The growing shortage of freshwater is likely to trigger increased environmental damage over the next 15 years, according to a widely researched report on the world's waters released recently by United Nations Environmental Programme UNEP on World Water Day.
Falls in river flows, rising saltiness of estuaries, loss of fish and aquatic plant species and reductions in sediments to the coast are expected to rise in many areas of the globe by 2020.
These in turn will intensify farmland losses, food insecurity and damage to fisheries along with rises in malnutrition and disease.
Overall agriculture ranks highest as the key concern on the freshwater front among the 1,500 experts involved in the final report of the Global International Waters Assessment (GIWA).
"Globally, there has been an increased demand for agricultural products and a trend towards more water-intensive food such as meat rather than vegetables and fruits rather than cereals".
Knowledge gaps are also to blame, with many developing countries operating in the dark on the size of their water resource, and the precise patterns of supply and demand.
"Aquifers represent the largest information gap, which is an increasingly significant hindrance for effective water management given the growing dependence on groundwater", says the report.
Market failures are also highlighted as important contributors to damage in both freshwaters and coastal zones.
"Most production inputs are under-priced compared with their full social and environmental costs", says the report, citing the under-pricing of water, subsidies for pesticides and fishing and incentives for infrastructure, like dams and water transfer schemes.
The damage to international waters from overfishing and destructive fishing methods is also underlined.
The report points to the excessive catches fuelled by $20 billion a year fishing subsidies, poor enforcement of fishing laws and destructive practices like blast fishing on coral reefs.
"The investment of one dollar (in blast fishing) can generate an immediate 200-fold return for local fishermen but leaves a devastated reef that takes 50 years to recover", says the report.
The report recommends ecosystem service payments as one way of better valuing the goods and services provided by natural features like coral reefs and wetlands.
Climate change is viewed as the overarching issue in the report, with specific concerns for fisheries and marine organisms.
It estimates that climate variability is the key controlling factor in fishing yields for about half of the world's large marine ecosystems.
Thus climate change may have important impacts on yields in these sensitive regions.
The report says further that the construction of the Akosombo Dam on the Volta River in Ghana has increased the proportion of children infected with the parasitic disease schistosomiasis from five percent to 90 percent.
Dumping of solid wastes is also a priority issue in many rivers and coastal areas. Chemical pollution is yet another issue.
Climate change, alteration of river flows, coastal developments, pollution and other factors are adding to habitat modification and changes in freshwater and coastal living communities.