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United States Department of Agriculture

Agricultural Research Service

Experimental Watersheds
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1 - Introduction
2 - Walnut Gulch Experimental Watershed
3 - Santa Rita Experimental Watersheds
4 - Instrumentation
Instrumentation
Raingage 81
Precipitation
Analog System

Since 1953, precipitation has been recorded at the Walnut Gulch Experimental Watershed in Universal weighing-type gages.  Within the protective housing, precipitation is collected in a bucket that rests on a weighing platform and frame, which are suspended from a spring.  As precipitation collects in the bucket, the load on the spring is increased, which lowers the platform and frame.  The deflection is proportional to the amount of precipitation collected.  The movement of the frame is mechanically transmitted to a pen, which marks a graduated revolving chart.

Digital System

Digital raingages were installed on the Watershed to provide a continuous data stream.  1999 was the first complete year of operation.

Lh3 Flume
Runoff

Channel runoff is measured on the watershed at several locations.  Small waterhseds (up to approximately 25 acres) are instrumented with runoff measuring flumes and traversing slot sediment samples.

Traversing slot

Flume 6
Flume 6 on the Walnut Gulch Experimental Watershed

Flow in the main channels on the Walnut Gulch Watershed is measured at 11 gaging stations.  Eight of the main tributaries are gaged, and three flumes measure flow in the main Walnut Gulch channel.

Flumes on Main Channel

Flume 1 Flume 2 Flume 6
capacity 640 cms
(22,500 cfs)
520 cms
(18,400 cfs)
425 cms
(15,000 cfs)
    
drainage area 150 sq km
(57.6 sq mi)
109 sq km
(43.2 sq mi)
93.6 sq km
(36.1 sq mi)
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Last Modified: 9/4/2012
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