Characterization of Drought in the South Atlantic, United States

Abstract

Drought has been less extensively characterized in the humid South Atlantic compared to the arid western United States. Our objective was to characterize drought in the South Atlantic and to understand whether drought has become more severe in this region over time. Here we used monthly streamflow to characterize hydrological drought. Hydrological drought occurred when streamflow fell below the 20th percentile over three consecutive months and terminated once streamflow remained above the 20th percentile for three consecutive months. We characterized the frequency, duration, magnitude, and severity of events using the above definition. Significant changes in drought characteristics were tested with Mann‐Kendall over three periods: 1930‐2010, 1930‐1969, and 1970‐2010. We show that 71% of drought events were shorter than six months, while 7% were multiyear events. There was little evidence of trends in drought characteristics to support the claim of drought becoming more severe in the South Atlantic over the 20th Century. The one exception was a significant increase in the joint probability of nearby basins being simultaneously in drought conditions in the southern portion of the study area from 1970 to 2010. While drought characteristics have changed little through time, decreasing average streamflow in non drought periods coupled with increasing water demand provide the context within which recent multiyear drought events have produced significant stress on existing water infrastructure.

A systematic assessment of drought termination in the United Kingdom

“…3) and has been reported by other studies (e.g. Patterson et al, 2013). Drought termination phases following shorter drought developments, for example driven by summer heatwaves, would not be well represented by the parameter settings used in this study.…”

“…Tomasella et al, 2011;Marengo and Espinoza, 2016), switches in Atlantic temperatures (Wilby, 2001;Folland et al, 2015), and tropical cyclones (e.g. Kam et al, 2013;Patterson et al, 2013) have been shown to be a factor in drought termination events. Further research is required to assess the extent to which changes in these and other synoptic drivers might be influencing the seasonality of drought terminations in the UK.…”

“…Mo, 2011;Kam et al, 2013;Maxwell et al, 2013;Patterson et al, 2013) have typically considered drought termination to be instantaneous. There are two notable exceptions: Bonsal et al (2011) subdivided drought into six stages, one of which is the concept of drought termination as a phase considered herein, and Nkemdirim and Weber (1999) expressed the concept of a rate of drought termination using Palmer Drought Severity Index units over time.…”

“…The approach adopted in these studies differs from others (e.g. Kam et al, 2013;Patterson et al, 2013) by considering drought termination to be a period of a drought event with its own start, end and duration between these points.…”

Challenges of Integrated Water Resources Management in Indonesia

“…Drought can change its characteristics through time [22] and mainly affects the second crop of irrigated and rain-fed rice fields, normally these rice fields have two rice cropping seasons, the first is a period from November to February and the second is that from March to June for each year [23]. Annually about a total of 0.250 million hectares, approximately 3% of the total planted rice fields, of the second crop of rice fields is affected by drought.…”