South Asia: Water surplus in Chambal Basin

South Asia: Water surplus to persist in Chambal Basin

20 September 2021

THE BIG PICTURE
The 12-month forecast through May 2022 indicates water surpluses in western India from Mumbai into Karnataka including exceptional anomalies on the coast and transitional conditions (pink/purple) inland. Widespread surpluses are expected from West Bengal through Uttar Pradesh north of the Ghaghara River. Anomalies will be exceptional in the Ganges Delta and the Gandaki River.

Surpluses of varying intensity are forecast in India’s far north and the Chambal River Watershed in Rajasthan, and moderate surpluses in pockets of central Maharashtra, Telangana, and the southern reaches of the Deccan Plateau. Exceptional deficits are expected in central Assam in the Far Northeast and in the tip of Tamil Nadu. Moderate deficits are forecast along the western Narmada River and pockets of western Rajasthan, Gujarat, Madhya Pradesh, Odisha, and southern Karnataka into Tamil Nadu.  

Extreme to exceptional surpluses will be widespread throughout Bangladesh and Nepal reaching into western Bhutan. Surpluses are also expected in Sri Lanka’s southwest corner. Many regions of Pakistan will experience surpluses including exceptional anomalies west of the Jhelum and Indus Rivers and south of Hyderabad. In Afghanistan, deficits will be severe to exceptional in the provinces surrounding Mazar-e Sharif; moderate deficits and transitions are forecast in the west; and surpluses in the far south.

FORECAST BREAKDOWN
The 3-month composites (below) show the evolving conditions in greater detail.

The forecast through November indicates that surpluses will shrink and downgrade considerably in the region. Surpluses will nearly disappear in India’s southern half, persisting primarily in pockets of Maharashtra, Karnataka, and southern Andhra Pradesh. Elsewhere in the nation, surplus anomalies will increase in the Chambal River Basin of eastern Rajasthan into northern Madhya Pradesh but shrink or downgrade in the far north and in Uttar Pradesh, Bihar, Jharkhand, and West Bengal. A column of extreme surplus will persist in central Haryana. Severe to exceptional deficits will persist in central Assam in the Far Northeast and emerge in western Tamil Nadu in southern India. Surpluses will continue to dominate Bangladesh and Nepal, but the extent of exceptional anomalies will shrink. Moderate to severe surpluses will persist in the southwest corner of Sri Lanka.

In Pakistan, surpluses are expected in the north and in the center of the nation, but transitions are also forecast in central Pakistan and in the south, while moderate deficits emerge in western Baluchistan Province. In Afghanistan, deficits in the north will downgrade to mild, surpluses will increase between the Harirud and Helmand Rivers, and transitions are expected in the west and south.

From December 2021 through February 2022, exceptional deficits will emerge in southern Gujarat, India, deficits will increase in Karnataka and Tamil Nadu, and shrink in Assam. Surpluses will persist in Haryana and the Chambal Basin, and shrink somewhat in the far north. Surpluses will persist in Indian regions bordering Nepal and Bangladesh; anomalies moderate in Bangladesh; and moderate to severe surpluses will persist in Nepal. In Pakistan, deficits will retreat and surpluses will re-emerge west of the Indus River and between its tributaries. Conditions will normalize in much of Afghanistan and surpluses will re-emerge near Mazar-e Sharif and in the west.

The forecast for the final months – March through May 2022 – indicates surpluses in India’s far north, the Chambal River Watershed, and regions bordering Nepal and Bangladesh where surpluses are also expected. Deficits will linger in Gujarat, southern India, and the Far Northeast. Surpluses and transitions are expected in Pakistan, and conditions in Afghanistan will be nearly normal.

Please note that WSIM forecast skill declines with longer lead times.

IMPACTS
Flooding and landslides have killed over 60 people in Nepal in recent weeks. In early September, 120 mm (4.7 inches) of precipitation was recorded in Kathmandu over just 8 hours and the Bagmati and Manohara Rivers breached their banks.

Intense rainfall in eastern India claimed nine lives in Odisha in mid-September as 341 mm (13.4 inches) of precipitation drenched Puri over a 24-hour period. On the other side of the nation in Gujarat, flooding closed schools in Rajkot where precipitation was 2,066 percent above normal over the course of one day, submerging many low-lying areas. And in northern India, extreme rainfall washed over the runways at India Gandhi International Airport in Delhi, delaying over 100 flights and diverting or canceling others.

Dengue, a mosquito-borne illness, is on the rise in India, particularly in Uttar Pradesh, where more than 1,500 cases of it and other viral fevers have been reported. The nation’s health secretary has asked states to control mosquito populations. Standing water provides a perfect breeding ground for mosquitoes and Uttar Pradesh has experienced heavy rain and deadly flooding recently.

Upheaval in Afghanistan since the Taliban takeover after U.S. withdrawal combined with several years of drought is threatening food security. Without increased humanitarian aid, U.N. agencies warn of imminent shortages.

NOTE ON ADMINISTRATIVE BOUNDARIES
There are numerous regions around the world where country borders are contested. ISciences depicts country boundaries on these maps solely to provide some geographic context. The boundaries are nominal, not legal, descriptions of each entity. The use of these boundaries does not imply any judgement on the legal status of any territory, or any endorsement or acceptance of disputed boundaries on the part of ISciences or our data providers.

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Many analyses reported in ISciences-authored blog posts are based on data generated by the ISciences Water Security Indicator Model (WSIM). Other sources, if used, are referenced in footnotes accompanying individual posts. WSIM is a validated capability that produces monthly reports on current and forecast global freshwater surpluses and deficits with lead times of 1-9 months at 0.25°x0.25° resolution. This capability has been in continuous operation since April 2011 and has proven to provide reliable forecasts of emerging water security concerns in that time-frame. WSIM has the ability to assess the impacts of water anomalies on people, agriculture, and electricity generation. Detailed data, customized visualizations, and reports are available for purchase.

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