Vol. 27, No. 2,  Fall/Winter 1999- "The Pennsylvania Geographer"

CLIMATE CHANGE AND WATER RESOURCES OF THE DELAWARE RIVER BASIN

Jay W. Hodny

W. L. Gore & Associates, Inc., Newark, DE

John R. Mather

Department of Geography

University of Delaware

Abstract

Increasing water demands, coupled with a finite water supply, provide the potential for water shortages in the Delaware Rive Basin due to changes in the region's climate. The Thornthwaite-Mather water budget is used to study potential changes in water resources in response to possible future climatic changes.

Two different General Circulation Models (GCMs) are used to examine the response of water budget variables to changes in temperature and precipitation. The changes in temperature and precipitation when going from a simulated 1xCO2atmospheric concentration to a simulated 2xCO2atmosphere are applied to a current climatic data set and interpolated to 29 0.5° of latitude by 0.5° of longitude grid points covering the study region. The Thornthwaite-Mather water budget is evaluated at each grid point for both GCM data sets.

Evaluation of data developed by two different GCMs over the Delaware River Basin shows only minor changes in temperature (an increase) and precipitation (a decrease) in going from current to hypothetical 2xCO2conditions. The hydroclimate of the area should experience warmer and dryer conditions with less surplus of water, a decrease in streamflow, as well as an increase in water deficit conditions, and a marked decrease in snow accumulation. Use of the GCM temperature and precipitation data in a climatic water budget approach permits 3 The Pennsylvania Geographer — Volume XXXVII No. 2 — Fall/Winter 1999 quantitative evaluation of the future hydroclimatology of an area under conditions of changing CO2conditions.