QUANTIFYING HYDROLOGIC CHANGES IN A RECLAIMED WATERSHED USING GIS AND GPS, THE WILDS, SOUTHEASTERN OHIO

Reclamation of a surface mine inherently changes the basic hydrology of a watershed. The area now occupied by The Wilds, a biological preserve, was mined for approximately 40 years starting in the 1950s. Mining proceeded from north to south with the southern part of the area mined during the mid-1980s. The Wilds is divided into two watersheds with the southern watershed being the smaller of the two. State Route 284, 340 and International Road along with Collins Fork delineate the boundary of the southern watershed. Hydrologic changes in this watershed were determined by GIS analysis of 7.5-minute quadrangles (1961, 1987) and DOQs (1994). This data was supplemented by GPS data collected during the summer of 2002. The southern watershed in 1961 covered 764.1 hectares and contained three sub-watersheds with areas of 685.7, 69.8 and 8.5 hectares. The main sub-watershed contained one small pond of 0.15 hectares and 10,673 meters of streams. Mining had disturbed 457.7 hectares, 67 percent of the watershed, by 1984. A total of eight ponds, seven constructed during reclamation, covered 12.9 hectares of the watershed The 1994 DOQs show an entirely different watershed compared to the 1961 watershed. Reclamation decreased the overall area of the watershed to 748.1 hectares. Eight ponds, four new ponds compared to 1984, cover a total of 34.9 hectares. The ponds subdivide the area into 5 sub-watersheds. The main watershed from 1961 was reduced by 39 percent to 264.1 hectares. Two of the upstream sub-watersheds could possibly drain into the main sub-watershed through pipes in their earthen dams effectively increasing its overall size to 513.4 hectares. The streams in the watershed were reduced by 66 percent to only 3644 meters of streams. The other major hydrologic change is that today the main source of water for the streams is springs. The spring water has TDS values that range from 1200 to 2500 mg/L. The stream system only drains into one lake that has average TDS values of 700 to 1100 mg/L; all the other lakes are filled by surface runoff from precipitation. The water in these lakes has average TDS values of 200 to 500 mg/L. Major changes in this watershed as a result of reclamation are the reduction of streams by 66 percent, the reduction of the main sub-watershed by 39 percent, and the influence of high TDS spring water on a lake and streams.