Abstract
Little is known about the amount and frequency of rainfall-induced runoff from the surface of cultivated fields in the western Great Plains; yet, this is the only renewable water supply for the region. The western Great Plains are best known for their chronic water deficit. There are no long-term runoff records available; thus, a set of equations which could extend the existing short term records would be very valuable. A set of equations was derived to compute rainfall-induced runoff from fallow fields using rainfall records, with suitable evaporation functions derived for the Texas High Plains, near Amarillo. The input data to the equation set was restricted to daily rainfall, maximum 1-hour rainfall for the day, and mean solar radiation data, all of which can be easily obtained. The equations may be used to compute daily runoff volume from fallow land for several decades. Computing equations for soil-water content were developed from an intensive 4-month study of soil water on small plots, and verified by infrequent soil water measurements available from other fields. Daily runoff equations were developed from measurements of daily runoff, and rainfall amount and intensity for 3 terraced fields, over a 10 year period. The soil was slowly permeable; had an average slope of 1.5 percent; was cropped in a wheat-sorghum-fallow sequence; and stubble mulch tillage was used to control wind and water erosion. Soil water content in the 0-2 ft layer was computed from daily rainfall, mean monthly solar radiation, and a function for water loss derived for the site. Runoff was computed from daily rainfall, maximum 1-hour rainfall for the day, and the computed soil water content. Runoff equations were required for 3 separate conditions, as follows: wet soil (soil water above field capacity); fallow-after-wheat (the period from wheat harvest to mid-winter where soil water was less than field capacity); and fallow (fallow-after-sorghum plus fallow-after-wheat from midwinter to summer, all for soil water less than field capacity). ...
Hauser, Victor LaVern (1973). Rainfall-induced runoff computed for fallow fields. Doctoral dissertation, Texas A&M University. Texas A&M University. Libraries. Available electronically from
https : / /hdl .handle .net /1969 .1 /DISSERTATIONS -156313.