During the two decades since the inception of terrain mapping in British Columbia, terrain maps have come to be used for a wide variety of purposes within the general realms of resource management and land use planning (see "Principle Clients" in Table 3). Commonly, government regulations for licensing and permitting require that resource-based companies utilize terrain maps in their planning processes. Terrain maps are also used for environmental impact assessment, planning of roads and other linear developments, various types of community plans, and location of industrial facilities.
At the present time, the forest industry is one of the chief users of terrain maps. Terrain maps/information are used at three levels of reliability: (1) "Es" (= environmental sensitivity) terrain mapping is used at a reconnaissance level (little field checking) to identify unstable areas and potentially unstable areas that remain undisturbed; (2) Terrain maps prepared by rigorous field checking are the basis of the "five-class slope stability" maps (typically 1:20,000; Section 10.2) that the large forest companies are required to employ in the preparation and annual updating of their five-year plans; Ministry of Forests staff also use these maps for planning the activities of small forest companies; and (3) Detailed terrain mapping (1:5000) and/or on-site inspections by terrain specialists, and interpretations related to slope stability, road locations and proposed cut-block boundaries, are required where roads and cut blocks extend onto steep slopes. Where logging is planned in areas susceptible to landslides and/or erosion, and where increased sediment production would have an adverse effect on fish-bearing streams or community water supplies, terrain maps are used to identify existing and potential sediment sources for planning purposes.
In the mining industry, terrain maps are used for planning, environmental impact assessment and exploration. Information conveyed on terrain maps and derivative maps are used in the mine planning and development stages, mine expansion and mine decommissioning stages (e.g., Maynard and Walmsley, 1981). Reclamation planning and land rehabilitation activities undertaken by industry and consultants to industry rely heavily upon the information presented on terrain maps to evaluate baseline environmental conditions and establish decommissioning and reclamation objectives. Planning of facilities such as access roads requires information about substrate conditions, aggregate sources, and potential hazards such as snow avalanches. Recently, terrain maps have begun to be used in the planning of till geochemical surveys and in assessing the results of such surveys, because knowledge of the origin of the surficial materials sampled is essential (see Bobrowsky et al., 1995).
The Ministry of Transportation and Highways makes extensive use of terrain maps, both for general and detailed planning purposes. For example, 1:50,000 scale terrain maps have been used, along with other information for comparison of alternative potential routes for new highway design. Large scale terrain maps (e.g., 1: 10,000) provide information relevant to detailed planning of road alignment, subgrade conditions, and sources of aggregate. Terrain maps are always an integral part of geotechnical studies (e.g., Broster and Bruce, 1990).
Terrain maps provide information used by various government agencies (e.g., Ministry of Environment, Lands and Parks; Ministry of Transportation and Highways; regional districts; municipalities) for the identification of natural hazards and the delimitation of zones for hazard control. Preliminary assessment of hazards can be made by interpretation of terrain maps at scales such as 1:50,000 and 1:100,000: for example, areas affected by slope processes (landslides, debris flows, snow avalanches) and floods can be identified. Detailed hazard investigation can be done by using larger scale terrain maps (e.g., l:lO,000) as a vehicle to portray relevant information. Micro-zonation for seismic hazards (seismic shaking, potential liquefaction) is based on maps of surficial materials (RIC, I 994b).
Government agencies at various levels also use terrain maps as the basis for preliminary or general planning of new residential areas, and urban and industrial facilities Relevant information includes hazards, substrate conditions that represent constraints to development (e g., poor drainage), and sources of aggregate. For example, terrain information is input to Official Community Plans, prepared by Regional Districts.
Terrain maps are used as the base for the biophysical mapping that is presently carried out by the British Columbia Ministry of Environment, Lands and Parks. Biophysical maps include information about soils, vegetation and wildlife habitat, keyed to map polygons that are defined largely on the basis of terrain conditions. (See description of bioterrain mapping, Appendix F.) Biophysical maps are being used for land use planning and resource management, for example as an aid to the identification of areas for protection, such as parks.