South Asia: Surpluses to persist in eastern Ganges basin, Nepal, Bangladesh

October 21, 2016

The Big Picture
The 12-month forecast map (below) shows the presence of significant water surpluses in northeastern Afghanistan, central India, Nepal, Bangladesh, and Myanmar’s western coast. Water deficits are forecast for western Afghanistan; western Pakistan; and Gujarat, Tamil Nadu, and Assam, India.

Impacts
In late September Nepal's Department of Hydrology and Meteorology began draining water from Lake Imja in the Himalayas to reduce the risk of glacial lake outburst floods (GLOFs). Around 96,562 people live in vulnerable areas downstream. The team plans to drain 4 million cubic meters of water, lowering the lake level by up to 3.5 meters. Due to rapid snowmelt, the surface area of the lake is said to have expanded from 0.4 to 1.01 square kilometers between 1984 and 2009.

Research from the Institute of Earth and Environmental Sciences, University of Potsdam, Germany indicates that one-fifth of the 177 hydropower projects located nearby to Himalayan glaciers - primarily in India but also in Nepal and Bhutan - are exposed to risk from GLOFs.

Also in Nepal, heavy rains caused flooding and landslides resulting in 11 deaths in Kalakhari, Sankhuwasabha, Lamjung, Orange, and Gorch, including the death of a Spanish mountain guide.

To decrease dependency on state relief Karnataka, India is now requiring compulsory crop insurance on farm loans procured from co-operative banks, as well as from nationalized banks. Karnataka is facing severe drought in the south and central regions and floods in Kalaburagi, Bidar, and Belagavi districts.

The government of Sri Lanka estimates that nearly 208,000 people have been affected by drought in several provinces, with the majority facing water shortages in Eastern Province and North Central Province, according to the country's Disaster Management Center.

Forecast Breakdown
The 3-month composites (below) show the evolving conditions. From October through December exceptional water surpluses in the Chantal River basin of Rajasthan, India are forecast to diminish and transition to conditions of both deficit and surplus. A band of surplus is expected to persist in the eastern Ganges basin, ranging in severity from moderate to exceptional. A large pocket of moderate to extreme surplus is forecast to persist in coastal Andhra Pradesh into southern Odisha and southern Chhattisgarh. Exceptional surpluses will persist in Bangladesh and along much of Myanmar’s western coast, and moderate to exceptional surpluses will persist in Nepal, and western Bhutan. The extent and severity of deficits north of New Delhi are forecast to increase, and deficits will persist in India’s southern tip, though of somewhat lesser severity than in prior months. Primarily moderate deficits are expected to emerge in Sri Lanka. Exceptional deficits will diminish in Afghanistan and Pakistan though moderate deficits will continue to emerge, and both deficits and surpluses are expected along rivers in Afghanistan.

From January through March deficits in India’s north and south, Sri Lanka, Afghanistan, and Pakistan will diminish, but exceptional deficits are forecast to emerge in Gujarat. Surpluses are forecast to persist along the eastern Ganges Basin and in Odisha, Bangladesh, eastern Nepal, and western Bhutan. Surpluses in central Nepal and along much of Myanmar’s western coast are expected to transition to both surplus and deficit.

(It should be noted that forecast skill declines with longer lead times.)