. Contour trenching effects on streamflow from a Utah watershed. Watershed management Utah; Drainage. Figure 6.—Typical contour trench cross-section showing cut and fill grade METHOD OF INVESTIGATION Trench Construction During the summer of 1964, contour trenches were constructed on the upper 15 per- cent of the Halfway Creek drainage according to standards outlined in Forest Service Handbook ( Dep. Agr. 1959). These trenches were designed to hold 50 per- cent of precipitation from a 2-inch storm lasting 1 hour, plus allowing an additional feet freeboard. Because of va
. Contour trenching effects on streamflow from a Utah watershed. Watershed management Utah; Drainage. Figure 6.—Typical contour trench cross-section showing cut and fill grade METHOD OF INVESTIGATION Trench Construction During the summer of 1964, contour trenches were constructed on the upper 15 per- cent of the Halfway Creek drainage according to standards outlined in Forest Service Handbook ( Dep. Agr. 1959). These trenches were designed to hold 50 per- cent of precipitation from a 2-inch storm lasting 1 hour, plus allowing an additional feet freeboard. Because of variations in slope gradient, the slope distance between trenches ranges from 40 to 120 feet. The vertical height from trench bottom to fill crest was maintained at feet. The profile is shown in figure 6. This gave approximately 10 cubic feet of storage capacity per linear foot. When the trenches were completed they were seeded with a mixture of yellow clover (^Melilotus officinalis), smooth brome {Bromus inermis), mountain brome {Brorms carinatus), intermediate wheatgrass {Agropyvon intermedimi), and tall oatgrass {Arrhenatherum elatius). Instrumentation The locations of most instruments used in this study are shown in figure 1. Modified Venturii-trapezoidal flumes were installed on the Halfway Creek and Miller Creek drainages in the 1930's. The trapezoidal section was built into the bottom of a broad-crested weir (fig. 7). Except for a brief period following the 1947 flood when operation of the Halfway Creek gage was disrupted, both structures have been maintained and continuous strip chart records of streamflow gathered since their construction. A network of recording precipitation gages has been maintained and operated during the summer months in the Farmington Canyon area since 1942. A comprehensive report on these data has been published by Farmer and Fletcher (1969). In addition, two precipi- tation storage gages are maintained on the Farmington Canyon watershed, the
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Keywords: ., bookcentury1900, bookcollectionbiodiversity, booksubjectdrainage
