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 ~ 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 Back Water Area Delta formation Area Bottom Deposit Area Reservoir Level DAM Streambed

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 Outlet SLUICE OPEN – RAINY SEASON WATER & SEDIMENT

HYDROSUCTION BYPASSING Outlet SEDIMENT DIVERSION BYPASS PIPELINE

SEGMENTATION & DRY EXCAVATION AREA CLOSED BY DYKES & DRIED FOR EXCAVATION DYKE CUM ROAD FOR MACHINERY

DREDGING Material Process Dredger types Disposal

. Thank You.