Short notes on river water conflicts and on eutrophication

The question asks for any two of the three notes. Notes (i) and (ii) are answered.

(i) River water conflicts

A river water conflict is a dispute between users, regions, states or countries over how much of a river's water each may take, when, and on what terms. The DU syllabus lists international and inter-state conflicts over water under water resources.

Why such conflicts arise

• Rising demand on a fixed supply. The world now withdraws about twice as much fresh water each year as it did fifty years ago, while the supply of fresh water stays limited.
• Position on the river. A party upstream can hold back or divert water that the people downstream depend on; with about 100 countries sharing the waters of 13 large rivers and lakes, this is a lasting source of tension.
• Unequal costs and benefits. When a river is dammed, the water and most of the gain may go to better-off farmers downstream, while people in the valley lose their land and homes.
• Weakened local arrangements. Where the old local controls over fair sharing have broken down, disputes multiply.

Example. Quarrels over river water in India have spread from local users to whole states, with Karnataka and Tamil Nadu as a standing example; the Cauvery river water conflict is the case the DU syllabus names.

Impacts. Less water reaches downstream farms, wetlands and towns; crops fail in deficit years; and the dispute turns into political tension between the parties, which across borders can make whole regions unstable.

Way forward. Sharing by agreement for the whole basin, more efficient irrigation and saving water in cities all reduce the pressure that causes conflict.

(ii) Eutrophication and its impacts

Meaning. Eutrophication is the excessive growth of algae and other aquatic plants in a water body that has received extra plant nutrients, chiefly the water-soluble nitrates and phosphates.

How the nutrients get in

• Farm run-off. Farmers often apply far more fertiliser than the crop takes up; the surplus is washed into ponds, lakes and rivers.
• Sewage. Untreated sewage from towns enriches lakes and rivers, and the nitrates and phosphates it carries feed the algae.

Impacts

• Loss of oxygen. The algal bloom dies and decays; its decomposition uses up the dissolved oxygen, so fish, crustaceans and other oxygen-dependent life die.
• Foul water. The water gains a bad smell and taste and becomes unfit for drinking or bathing.
• Clogging. Dense weed growth blocks water intake pipes and channels.
• Loss of the ecosystem. Gradually the natural plants and animals of the lake or river disappear, and with them the fishing income of the people who depend on it.

Control. Cut nutrient inflow at the source: use fertiliser in the amounts crops need, and treat sewage before it reaches a lake or river, so that fewer nutrients enter the water. A town lake choked with water hyacinth after years of untreated drains is a familiar sight in Indian cities; diverting the drains is the first step to its recovery.