2. Physical setting

1. Background

2 Hydrology of Artificial and Controlled Experiments

types of NAEW data available.

In the decades leading up to the mid-1930s in the United States (USA), agricultural enterprises were increasingly physically and economically unsustainable due to soil erosion and flooding. The United States Department of Agriculture (USDA) recognized that there was insufficient underlying science supporting the management of agricultural lands that could be assembled into practical land-management guidance for producers. As a result, a national effort established large and small scale research projects that would test the effectiveness of landmanagement practices under natural-weather conditions in different regions of the country to

Consequently, three large-scale experimental watersheds were established in the USA in the mid-1930s [1]. In 1935, one of the large-scale areas established was the outdoor laboratory for land and water management research at the North Appalachian Experimental Watershed (NAEW, also known as the "Coshocton watersheds") near Coshocton, Ohio, the focus of this chapter. This chapter draws heavily from three prior publications that describe the NAEW. Reference [1] describes the NAEW as part of the three original large-scale experimental watersheds, Ref. [2] concentrates on the NAEW history and capabilities, and Ref. [3] describes the

The purposes of this chapter are to: (1) present the history and design of the NAEW, instrumentation, physical features, unique capabilities, data available, research portfolio, and examples of accomplishments, and (2) discuss challenges likely to be encountered when establishing new experimental watersheds and suggest possible remedies. This chapter summarizes the information given in the NAEW history, research portfolio, and capabilities found in [2]. It differs from the other publications on the NAEW listed above in that it raises challenges and provides guidance for establishing new experimental watersheds based on the research experiences at the NAEW. Some of the information in [2] is reiterated here, and the reader is referred to that publication for more detailed information. As noted in this chapter, the NAEW

was unique in data collected and physical features found nowhere else in the USA.

1. "To determine the effect of land use and erosion control practices upon the conservation of water for crops and water supply and upon the control of floods under conditions

2. "To determine the effect under (1) for small and large areas and to trace variations in this effect from the smallest plot and lysimeters through a series of intermediate watersheds to

3. "To determine the rates and amounts of run-off for precipitation of different amounts and intensities for watersheds typical of the NAR of different configuration, size, shape, topography, cover, underground conditions, land use, and erosion control practices. To furnish data needed for use in the design of erosion control structures and in the design and operation of the Muskingum Watershed Conservancy District and other flood control

The founding document for the NAEW [4] listed three overall objectives:

prevailing at the North Appalachian Region [NAR] of the US";

the largest watershed on the project"; and

projects lying within the NAR."

minimize agricultural environmental problems nationwide.

The NAEW was chosen for its "representativeness" in the NAR which included southeast Ohio, eastern Pennsylvania, northern Kentucky, and northern West Virginia (Figure 1). Physical features considered for "representative" experimental watershed selection included soil types, climate, and other factors. Determining representativeness using physical map overlays at the time was comparable to the use of modern-day geographical information systems (GIS). The selected site was one of 86 candidate sites [2, 4].

The NAEW consisted of agricultural lands in east-central Ohio (Ohio map inset in Figure 2) with slopes typically ranging from 18 to 25% and elevations ranging from about 250 to 350 m. About half of the area was in grassland with corn, soybeans, wheat, and forest comprising the remaining area [2]. The latitude of the NAEW is about 40.4<sup>o</sup> N.

Originally, the NAEW comprised a 1854-ha watershed area with several nested gauged watersheds (Little Mill Creek [LMC] watershed, Figure 2, left). This watershed was chosen to address

Figure 1. View of NAEW landscape and administrative buildings.

The average annual air temperature is 10.4C and the average annual precipitation is 959 mm. Cool air from the northwest and moist air from the south often converges to form storms over the NAEW [2]. Soil during winter often freezes for short periods causing precipitation to

Figure 3. Schematic drawing of perched water table due to geological clay layers in unglaciated sedimentary strata on the NAEW in a hilltop, landscape incision of a stream channel intercepting these water sources, and elements of nonuniform

Experimental Watersheds at Coshocton, Ohio, USA: Experiences and Establishing New Experimental Watersheds

http://dx.doi.org/10.5772/intechopen.73596

5

The geology of the NAEW consists of unglaciated sedimentary strata composed of mostly sandstone and shale, with interbedded strata of coal, clay, and limestone. An underlying anticline, local synclines, and strata slightly dipping to the southeast characterize the structure

Soils of the NAEW were developed in residua of weathered sandstone and shale. Three dominant soil types include well-drained sandstone-derived soils (Inceptisols), soils with an argillic horizon derived from shale (Alfisols & Ultisols), and soil between these extremes [2, 5]. Small watersheds were chosen from many swale areas on the landscape. They were characterized by ephemeral areas that shed water only during heavy rain storms and snowmelt, with no incised channel. Larger watersheds have incised channels and drain areas with multiple land-

3. Serendipitous physical features affecting hydrology and water quality

Using general factors such as geology, soils, weather, etc., to select a "representative" site for the NAEW was necessary. Other hydrologically beneficial features of the NAEW location,

1. The imperviousness of geological clay layers underlying coal seams supported perched water tables [2]. These perched water bodies allowed an index measure of the ground-water impacts of surface land-management treatments. Ground-water impacts were evaluated, where the intersection of geological clay layers intersected the landscape surface forming springs that were monitored beneath treated hilltops [5], (Figure 3). Ground water beneath areas as

however, became apparent as experiments were conducted on the site. For examples:

immediately runoff. Snowmelt also is a source of runoff.

of geological formations [5], (Figure 3).

management areas.

runoff generation.

Figure 2. The North Appalachian Experimental Watershed (NAEW) comprises the 1854-ha Little Mill Creek (LMC) watershed (left) and the smaller 425-ha NAEW area (right). Inset shows the location of the NAEW within the state of Ohio.

mainly objective 2—scaling issues. Additionally, part of the NAEW included 425-ha in the southeast area of LMC (Figure 2, right). On this area were several small monitored watersheds of the order of 0.4 ha to address mainly objective 1—evaluating impacts of specific practices on a small (producer-managed) areas, where there were no confounding influences of other landmanagement activities. In approximately 1970, monitoring in the LMC watershed ceased and the NAEW was reduced in size to 425-ha with the largest gauged watershed at 123 ha (Figure 2, right). Experimental Watersheds at Coshocton, Ohio, USA: Experiences and Establishing New Experimental Watersheds http://dx.doi.org/10.5772/intechopen.73596 5

Figure 3. Schematic drawing of perched water table due to geological clay layers in unglaciated sedimentary strata on the NAEW in a hilltop, landscape incision of a stream channel intercepting these water sources, and elements of nonuniform runoff generation.

The average annual air temperature is 10.4C and the average annual precipitation is 959 mm. Cool air from the northwest and moist air from the south often converges to form storms over the NAEW [2]. Soil during winter often freezes for short periods causing precipitation to immediately runoff. Snowmelt also is a source of runoff.

The geology of the NAEW consists of unglaciated sedimentary strata composed of mostly sandstone and shale, with interbedded strata of coal, clay, and limestone. An underlying anticline, local synclines, and strata slightly dipping to the southeast characterize the structure of geological formations [5], (Figure 3).

Soils of the NAEW were developed in residua of weathered sandstone and shale. Three dominant soil types include well-drained sandstone-derived soils (Inceptisols), soils with an argillic horizon derived from shale (Alfisols & Ultisols), and soil between these extremes [2, 5].

Small watersheds were chosen from many swale areas on the landscape. They were characterized by ephemeral areas that shed water only during heavy rain storms and snowmelt, with no incised channel. Larger watersheds have incised channels and drain areas with multiple landmanagement areas.
