Because of its value and its importance in all aspects of life, water is a highly political issue.

International water law concerns the rights and obligations that exist, primarily between States, for the management of transboundary water resources. Such legal rules and principles are dedicated to preventing conflict and promoting cooperation of shared water resources.

The chief international legal document related to international water resources management is the ‘United Nations Convention on the Law of the Non-navigational Uses of International Watercourses’, adopted by the UN General Assembly in May 1997. This Convention applies to uses of international watercourses and of their waters for purposes other than navigation and to measures of protection, preservation and management related to the uses of those watercourses and their waters. Read more

Erosion is defined as the wearing away and transport of the soil by running water, glaciers, wind or waves. Sedimentation is the process of settling and depositing by gravity of suspended matter in water.

Water transforms landscapes and moves large amounts of soil and fine-grained materials in the form of sediment. Sediment is:
1) eroded from the landscape,
2) transported by river systems and eventually
3) deposited in a riverbed, wetland, lake, reservoir or the ocean.
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Water is used by industry in a myriad of ways: for cleaning, heating and cooling; for generating steam; for transporting dissolved substances or particulates; as a raw material; as a solvent; and as a constituent part of the product itself (e.g. in the beverage industry).

• The water withdrawals for industry is:
• World: 22% of total water use.
• High-income countries: 59% of total water use.
• Low-income countries: 8% of total water use.

Industries based on organic raw materials are the most significant contributors to the organic pollutant load with the food sector being the most important polluter. Read more

Water pollution has been defined as the presence in water of harmful and objectionable material – obtained from sewers, industrial wastes and rainwater run-off – in sufficient concentrations to make it unfit for use.

We have long used air, land and water resources as ‘sinks’ into which we dispose of the wastes we generate. These disposal practices leave most wastes inadequately treated, thereby causing pollution. This in turn affects precipitation, surface waters, and groundwater, as well as degrading ecosystems.

Pollution from agriculture, industry and domestic wastewater is making water resources, both surface water and groundwater, increasingly scarce and decreasingly poor in quality.
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An estuary is a body of water partially surrounded by land, where fresh water from a river mixes with ocean water.

Estuary habitats include salt marshes, mangroves, seagrasses, coastal forests and beaches.

Estuaries may form under a number of circumstances: at drowned river mouths, within steep glacially eroded fjords, within barrier islands or a barrier spit parallel to the coast, or within coastal indentations formed by faulting or local subsidence.

Tides define estuaries. Estuaries are washed either daily or twice daily with seawater. At high tide the salinity of the estuary will rise as sea water (20-35 parts per thousand of salt dissolved in the water) enters the estuary mixing with freshwater (0-0.5 parts per thousand) coming downstream. Estuary salinity can thus vary from 0-35 parts per thousand depending on the tide and amount of freshwater input.
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