PRELIMINARY STUDY OF GROUND AND SURFACE WATER INTERACTIONS IN WETLAND ENVIRONMENTS OF A PORTION OF THE GRAND RIVER WATERSHED, NORTHEAST OHIO

Wetlands are important elements of a watershed and this study examines the interaction between surface water and groundwater in five separate forested wetlands in Farmington Township of Trumbull County, located within the headwater area of the Grand River watershed. The Grand River is 98 miles long and drains 712 mi2 (455,680 acres) into Lake Erie. The upper reach of the river flows through the broad valley of an ancient glacial lake and past some of Ohio's largest wetlands, marshes, swamps, and floodplain forests. The wetlands of the study area (one to three acres in size) are located in depressions within glacial till on an upland divide between two tributary streams of the Grand River. A total of 27 piezometers, with screen depths at 20, 39, and 58 inches, were installed within the five wetlands in ten different nests containing two to three piezometers each. Two core borings to depths of 45 and 54 inches were also conducted within two of the wetlands. Boring samples show soil compositions ranging from silty-clay-loam, silty-loam, to loam within four to five horizons. The parent material is ‘slack water lacustrine sediment' overlying glacial till. Preliminary data of piezometer water depths (over an eight month monitoring period) show a remarkable complexity in water flow. One wetland shows increased hydraulic head with depth in the piezometers, indicating the existence of upward vertical gradients of groundwater discharge to the wetlands. A downward vertical gradient (shown by decreased hydraulic head with depth in the piezometers) occurs in two wetlands indicating groundwater recharge from these areas. A through-flow system also exists in two wetlands where upward vertical gradients occur at one end of a wetland while downward vertical gradients occur at the opposite end. This study shows that the hydrology of wetlands can be very diverse even when they are located within a very small area (230 acre study area) of a river watershed.