Understanding flood regime changes of the Mahanadi River

ABSTRACT

Understanding trends in flood severity and the persistence in peak discharge timing along a vast river network is vital for basin-scale flood risk management and reinsurance purposes. The Mahanadi River Basin (MRB) in Odisha, India, is one of the largest river basin systems in Peninsular India with a drainage area of 141,600 km², has experienced a series of catastrophic floods in its Middle reaches and Delta areas between 1969 and 2019. Leveraging gauge-based daily streamflow records (1971–2016), we analyse floods using Monsoonal (from June – September) Maxima Flood (MMF) and Peak over Threshold Flood (PTF) events. We detect potential hotspots, where up/downward trends in floods coincide with early (or delayed) dates of occurrences. We show that at upper MRB, the MMF series tends to have an earlier occurrence of floods with a (field significant) decreasing trend in its magnitude. Up to one-third of gauges show delayed flood timings with an upward trend in peak discharge magnitude, indicating delayed arrival of rare events with changes in flood footprints. The obtained insights aid in forecast efforts and devise disaster response to mitigate the impact of disaster (flood)-climate-health nexus.

KEYWORDS:

• Floods
• concurrent extreme
• persistence
• disaster-climate-health nexus

Acknowledgments

The work was primarily funded by two Department of Science and Technology (DST) research grants, namely, the IFR (grant number DST/CCP/CoE/79/2017), “Impact of Climate Change on Flood Risk” as part of the Centre of Excellence in Climate Change Studies established at IIT Kharagpur and the HLR (grant number SRG/2019/000044), “Hydrological Drought Co-incidence Risk Analysis over Large River Basins in India”. Ministry of Human Resources Development (MHRD), Government of India provided partial funding. The daily streamflow discharge data are obtained from the Water Resources Information System (India-WRIS: http://indiawris.gov.in/wris/#/) maintained by the Central Water Commission (CWC), Government of India.

Data Availability

The time series of daily discharge stream flow records are obtained from archived database of India-Water Resources Information System (India-WRIS: http://indiawris.gov.in/wris/#/), Government of India.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work is supported by the Department of Science and Technology India [Grant ID: DST/CCP/CoE/79/2017]; and Science and Engineering Research Board [Grant ID: SRG/2019/000044]. The second author was supported through the MHRD scholarship for M.Tech studies at the Indian Institute of Technology Kharagpur.