Context: The Environment Ministry informed the Lok Sabha that no Karnataka proposal for environmental clearance of the Mahadayi diversion is under consideration, and the NBWL has not approved forest diversion for the Kalasa Nala scheme in the Kali–Sahyadri tiger corridor.
About The Mahadayi (Mandovi) River:
What It Is?
- The Mahadayi River (known as the Mandovi River in Goa) is a vital, west-flowing inter-state river in peninsular India. Serving as the primary lifeline of Goa, it flows through the rugged Western Ghats before discharging into the Arabian Sea.
Origin & Course:
- Origin: Originates from a cluster of 30 springs in the Bhimgad Wildlife Sanctuary near Degao/Khanapur in the Belagavi (Belgaum) district of Karnataka in the Western Ghats.
- Length: Flows for a total length of approximately 117 km (around 35 km in Karnataka, ~81 km in Goa, and a small catchment stretch in Maharashtra) before draining into the Arabian Sea at Panaji (North Goa) through the Mormugao and Aguada bays.
States Flowing Through: Karnataka, Maharashtra and Goa.
Major Tributaries:
The Mahadayi is fed by several prominent streams (nalas) and rivers, including:
- Kalasa Nala & Banduri Nala (key streams in Karnataka’s Kalasa-Banduri drinking water project)
- Bail Nala, Pansheer Nala, Andher Nala, Khandepar River, Ragada River, and Mapusa River (within Goa)
Key Geographical Features:
- Compact, High-Yield Catchment: Spans a total basin area of approximately 2,032 sq km, receiving heavy orographic monsoon rainfall ranging from 1,918 mm in the plains (Khanapur) to over 5,425 mm in the Ghats (Gavalli), generating a substantial water yield of 3,164 to 5,703 M.cum.
- Steep Gradients & Iconic Waterfalls: Features dramatic elevation drops (from over 980 m in the Western Ghats down to sea level) with slopes up to 150% across the Braganja Ghats, giving rise to prominent cascades like the Dudhsagar Falls and Vajra-Poha Falls.
- Rich Mineral & Forest Landscape: Dense evergreen, semi-evergreen, and moist deciduous forests cover over 36% of the basin, situated over granite, schists, and quartzite formations with rich reserves of iron ore, bauxite, limestone, and manganese.
- Critical Ecological Corridor: Forms an essential wildlife corridor connecting the Kali Tiger Reserve (Karnataka), Bhagwan Mahaveer Sanctuary/Mhadei Wildlife Sanctuary (Goa), and the Sahyadri Tiger Reserve (Maharashtra), harboring tigers, black panthers, King Cobras, and the endangered, endemic Wroughton’s Free-tailed Bat.
Significance:
- Supplies a major share of Goa’s drinking water, supports farming, and helps prevent saline intrusion.
- Supports inland navigation, fisheries, and tourism around Dudhsagar Falls and mangrove backwaters.
