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

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).

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.

Figure 1. View of NAEW landscape and administrative buildings.

4 Hydrology of Artificial and Controlled Experiments

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 large as 15 ha have been monitored by using springs because of this favorable geological structure. Impacts of land management on ground water became a significant area of research on the NAEW.

runoff occurs during large intensity rains and snowmelt. These watersheds were used as "test beds" to determine the effectiveness of different land-management treatments. The treatment for an individual watershed was implemented over the entire area so that runoff-response data were not confounded by runoff from other areas with different land managements. Runoff from the smaller watersheds were measured using H flumes ([6], Figure 4). More recently, two watersheds were monitored using drop-box weirs which provide better flow measurement in sediment-laden runoff water [7], (Figure 5). Because of spatial variability of precipitation, each watershed was instrumented with a weighing-bucket rain gauge. Runoff and precipitation data were historically tabulated with depth and time resolutions of 0.25 mm and 1 min, respectively, and when a change in flow depth or precipitation intensity was apparent. Larger watersheds on the 425-ha area up to 123 ha were monitored using Parshall flumes initially and

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

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

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The LMC watershed was instrumented with a network of recording rain gauges and weirs (Figure 2, left). Nested watersheds ranged in size from approximately 39 to 1854 ha. As mentioned before, LMC was closed in about 1970 so there is approximately 30 years of runoff and precipitation data available from most of these watersheds and rain gauges. These watersheds were useful for documenting the nonlinearity of runoff ("scaling," Figure 7) at Coshocton, and have potential for other investigations such as for regional model parameter-

later short-crested V-notch weirs replaced them [6], (Figure 6).

Figure 4. H flume and original Coshocton wheel rotating-slot sampler.

ization and routing.

