel of air must be cooled at constant pressure and constant water-vapor content in order for saturation to occur. Drainage area of a stream at a specific location. The contributing area of a stream, measured in a horizontal plane, bounded by topographic divides. Drainage area is given in square miles. One square mile is equivalent to 2.590 square kilometers. Flash flood. A local and sudden flood which usually follows brief heavy precipitation. Flood. Any high streamflow that overtops natural or artificial banks of a stream and overflows onto land not usually underwater and causes or threatens damage. Flood peak. The highest value of the stage or discharge attained by a flood. Flood profile. A graph of the elevation of water surface of a river in flood, plotted as ordinate, against distance, plotted as abscissa. Flood stage. The approximate elevation of the stream when overbank-flooding begins. Front. The interface or transition zone between two airmasses of different density.

Recent Changes in United States Extreme 3-Day Precipitation Using the R-CAT Scale

“…These extremely high R-CAT events were-by far-the largest R-CAT storms ever recorded, Hurricane Harvey (R-CAT 9) over the Houston, TX, area in 2017 and Hurricane Florence (R-CAT 7) over the Carolinas in 2018. The strongest R-CAT storm recorded before these two was an R-CAT 6 event resulting from an interaction between the remains of two tropical storms (Amelia and a storm from over the eastern Pacific; Schroeder et al 1987) over northeastern Texas in August 1978. More recently still, landfalling Tropical Storm Imelda yielded an R-CAT 6 episode in 2019.…”