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Temescal Creek, California — ' 



The effect of moist-land vegetation on depletion of stream 

 flow is well known to hydrologists , despite a scarcity of publish- 

 ed data. Engineers have long observed diurnal changes in stream- 

 flow records which are attributable principally to consumptive use 

 of water by vegetation on adjoining lands. It can be shown that 

 these fluctuations may be correlated not only with transpiration 

 and evaporation but also with air and water temperatures, and that 

 minimiim flow follows maximum transpiration. 



Canyon- bottom vegetation . --A brief opportunity for this 

 type of investigation was presented in a section of Temescal 

 Creek, near Corona, Calif., in April and May 1929. A reach of 

 creek bottom, 2,100 feet In length, was selected. The total area 

 was 12.8 acres of coarse gravelly soil supporting a dense growth 

 of brush and trees and other moist-land vegetation. Of the total 

 area, approximately two-thirds was classified as wet land (that is, 

 land with water at or above the surface) , while the remainder had 

 ground water from 2 to 6 feet below. The investigation was limit- 

 ed to a few weeks in the spring because prior to April water was 

 pumped from the area and late in May the stream became dry. At 

 this time of year there was no appreciable precipitation and no 

 side inflow occurred from the adjoining hillsides. 



At the upper end of the 2,100-foot section the remains of 

 a small masonry dam brought the underflow to the surface where 

 measurement was made through a Parshall flume. At the lower end 

 the abutments of a small highway bridge forced the creek into a 

 narrow section where it was measured by a second Parshall flume. 

 Water-stage recorders were maintained at both controls. At the 

 lower end, the coarse soil permitted some underflow which was 

 estimated as follows: By means of recorder charts at the upper 



XT The field investigation was made by Colin A. Taylor, Associ- 

 ate Irrigation Engineer, Division of Irrigation, in cooperation 

 with the Division of Water Resources, Department of Public Works, 

 State of California. 



