Naba Bhattacharjee Threats to Umiam
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Transcript Naba Bhattacharjee Threats to Umiam
UMIAM LAKE
FACING EXTINCTION!
Umiam Lake - Snippets
Reservoir of Umiam Hydel Project – Stage I.
Commissioned in 1965 – Ist Hydel Project of NE.
Area –10.27 sq km; Area of catchment –220 sq km
Engineering marvel with life span till 2115 faces
extinction within 2040 if present ecological
impingement continues unabated.
Immense tourism potential besides power
generation remains to be harnessed.
FACTORS ENDANGERING LIFE OF
LAKE.
Colossal flow of the following from catchments:
Sediment & Silt.
Sewage.
Solid Waste.
Multiple pollutants.
Rise of lake bed level due to enormous deposit of above materials
reducing volume of water holding capacity.
What causes such inflow into the lake:
Topographical location – valley; surrounded by hilly catchments.
Extensive ecological degradation including loss of forest cover in
catchments made soil totally vulnerable to erosion & displacement.
Multiple network of streams originating & flowing through
catchments discharge into Wah Umkhrah or Umshyrpi which join
with Wah Roro & finally drain into the lake.
What reveals the grim scenario!
Hydrographic survey
Water quality analysis
Situation analysis & assessment study of lake
catchments.
Sediment flow rate data.
Factors responsible for denigration of
catchments:
Hilly terrain with deep gorges & ravines.
Extensive loss of forest cover rendering vast
stretches into “open” land exposed to severe
erosion leading to destabilization of soil profile &
structure.
Population growth and human activities like
deforestation; diverse land use pattern; faulty
cultivation; lack of soil & water conservation;
random
mining
&
quarrying;
unplanned
development of road, buildings et al.
Is the situation beyond salvage?
Grim! But not yet if we act now.
Implement tangible remedial & preventive
measures simultaneously.
Multi pronged approach both short & long term.
Administrative measures & enactment of relevant
prohibitive Acts & invoking existing ones with
diligence.
People’s participation through mass awareness &
sensitization campaign.
Interventions ~
Holistic Action Plan for reclamation & rehabilitation of
catchments: Massive afforestation programme – all other
measures incidental & essential with depletion of this cover.
Extensive soil conservation measures with focus to check
run-off & haphazard movement of water to the lake.
Stream management strategy to check silting of such
seasonal / perennial drainage channels; reducing flooding &
maintaining optimal capacity to canalize storm water.
Essence of rehabilitation need to be based on National River
Conservation Plan & National Lake Conservation Plan.
Regulate inflow into Lake.
A viable cyclic technology for treatment of sewage, effluent &
other pollutants and regulating sediment, plastic, paper et al
in waste water including tertiary treatment before transfer is
allowed into the lake.
An alternative route for sewage transfer avoiding the lake.
Dredging & Excavation – most effective mechanism to
remove huge silt and other contaminant deposit.
Plug possible seepage points evident in reservoir revealed
from down stream discharge study.
Engineering structures as ancillary preventive measures.
Remedial measures primarily desiltation techniques like
flushing, density current venting, sluicing et al is imperative.
CYCLIC ACTIVATED SLUDGE TECHNOLOGY
RESERVOIRS –
Meant for ~
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FLOOD CONTROL
IRRIGATION
DRINKING WATER
HYDROPOWER
INDUSTRIAL
Endangered by
Sedimentation
RESERVOIR SEDIMENTATION
PROBLEM
• STORAGE CAPACITY LOSS
• DECREASE OF LIFE TIME
SEDIMENTATION FACTORS
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RESERVOIR SHAPE
SEDIMENT CHARACTERISTICS
RESERVOIR OPERATION
SEDIMENT/ RESERVOIR VOLUME RATIO
• INFLOW CAPACITY RELATIONSHIP
DEPOSIT AREA
Reservoir
Level
Streambed
Back
Water
Area
Delta
formation
Area
DAM
Bottom
Deposit
Area
STAGE: II
Flood control space
Conservation Storage
Inactive Storage
Dead Storage
Outlet
STAGE: III
Flood control space
Conservation Storage
Inactive Storage
Dead Storage
Outlet
STAGE: IV
Flood control space
Conservation Storage
Inactive Storage
Dead Storage
Outlet
STAGE: V
Flood control space
Conservation Storage
Inactive Storage
Dead Storage
Outlet
BACKWATER DEPOSIT
CHARACTERISTICS
• COARSE SAND & GRAVEL
• UPSTREAM DEPOSIT ABOVE RESERVOIR
LEVEL
• DEPOSIT GROWS UPSTREAM & RESERVOIR
• POSSIBLE EROSION DURING HIGH POOL
WATER LEVEL
BOTTOM DEPOSIT
CHARACTERISTICS
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SILT & CLAY
TRANSPORTED BEYOND DELTA
SEDIMENTATION CLOSE TO DAM
RESERVOIR TURBIDITY
FLUSHING
Flood control space
Conservation Storage
Inactive Storage
Dead Storage
SLUICE OPEN –
RAINY SEASON
Outlet
WATER &
SEDIMENT
HYDROSUCTION BYPASSING
SEDIMENT
DIVERSION
BYPASS
PIPELINE
Outlet
SEGMENTATION & DRY EXCAVATION
DYKE CUM
ROAD FOR
MACHINERY
AREA CLOSED BY DYKES &
DRIED FOR EXCAVATION
DREDGING
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Material
Process
Dredger types
Disposal
.
Thank You.