it includes major reservoir(dam). it includes defenition of dams.it includes its uses.it also includes major types . includes advantages and disadvatages. it icludes various ecological aspects related to the dam

1. ARYA D B
M.Phil
Dept. of Environmental sciences
Uty of kerala

2.  Reservoir
 Is a storage space for fluids.
 Reservoirs can be created by controlling a
stream that drains an existing body of water.
 Eg:- dam

3.  Artificial barrier against a stream flow
 Uses
 Reduce flood
 Irrigation
 Human consumption
 Industrial use
 Aquaculture
 Navigability

4. By structure
 Arch dam
 Gravity dam
 Arch-gravity dam
 Barrages
 Embankment

5. By size
 International standards (including
the International Commission on Large Dams,
ICOLD) define
 large dams as higher than 15 m (49 ft)
 major dams as over 150 m (490 ft) in height.

6. By use
 Saddle dam- permits higher water elevation and
storage
 Weir- small overflow dam
 Check dam –designed to reduce the flow
 Dry dam- designed to control flood
 Diversionary dam- to divert the flow of river
 Underground-used to trap underground water
 Tailings dam- produced during mining
operation

7. By material
 Steel dam using steel plate for dam creation
 Timber dam
 Rock dam
 Concrete dam
 Earthen dam

8.  Tehri dam – bhagiradhi river –utharakhand
 Mullaperiyar dam –periyar river-Kerala
 Bhakra nangal-Sutlej river-punjab, himachal
predesh
 Hirakud –mahanadhi – odisha
 Nagarjuna sagar –krishna river-Andhra
predesh
 Sardar sarovar- Narmada river-Gujarat

9.  Indira sagar- Narmada river- madhya
predesh
 Bhavnisagar –bhavani- Tamil nadu
 Idukki –periyar-idukki
 Malabuzha dam- bharathapuzha -palakad
 Sresailam-krishna river-andhra predesh
 Thungabhadra –thungabhadra river –
karnataka

12. ECOLOGICALASPECTS OF RESERVOIRS

13.  Terrestrial ecosystem biodiversity
 Green house gas emissions
 Erosion and sedimentation
 Effect on riverine ecosystems
 Water temperature
 Blocking migration of aquatic organism
 Effect on coastal and marine ecosystems
 Social effects of dams

14.  Construction affects terrestrial plants and
forests.
 Unique wild life habitat affected.
 Mitigation – Replantation
- compensatory project approach

15.  Green house gas emissions in the catchment
area
 Due to rotting vegetation – small amount
 Microbial activity in the bottom sediment
 By the proper investigation of catchment area
– helps to find out the level of green house
emissions

16.  Natural flow and drainage of the land is altered.
 Altering of the natural sediment load carried by
the waters of the previously free-flowing river.
 As the sediment-laden upstream waters flow
into the impoundment behind the dam
 suspended sediments drop out and form thick
layers of silt at the bottom of the impoundment.
 when water is released through the dam it is
relatively sediment-free, and hungrily picks up a
sediment load as it moves downstream
 Leads to degradation of river channel

17.  fragmentation of watercourses on riverine
ecosystems.
 The interconnected ecologies of riparian
environments are profoundly altered
 Plant and animal populations are thrown out of
all balance as invasive species move into the
disrupted riparian ecologies and native species
are displaced, reduced and in some cases
eradicated.

18.  The reservoirs impounded behind dams alter the
temperature regimes both within the upstream
reservoir and the downstream water channels as the
water is released through the dam.
 Within the impounded water the natural
thermodynamics of a free flowing river can be
replaced by stratified temperature gradients, which
can have profound effects upon the aquatic life both
upstream and downstream of the impoundment.
 Many aquatic planktons, invertebrates, mollusks and
fish are extremely sensitive to these thermal changes
and must either adapt, relocate or perish.

19.  Dams acts as a physical barrier and disrupts
the movement of species from upstream to
downstream
 River dwelling species have several migration
patterns
 According to world commission on dams
(WCD) survey, large amount of fish
populations were died out as a result of dams
blocking their migratory routes

20.  The construction of large dams can have adverse effects on
coastal and marine environments hundreds and even
thousands of kilometers downstream.
 The blocking of the riverine silt and nutrient load as well, has
altered the ecologies of many river deltas, estuaries, coastal
wetland and marine environments.
 Without the annual burden of silt from floodwaters, many
delta wetlands have become subject to severe erosion, and the
reduced dispersal of organic nutrients from river outflow has
severely stressed many marine populations from
phytoplankton up through the food chain to many fish
populations.
 Reduced outflow has also increased the salinity of estuarine
and coastal wetland ecosystems, having a severe impact on
the delicate ecostructures of these environments.

21.  The World Commission on Dams estimates that 40-80
million people have been displaced by dam construction
 There are also increased health risks associated with the
construction of large dam and reservoir systems- growth
of waterborne disease vectors.
 The increased transmission of malaria has been directly
linked to the construction of dam impoundment reservoirs
in Southeast Asia and Africa.
 A further health risk associated with dam reservoirs is the
accumulation of toxins that can leech into impounded
waters and be released downstream into the water supply
used by people.

23.  Dams are created by blocking the flow of
water
 They are different types
 There are many advantages as well as
disadvantages
 But in an ecological point of view
disadvantages are more than advantages