IIT Mandi team explores relationship between drought, altitudinal variation in Indus river basin

New Delhi: Researchers at the Indian Institute of Technology (IIT), Mandi, have studied the relationship between elevation and drought characteristics in the Indus river basin to explore water management and climate adaptation strategies for the region.

These findings have been published in the journal "Atmospheric Research".

According to the researchers, with an exponential increase in population, there is a growing demand for water but limited availability. This coupled with global climate change and extreme water-related events like floods and drought, poses a threat to human society.

"As per a report by India's Ministry of Earth Sciences, the period from 1951 to 2016 witnessed an increase in the frequency of droughts in India, with more than two droughts per decade in many areas. Understanding drought dynamics is therefore crucial for effective water management and planning," said Deepak Swami, Associate Professor, School of Civil and Environmental Engineering, IIT Mandi.

High-altitude regions are particularly sensitive to the effects of climate change, like droughts. Analysing the relationship between drought trends and elevation across different time scales can help predict droughts and frame policies to mitigate their effects.

"The researchers have focused on the Indus river basin. This basin holds immense importance in terms of agricultural productivity and water supply in the Indian subcontinent. Furthermore, the wide range of elevations within the basin, ranging from 93 to 8,489 metres, provides an ideal setting to explore the connection between elevation and drought characteristics," he said.

The research team employed statistical techniques using extensive data on monthly precipitation, and maximum and minimum temperatures spanning 42 years (1979-2020) to study drought patterns. The drought quantification was done using a drought indicator based on climatic water balance, which is integral to understanding droughts.

"We saw a strong correlation between drought and elevation. Areas below 2,000 metres experienced wetting trends, while altitudes between 2,000 and 6,000 metres showed drying trends. However, elevations above 4,000 metres had a slower rate of drying," said Vivek Gupta, Assistant Professor, School of Civil and Environmental Engineering, IIT Mandi.

Furthermore, the research findings highlighted the significant heterogeneity in drought trends across different seasons.

"Monsoon and post-monsoon seasons experienced larger areas with wetting trends, while the pre-monsoon season saw a larger area with drying trends. Notably, extreme drought frequencies in the study region ranged from 0 per cent to 5 per cent from 1979-2020. Ultimately, the findings of the study point towards dryness of the region at higher altitudes whereas wetting is associated with lower elevations.

"These insights hold particular importance for India as rain-fed agriculture is prevalent in the highlands of the Indus river basin. The topography of the region restricts water storage and proper irrigation infrastructure, making it vulnerable to water scarcity and decreasing crop yields during dry periods. Understanding the effect of elevation on meteorological variables is crucial for effective policy formulation to mitigate the negative impacts of drought," he said.