Widespread Flooding Research Articles

Sensitivity of Estuaries to Compound Flooding

Fluvial and surge-tide extremes can occur synchronously resulting in compound flooding in estuaries, greatly intensifying the hazard. This flood risk has the potential to increase in the future as the frequency, phasing and/or intensity of these drivers change. Improved understanding of how extreme fluvial discharge and surge-tides interact will help inform future flood mitigation methodology. In this paper, therefore, we resolve for the first time intra-estuary sensitivities to fluvial and surge-tide extremes, for two contrasting UK estuaries (Humber and Dyfi). Model simulations at hyper-spatial resolution (< 50 m) using a 2D hydrodynamic model predicted compound flooding hazards based on: (1) present-day extreme events (worst on record); (2) present-day extreme events with shifted timings of the drivers to maximise flooding; and (3) modified drivers representing projected climate change. We found that in a small estuary with short-duration, high-intensity fluvial inputs (Dyfi), flood extent is sensitive to the relative timing of the fluvial and surge-tide drivers. In contrast, the relative timing of these drivers did not affect flooding in a larger estuary with a slower fluvial response to rainfall (Humber). In the Humber, extreme fluvial inputs during a compound hazard actually reduced maximum water depths in the outer estuary, compared with a surge-tide-only event. Projected future changes in these drivers by 2100 will increase compound flooding hazards: simulated sea-level rise scenarios predicted substantial and widespread flooding in both estuaries. However, projected increases in surge-tide behaved differently to sea-level rise of the same magnitude, resulting in a greater seawater influx and more flooding. Increased fluvial volumes were the weakest driver of estuarine flooding. In this paper we show how these interactions are complex and how the hydrodynamics vary considerably between different estuaries and sites within estuaries, making it difficult to generalise, use probabilistic or use 1D approaches for assessing compound flooding hazards. Hence, we contribute new knowledge and methods for catchment-to-coast impact modelling used for flood mitigation strategies.

Characterizing the psychological distress of treatment-seeking youth and adults impacted by Hurricane Harvey

Hurricane Harvey was one of the most destructive hurricanes in U.S. history, resulting in widespread flooding and property damage in the greater Houston-metropolitan area. This study aims to characterize a group of treatment-seeking youth and adults up to 2.5 years following Hurricane Harvey. A total of 154 children, 165 adolescents, and 531 adults who presented to publicly-funded mental health services were assessed on demographics, depressive and anxiety symptomatology, and hurricane impact. Age, sex, race/ethnicity, family/social support, time since the hurricane, and hurricane impact were examined as correlates of depressive and anxiety symptoms at treatment initiation. Overall, participants presented with elevated depressive and anxiety symptoms to the clinic. Greater hurricane impact was correlated with depressive and anxiety symptoms in adults and adolescents, but not in children. In addition, poorer family/social support was linked to greater anxiety in children and higher depression scores in children and adolescents. Adolescent females had higher anxiety and depression than adolescent males. Days since Harvey and anxiety symptoms were negatively associated for adults. Clinical and research implications for psychological distress in the medium-to-long-term post-natural disaster period are discussed. • Treatment-seeking youth and adults reported elevated depressive and anxiety symptoms up to 30 months after Hurricane Harvey. • Greater diasaster impact was associated with more depressive and anxiety symptoms in adults, but not youth. • Further research is warranted to examine factors that affect individuals who do not recover in the post-acute disaster period.

Location Matters: A Framework to Investigate the Spatial Characteristics of Distributed Flood Attenuation

Distributed attenuation in flood management relies on small and low-impact runoff attenuating features variously distributed within a catchment. Distributed systems of reservoirs, natural flood management, and green infrastructure are practical examples of distributed attenuation. The effectiveness of attenuating features lies in their ability to work in concert, by reducing and slowing runoff in strategic parts of the catchment, and desynchronizing flows. The spatial distribution of attenuating features plays an essential role in the process. This article proposes a framework to place features in a hydrologic network, group them into spatially distributed systems, and analyze their flood attenuation effects. The framework is applied to study distributed systems of reservoirs in a rural watershed in Iowa, USA. The results show that distributed attenuation can be an effective alternative to a single centralized flood mitigation approach. The different flow peak attenuation of considered distributed systems suggest that the spatial distribution of features significantly influences flood magnitude at the catchment scale. The proposed framework can be applied to examine the effectiveness of distributed attenuation, and its viability as a widespread flood attenuation strategy in different landscapes and at multiple scales.

A river flowing through a desert: late Quaternary environments in the Nile basin – current understanding and unresolved questions

Late Quaternary environments in the Nile Basin reflect the influence of the African summer monsoon upon plant cover, sediment yield and flood discharge in the Ethiopian and Ugandan headwaters of the Nile. Intervals of prolonged and very high Nile flow coincide with times of stronger summer monsoon and have been dated using a combination of 14C, OSL and 10Be methods. Periods of high Nile flow into the eastern Mediterranean coincide with the formation of highly organic sedimentary layers termed sapropels. Ages obtained so far for these times of sustained middle to late Pleistocene high flow in the Blue and White Nile are broadly coeval with sapropel beds S8 (ca 217 ka), S7 (ca 195 ka), S6 (ca 172 ka), S5 (ca 124 ka), S4 (ca 102 ka) S3 (ca 81 ka), S2 (ca 55–50 ka) and S1 (10–6.5 ka). Sapropel 5 (ca 124 ka) was synchronous with extreme Blue Nile floods and the formation of the 386 m lake in the lower White Nile Valley, as well as with a prolonged wet phase in the eastern Sahara. Fluctuations in Nile flow and sapropel formation reflect the influence of the precessional cycle upon the East African monsoon. Between 75 ka and 19 ka the climate in the Nile headwaters region became progressively colder and drier. During the Last Glacial Maximum, Lake Tana in Ethiopia and Lake Victoria in Uganda became dry, flow in the White Nile was reduced to a trickle, and the Blue Nile and Atbara became highly seasonal bed–load rivers. The return of the summer monsoon at 14.5 ka ushered in extreme Blue Nile floods, widespread flooding across the Nile Basin and the formation of the 382 m lake in the lower White Nile Valley. There was a brief return to aridity during the Younger Dryas (12.8–11.5 ka), after which the climate again became wetter and widespread flooding in the Nile Valley resumed. The early Holocene floods were later followed by incision and creation of the modern relatively narrow flood plain.

Spatially distributed simulations of the effect of snow on mass balance and flooding of Antarctic sea ice

AbstractSouthern Ocean sea ice can exhibit widespread flooding and subsequent snow-ice formation, due to relatively thick snow covers compared to the total ice thickness. Considerable subkilometer scale variability in snow and ice thickness causes poorly constrained uncertainties in determining the amount of flooding that occurs. Using datasets of snow depth and ice thickness acquired in the Weddell Sea during austral winter 2013 (AWECS campaign) from three floes, we demonstrate large spatial variability of a factor 10 and 5 for snow and combined snow and ice thickness, respectively. The temporal evolution after the floe visit was recorded by automatic weather station and ice mass balance buoys. Using a physics-based, multi-layer snow/sea ice model in a one-dimensional and distributed mode to simulate the thermodynamic processes, we show that the distributed simulations, modeling flooding across the entire heterogeneous floe, produced vastly different amounts of flooding than one-dimensional single point simulations. Three times the flooding is produced in the one-dimensional simulation for the buoy location than distributed (floe-averaged) simulations. The latter is in close agreement with buoy observations. The results suggest that using point observations or one-dimensional simulations to extrapolate processes on the floe-scale can overestimate the amount of flooding and snow-ice formation.

Thin ice, deep snow and surface flooding in Kotzebue Sound: landfast ice mass balance during two anomalously warm winters and implications for marine mammals and subsistence hunting

AbstractThe inaugural data from the first systematic program of sea-ice observations in Kotzebue Sound, Alaska, in 2018 coincided with the first winter in living memory when the Sound was not choked with ice. The following winter of 2018–19 was even warmer and characterized by even less ice. Here we discuss the mass balance of landfast ice near Kotzebue (Qikiqtaġruk) during these two anomalously warm winters. We use in situ observations and a 1-D thermodynamic model to address three research questions developed in partnership with an Indigenous Advisory Council. In doing so, we improve our understanding of connections between landfast ice mass balance, marine mammals and subsistence hunting. Specifically, we show: (i) ice growth stopped unusually early due to strong vertical ocean heat flux, which also likely contributed to early start to bearded seal hunting; (ii) unusually thin ice contributed to widespread surface flooding. The associated snow ice formation partly offset the reduced ice growth, but the flooding likely had a negative impact on ringed seal habitat; (iii) sea ice near Kotzebue during the winters of 2017–18 and 2018–19 was likely the thinnest since at least 1945, driven by a combination of warm air temperatures and a persistent ocean heat flux.

Ecological characterization of mosquitoes (Diptera: Culicidae) in areas of the Mato Grosso Pantanal, Mato Grosso State, Brazil

Bimonthly diurnal and nocturnal captures were conducted in four different sampling sites of the Mato Grosso Pantanal region over 24 consecutive months between March 2009 and January 2011. The goal of performing these collections was to elucidate aspects of the biology and ecology of mosquitoes in this region since little to nothing is known about these aspects for many species. A total of 17,532 specimens were captured, comprising two subfamilies, nine genera, and 44 species. The main species of culicids found in the Mato Grosso Pantanal had strong ecological compatibility with well-preserved environments and with some of the specific habitats found in at least one of the four selected collection sampling sites. Anopheles darlingi, An. albitarsis, and An. triannulatus are well-suited to environments with large water bodies and greater anthropic activity. Culex nigripalpus and Cx. quinquefasciatus prefer environments with bush fragments and pronounced human action and movement. Culex declarator and Psorophora albigenu, the most eclectic, prefer wild areas and with some anthropic activity. Mansonia titillans is associated with environments offering a wide variety of natural breeding areas that enable its development, in particular natural swamp areas covered with macrophytes, which is one of the natural components of the Pantanal biome. The effect of the flooding season on the population density of anophelines is especially advantageous, with an explosion in the number of individuals in periods of widespread flooding. The region’s environmental dynamics are regulated by flooding cycles with alternating periods of flooding and drought, which are the main factors governing the ecology of the local fauna and flora. Flooding periods contribute to raising culicid species’ richness and diversity, while the droughts result in a more even distribution of specimens within species. The flooding season of the Pantanal occurs between November and May and coincides with the greatest abundance of culicid species. During this period, the human population of the region has greater contact with mosquito vectors carrying pathogens, including arboviruses, which previous studies have confirmed via seropositivity in the region’s equines and birds.

Unraveling the Mechanism of Extreme (More than 30 Sigma) Precipitation during August 2018 and 2019 over Kerala, India

AbstractDuring August 2018 and 2019 the southern state of India, Kerala, received unprecedented heavy rainfall, which led to widespread flooding. We aim to characterize the convective nature of these events and the large-scale atmospheric forcing, while exploring their predictability by three state-of-the-art global prediction systems: the National Centers for Environmental Prediction (NCEP)-based India Meteorological Department (IMD) operational Global Forecast System (GFS), the European Centre for Medium-Range Weather Forecasts (ECMWF) Integrated Forecast System (IFS), and the Unified Model–based NCUM being run at the National Centre for Medium Range Weather Forecasting (NCMRWF). Satellite, radar, and lightning observations suggest that these rain events were dominated by cumulus congestus and shallow convection with strong zonal flow leading to orographically enhanced rainfall over the Ghats mountain range; sporadic deep convection was also present during the 2019 event. A moisture budget analyses using the fifth major global reanalysis produced by ECMWF (ERA5) and forecast output revealed significantly increased moisture convergence below 800 hPa during the main rain events compared to August climatology. The total column-integrated precipitable water tendency, however, is found to be small throughout the month of August, indicating a balance between moisture convergence and drying by precipitation. By applying a Rossby wave filter to the rainfall anomalies it is shown that the large-scale moisture convergence is associated with westward-propagating barotropic Rossby waves over Kerala, leading to increased predictability of these events, especially for 2019. Evaluation of the deterministic and ensemble rainfall predictions revealed systematic rainfall differences over the Ghats mountains and the coastline. The ensemble predictions were more skillful than the deterministic forecasts, as they were able to predict rainfall anomalies (greater than three standard deviations from climatology) beyond day 5 for August 2019 and up to day 3 for 2018.

IMPACT OF FLOODING ON AIRPORTS USING REMOTE SENSING AND GIS TECHNIQUES

Floods are considered one of the worst weather-related natural disasters. They are sudden and highly unexpected following brief period of heavy rain. Egypt is subjected to flash floods, their impact vast areas causing serious damages with thousands of human injuries, economic losses and heavy damage to man-made features. According to the importance and criticality of severe rains that may lead to floods that make us thinking about making flood management to avoid risks resulting from it. Flood management is an approach that is virtually unknown in Egypt and has not been widely discussed despite the growing problem of widespread flood damage in recent years. This study aims to evaluate the comprehensive of flash flooding occurrences, impacts, and possible mitigation on the Airports. In this study, Alexandria (Borg El-Arab district) was selected for flash flooding vulnerability assessment, because it is a coastal city and exposed to heavy rains for long periods causing floods, especially Borg El-Arab international airport, it’s about 49 km away from Alexandria city in the southwestern direction, and it is 14 km away from the new city of Borg El Arab in the eastern direction. It was established to relieve Alexandria International Airport, the area of ​​the airport is about 43,669 square meters, the airport served about 189,064 passengers and this number is expected to rise especially after the opening of the new terminal, Runway and other buildings in the airport. Using digital elevation model (DEM) implemented into a Geographic Information System (GIS), the climate maps and metalogical data of this study can help initiating appropriate measures to mitigate the probable hazards in the area. During this research review the impact of floods, how they predict their occurrence to the Disaster Risk Reduction and avoid of danger impacts on vital areas in cities through surveying techniques. how to protect the assets and infrastructure of the airport by predicting the crisis appropriate to mitigate the probable hazards in the airport. يعتبر النقل الجوي من أفضل وسائل السفر ولکن أصبح غير موثوق به بسبب عوامل کثيرة , تم اختيار الإسکندرية لتقييم مدى تعرضها للفيضانات ، لأنها مدينة ساحلية ومعرضة للأمطار الغزيرة. تم استخدام نظم المعلومات الجغرافية (GIS) وعمل التحليلات لتقييم مخاطر الفيضانات وتم عمل نمذجة للفيضانات من خلال الاستشعار عن بعد ، و بيانات الأرصاد الجوية التى تساعد على إنشاء نظام إنذار مبکر وتهدف الدراسة إلى التنبؤ بحدوث الفيضانات و التحکم في المخاطر الناتجة عنها باستخدام تقنية تحليل متعددة المعايير من خلال دراسة الخرائط المناخية و عمل أنظمة حماية و تجميع لمياه الامطار بحيث لا تؤثر على البنية التحتية في المطار. وقد تم عمل دراسة شاملة للفيضانات في مطار برج العرب وتوفير نظام محاکاة ديناميکي لتحديد أماکن ومستويات السيول , القضاء على التعديات و إزالة العوائق في الوديان وعمل حملات توعية عن مخاطر السيول وکيفية التعامل معها .

The sequence of heavy precipitation and flash flooding of 12 and 13 September 2019 in eastern Spain. Part II: A hydro-meteorological predictability analysis based on convection-permitting ensemble strategies

AbstractOn 12 and 13 September 2019, widespread flash flooding caused devastating effects across eastern Spain. Within the framework of the HyMeX program, this study examines predictability of the long-lasting heavy precipitation episode (HPE) conducive to flash flooding. A set of short-range, convection-permitting ensemble prediction systems (EPSs) is built to cope with different sources of meteorological uncertainty. Specifically, the performance of an Ensemble Kalman Filter, tailored bred vectors and stochastic model parameterizations is compared to more standard ensemble generation techniques such as dynamical downscaling and multiple physics. Results indicate EPS focusing on sampling model uncertainties related to parameterization of subgrid process are skillful, especially when deep convection and its interaction with complex orography are important. Furthermore, representation of small-scale thermodynamical aspects is improved through data assimilation, leading to an enhanced forecasting skill as well. Nevertheless, predictability remains relatively low at the catchment scale in terms of exceedance probabilities in cumulative precipitation and peak discharge. The analysis presented herein could serve as a basis for the future implementation of real-time flash flood warning systems based on skillful meteorological EPSs over small-to-medium, semi-arid watersheds in eastern Spain and, by extension, over the flood-prone Western Mediterranean region.

Implications of surface flooding on airborne estimates of snow depth on sea ice

Abstract. Snow depth observations from airborne snow radars, such as the NASA's Operation IceBridge (OIB) mission, have recently been used in altimeter-derived sea ice thickness estimates, as well as for model parameterization. A number of validation studies comparing airborne and in situ snow depth measurements have been conducted in the western Arctic Ocean, demonstrating the utility of the airborne data. However, there have been no validation studies in the Atlantic sector of the Arctic. Recent observations in this region suggest a significant and predominant shift towards a snow-ice regime caused by deep snow on thin sea ice. During the Norwegian young sea Ice, Climate and Ecosystems (ICE) expedition (N-ICE2015) in the area north of Svalbard, a validation study was conducted on 19 March 2015. This study collected ground truth data during an OIB overflight. Snow and ice thickness measurements were obtained across a two-dimensional (2-D) 400 m × 60 m grid. Additional snow and ice thickness measurements collected in situ from adjacent ice floes helped to place the measurements obtained at the gridded survey field site into a more regional context. Widespread negative freeboards and flooding of the snowpack were observed during the N-ICE2015 expedition due to the general situation of thick snow on relatively thin sea ice. These conditions caused brine wicking into and saturation of the basal snow layers. This causes the airborne radar signal to undergo more diffuse scattering, resulting in the location of the radar main scattering horizon being detected well above the snow–ice interface. This leads to a subsequent underestimation of snow depth; if only radar-based information is used, the average airborne snow depth was 0.16 m thinner than that measured in situ at the 2-D survey field. Regional data within 10 km of the 2-D survey field suggested however a smaller deviation between average airborne and in situ snow depth, a 0.06 m underestimate in snow depth by the airborne radar, which is close to the resolution limit of the OIB snow radar system. Our results also show a broad snow depth distribution, indicating a large spatial variability in snow across the region. Differences between the airborne snow radar and in situ measurements fell within the standard deviation of the in situ data (0.15–0.18 m). Our results suggest that seawater flooding of the snow–ice interface leads to underestimations of snow depth or overestimations of sea ice freeboard measured from radar altimetry, in turn impacting the accuracy of sea ice thickness estimates.

Microbial Contamination of Drinking Water Supplied by Private Wells after Hurricane Harvey.

Hurricane Hurricane Harvey made landfall on the Texas Gulf Coast on August 25, 2017, as a Category 4 hurricane and caused widespread flooding. We explored spatial and temporal distributions of well testing and contamination rates; relationships between contamination and system characteristics and recovery behaviors; and efficacy of mitigation strategies. We estimated that over 500 000 well users (∼130 000 to 260 000 wells) may have been affected, but only around 15 000 well users (∼3800 to 7500 wells) had inundated systems based on inundation maps. Local health departments and our team sampled 8822 wells in 44 counties in the 10 months that followed. Total coliform occurrence was 1.5 times and Escherichia coli was 2.8 times higher after Hurricane Harvey compared to baseline levels. Microbial contamination was more likely (1.7-2.5 times higher) when wells were inundated and/or residents felt their water was unsafe. Although more wells in urban counties were affected, E. coli rates were higher in wells in rural counties. Disinfection did not always eliminate contamination, highlighting concerns about the implementation and efficacy of chlorination procedures. Despite this extensive well testing conducted after Hurricane Harvey, we estimate that only 4.1% of potentially affected wells were tested, underscoring the magnitude of recovery assistance needed to assist well users after flooding events.

Economic damages from Hurricane Sandy attributable to sea level rise caused by anthropogenic climate change

In 2012, Hurricane Sandy hit the East Coast of the United States, creating widespread coastal flooding and over $60 billion in reported economic damage. The potential influence of climate change on the storm itself has been debated, but sea level rise driven by anthropogenic climate change more clearly contributed to damages. To quantify this effect, here we simulate water levels and damage both as they occurred and as they would have occurred across a range of lower sea levels corresponding to different estimates of attributable sea level rise. We find that approximately $8.1B ($4.7B–$14.0B, 5th–95th percentiles) of Sandy’s damages are attributable to climate-mediated anthropogenic sea level rise, as is extension of the flood area to affect 71 (40–131) thousand additional people. The same general approach demonstrated here may be applied to impact assessments for other past and future coastal storms.

Before, during and after the Dana of September 2019 in the region of Murcia (Spain), as reported in the written press

In September 2019 a DANA affected the Southeast of Spain with a special impact on the Segura Basin and the Region of Murcia. Heavy rainfall caused widespread flooding, very serious damage and generally affected the whole population. The main objective of this work was to analyse this episode through a follow-up of all the news published in two regional newspapers, La Verdad and La Opinión. To this end, a methodological proposal was made to classify the news according to: the typology of the subject, the relevance of the DANA in terms of frequency and how the news developed. A total of 816 news articles covering 52 days were studied and grouped into 26 subjects. The issues that aroused most interest, were those relating to the solidarity offered and aid provided to those affected, the effects on the Mar Menor (a nearby coastal lagoon); visits by politicians, personalities and their statements; solutions and mitigation measures; evacuations, rescues and displacements. The database analysed allowed us to organise the information into different aspects and in sequence: (i) prevention tasks and warnings prior to the materialisation of a risk situation; (ii) rescues, relief and assistance to persons, and (iii) response, rehabilitation and reconstruction.

The 2019/2020 floods in the UK: a hydrological appraisal

The 2019/2020 floods in the <scp>UK</scp>: a hydrological appraisal

China's ‘Sponge Cities’: The role of constructed wetlands in alleviating urban pluvial flooding

AbstractResearch examined constructed wetlands (CWs) in piloting the ‘Sponge City’, a Chinese initiative designed, in part, to curtail extensive urban pluvial flooding. In Yangzhou a small number of exploratory qualitative interviews with relevant professionals elucidated key issues. The interviewees supported the concept of CWs but were uniformly sceptical about their viability. A possible CW in the city was also modelled, quantifying its effects and limitations. Results show that CWs can help attenuate urban flooding but there are important caveats concerning their implementation. These concern their size and capacity, sufficiency of urban space, and their economic sustainability. The political dimension of the Sponge City concept, including support from President Xi Jinping, suggests that CWs may be a distraction from more widespread urban flooding, which CWs may well not alleviate. Piloting is continuing and results will need to be more positive if Sponge Cities can be a strategically important flood attenuation measure.

Larger Spatial Footprint of Wintertime Total Precipitation Extremes in a Warmer Climate

AbstractThe simultaneous occurrence of extremely wet winters at multiple locations in the same region can contribute to widespread flooding and associated socio‐economic losses. However, the spatial extent of precipitation extremes (i.e., the area in which nearby locations experience precipitation extremes simultaneously) and its future changes are largely overlooked in climate assessments. Employing new multi‐thousand‐year climate model simulations, we show that under both 2.0 °C and 1.5 °C warming scenarios, wintertime total precipitation extreme extents would increase over about 80%–90% of the Northern Hemisphere extratropics (i.e., of the latitude band 28°–78°N). Stabilizing at 1.5 °C rather than 2.0 °C would reduce the average magnitude of the increase by 1.7–2 times. According to the climate model, the increased extents are caused by increases in precipitation intensity rather than changes in the spatial organization of the events. Relatively small percentage increases in precipitation intensities (e.g., by 4%) can drive disproportionately larger, by 1–2 orders of magnitude, growth in the spatial extents (by 93%).

The Impact of Tropical Cyclones in Premonsoonal Season on Local Convection over the Al-Hajar Mountains in Oman during 2007–2018

The tropical cyclones (TCs) and convective storms have a significant impact on triggering widespread flooding in vulnerable areas. However, it is not clear whether the TCs stimulate the convective precipitation over the Al-Hajar Mountains in Oman or suppress it although it had been shown in many studies that TCs suppress the local convection development. This study aims to test the applicability of the hypothesis that the TCs suppress the convection over mountainous to the Al-Hajar Mountains. In order to test the hypothesis of tropical cyclones’ impact on local convection development over the Al-Hajar Mountains, this study considers three different cases during the premonsoon season between 2007 and 2018. The results revealed that weak local convection is reported over the Al-Hajar Mountains during the presence of the cyclones in the Arabian Sea and during the period of their direct impacts. The rainfall in these cases was mainly from stratiform clouds. Therefore, the impact of TCs on the convective suppression over the mountains is applicable to the Al-Hajar Mountains. This study will provide decision-makers and policy creators with knowledge as to whether the Al-Hajar Mountains are susceptible and vulnerable to the risk of torrential downpour, flash flooding, and thunderstorms as what is believed to be.

Wet winters awaiting

Climate Change Wet weather occurring simultaneously in many places within a given region can cause widespread flooding. To assess whether climate change will affect the incidence of that type of flooding, Bevacqua et al. performed climate model simulations of wintertime precipitation. These simulations showed that the areal extent of extratropical extreme wintertime precipitation in the Northern Hemisphere would nearly double if global warming were to increase the mean surface air temperature by 2.0°C above the preindustrial average. Only small increases of precipitation intensity are needed to cause relative growth of the spatial coverage of extreme precipitation events of an order of magnitude or more. Geophys. Res. Lett. 10.1029/2020GL091990 (2021).

Soil Carbon Isotope Values and Paleoprecipitation Reconstruction

AbstractAnthropogenic climate change has significant impacts at the ecosystem scale including widespread drought, flooding, and other natural disasters related to precipitation extremes. To contextualize modern climate change, scientists often look to ancient climate changes, such as shifts in ancient precipitation ranges. Previous studies have used fossil leaf organic geochemistry and paleosol inorganic chemistry as paleoprecipitation proxies, but have largely ignored the organic soil layer, which acts as a bridge between aboveground biomass and belowground inorganic carbon accumulation, as a potential recorder of precipitation. We investigate the relationship between stable carbon isotope values in soil organic matter (δ13CSOM) and a variety of seasonal and annual climate parameters in modern ecosystems and find a statistically significant relationship between δ13CSOM values and mean annual precipitation (MAP). After testing the relationship between actual and reconstructed precipitation values in modern systems, we test this potential paleoprecipitation proxy in the geologic record by comparing precipitation values reconstructed using δ13CSOM to other reconstructed paleoprecipitation estimates from the same paleosols. This study provides a promising new proxy that can be applied to ecosystems post‐Devonian (∼420 Ma) to the Miocene (∼23 Ma), and in mixed C3/C4 ecosystems in the geologic record with additional paleobotanical and palynological information. It also extends paleoprecipitation reconstruction to more weakly developed paleosol types, such as those lacking B‐ horizons, than previous inorganic proxies and is calibrated for wetter environments.