Mullaperiyar Dam
1886: British (Madras Presidency) signed a 999-year lease with Travancore Kingdom to construct the Mullaperiyar Dam.
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1970: Kerala and Tamil Nadu ratified this agreement post-independence.
Purpose:
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Primary Objective: Divert the westward-flowing Periyar River eastwards to supply water to the arid rain-shadow region of Madurai in the Madras Presidency.
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Reservoir Creation: Formed the Periyar Thekkady Lake, from which water is diverted through a tunnel to the Vaigai River basin.
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Beneficiary Areas: Supports irrigation in Theni, Dindigul, Madurai, Sivagangai, and Ramanathapuram districts.
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Initial irrigation area: 68,558 hectares (169,411 acres).
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Current Uses:
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Water flows from Periyar Lake → Forebay Dam (Kumily) → Hydel pipelines → Periyar Power Station (Lower Periyaru).
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Power Generation: 180 MW capacity.
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Water then flows into Vairavanar → Suruliyar → Vaigai Dam.
Design:
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Type: Gravity dam (stability from its own weight and gravity).
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Material: Built using concrete made from limestone and surkhi (burnt brick powder), with an outer rubble masonry facing.
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Reinforcement: Strengthened with concrete backing by Tamil Nadu PWD.