Accepted Papers - 3.pdf - UNESCO

(1) Recharge in low = Area of the watershed
(in sq Km) x Average Rainfall in meters
Rainfall Year x Recharge Coefficient
= 125.82 X .400 X .15
= 7.54 mcm
(2) Recharge in Normal = Area of the watershed
(in sq Km) x Average Rainfall in Rainfall Year
Mtrs X Recharge Coefficient
= 125.82 X .700 X .15
= 13.21 mcm
(3) Recharge in Good = Area of the watershed
(in sq Km) x Average Rainfall in Rainfall Year
meters X Recharge Coefficient
= 125.82 X 1.0 X .15
= 18.87 mcm
Runoff Estimation
Before recommending water conservation
measures it is necessary to evaluate runoff potential
of the watershed and it is the main input for
recharging the ground water. Therefore micro
watershed based run-off potential of the watershed
corresponding to normal rainfall of the area. The
runoff is assessed for each micro-watershed based
on its geomorphic character. In a process a weighted
average value for runoff coefficient has been
considered, and based on that entire calculation was
done. The total run-off is 8.46 mcm, (calculated for
616mm (10 years Average since 2003-04 rainfall
were exceptionally high) of rainfall using Strangers
Table), which is available for harnessing to meet
the future demand. It is essential to arrest runoff by
constructing suitable recharge structures at
appropriate locations.
Assessment of water availability Situation
Since the project is aimed at preparation of
action plan for rain water harvesting and artificial
recharge it is eminent to assess the water requirement
visa vis water availability to identify the priority
areas for implementation. Considering this the
drinking water requirement for human and cattle
population, based on projected population of 2011
and also water requirement for irrigation has been
assessed and the findings of the same are as under.
390
Water Requirement
A] Drinking Water
The total drinking water requirement of the
watershed as per 2011 population has been worked
out where in it is observed that the water requirement
is 0.713 mcm for a population of 19818 souls and
drinking water demand for cattle is 0.356 mcm
(considering 50% of the human requirement) The
total drinking water requirement is 1.069 mcm
B] Irrigation
The area is predominantly rice growing, which
is a rainfed and grown in Kharif season, however,
with the availability of power supply the farmers
are inclined to raise double crop as a result rice is
also grown in Rabi and summer through irrigation
dug wells and bore wells. The land Use statistics of
the area indicates that the area under Rabi and
summer cultivation is around 136 ha. Considering
the above figures the water requirement for irrigation
would be @ 0.010 mcm per hectare i.e.1.36 mcm.
The demand for irrigation is also expected to go
higher as currently only 1.08% of the cultivable land
is under irrigation. The expected future irrigated area
would be around 10% of the cultivable land.
Considering this the future demand for irrigation
would be 6.22 mcm.
Thus, the total future water demand of the
watershed would be 7.28 mcm.
Result and Discussion
In view of the above situation, the drainage
lines have been thoroughly explored in which, it is
observed that the 1 st and 2 nd order streams are very
shallow and have been explored for paddy
cultivation leaving no scope for construction of any
structure. However, 3 rd and 4 th orders of the streams
were found to be suitable for construction of water
harvesting structures. To this, at favorable locations
Masonry Stop Dams, Boulder Check Dams,
Desiltation tanks, Rooftop Rain water harvesting
structures, Sub-Surface Dykes and Percolation Tank
have been suggested. Refer Map 2.1
Considering the local needs only maintenance
free permanent structures have been suggested. The
detailed engineering design and cost estimates have
been prepared for each site. Based on this following
structures have been suggested at appropriate
locations.