Spatiotemporal characteristics of extreme droughts and their association with sea surface temperature over the Cauvery R
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Spatiotemporal characteristics of extreme droughts and their association with sea surface temperature over the Cauvery River basin, India Pravat Jena1 · K. S. Kasiviswanathan2 · Sarita Azad1 Received: 4 April 2020 / Accepted: 27 August 2020 © Springer Nature B.V. 2020
Abstract Drought is a function of time as well as climate variables such as temperature and precipitation. The process of drought forming is slow, and it manifests at different time scales, which adversely affects the economy of a country. The identification and characterization of droughts at various spatiotemporal scales are of great importance. It helps in the planning and management of water resources, policymaking, and agribusiness industries. In the present paper, the Cauvery River basin is chosen as a study area to analyze the changes in the frequency distribution of extreme droughts and duration, with the combined effect of evapotranspiration and rainfall. The drought indices such as Standard Precipitation Index (SPI) and Standard Precipitation Evapotranspiration Index (SPEI) are implemented on monthly rainfall data and potential evapotranspiration of resolution 0.25° × 0.25° long./lat. for the period 1931–2010. The results reveal that the frequency of the extreme droughts over the basin has significantly increased over the post-era of global warming. The increased rate of extreme droughts is particularly evident in downstream of the basin, mainly due to the increase in temperature and deficit rainfall. Further, the implementation of continuous wavelet transform reveals that SPI at 3-(SPI-3) and 12-(SPI-12) month scale are associated with extended reconstruction of sea surface temperature (ERSST) in antiphase and in-phase, respectively. It is concluded that the in-phase association of SPI-12 and ERSST enhances the drought situation compared to the anti-phase link of SPI-3 and ERSST. Keywords SPI · SPEI · River basin · Wavelet · TBO · Drought intensity · Extreme drought
* Sarita Azad [email protected] 1
School of Basic Sciences, Indian Institute of Technology Mandi, Kamand 175 005, India
2
Department of Water Resources Development and Management, Indian Institute of Technology Roorkee, Roorkee 247 667, India
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Natural Hazards
1 Introduction The hydrological cycle is known to be very susceptible to projected climate changes. It has been shown in several studies that global warming has affected precipitation patterns (Fowler and Hennessy 1995; Xie et al. 2010), and more frequent floods, droughts, and rainstorms have been witnessed due to extreme weather conditions (Zhang et al. 2008). Flooding is, in general, an immediate response of catchment. In contrast, droughts are a slow and long-term process mainly resulting from the change in meteorological variables such as precipitation and temperature. Droughts occur at different time scales, which affect large regions directly or indirectly and cause significant damages mainly to agricultural activities and loss of livelihood (Vasiliades et al. 2011; Narasimhan a
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