Carrying Capacity Study of Teesta Basin in Sikkim - Affected ...

important to ascertain not only the total quantity available but also its
special and temporal distribution. Water though not strictly divided may
broadly occur as surface and ground water. The appraisal of surface
water resource generally includes estimation of (i) annual runoff and its
monthly/ten daily distribution (ii) aerial distribution of water resource
within the basin, (iii) flood flows (iii) low flows (v) return flows and (vi)
sediment load. Similarly ground water involves identification of
dependable aquifers and annual replenishable quantities therein.
Usually for a reliable appraisal of water resource, stream flow
records for around 40 to 50 years are desirable or else in case of short
records, temporal extrapolation may be required. In case where the
length of stream flow data is not adequate but the length of precipitation
data is available for sufficiently long period, a statistical co-relation is
developed between precipitation and run-off using concurrent data.
Using this relationship, long-term run-off is obtained from the available
precipitation date. For flood studies, especially peak flows, flood
frequency analysis is carried out. The rate of sedimentation is obtained
from sediment-discharge observation which also takes into account the
differences in sediment producing characteristics of different catchments
in terms of soil conservation measures if any, undertaken in the
catchment.
The appraisal of land resources includes assessment of existing
land use pattern, areas suitable for irrigation, areas requiring drainage
and areas that can be reclaimed and used for cultivation which would be
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CISMHE