Analyse river linking projects in India.

River linking project aims to transfer water from surplus to deficit basin through a network of canals & reservoirs.

[Diagram present showing major river linking projects under NRLP with connections between various rivers including Kosi-Ghaiya, Ken-Betwa, Godavari-Krishna, Perma-Cauvery, Maros-Sadiasth-Teesta-Ganga, and Damodarjor-Pujab]

Benefits of river linking:

1. Water stress management - no redistribution of water from surplus to scarce areas eg. Ken-Betwa

2. Enhance irrigation potential & therefore ensuring food security eg. Godavari-Krishna dams propose irrigation expansion

3. Flood & drought mitigation - balancing extreme water events, increasing with changing climate with water stress regulation through spillage and drought management

4. Hydropower generation - empower ensuring meeting of mechanised targets & phasing down fossil fuels

5. Inland navigation - diversifying cargo movement, currently on dependent on roads

Socio-Economic concerns:

1. Displacement of locals due to land submergence

2. Inter-state disputes - conflict on water sharing & control

3. High initial costs & issues of long-term funding - NRLP projected to cost over ₹10 lakhs crore

4. Impact on livelihood because of loss of forest based & surviving livelihoods eg. fishing & farming

5. Technological uncertainties impeding long-distance water transfer

Environmental concerns:

1. Loss of biodiversity because of habitat destruction & submergence eg. Ken-Betwa

2. Altered river ecology - changed flows, disruptions, sedimentation

3. Navigation & vicious loop of emissions, contributing to climate change

4. Incomplete understanding of long-term impact on local ecology

Way forward:

1. Ensuring detailed & independent social and environmental impact assessments for proposed projects

2. Pilot testing to precede full implementation

3. Building federal consensus to thwart inter-state disputes

4. Ensuring participatory planning, implementation & monitoring of projects

While imperative to address water asymmetry, proactive measures must ensure balancing SDG goals (6-clean water, 13-climate change) so as to not worsen present extreme water stress situation.

Rain shadow effect suffers to topographic phenomena wherein mountain ranges block moist air causing heavy precipitation on the windward side. This causes dry arid conditions on the leeward side.

Mechanism of rain shadow effect:

1. Moist air from dry and sea/ocean approaches mountain range

2. As it rises on the windward side, it cools, condenses & causes orographic rainfall

3. After crossing the plate, dry air now descends on the leeward side & warms up, reducing chances of precipitation

4. This is referred to as scasc shadow effect - region masked by and conditioned

Impact on distribution of precipitation:

1. Windward side - heavy rainfall due to uplift of moist air, ie., orographic varial eg. western ghats windward side receives >800 cm of rain

2. Leeward side - low rainfall because of descending dry air eg. eastern side of western ghats, northern slope of Himalayas

Impact on vegetation:

1. Wind-ward side - dense forests, tropical vegetation eg. evergreen forests in Kerala & Konkan ranges

2. Leeward side - characterised by shrublands from forests, grasslands. eg. Vidarbha, Rayalseema regions

Global examples:

The main shadow effect is crucial in understanding local climates & biomes. It assists in agricultural planning, settlements pattern, preparing disaster management plans (eg. cloudburst likely on windward side)