Severe to Exceptional Water Deficits Forecast for Indian Monsoon Season

Figure 1. WSIM Composite Water Anomaly Index for the Indian Monsoon Season (May-October 2015)*

Severe to exceptional water deficits are forecast during the South Asian Monsoon season for large portions of India, particularly in the north in Himachal Pradesh and Uttarakhand, and in a central eastward swath that includes Madhya Pradesh, Chhattisgarh, and Orissa. This pattern is similar to deficits encountered during the 2014 monsoon season and, as a result, may lead to significant impacts on people, agriculture, and industry.

The South Asian monsoon season typically runs from late May through early October and is the primary source for fresh water for the Indian subcontinent. Below normal monsoons can have significant consequences for agriculture, electricity demand, and electricity generation. Figure 1, top right, depicts the WSIM Composite Water Anomaly Index for May through October 2015 based on observed temperature and precipitation data through May 2015, and an ensemble of 28 forecasts issued the last week of May 2015.  Note that almost the entire subcontinent is forecast to have a below normal monsoon (abnormal deficits), and large areas are forecast to have severe to exceptional deficits.

Figure 2. WSIM Composite Water Anomaly Index for the Indian Monsoon Season  (May-July and August-October 2015)*

The strongest deficits are forecast to occur in the first half of the monsoon season (May-July 2015) as shown in Figure 2. Note the Ganges River basin in the north and a wide east/west band across the center of the country. During the second half of the season (August-October 2015) a large area of severe deficits is forecast to emerge in Tamil Nadu in the south.

Figure 3. WSIM Composite Water Anomaly Index for the past ten Indian Monsoon Seasons (May-October 2006-2015)*

Our final image, Figure 3, examines the water anomalies for the past ten Indian Monsoon seasons to identify potential analogs. The closest recent analogs are 2009 and 2014. The possibility of a monsoon failure in 2015 is even more troubling given that it follows a similar failure in 2014. While the impacts of the 2014 failure were limited due to strong second half of the season (Dutta 2009), the possibility of back to back failures raises the possibility of compound impacts. The failure of the 2009 Indian Monsoon has been written about extensively (see the Economist 2009, NASA 2009, Stellar 2009, and Preethi et al 2009).   

 

*  Some boundaries between India and Pakistan and between India and China are in dispute.  For simplicity these maps depict de facto lines of control.   ISciences does not take a position with respect to these boundary disputes.

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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