Hydrology is concerned with study of the motion of the earth’s waters through the hydrologic cycle, and the transport of constituents such as sediment and pollutants in the water as it flows. GIS is focused on representing the landscape by means of locationally referenced data describing the character and shape of geographic features. A spatial hydrology model is one which simulates the water flow and transport on a specified region of the earth using GIS data structures.

Water professionals need to be able to manage surface and groundwater resources over the scale of an entire watershed. Within any given watershed, there may be thousands of groundwater monitoring wells, numerous stream reaches with gages, as well as snow measurements and weather stations. The effects of land cover, vegetation, soil type, topography, geology, water quality, and other factors must be considered in order to make sound management decisions. The data are available from a variety of public agencies, but often in different coordinate systems, at different scales, and from different time periods. How is it possible to synthesize all these data to form a holistic view of the watershed?

The answer is by using a GIS.  A GIS can be thought of as a “smart map” that has features that are associated with information typically derived from a database, which is simply a table of information. GIS user can access and manipulate information associated with geographic features and look for spatial and temporal patterns and relationships.

Water resource managers use geographic information system (GIS) technology to visualize and analyze hydrologic data for tasks such as assessing water quality, estimating water availability, planning ­ flood prevention, understanding the natural environment, and managing water resources.

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