Civil Insight: A Technical Magazine Volume 2 | Página 32

32
TEACHERS’ SECTION
CIVIL INSIGHT 2018
To a major extent, these loopholes can be patched up by determining the e-fl ow requirement. The fl ow
requirements may vary depending on the location. The human activities and the biodiversity of a particular
place may vary from another place. Hence, the scientifi c study of the correlation of the fl ow, depth and velocity
with the lifestyle, socio-economic activities and environmental requirements of fl ora and fauna available in a
particular river stretch which when done, rather than generalizing the fl ow requirement, will defi nitely provide
a proper guideline for the regulation of the fl ow d/s of the infrastructure developed or to be developed.
Another concern for maintaining the balance between the development of infrastructures and the environment
is the economy. The effect of release of e-fl ow to the economic output of the hydropower is a major concern
for the developers. In a study of an arbitrary site at Lete, Mustang, which could be developed as a good Storage
Hydropower of 141 MW, the scenarios for various e-fl ow discharges were analyzed and the comparison of its
economic output and power generation was conducted by the students of Kathmandu University. The table 2
below shows four conditions of e-fl ow discharges and their economic comparison:
No EF- no release of water d/s of the dam; EF1- 10%release; EF2-20% release; EF3-30% release
Table 2: Economic analysis at different e-fl ow conditions of Lete Storage Hydropower
(Gautam, Shrestha, Oli, Bhandari, & Shah, 2016)
EF Scenario B/C IRR Payback
No EF 1.26 12% 11.01
EF1 1.14 11.30% 11.61
EF2 1.07 10.70% 12
EF3 1 10% 12.41
13
12.5
12
11.5
11
10.5
10
Figure 5 below shows the same comparision on the basis of pay back period and fi gure 6 shows the power
generation which shows a reduction of power generation by 20% when 30% of fl ow is released in comparison
to no e-fl ow condition.
No EF
EF1
EF2
EF3
Figure 5: Comparison of payback period
of Lete Storage Hydropower at different
e-fl ow conditions (Gautam, Shrestha, Oli,
Bhandari& Shah, 2016)
6000
5000
4000
3000
2000
1000
0
2016)
NO EF EF1
EF2
EF3
Figure 6: Comparison of energy generation
of Lete Storage Hydropower at different
e-fl ow conditions (Gautam, Shrestha, Oli,
Bhandari & Shah, 2016)
In present context, everything is associated with money. So, the environment conservation in context of money
is evaluated in order to optimize environmental fl ow with respect to environmental conservation cost. Though
there is reduction in the power generation and an increment in the payback period, the trade-off between the
total cost of environmental conservation and external cost to be borne for the degradation of environment
and the risk, as shown in the fi gures below, will give an optimized capacity and environmental fl ow.