Paul T. Jacobson

In recent years, flooding in several hydrologically altered river basins across the country has resulted in loss of life and extensive property damage. Likewise, landslides on logged slopes in the Pacific Northwest have resulted in damage to property and risk of injury and death in adjacent residential areas. These and other disasters have highlighted connections between environmental management and ostensibly natural hazards. The emerging paradigm for comprehensive environmental management is the ecosystem approach, which has been endorsed by the U.S. Environmental Protection Agency (USEPA) and many State agencies and is being applied at a variety of spatial scales across the United States.

A fundamental requirement of the ecosystem approach to environmental management is definition of system boundaries by using ecological criteria. Two approaches have been widely used for defining ecosystem boundaries for environmental management. One approach is the ecoregion approach, in which areas are delineated on the basis of similarity of geology, climate, soils, biota, and hydrology. Ecoregions are considered useful units for management because they are relatively homogeneous with respect to their structural components and dominant ecological processes. The other common approach is the watershed approach, in which ecosystems are delineated by using hydrologic boundaries. Both approaches rely upon mapped geologic information.

The ecoregion approach is strongly influenced by geology, as is apparent from examination of continental-scale ecoregion maps prepared by USEPA (Omernik, 1987). Current work by USEPA focuses on developing more precise, homogeneous ecoregions mapped at a larger scale; this requires accurate, high-resolution geologic maps.

The watershed approach defines ecosystems on the basis of the flow of water. The approach was inspired by the classic, long-term Hubbard Brook Ecosystem Study (Likens and Bormann, 1977; Bormann and Likens, 1994), which used the powerful mass-balance approach with paired treatment and reference watersheds. The geologic setting of the Hubbard Brook Ecosystem Study, however, was well known and nearly ideal. High topographic relief combined with shallow, impervious bedrock ensured precise definition of the system boundaries. Widespread use of the watershed approach implies more complex geologic settings and a need for extensive coverage of large-scale geologic and hydrogeologic maps.

Douglas J. Riddle

Applications of geologic map information use by the speaker are presented in the context of 20 years of work in the Baltimore-Washington area. The focus of the talk is to highlight a series of examples of projects where the speaker has been the principal investigator and geologic maps have been used. These projects fall under the broad categories of economic geology, engineering geology, and environmental geology. The primary project examples deal with the panel discussion topic of natural and induced hazards, but other examples are also presented. The three categories and the respective project applications discussed are as follows:

Economic Geology

• Sand and gravel deposits and land value (Prince Georges County, Maryland)
• Regional clay sources identification (Delaware, Maryland, and Virginia)

Engineering Geology

• Underground energy storage and host rock selection (Maryland)
• Forensic study of trench collapse (Fairfax County, Virginia)*
• Construction claim--dewatering (Prince Georges County, Maryland)*
• General use of geologic maps for tunnels, dams, and building foundations
• Slope instability--Cretaceous clay and Marlboro Clay (Maryland and Virginia)*
• Karst and building foundations (Frederick County, Maryland)*

Environmental Geology

• Sludge entrenchment sites and leachate generation (Maryland)*
• Remediation of military installations (Virginia and Maryland)*
• Hawkins Point hazardous waste facility (Baltimore, Maryland)*
• Former chrome-ore processing facility (Baltimore, Maryland)*

The speaker's viewpoint, based on performing numerous projects in the area, is that vast amounts of data have been collected since many of the maps we are using were developed. These data deserve to be incorporated in updated maps if we are to meet the challenges of redevelopment of urban areas, brownfields development (for example, the SMART program in Maryland), and new development.

---

*Denotes a project dealing with a natural or induced hazard.

Sean Smith

The Maryland Watershed Restoration Division (WRD) is involved in a wide variety of activities that focus on the restoration or enhancement of wetland and stream ecosystems. Our work involves the analysis of water chemistry and physical landscape conditions that influence the quality and abundance of aquatic habitat for macroinvertebrates and finfish. It has been our experience that geologic map information has direct application in our monitoring, assessment, and restoration activities. This information is useful because of the relationship between the State's geology and the physical and chemical characteristics of the associated waterways and wetlands.

One of WRD's primary activities is related to the evaluation of best management practices for the control of nonpoint source pollution generated from land uses in both urban and rural watershed areas. General knowledge of the geological characteristics of contributing watersheds provides useful information for identifying background water- quality trends. An excellent example of this use is provided in the "Synthesis of Nutrient and Sediment Data for Watersheds within the Chesapeake Bay Drainage Basin" (Langland and others, 1995) published by the U.S. Geological Survey in cooperation with the U.S. Environmental Protection Agency. This effort evaluated the potential correlations between nutrients and sediment with respect to land uses, rock type, and physiographic province. Similar investigations can be conducted at higher resolution with more detailed geologic information. The cultivation of a greater understanding of the influence of the State's geology on surface-water quality can be helpful in the development of local and regional watershed management strategies, including the Chesapeake Bay Tributary Strategies.

The physical restoration of aquatic environments has become a significant focus of the environmental management agencies in the Washington-Baltimore metropolitan area. Stream restoration has become increasingly popular as an option for the remediation of ecological damages resulting from past land-use changes and the manipulation of natural channels for development purposes. Numerous new approaches to stabilizing natural channels or enhancing aquatic habitat conditions have been developed in recent years that give closer attention to the geomorphology of natural channels. However, in many cases inadequate attention is being given to the landscape surrounding the channel and the general geologic conditions in Maryland's primary physiographic regions. The WRD is attempting to develop improved approaches for restoration planners and designers that give more thorough consideration to the elements that influence the appearance of stream channels. An improved understanding of Maryland's geology and the landscape con-ditions occurring across the State's varied physio- graphic regions is the foundation for this approach. In addition, knowledge of the geologic characteristics in specific stream reaches can be used to develop conclusions regarding stream bottom sediment characteristics, stream bank stability, and the potential for widening or deepening of the channel.

The benefits of geologic mapping resources are most closely related to WRD's goal of improving the understanding of waterways and wetlands in Maryland. As with other mapping resources, they are most useful during the planning stages of watershed protection and restoration projects. They also have potential application in the design of site remediation projects. We have found them useful in the development of conclusions regarding water-quality data and believe that they have potential application in the development of criteria for the targeting of riparian reforestation and stream restoration activities. Improvements in the quality and availability of geologic mapping resources in the State will be important contributions to the State's future watershed planning activities.