HYDROLOGIC MODELING OF 2 GLACIATED WATERSHEDS IN NORTHEAST PENNSYLVANIA

A hydrologic modeling study, using the Hydrologic Simulation Program - FORTRAN (HSPF), was conducted in two glaciated watersheds, Purdy Cree k and Ariel Creek in northeastern Pennsylvania. Both watersheds have w etlands and poorly drained soils due to low hydraulic conductivity and presence of fragipans. The HSPF model was calibrated in the Purdy Cre ek watershed and verified in the Ariel Creek watershed for June 1992 t o December 1993 period. In Purdy Creek, the total volume of observed s treamflow during the entire simulation period was 13.36 x 10(6) m(3) a nd the simulated streamflow volume was 13.82 x 10(6) m(3) (5 percent d ifference). For the verification simulation in Ariel Creek, the differ ence between the total observed and simulated flow volumes was 17 perc ent. Simulated peak flow discharges were within two hours of the obser ved for 30 of 46 peak flow events (discharge greater than 0.1 m(3)/sec ) in Purdy Creek and 27 of 53 events in Ariel Creek. For 22 of the 46 events in Purdy Creek and 24 of 53 in Ariel Creek, the differences bet ween the observed and simulated peak discharge rates were less than 30 percent. These 22 events accounted for 63 percent of total volume of streamflow observed during the selected 46 peak flow events in Purdy C reek. In Ariel Creek, these 24 peak flow events accounted for 62 perce nt of the total flow observed during all peak flow events. Differences in observed and simulated peak flow rates and volumes (on a percent b asis) were greater during the snowmelt runoff events and summer period s than for other times.