Battle Flat Pilot Watershed Project - Description and History

Following 20 years of research on small experimental watersheds in the chaparral shrublands, planning began for a joint pilot application project in 1976 between the Southwestern Region of the USDA Forest Service and the Rocky Mountain Forest and Range Experiment Station (Bolander 1986, Hassell 1976, Krebill and Tackle 1978). The objective of this pilot application program was to test the state-of-the art technology on a larger, operational-scale chaparral watershed. Management techniques aimed at improving the production of water, maintaining water quality, increasing livestock and wildlife forage, enhancing wildlife habitat, reducing fire hazard and erosion, and determining the economic feasibility of chaparral management was to be evaluated and refined. This program also provided research opportunities for studying fire effects on nutrients, erosion and sedimentation rates, plant productivity and growth, and fire history (DeBano et al. 1999b).

Study Area

A 3,780-ac watershed (Battle Flat) on the Prescott National Forest in central Arizona was designated as a pilot application area in chaparral shrublands in July 1977 (Hassell 1976). The Battle Flat Demonstration Area in the Bradshaw Mountains was chosen to test the current knowledge of managing chaparral shrublands on an operational-size watershed (Bolander 1986). The results of all information gained on experimental chaparral watersheds (both in Arizona and in California) were used to design treatments.

The demonstration area consists of two adjacent watersheds. The southern-most watershed (1,600 ac) is drained by the northeast trending Tuscumbia Creek; the northern-most watershed (2,174 ac) is drained by the east-southeast trending Battle Flat Creek. The elevation at the point of junction of the two stream channels is 4,969 ft.

The topography is highly dissected and rugged. Most of the watershed faces southeast with slopes ranging from 8 to 30 degrees. Parent rock materials in the study area consists of granitics, volcanics, and alluvium. The Battle Flat watershed contains 11 different soil map units (Humbert et al., 1981) whose texture range from sandy loams to very gravelly coarse loams. These soils are located on slopes from 0 to 60% and are all less than 16 inches deep. Runoff on these slopes is rapid and erosion hazard is moderate to high.

Annual precipitation averaged 27 inches over a 10-year period. The watersheds were dominated by shrub live oak (48%), birchleaf mountainmahogany (27%), and pointleaf manzanita (19%). The remaining 6% cover was made up of several other species.

Cooperators

In collaboration with the pilot application program, several research studies were initiated by Rocky Mountain Forest and Range Experiment Station scientists and other scientists from Arizona State University and the University of Arizona. These studies included establishing baseline information on streamflow, erosion and sedimentation, shrub biomass, scenic beauty, effects of fire on nutrient cycling, fire history, and the effect of fire on erosion. Streamflow, precipitation, and sediment measurements were a joint effort between the Rocky Mountain Research Station and the Prescott National Forest. Overall program management was jointly shared by a project leader for the Rocky Mountain Research Station, the supervisor of the Prescott National Forest, and the lead hydrologist for the Southwestern Region of the Forest Service.