Application of gis in Water resource

INTRODUCTION:

       Life is literally dependent on our ability to match the supply and demand of water of appropriate quality to specific communities and users at specific times or rates. Our homes, factories, cities, farms, and recreation areas require water, and their success (i.e., sustainability) relies on the effective functioning of natural and human water delivery systems. Extensive time, money, and effort have been invested in learning more about the spatial and temporal patterns and characteristics of individual hydrologic processes so that we can anticipate, manage, and modify system behavior to sustain modern lifestyles and prevent shortages (droughts), surpluses (floods), and resource impairment (pollution). While concerns regarding such issues as population growth, point source pollution, soil degradation, food supply, and energy may have eased over the past years with many positive trends, fundamental problems still exist. Several other water-related issues, notably those concerned with water supply, non-point source pollution, and surface and groundwater quality impairment remain of great concern locally and globally Solving these water resource problems will require an improved understanding of the fundamental physical, biological, economic, and social processes, and a better knowledge of how all of these components operate together within watersheds.

 For example,the National Research Council (1999: 2-8) recently identified five improvements required for the management of water resources:

 increased knowledge of the linkages among watershed components (e.g., uplands, rivers, wetlands, and groundwater);increased understanding of the feedback among processes operating at different spatial and temporal scales;increased availability of inexpensive, useful indicators of watershed conditions and quantitative methods to evaluate land use and watershed management practices; increased availability of advanced watershed simulation models that can be operated by managers who are Scientific experts; andIncreased understanding of the roles of risk and uncertainty in the decision-making process.

Major GI Science Contributions and Their Significance: GI Science has played a major role in the development of distributedhydrologic models and in improving our understanding of the spatial aspects of the distribution and movement of water in landscapes. It has also greatly influenced the study of the impact of land use on water resources. The following illustrate some ways in which GIS technology has already advanced water resource management.

New GIS Data, Their Management and Delivery: The management of water resources requires a wide range of spatialdata, from hydrography and water distribution and collectionsystems, representing the status of water resources, tophenomena influencing the quality and movement of water suchas terrain, climate, soils, and land use.

Hydrologic and Water Quality Data: GIS has enabled government agencies and private organizations to extend the delivery of their data from numerical tables to maps and to support various forms of spatial searches for relevant data. A good example of the latter is the Environmental Protection Agency “Surf Your Watershed” site, which allows the user to obtain water quality data in the form of maps and tables. Similarly, the U.S. Fish and Wildlife Service’s National Wetlands Inventory provides information about wetlands and the National Weather Service’s Hydrologic Information Center provides information on river and stream flow conditions, floods, droughts, etc.  Numerous state agencies provide state or regional data, such as the Illinois Stream Information System info systems/ISIS/isis.html for details) and the Montana Water Information System. The University of Arizona has compiled a list of approximately 300 land-surface hydrology data links

Land-cover Data: Most of the recent attempts to prepare land coverassessments for large areas (e.g., multiple counties, states,or continents) have used meteorological satellite data. Lovelandet al. (1995), for example, generated a multilevel land-cover databasefrom the statistical analysis of multi dated Advanced VeryHigh Resolution Radiometer satellite data for the continentalU.S. that serves as a prototype for a global land-cover databasecurrently under development. Homeric (1996) also used satellitedata with other digital data sources to produce an eco-region mapand database for the continental U.S. The Gap Analysis Program(Scott and Jennings 1998) used similar source data and aims toproduce maps of biodiversity on a state-by-state basis (for additionaldetails on these products and their availability, Finally, the Digital Ortho photo Quadrangle program of the United States Geographical Survey (USGS aims to produce digital ortho photos for the continental U.S. at a horizontal resolution of 1 m and positional accuracy of 6 m. These photographs will help tremendously with the verification and integration of some of the other data sets and the visualization of the results of GIS-based modeling applications.