Introduction

Decision Support System (DSS) is a computer-based system for decision makers who deal with semi-structured problems. DSS is designed and implemented to ease and speed up the use of environmental analysis and techniques. It is an interactive, flexible and adaptable computer based information system, specially developed for supporting the solution of a particular ill-structured problem for improved decision making. It utilizes data, provides easy user interface and allows decision maker's own insights. DSS Frame work can be designed and implemented for environmental systems. Spatial DSS (SDSS) refers to those systems based on the use of GIS technology. Geographic Information Systems (GIS) provides an important source of tools and techniques, which can usefully be incorporated in a DSS, which makes use of geographic or spatial data. SDSS has been defined as an interactive, computer-based system designed to support a user or group of users in achieving a higher effectiveness of decision making while solving a semi-structured spatial decision problem. SDSS are designed to help decision-makers solve complex spatial problem

It provides a framework for integrating:

SDSS assist in strategic decision-making activities considering spatial and temporal variables, which help in regional planning. Energy is an imperative component, playing a pivotal role in development of a region. The focus of regional energy planning is being shifted towards renewable sources and energy conservations considering the diminishing stock and environmental impacts associated with the fossil fuels. DSS assist in decision-making at disaggregated levels, which is required for integrated regional energy planning considering renewable sources and conservation.

Energy from hydel sources is a clean, renewable and reliable energy source that serves national environmental and energy policy objectives. Hydraulic potential is the combination of possible flow and the distribution of the gradients and the hydraulic resource is that fraction of hydraulic potential which is still accusable after allowing for economic considerations. Hydro energy is derived from falling water, either from rivers and streams flowing downhill to the sea or to lakes and dams along the river's course due to the force of gravity. The energy of this movement of water, known as kinetic energy, is usually released through friction as the water flows over rocks and sediments on the riverbed. Harnessing the kinetic energy that is by using the force of the flowing water to drive a turbine generates hydro electricity. The amount of kinetic energy stored in moving water is directly related to the volume of water and the velocity, due to pressure, with which the water flows. Hydropower, large and small, remains by far the most important renewable source for electric power production.

Large-scale hydroelectric power projects are economically unviable when ecological aspects are included. Post reservoir construction studies show that, large hydel projects have been responsible for massive and dramatic ecological changes in the rivers, especially below hypolimnial discharge. Increased understanding and awareness of complex technical, environment and social issues (inherent to large dam projects), realization that the development of large dam project involves a trade-off between the benefits gained against losses and to ensure environmental sustainability, the focus has shifted towards the development of micro, mini and small hydropower plants.

Mini, micro and small hydro plants combine the advantages of large hydro plants on one hand and decentralized power supply on the other. Small-scale hydro in most cases "run-of-river", with no dam or water storage and is one of the most cost effective and environmental benevolent energy technologies. Table 1 shows the category of hydro power plant based on quantity of water and head available at a particular location. These can divert only potential energy of the water, which would have been dissipated to no benefit in the natural flow. The disadvantages associated with large hydro power plants, high transmission costs, environmental costs of submergence of prime lands (forests, crop lands, etc.), displacement of families etc., are not present in the case of small plants. Moreover, the harnessing of local resources, like hydro energy, being of a decentralized nature, lends itself to decentralized utilization, local implementation and management, rural development mainly based on self reliance and the use of natural, local resources.

World's technically feasible hydro potential is estimated at 14,370 TWh/year, which equates to 100% of today's global electricity demand. The economically feasible proportion of this is currently considered to be 8080 TWh/year. Karnataka has a potential of developing 7500 MW of hydroelectric projects, of which only 2755 MW constituting about 36.75% of the potential has been exploited. Large-scale hydroelectric schemes have been producing power in Karnataka State for many years, with the first hydroelectric power station built in 1902. Due to environmental constraints further construction of storage reservoir is limited and attention is now focused to develop small-scale hydro schemes in an environmental friendly way to cater the needs of the region. KPCL has identified in more than 166 locations in the state for small hydro power plants about 700 MW. The potential sources of small hydropower are at the base of existing irrigation dams, anicuts, canal drops and hill streams. The state government has so far accorded permission to private developers to establish small hydro projects in more than 79 locations amounting to 465 MW. Private developers have commissioned eight projects with an installed capacity of 49 MW. In the case of Mini/Micro hydel projects about 30 locations netting 40.37 MW capacity were identified of which 17.20 MW capacity projects have already been installed in 12 different locations.

Criteria for hydel site selection: The choice of site is based on a close interaction between the various conditions like-the pattern of the river, integrity of the site works, environmental integration and conditions defining the costs and benefits. It is necessary to establish the inventory of energy demand in various sectors and assessment of various other sources like solar, biomass, wind, etc. Various factors considered while estimating hydro potential are:

• Topography,

• The head (elevation difference),

• Land use pattern in the catchment,

• Hydrological pattern: defined from measurements or from inter-relationships between effective rain and discharge,

• Usage of water, upstream of the intake to determine the flow which is available and downstream to determine the effects of diverting the water from present and future uses,

• Distance from the intake to the power station and from the power station to the consumer site and

• Size of the scheme involved and evaluation of their stability depending on various litho logical, morphological and topographical conditions.

The objective of this study was to design a decision support system, which helps in planning and assessing the potential of hydro resources, location wise that can be exploited to meet the regional energy demand in a decentralized way.