Ground water in Delaware is produced from porous and permeable geologic formations known as aquifers that are separated by low-porosity, relatively impermeable confining layers. The USGS is participating in the Delaware Source-Water Assessment and Protection Program with State, Federal, and local agencies, and other interested parties to develop a plan to delineate source areas in Delaware and identify potential sources of contamination. USGS work with DelDOT provides the State agency with information on flood magnitude and frequency, which is used in designing and maintaining highway bridges. Water-level measurements in natural and created wetlands also are obtained for DelDOT to determine the effect of road construction on marshy areas and swamps. The rapid increase of urbanization in the United States has affected the environment, leading to problems for both the local urban population and the global environment.
Cities consume large quantities of energy and produce concentrated pollution.
Decreased vegetation leads to climatic and atmospheric changes, which together with higher noise and physical stress levels affect human health and animal habitat. Impermeable ground cover allows less infiltration of water and puts people and property at risk from flooding. Areal changes around Philadelphia, Pa. from 1940 to 1990. To study the nature and effects of urban growth, the USGS implemented the Urban Dynamics Program, in which the unique problems of cities and their surrounding areas are investigated. USGS researchers converted topographic maps of the area dating from 1940 to 1990 to digital form to create a data base of land-use change.