Shifting in the global flood timing

Fang, Gonghuan; Jian, Yang; Li, Zhi; Chen, Yaning; Duan, Weili; Amory, Charles; Maeyer, Philippe De

doi:10.1038/s41598-022-23748-y

Cited by 19 publications

(8 citation statements)

References 51 publications

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“…Observation‐based analyses quantifying past changes in flooding over Europe and the Alps have shown spatially heterogeneous change patterns with rather weak and spatially heterogeneous changes in flood magnitude (Bertola et al., 2020; Blöschl et al., 2019) but clear shifts in timing over the last decades, that is, earlier floods occurrences (Blöschl et al., 2017; Fang et al., 2022). These shifts in seasonality are related to temporal shifts in the spring snowmelt season that starts earlier under warmer temperatures and earlier soil moisture maxima (Blöschl et al., 2017).…”

Section: Discussionmentioning

confidence: 99%

Future Changes in Floods, Droughts, and Their Extents in the Alps: A Sensitivity Analysis With a Non‐Stationary Stochastic Streamflow Generator

Brunner,

Gilleland

2024

Earth's Future

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Spatially compounding droughts and floods challenge water management and may become more severe in a warming climate. However, the influence of climate change on widespread hydrologic extremes remains largely unknown because they are neither well represented in observations nor in models. Here, we present a non‐stationary stochastic streamflow generator that captures streamflow dependencies between different catchments and represents seasonal covariations of streamflow with temperature. We run this model for 925 nearly natural catchments in the Alps to generate daily streamflow time series for a reference period and three warming levels of 1, 2, and 3°C. Then, we identify drought and flood events, determine their spatial extents, and assess changes in all of these characteristics. This sensitivity analysis for different warming levels suggests that changes in flood characteristics and spatial extent are substantially weaker than those in drought characteristics and spatial extent. While floods show changes in their timing toward earlier in the year, simulated changes in magnitude, volume, duration, and spatial extent are negligible. In contrast, droughts show changes not just in timing but also intensity, deficit, duration, and extent. Specifically, droughts are projected to intensify, last longer, and slightly increase in spatial extent, with the magnitude of change increasing with the warming level. These projected changes highlight the need to develop adaptation strategies in particular for droughts. Such adaptation strategies should go beyond local adaptation and consider that extreme events become more widespread in a warming world.

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Section: Discussionmentioning

confidence: 99%

Future Changes in Floods, Droughts, and Their Extents in the Alps: A Sensitivity Analysis With a Non‐Stationary Stochastic Streamflow Generator

Brunner,

Gilleland

2024

Earth's Future

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“…The annual and seasonal streamflow totals were analysed more recently for 467 gauging stations [50]. The mean flood seasonality and changes in timing focusing on the Australian continent with a smaller data set or global studies have recently been researched [27,94]. Our findings are consistent with those studies but also provide (i) a more comprehensive analysis and interpretation using longer data sets (596 stations, 1950 to 2022); (ii) analysis of regional significance at the drainage division scale; and (iii) evidence of decadal variability of flood seasonality.…”

Section: Consistency and Enrichmentmentioning

confidence: 99%

Changes in Magnitude and Shifts in Timing of Australian Flood Peaks

Bari,

Amirthanathan,

Woldemeskel

et al. 2023

Water

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We analysed changes in magnitude and timing of the largest annual observed daily flow (Amax), in each water year, for 596 stations in high-value water resource catchments and flood risk locations across Australia. These stations are either included in the Bureau of Meteorology’s Hydrologic Reference Stations or used in its operational flood forecasting services. Monotonic trend (which is either consistently increasing or decreasing) analyses of the magnitude and timing of flood peaks (estimated using Amax) were performed using the Theil–Sen and Mann–Kendall approaches and circular statistics to identify the strength of seasonality and timing. We analysed regional significance across different drainage divisions using the Walker test. Monotonic decreasing trends in Amax flood magnitude were found in the Murray–Darling River Basin and in other drainage divisions in Victoria, southwest and midwest of Western Australia and South Australia. No significant obvious pattern in Amax magnitude was detected in northern Queensland, coastal NSW, central Australia and Tasmania. Monotonic increasing trends were only found in the Tanami–Timor Sea Coast drainage division in northern Australia. Monotonic trends in Amax magnitude were regionally significant at the drainage division scale. We found two distinct patterns in flood seasonality and timing. In the northern and southern parts of Australia, flood peaks generally occur from February to March and August to October, respectively. The strength of this seasonality varies across the country. Weaker seasonality was detected for locations in the Murray–Darling River Basin, and stronger seasonality was evident in northern Australia, the southwest of Western Australia, South Australia, Victoria and Tasmania. The trends of seasonality and timing reveal that in general, flood peaks have occurred later in the water year in recent years. In northern Australia, flood peaks have generally occurred earlier, at a rate of 12 days/decade. In Victoria, New South Wales and Tasmania, the trends in timing are generally mixed. However, in the southwest of Western Australia, the largest change in timing was evident, with Amax peaks commencing later at a rate of 15 days/decade. Decadal variability in flood timing was found at the drainage division scale as well. Most stations show a decreasing trend in Amax magnitude, but how that trend is associated with the change in timing is not clear.

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“…In the past 20 years, the global population affected by floods has increased by 20-24%, and the loss caused by floods has reached USD 6510 × 10 8 [11,12]. It is predicted that the uncertainty and risk of extreme weather and hydrological events will continue to increase in the future and the resulting flood risk will bring serious obstacles to human sustainable development [13,14]. Therefore, it is urgent to carry out flood-related research, which has important practical significance and long-term value for regional flood risk management, improving water resource utilization efficiency, seeking benefits, and avoiding hazards.…”

Section: Introductionmentioning

confidence: 99%

Synoptic Analysis of Flood-Causing Rainfall and Flood Characteristics in the Source Area of the Yellow River

Jin,

Yan,

Yuan

et al. 2024

Water

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The source area of the Yellow River (SAYR) in China is an important water yield and water-conservation area in the Yellow River. Understanding the variability in rainfall and flood over the SAYR region and the related mechanism of flood-causing rainfall is of great importance for the utilization of flood water resources through the optimal operation of cascade reservoirs over the upper Yellow River such as Longyangxia and Liujiaxia, and even for the prevention of flood and drought disasters for the entire Yellow River. Based on the flow data of Tangnaihai hydrological station, the rainfall data of the SAYR region and NCEP-NCAR reanalysis data from 1961 to 2020, three meteorological conceptual models of flood-causing rainfall—namely westerly trough type, low vortex shear type, and subtropical high southwest flow type—are established by using the weather-type method. The mechanism of flood-causing rainfall and the corresponding flood characteristics of each weather type were investigated. The results show that during the process of flood-causing rainfall, in the westerly trough type, the mid- and high-latitude circulation is flat and fluctuating. In the low vortex shear type, the high pressures over the Ural Mountains and the Okhotsk Sea are stronger compared to other types in the same period, and a low vortex shear line is formed in the west of the SAYR region at the low level. The rain is formed during the eastward movement of the shear line. In the subtropical high southwest flow type, the low trough of Lake Balkhash and the subtropical high are stronger compared to other types in the same period. Flood-causing rainfall generally occurs in areas with low-level convergence, high-level negative vorticity, low-level positive vorticity, convergence of water vapor flux, a certain amount of atmospheric precipitable water, and low-level cold advection. In terms of flood peak increment and the maximum accumulated flood volume, the westerly trough type has a long duration and small flood volume, and the low vortex shear type and the subtropical high southwest flow type have a short duration and large flood volume.

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Shifting in the global flood timing

Cited by 19 publications

References 51 publications

Future Changes in Floods, Droughts, and Their Extents in the Alps: A Sensitivity Analysis With a Non‐Stationary Stochastic Streamflow Generator

Future Changes in Floods, Droughts, and Their Extents in the Alps: A Sensitivity Analysis With a Non‐Stationary Stochastic Streamflow Generator

Changes in Magnitude and Shifts in Timing of Australian Flood Peaks

Synoptic Analysis of Flood-Causing Rainfall and Flood Characteristics in the Source Area of the Yellow River

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