Indian power sector has an installed capacity of
86000 MW. Out of which 25% is hydro power and remaining are thermal, nuclear and
gas-based projects. Power shortages in our country are estimated as 9% of total
energy and 18 % of peak capacity requirements. Thermal based power projects have
environmental repercussions related to emission of suspended particles and
gases. While, large hydro power plants could lead to degradation and erosion of
soil, loss of forests, wild life habitat and bio-diversity and most important is
the resettlement of people. To promote the environmentally sound energy
investments as well as to help in mitigating the acute shortfall in power
supply, the Government of India is promoting development of country's renewable
energy resources and had made it a priority thrust area under India's National
Environmental action plan. As there is vast potential for development of Small
Hydro Power projects, enormous funds shall be required to tap this potential.
Considering the large requirement of funds, it may not be possible alone by
Government to provide adequate finances. To mobilize additional resources for
the small hydro power, private sector participation has to be encouraged. In
many states, private sector has been invited to tap the hydro power resources
for captive use as well for commercial purpose. Private sector participation in
renewable energy has also increased significantly in recent years as Government
of India has opened the power sector to private sector participation. The
run-of-river schemes are existing mainly in hilly areas of Jammu and Kashmir,
Himachal Pradesh, Uttar Pradesh, West Bengal and North Eastern States of our
country. A significant number o:f potential sites have been identified for
development by private developers (table 2). The categories of sites identified in Himachal Pradesh have been shown
in
table 3. The schemes allotted to
private sector, specially in Uttar Pradesh and Himachal Pradesh, have limited
hydrological data. These projects if planned and designed scientifically, based
on regional hydrology, may be less affected by risk and provide excellent
opportunity for development.
Utility of Regional flow Duration
ModelsFlow duration curve is a simple graphical depiction of variability
of water flow at a location without any reference to the sequence in which this
flow would be available. Flow duration curve for the site for which adequate
flow data is available can be directly developed. Flow for various levels of
dependability for gauged site may be estimated from this curve. It is quite
obvious that most of the prospective sites for hyrdo-power projects are likely
to be ungauged. For such potential sites, there are either insignificant data or
no flow data available for such analyses.
To derive: a flow duration
curve for a location on a stream for which adequate flow data are not available,
Regional flow duration curve may be used. Regional flow models are developed on
the basis of data available for a few other gauged catchments in the same region
or transposed from similar nearby region. Such models are employed to compute
flow duration curves for ungauged catchments in that region. Availability of
such regional flow duration models is of paramount significance in estimating
the potential of hyrdo-power in remote hilly regions of the country.
Regional Flow Duration Model Developed Under UNDP-GEF
StudyThe regional flow duration models for hilly states have been
developed by National Institute of Hydrology, Roorkee in association with
Alternate Hydro Energy Centre (AHEC) under Zonal Plan Activity of UNDP-GEF Hilly
Hydro Project - Ministry of Non-Conventional Energy Resources, Govt. of India.
The yearly flow duration model provides the pattern of flow at an ungauged
catchment. For the development of flow duration model, the physiographic
characteristics of catchment like catchment area, perimeter, length of main
channel, elevation of highest and lowest points, geology of area, hydro-geology
of area, land use pattern. climate and other parameters should have been taken
into account. However the model developed under above study is based on
catchment area of gauged site only. The main reason was non-availability of
topo-graphical features for significant number of gauged catchments,
availability of data for individual catchment for short length and paucity of
time and resources in carrying out detailed study. It was decided to pool the
available data together within a region to form a single data series by making
them non-dimensional for obivating the need of relating the flow data of
individual catchment with their physiographic characteristics. Only mean flow
from a catchment, used for making the flow record non-dimensional, was related
to catchment area.
The flow duration models, under the above study, were
developed for nine regions covering all thirteen states of Himalayan region.
These models are expressed mathematically in the form of algebric equations and
graphically in the form of plots. The model data was verified with the actual
measured data in case study. As the confidence limit is not very encouraging, so
the flow duration obtained from above regional flow model may be used only for
pre-feasibility studies. The installed capacity may be based on the actually
measured discharge data.
Utility of Remote Sensing Data for Catchment
AnalysisRemote Sensing data available in the near infrared region (0.8
um - 1.1 um) provides clearly the contrast between land and water features and
therefore is best suited for mapping perennial streams. IRS-LISS III-Geocoded
False Colour Composites (FCCs) data may be used for identification of catchment
boundary, drainage network, perennial streams, landuse and vegetation cover for
these projects. Digital Elevation model (DEM) of these catchments may be
generated by digitizing the elevation contours and spot heights from topographic
maps and using capabilities of ARC/INFO GIS module (ARC-TIN) with user defined
azimuth, elevation and look angle. The catchment boundary, drainage network and
location of major habitation may be overlaid on these DEMs for further analysis.
Objective of Present StudyThe objective of study in progress
at this centre is to develop the modified regional flow duration model by
collecting the discharge data of more gauged catchments with longer duration and
relating more physiographic characteristics of gauged catchment with the mean
flow. The database of Small Hydro Potential sites will also be updated with the
availability of additional information about the catchments