Final Evaporation Control in reservoirs

7.2.2
 
Measures adopted in Gujarat and Other States 
Compartmentalisation by construction of dykes to isolate the shallow area of water 
was adopted in Wadhwan Bhogavo-I (Naika dam) in Gujarat during the beginning of 

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1988. This dam maintains supply of water to the twin cities of Surendranagar and 
Wadhwan. The evaporation loss in and around Surendranagar is reported to be 
between 2.5 to 3.0 / annum. To reduce this huge loss of water due to evaporation, a 
bund was constructed to isolate the shallow portion of the reservoir, which resulted in 
reduction of 20% of the surface area of reservoir. Water from this shallow portion 
was pumped into deeper pocket. By adopting this measure it is reported that a 
quantity of 0.23 MCM of water could be saved between January and July 1988. The 
expenditure involved in the evaporation control measures was Rs. 27 lakh, 
comprising Rs. 12 lakh on construction of bund and Rs. 15.00 lakh on pumping 
water. By adopting this measure, it is reported that an amount of Rs. 110 lakh on 
transportation of water in tankers from a distance of about 25 km could be saved. 

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TABLE 7.17 Details Of Evaporation Losses In Red Hill Lake Before And After Compartmentalisation 
5 year average values 
Chemical 
required 
(as of 
today in 
Tonnes)
Chemical 
required after 
bifurcation 
Tonnes 
Before compartmentalisation 
After Compartmentalisation 
Month 
Stage 
in m.
Area 
Sq.Km
.
Volum
e 
MCM
Avera
ge 
area 
for the 
month 
Sq.K
m.
Mean 
month
ly 
averag
e mm
Evapo
ration 
loss 
MCM
Area 
after 
bifurc
ation 
Sq.K
m.
Avera
ge 
area 
Sq.K
m. 
Evapo- 
ration 
loss 
MCM
Monthwise 
reduction in 
evaporation 
% 
MCM 
Jan 
12.99 14.82 14.52 
14.66 
5.00 
2.05 
12.38 
12.27 
1.90 
0.15 
7 
20.50 
17.30 
Feb 
12.82 14.50 44.22 
14.39 
6.00 
2.68 
12.16 
11.95 
2.00 
0.68 
25 
22.30 
18.80 
Mar 
12.70 14.28 42.33 
13.87 
6.80 
2.83 
11.75 
10.90 
2.29 
0.54 
19 
20.80 
17.60 
Apr 
12.20 13.47 34.37 
12.42 
8.00 
3.08 
10.05 
8.76 
2.10 
0.98 
32 
19.30 
15.60 
May 
11.49 11.38 26.91 
10.7 
7.80 
2.52 
7.47 
6.61 
1.60 
0.92 
36 
16.20 
11.20 
June 
11.10 10.17 22.43 
9.64 
6.40 
1.91 
5.75 
5.35 
1.03 
0.88 
46 
14.90 
8.90 
July 
10.70 
9.11 
18.61 
8.67 
5.70 
1.53 
4.96 
4.75 
0.84 
0.69 
45 
13.40 
7.70 
Aug 
10.35 
8.23 
15.71 
7.47 
5.40 
1.21 
4.55 
4.13 
0.69 
0.52 
43 
11.20 
6.20 
Sep 
9.75 
6.71 
11.22 
7.27 
4.20 
0.95 
3.71 
4.03 
0.51 
0.44 
46 
11.30 
6.20 
Oct 
10.19 
7.83 
14.36 
10.43 
3.50 
1.12 
4.36 
7.08 
0.77 
0.35 
31 
15.60 
10.60 

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Nov 
12.04 13.04 33.25 
13.25 
3.40 
1.27 
9.81 
10.14 
1.07 
0.20 
15 
20.50 
15.70 
Dec 
12.26 13.45 36.39 
14.13 
4.10 
1.78 
10.48 
11.43 
1.45 
0.33 
18 
21.90 
17.70 
Jan 
12.99 14.82 46.52 
12.38 
22.93 
16.25 
207.90 
153.50 

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TABLE 7.17 (Contd.) 
For present 
configuration of the lake
After compartmentalisation
Annual evaporation loss
MCM 
22.93 
16.25 
Chemical requirement
(a) For whole year
Qty. 
Cost 
207. 90 Tonnes 
Rs. 6.5 Million 
0.50 Tonnes 
Rs. 4.8 Million 
(b) For selected period (March-June)
Qty. 
Cost 
78. 60 Tonnes 
Rs. 2.5 Million 
63.20 Tonnes 
Rs. 2.0 Million 
Savings in evaporation loss due to 
application of chemical:
(a) For whole year
(b) For selected period (March-June)
MCM 
MCM 
8 
2.5 
5.90 
1.85 
Savings 6.68 MCM i.e. 29% without chemical i.e. 6380 Million gallons or say 100 day supply.

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Also an amount of Rs. 40 lakh were earned by raising fodder crop in the emptied 
reservoir bed by using available soil moisture.
Providing underground storages for prevention of evaporation was also reportedly 
done in Talaji rivulet near town of Talaja in Bhavanagar district in the Saurashtra 
region. Significant increase in ground water level was registered by recharging the 
aquifers in the locality. Minimising exposed water surface through storage 
management or integrated reservoir operation was also used successfully in the lakes 
of Vaitarana, Tansa, Vihar and Tulsi supplying water to Mumbai city. This method 
was also used successfully for the two Hiran Reservoirs in Junagarh district of 
Saurashtra area in Gujarat State.

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