Water Resources Investigations Report 84-4189 "Termperature of ground water at Philadelphia, Pennsylvania, 1979-1981" by G.N. Paulachok       Anthropogenic heat production has undoubtedly caused increased ground-water temperatures in many parts of Philadelphia, Pennsylvania, as shown by temperatures of 98 samples and logs of 40 wells measured during 1979-81. Most sample temperatures were higher than 12.6 degrees Celsius (the local mean annual air temperature), and many logs depict cooling trends with depth (anomalous gradients). Heating of surface and shallow-subsurface materials has likely caused the elevated temperatures and anomalous gradients. Solar radiation on widespread concrete and asphalt surfaces, fossil-fuel combustion, and radiant losses from buried pipelines containing steam and process chemicals are believed to be the chief sources of heat. Some heat from these and other sources is transferred to deeper zones, mainly by conduction. Temperatures in densely urbanized areas are commonly highest directly beneath the land surface and decrease progressively with depth. Temperatures in sparsely urbanized areas generally follow the natural geothermal gradient and increase downward at about that same rate. Return to the Water Resources of Pennsylvania Home Page or go directly to: The URL for this page is http://pa.water.usgs.gov /abstracts/wrir_84-4189.html Please note our privacy statement and disclaimer Accessibility Answers to many common questions can be found on our Frequently Asked Questions (FAQ) page. Please direct content comments or questions to: Information Specialist U.S. Geological Survey 215 Limekiln Road New Cumberland, PA 17070-2424 Phone: (717) 730-6916 FAX: (717) 730-6997 Email: is_pa@usgs.gov or contact: Director, USGS Pennsylvania Water Science Center U.S. Geological Survey 215 Limekiln Road New Cumberland, PA 17070-2424 Phone: (717) 730-6960 FAX: (717) 730-6997 Email: dc_pa@usgs.gov Please direct web related comments to webmaster@pa.water.usgs.gov vaww50