South Asia is home to about a quarter of the global population, but has less than 5 per cent of the world’s annual renewable water resources. Low per capita water availability, coupled with a very high relative level of water use (dominated by irrigation), makes South Asia one of the most water scarce regions of the world, and a region where scarcity impacts on economic development (Figure 1).

Figure 1: Water stress by major river basins. (From the 4th World water Development Report, World Water Assessment Programme, 2012).

Disparities in water availability and use make management of water resources for maximum regional benefits a major challenge. Limited water availability, floods and droughts, inadequate water supplies and sanitation, groundwater depletion and pollution, food and energy insecurity, environmental degradation, weak water institutions and a limited transboundary cooperation (both within and between countries) on resources management and information sharing, are the key water resources management challenges of the region.

South Asia is extremely vulnerable to weather-related natural disasters. In recent years, natural disasters have been frequent, resulting in tremendous loss of life, livelihoods and property. For example, severe flooding along the Ganges and Brahmaputra rivers in 2007 affected over 13 million people in Bangladesh, while flooding in the Indus in 2010 severely affected more than 20 million people in Pakistan. The economic cost of these floods was over US$1 billion in 2007 and nearly US$10 billion in 2010. Crop and land damage added unknown numbers of food security-related deaths to the thousands of deaths caused directly and indirectly by flooding. In Uttarakhand in India in 2013, more than 100,000 people were rescued following floods and landslides and over 3500 were officially confirmed as missing.

Inadequate drinking water supplies (quantity and quality) and poor sanitation are ubiquitous in South Asia. Around 20 per cent of the regional population lacks access to improved water supplies and only a minority are connected to piped sewer systems, even in urban areas (e.g. around one third in urban India). The consequences of inadequate water supply and sanitation are high: on average, 1.6 million children die every year from diarrhea, mainly as a result of inadequate sanitation, inadequate water supply, and poor hygiene.

Groundwater is the primary source of drinking and irrigation water in South Asia. Collectively, India, Pakistan, Bangladesh, and North China use 380–400 km3 of groundwater per year, an amount approaching half of the world’s total annual groundwater withdrawals. Groundwater quality issues are widespread caused by ingress of untreated urban wastewater and chemical-laden irrigation drainage. Natural contamination of groundwater with arsenic and fluoride is common in Bangladesh, Nepal and Pakistan, and fluoride contamination is widespread in India.

Almost 95 per cent of total water withdrawals in the region are for irrigated agriculture – higher than the global average of 70 per cent. Water productivity – in terms of Gross Domestic Product generated per cubic meter of water – is less than US$4, compared with US$24 for the world’s top food producers. Water resources management and agricultural management are both therefore critical to regional food security.

The region faces endemic energy security challenges that hamper industrial and socioeconomic growth, with nearly 600 million people in the region lacking access to electricity. Hydropower is one of the largest potential energy resources in the region. Total generating potential is around 436 GW (India 300 GW, Bhutan 50 GW, Nepal 43 GW, Pakistan 40 GW, Sri Lanka 2 GW and Bangladesh of <1 GW) of which only 9 per cent has been developed. Long-term planning of water resources allocations and development is needed to guide hydro power development, in order to improve electricity supplies, which is critical to sustaining economic growth and improving social services in the region.

The rivers of South Asia carry extremely high sediment loads – particularly the combined Ganges-Brahmaputra system which has an average annual load of over one billion tons. These make these high energy rivers very difficult to manage, especially during floods, and create major challenges for hydro-power due to both reservoir sedimentation and turbine damage. Changes in temperature, precipitation, and Himalayan glacier dynamics are likely to affect river flow regimes, impacting water, food, and energy security in the region.

Population growth and urbanization are also major drivers of change and increasing water stress. Annual population growth in the region is around 1.5 per cent; the regional population is projected to increase from around 1.6 billion to over 2.0 billion by 2050 – greatly reducing per capita water availability. Over the same period, this growth combined with the movement of people from rural areas to cities and towns will see urban populations grow from around 30 per cent of the total (currently) to between 40 and 50 per cent of the total.

The rivers that emanate from the Greater Himalaya are shared across borders; Bangladesh, Bhutan, India, Nepal and Pakistan, for example, share twenty major rivers. The largest three trans-boundary basins in the region – in terms of area, population, water resources, irrigation and hydropower potential – are the Indus, Ganges and Brahmaputra. There has been recognition for the need for regional cooperation in the management and development of water as means to support growth and regional stability. For example, the World Bank has played an important role in the 1960 Indus Waters Treaty between India and Pakistan that allowed the countries to share water from the Indus River.

Moving forward, regional economic integration and cooperative transboundary water resources management holds significant potential for growth and increased security for the region. In the water resources sector, there is a clear need for a regional integrated water resources management (IWRM) approach that incorporates water, soil and erosion, and land-use management into the plan to increase agricultural productivity, hydropower production, and conservation of natural resources. This requires investments to improve technology, infrastructure, and delivery of services, social institutions capacity and markets access, as well as greater accountability and transparency of governments. Achieving these in the context of steady population growth, rapid urbanization and a changing climate, represent major challenges for the countries of South Asia.