DESCRIPTION OF 

 PINE CREEK STUDY 



The Pine Creek study was established originally to evaluate 

 subsurface flow occurrence on representative granitic slopes 

 and the effect of clearcutting and road construction on subsur- 

 face flow emerging on the face of road cut slopes. 



Physiographic Setting 



The Pine Creek drainage is a tributary to the Middle Fork of 

 the Payette River above Crouch, Idaho. The study was installed 

 on two small undisturbed watersheds of 2.4 and 0.8 acres (1 .0 

 and 0.3 hectares). These microwatersheds are representative 

 of first order drainages found in midelevation, fluvial landscapes 

 of the Idaho batholith. 



Slope gradients on the two study watersheds range from 35 

 to more than 70 percent and aspects range from northeast to 

 northwest (see fig. 8). The soil is a Koppes loamy coarse sand 

 and is a member of the sandy-skeletal mixed family of typic 

 cryoborolls (Nelson 1976). Sandy loam to loamy sand soils 

 overlie moderately weathered and fractured bedrock and range 

 in depth from 6 inches (15 cm) on ridges to about 48 inches (1 22 

 cm) in drainage bottoms. Surface soils were almost entirely 

 covered by litter up to 1 inch (2.5 centimeters) deep before 

 disturbance. Soils are poorly developed, exhibiting only shallow 

 A and C horizons. Average physiographic and soils data are 

 summarized by watershed in table 1 . A general view of the study 

 watershed is shown in figure 9. 



Vegetation on the watersheds before disturbance consisted 

 of an overstory of ponderosa pine (Pinus ponderosa Laws.), 

 Douglas-fir (Pseudofsuga menz/es// [Mi rb.] Franco), and Engel- 

 mann spruce [Picea enge/mann/; Parry), and an understory of 

 small trees and shrubs. 



Figure 8. — Pine Creek study area showing location of instrument and 

 data collection stations in the watersheds. 



Annual precipitation in the vicinity averages approximately 32 

 inches (81 cm). A large portion occurs as snowfalls; conse- 

 quently, a large snowpack accumulates often to a total depth in 

 excess of 60 inches (152 cm), or 20 inches (51 cm) of water 

 equivalent. During the spring, the snowpack melts in a relatively 

 short time, contributing large volumes of water to the soil that 

 generate subsurface flow and measurable piezometric heads. 



Table 1. — Descriptive data for Pine Creek study watersheds, 

 Boise National Forest 



Average Average Average 



Average soil Average aspect crown 

 Watershed slope depth elevation (azimuth) cover 



Percent Inches Feet Degrees Percent 



Watershed No. 1 



(clearcut) 52 32 5,050 337 NNW 63 



Watershed No. 4 



(uncut) 62 30 5,005 335 N 43 



Figure 9. — View of Pine Creek study area. Watershed No. 1 , Boise 

 National Forest, Idaho. Arrows point to slope failures. (Photo taken 

 July 1977.) 



History of Land Use 



The study was initiated in 1969 and proceeded on schedule 

 until November 1972 when the larger watershed (No. 1) was 

 clearcut. A total of 36 ponderosa pines, averaging 25.8 inches 

 (65.5 cm) in diameter, and 126 Douglas-fir, averaging 13.4 

 inches (34.0 cm) in diameter, were removed as a result of the 

 logging. The total volume of timber removal averaged 14,500 

 board feet per acre (203 mVha). Slash treatment included 

 lopping, scattering, and some hand piling. On August 20, 1973, 

 a wildfire swept through the Pine Creek drainage, including the 

 two study areas. This unplanned event compromised some of 

 the hydrologic studies, but also provided an opportunity to 

 compare the postburn response of a cutover and adjacent 

 undisturbed watershed. 



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