Download 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:
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



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 ~
•
•
•
•
•
FLOOD CONTROL
IRRIGATION
DRINKING WATER
HYDROPOWER
INDUSTRIAL
Endangered by
Sedimentation
RESERVOIR SEDIMENTATION
PROBLEM
• STORAGE CAPACITY LOSS
• DECREASE OF LIFE TIME
SEDIMENTATION FACTORS
•
•
•
•
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
•
•
•
•
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
•
•
•
•
Material
Process
Dredger types
Disposal
.
Thank You.