GEOCHEMICAL AND HYDROLOGIC ANALYSIS OF INTERBASIN GROUNDWATER TRANSFER BETWEEN TWO KARST VALLEYS IN CENTRAL PENNSYLVANIA

Nippenose Valley is a nearly-closed anticlinal valley situated in the northernmost fold sequence of the Valley and Ridge Physiographic Province. Previously conducted water balance calculations show that discharge from the valley is greater than expected for the topographic size of the basin. It was hypothesized that Sugar Valley, located 9 km southwest, might be supplying water to Nippenose Valley by flowing underneath a major synclinal ridge. To verify this a study of the hydrology and geochemistry was undertaken. The hydrology may have been affected by glaciation, when Nippenose Valley was an embayment of Lake Leslie, with a depth of 100m. The present theoretical hydraulic gradient is 0.015 from Sugar Valley to Nippenose. Water samples were collected from 2 locations in Eastern Sugar Valley, in an area where a major stream is known to lose water. Water samples were also taken from 4 locations in Nippenose Valley, at each of the three known resurgence springs, and in a karst fenster located directly in-line between the sites in the two valleys. Standard field parameters were measured, and samples were analyzed for major ions. TDS for the samples ranged from a high of 235 mg/L at one of the springs, to a low of 48.2 mg/L at the fenster. Piper diagrams show a strong grouping. Water from the stream in Sugar Valley is generally sodium/potassium bicarbonate rich. Water from the fenster is a sodium/potassium type with no dominant anion. Water from the springs in Nippenose Valley can be classified as calcium bicarbonate rich waters. For the most part, these classifications are concordant with our concept of the flow system. Water from the three springs in Nippenose Valley traverses a much longer pathway through carbonate rocks than the waters collected in Sugar Valley. The Sugar Valley waters are collected shortly after the siliciclastic-carbonate boundary was traversed, and as such have higher concentrations of sodium and potassium than calcium. The most peculiar results come from the analysis of water from the fenster. There is a perennially flowing stream that flows in this area in a half moon shape and gradually loses its flow underground until it disappears altogether. It was suspected that it would be more calcium carbonate rich, but it seems to be closer in composition to the Sugar Valley water.