BENGALURU: Droughts occur more or less at regular fixed intervals called stationarity, according to available data.
But a recent study by Prof Pradeep Mujumdar of Indian Institute of Science’s (IISc) civil engineering department and his PhD student Arpita Mondal suggests that stationarity may not hold good any longer due to human-induced climate change.
“Traditionally, the concept of stationarity is used for hydrologic designs (say, long-term planning against droughts). That is, a water manager may plan for a drought that is expected once in 100 years.
However, in view of climate change, stationarity may not be a valid assumption,” Arpita says in a paper published in the journal ‘Advances in Water Resources’.
The researchers have analysed data on Colorado river in the US to predict how frequently droughts return.
Using a mathematical model that takes into account the effects of climate change, they concluded that historical data may not give reliable clues to predicting the frequencies of droughts.
This is because rising temperatures have already started influencing rainfall and evaporation rate, the two main drivers in the water cycle.
The studies clearly show that the methods that worked till now may not be so successful in the backdrop of climate change.
“Climate change is expected to significantly influence the water cycle and further aggravate the water stress already existing in the country. These research contributions are thus an attempt at a better understanding of these changes with a view to improve drought resilience,” she says.