Conservation Conversations

LINEAR BARRIERS IN WESTERN GHATS WILL LEAD TO CASCADING EFFECT ON RIVER CATCHMENT AREAS

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Dr Jagdish Krishnaswamy is India’s leading eco-hydrologist and has worked on ecological flows in regulated rivers, landscape ecology, conservation planning, ecosystem services and applications of Bayesian approaches in understanding complex changes in the environment. He is Senior Fellow at the Centre for Biodiversity and Conservation, Ashoka Trust for Research in Ecology and the Environment. 

Q1. How do projects like Sharavathi Pumped Storage, Hubballi-Ankola Railway line etc. have an impact on the catchment area of rivers?

Apart from loss of forest directly, they fragment and disturb forests through roads and other supporting infrastructure.  Fragmented forests have less ability to provide regulating ecosystem services such as carbon storage and hydrological services and may be more vulnerable to extreme weather, edge effects and invasive species.  Linear barriers like rail lines can disrupt movement of wildlife.  Soil erosion and impacts on run-off and water quality are also expected. The changes to the hydrology of the basin would have impacts on aquatic biodiversity of the Western Ghats. Such disturbance in a global biodiversity hotspot that is important nationally and regionally as one of India’s important carbon and hydro-climatic regulating landscape could lead to cascading and irreversible effects.

Q2. How do we address the growing need for drinking water, irrigation and power generation without building more dams? Any alternatives?

We can manage our existing dams and reservoirs better as there is now a significant potential for renewable energy which if carefully planned/sited will have far fewer ecological impacts than dams.  In terms of need for water resources, a reduced dependence on water-intensive crops and their replacement with other crops. This can be through economic incentives and farm extension and reduce our consumption of water in agriculture.  In industry and urban areas, investment in waste-water recycling and reduced pollution of surface and ground-water would help in the long-term.

Q3. How important is conservation of forests and wildlife to ensure flows in rivers and how will a dam/barrage affect the flow?

A catchment that has its natural forests/grasslands and healthy organic matter enriched soils intact is likely to regulate the hydrology – the so called “sponge” effect by allowing infiltration and deep recharge to ground-water. This sustains base-flow and dry-season flow (although this depends on geology, soil type and if the forest is older or a secondary succession) as that can influence evapo-transpiration and thereby, reduced water for dry-season. 

However, a well vegetated catchment (grasses, shrubs and trees) will definitely improve the water-quality of the river and reduce high levels of soil erosion and sedimentation.  Natural atmospheric recycling evapo-transpiration from Western Ghats can influence rainfall in drier parts of the peninsula. This is an emerging area of research work.

Q4. Water reaching the sea is often considered a waste. Elaborate.

Fresh-water from rivers reaching the sea and mixing with it generates many ecosystem services. They sustain through sediment, water and nutrients highly productive estuarine and deltaic ecosystems that are vital for coastal fisheries. The sediment deposited contains organic/inorganic carbon that effectively serves as a carbon sink buried deep under many layers of sediment.

They sustain mangrove forests which have high levels of carbon sequestration and sustain biodiversity and produce other services like honey, provide habitat for fish species – important for fisheries.  There is evidence from the Bay of Bengal that fresh-water from rivers may be playing a role in the rates of evaporation and sustaining dynamics of the Monsoon and generating rain.

Q5. Can you please elaborate on the dangers of interlinking of rivers?

Inter-linking of rivers is based on the premise that some river basins are having surplus water while others are deficient. This so-called “surplus” in the Monsoon performs important functions such as transporting sediment from hills, all the way to other larger rivers and finally to the sea.  This movement of sediment as also the habitat it creates in rivers (sand bars, islands and sand-banks) is vital for biodiversity and river ecology.

Finally, this sediment along with fresh-water mixing with sea-water sustains highly productive estuaries and deltas and coastal ecosystems that sustains our rich fisheries. Even if you buy the argument of surplus/deficient basins climate change and its effects on extreme weather events is already changing and is likely to continue to change the moisture and temperature regimes in these basins, so no permanency.

This is a huge investment with major displacement of people and ecosystems throughout the country. Resources should be spent on improving existing dams, adjusting land use and development to the unique moisture regimes of diverse biomes and agro-eco-zones. Inter-linking of rivers with different geologies, bio-geographies and water quality regimes is likely to destroy eco-communities in river ecosystems, introduce pollution from one river to another and also invasive fishes in less disturbed river systems.

Q 6. What about Inland Waterways?

Inland waterways involve dredging and other civil engineering-based channelization of rivers that poses severe threat to water quality and fisheries including contamination through churning up of sediments that have accumulated toxic substances from agriculture, industry and urban areas.  The destruction of river islands will impact many endangered species such as the gharial.

The conversion of many sites and stretches along the river banks into concretized water fronts or ports will also impact the flood-plain dynamics and overall river ecosystems. Heavy boat traffic also changes the under-water sound environment and disrupts the ability of many species especially the Gangetic river dolphin that depends on echo-location for navigation and foraging.

Q7. The current state of water management in our country and solutions to improve the same?

The National Water Policy should ideally inform a more ecology oriented and sustainable management of water resources that recognizes the role of flowing rivers and the ecosystem services they perform from the head-waters to the sea.

(In Conversation with R S Tejus)