204
S. K. Lahiri et al.
Box 1 Reservoir characteristics for the Siang hydrological project
From the data available from Siang hydrological project the reservoir characteristics are mentioned in Box 1.
A Central Electricity Authority, Govt of India Report (2001), identifies the northeast as the ‘future powerhouse’ and at least 168 large hydroelectric projects with a
total installed capacity of 63,328 MW are either under construction or in the near-final
stage of implementation.
Now, a simple calculation suggests that if the required volume of water held by the
reservoir to produce 2700 MW of electricity = 1421.0 Mcum then for 63,328 MW
of electricity volume of water required to be in the reservoir will be 33,329 Mcum
which is much higher than the areal extent covered by a 2.5 m increase in water
level. Recent seismicity status (Fig. 7b) since the year 2000, as monitored by the
NEIST-CSIR, Jorhat shows that the Siang Himalayas is highly active and the current
state of our knowledge is inadequate to guarantee that every possible factor causing
dam outburst had been taken care of.
Besides the upstream side, high altitude causes of flood triggering, as discussed
earlier every year frequency of embankment breaching is increasing. The life of
an embankment is generally set at 25–30 years, but the field evidences suggest
that the complete construction of embankments takes nearly 20–25 years as these
are mostly built on piecemeal basis. Older stretches are more vulnerable than the
newer ones. However, lack of reliability in the official records of the exact dates of
commencement and completion of different stretches of embankments and hence
the needs for additional monitoring and maintenance measures are simply absent.
During bankfull condition, repairing works are mostly done on ad hoc basis when
actual seepages are being reported.
S. K. Lahiri et al.
Box 1 Reservoir characteristics for the Siang hydrological project
From the data available from Siang hydrological project the reservoir characteristics are mentioned in Box 1.
A Central Electricity Authority, Govt of India Report (2001), identifies the northeast as the ‘future powerhouse’ and at least 168 large hydroelectric projects with a
total installed capacity of 63,328 MW are either under construction or in the near-final
stage of implementation.
Now, a simple calculation suggests that if the required volume of water held by the
reservoir to produce 2700 MW of electricity = 1421.0 Mcum then for 63,328 MW
of electricity volume of water required to be in the reservoir will be 33,329 Mcum
which is much higher than the areal extent covered by a 2.5 m increase in water
level. Recent seismicity status (Fig. 7b) since the year 2000, as monitored by the
NEIST-CSIR, Jorhat shows that the Siang Himalayas is highly active and the current
state of our knowledge is inadequate to guarantee that every possible factor causing
dam outburst had been taken care of.
Besides the upstream side, high altitude causes of flood triggering, as discussed
earlier every year frequency of embankment breaching is increasing. The life of
an embankment is generally set at 25–30 years, but the field evidences suggest
that the complete construction of embankments takes nearly 20–25 years as these
are mostly built on piecemeal basis. Older stretches are more vulnerable than the
newer ones. However, lack of reliability in the official records of the exact dates of
commencement and completion of different stretches of embankments and hence
the needs for additional monitoring and maintenance measures are simply absent.
During bankfull condition, repairing works are mostly done on ad hoc basis when
actual seepages are being reported.