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WATER
RESOURCES
Kerala gets
on an average of 307 cms rainfall, the bulk of which (70%) is received
during the South-West monsoon which sets in by June and extends
upto September. The state also get rains from the North-East monsoons
during October to December.
The state experience
severe summer from January to May when the rainfall is minimum.
The two monsoons have a direct bearing on the ground water potential
of the state which also follows the same seasonal trends.
The ground water
level receding drastically during the summer months and drying up
of wells are common features of the ground water levels in many
parts of Kerala. The ground water replenishment and hence the levels
depends also on the geo-morphological, physical and chemical properties
of the soil in general, the depth of water level in Kerala state
varies from few cm bgl to 56 M bgl and most of the area fall under
0-20 M bgl. The depth of the water level in the weathered crystalline
of midland areas in Kerala varies from 3- 16 M bgl. The midland
area sustains medium capacity dugwelts Borewells tapping deeper
fractured aquifer are feasible along potential features in the midland
and hill ranges. Potential fractures are seen down to 240 M and
the most productive zone is between 60 M and 175 M. The discharge
of borewells range between 3,600 Iph and 1,25,000 Iph. In laterites,
which is the most widely distributed lithological area in the state
having a thickness from a 3 M to 30 M, the depth of water level
ranges from less than a meter to 25 M.bgl. lateries from potential
aquifer along valleys and can sustain wells with yields in the range
of 0.5 M3 to 6 M3 per day. Along the coastal plains the ground water
occurs at depth ranging from less than a meter to 6 M.bgl. filter
point wells are feasible wherever the saturated availability indicate
that ground water depths are farthest for laterite regions and shallowest
for coastal alluvium during all times of the year. The availability
of the groundwater level between the post and ore monsoon levels
varies widely. The water level fluctuations in the post monsoon
and ore monsoon vary between coastal alluvium, river alluvium and
valley hills.
Kerala has got
41 west-flowing and 3 east-flowing were originating from the Western
Ghats. The total annual yield of all these rivers together is 78.041
Million Cubic Meters (MCM) of which 70,323 MCM is in Kerala. The
peculiarity of the rivers flowing across Kerala is short length
of the river and the elevational difference between the high and
the low land leading to quick flow of water collected from the river
basin and quickly discharged into the Lakshsdweep sea, the state
has not been able to utilise the river water sources to a major
extent. The major portion of the runoff through the rivers takes
place during the monsoon seasons. 67.29% of the surface water area
of 3.61 lakh hectares is constituted by brackish water lakes, backwaters
and estuaries.
There are about
3000 watersheds in the state, the management of which through land
use patterns, conversation practices adapted to the topography and
soil conditions can determine the extend of run off retention and
infiltration. Here Is an urgent need for local community based micro
watershed management couple with broader integrated river basin
support and control management An overall and integrated approach
in water resource management in the State is yet to emerge. On a
rough estimate, the source wise dependence by rural households for
domestic water supply dependent on traditional ground water systems
is 80%, 10-15% use piped water supply systems, and 5% use traditional-surface
and other systems.
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