Major Flood Events Research Articles

Accelerated soil development due to seasonal water-saturation under hydric conditions

Pedogenesis is considered a long-term environmental process; however, it can be accelerated by periodic water saturation (hydric conditions). The exact nature and effectiveness of hydric conditions in the intensification of soil development are not clear yet. Our understanding of the timescales of the mineralogical changes occurring in soils is limited; however, the timeframe of soil organic matter accumulation is broadly known. Here, we described soil development over a period of 50 years.The studied soils Calcaric Mollic Gleysol (Endoarenic, Epiloamic, Hyperhumic) and a Calcaric Calcic Histic Gleysol (Endoarenic, Epiloamic) are located in a swampy area in Hungary, Central Europe. The start of the soil formation process is well documented here; the parent material was deposited during a major flood event in 1963. Therefore, the examined soil profile represents development over the last 50 years. We also studied the parent material of an adjacent dune as a reference. We used a CN elemental analyser to determine soil organic carbon and total bound nitrogen content. Selective extractions were also used to determine amorphous and crystalline Fe and Mn content alongside X-ray phase analysis (XRD) and transmission electron microscopy (TEM) for mineralogical analysis, X-ray fluorescence spectroscopy (XRF) for elemental analysis, and laser diffraction for particle size analysis of the bulk soil samples. Simple chemical tests were also performed in the field. Redox potential (Eh) and pH were measured by a field monitoring station.Fifty years under hydric conditions resulted in rapid vertical differentiation within the soil profile including remarkable soil organic matter enrichment in the topsoil, and the formation of smectite and Fe accumulation in the zone of groundwater fluctuation. A high proportion of amorphous and colloidal phases indicated that very intense processes had taken place in the zone of the most intensive redox oscillation. The presence of more crystalline goethite in the bulk soil reflects frequent Eh changes, associated with chemical or microbial processes, while the presence of amorphous ferrihydrite indicates the effect of plant roots. Permanently reductive subsoil conditions also facilitated intense carbonate precipitation. These findings demonstrate that soil formation can proceed faster than previously assumed under hydric conditions.

Analysis of Flood Fatalities in the United States, 1959–2019

Flooding is one of the main weather-related disasters that cause numerous fatalities every year across the globe. This study examines flood fatalities reported in the contiguous United States (US) from 1959 to 2019. The last two decades witnessed major flood events, changing the ranking of the top states compared to previous studies, with the exception of Texas, which had significantly higher flood-related fatalities than any other state. The rankings of counties within some states changed as well. The study aims to improve understanding of the situational conditions, demographics, and spatial and temporal characteristics associated with flood fatalities. The analysis reveals that flash flooding is associated with more fatalities than other flood types. In general, males are much more likely to be killed in floods than females. The analysis also suggests that people in the age groups of 10–19, 20–29, and 0–9 are the most vulnerable to flood hazard. Purposely driving or walking into floodwaters accounts for more than 86% of total flood fatalities. Thus, the vast majority of flood fatalities are preventable. The results will help identify the risk factors associated with different types of flooding and the vulnerability of the exposed communities.

Event loading drives distribution of the organochlorine pesticide metabolite DDE in a sub-tropical river system, Brisbane River, Australia

Past catchment practices can contribute to environmental impacts for decades following their cessation. We examine the distribution of the prevalent organochlorine pesticide, dichlorodiphenyltrichloroethane (DDT) and its metabolites (DDE, DDD) in the sediments of a sub-tropical river system (Brisbane River, Australia). This study aimed to identify sources of DDT, DDE, DDD into the lower reaches of the Brisbane River. Annual sediment sampling of the lower Brisbane River over a period of 15 years (2001–2015) revealed a significant increase in sediment DDT, DDE and DDD content following major floods. A regional survey detected elevated sediment DDT, DDE and DDD content at 32 of 79 sites sampled; however, these were generally below guideline trigger values. DDE was the sole fraction at all but one site with creek systems dominated by intensive cropping practices identified as legacy sources and major flood events as a driver of elevated sediment DDE content in the lower reaches.

The Texas flood registry: a flexible tool for environmental and public health practitioners and researchers

BackgroundMaking landfall in Rockport, Texas in August 2017, Hurricane Harvey resulted in unprecedented flooding, displacing tens of thousands of people, and creating environmental hazards and exposures for many more.ObjectiveWe describe a collaborative project to establish the Texas Flood Registry to track the health and housing impacts of major flooding events.MethodsThose who enroll in the registry answer retrospective questions regarding the impact of storms on their health and housing status. We recruit both those who did and did not flood during storm events to enable key comparisons. We leverage partnerships with multiple local health departments, community groups, and media outlets to recruit broadly. We performed a preliminary analysis using multivariable logistic regression and a binomial Bayesian conditional autoregressive (CAR) spatial model.ResultsWe find that those whose homes flooded, or who came into direct skin contact with flood water, are more likely to experience a series of self-reported health effects. Median household income is inversely related to adverse health effects, and spatial analysis provides important insights within the modeling approach.SignificanceGlobal climate change is likely to increase the number and intensity of rainfall events, resulting in additional health burdens. Population-level data on the health and housing impacts of major flooding events is imperative in preparing for our planet’s future.

A Climatology of Heavy Rain and Major Flood Events in Victoria 1876-2019 and the Effect of the 1976 Climate Shift

An extensive search has been carried out to find all major flood and very heavy rainfall events in Victoria since 1876 when Southern Oscillation (SOI) data became available. The synoptic weather patterns were analysed and of the 319 events studied,121 events were found to be East Coast Lows (ECLs) and 82 were other types of low-pressure systems. Tropical influences also played a large role with 105 events being associated with tropical air advecting down to Victoria into weather systems. Examples are presented of all the major synoptic patterns identified. The SOI was found to be an important climate driver with positive SOIs being associated with many events over the 144 years studied. The 1976 Climate Shift and its influence on significant Victorian rainfall events is studied and negative SOI monthly values were shown to dominate following the Shift.However,one of the most active periods in 144 years of Victorian heavy rain occurred after the shift with a sustained period of positive SOI events from 2007 to 2014. Therefore, it is critical for forecasting future Victorian heavy rainfall is to understand if sequences of these positive SOI events continue like those preceding the Shift. Possible relationships between the Shift and Global Temperature rises are also explored. Upper wind data available from some of the heaviest rainfall events showed the presence of anticyclonic turning of the winds between 850hPa and 500hPa levels which has been found to be linked with extreme rainfall around the Globe.

Changes in precipitation patterns in Houston, Texas

There has been an alarming increase in the frequency of major flooding events along the Gulf Coast over the last three decades, primarily due to events of unprecedented, or extreme, rainfall. Using data from 63 rain gauges maintained by the Harris County Flood Control District's Flood Warning System (HCFCD FWS), this study examines the changes in daily precipitation amounts in the highly urbanized city of Houston, Texas, USA. The potential shift in annual precipitation patterns over a period of three decades (1989-2018) was examined by investigating the numbers of dry and wet days as well as annual precipitation totals over the study period. Wet days were then further scrutinized based on daily rainfall amounts (e.g., R10, R20, R30, R40, R50, R100) to determine if extreme events are beginning to dominate annual rainfall amounts. Trends were analyzed for statistical significance temporally using the Mann-Kendall and Sen's slope methods and for spatial trends using GIS applications. The results indicate a statistically significant increase in extreme rainfall at the expense of light, moderate, and heavy rainfall over time. The only negative relationship is found in dry days. The most statistically significant trends exist in the 99th percentile, maximum, and R100 parameters with p-values of 0.07, 0.08, and 0.11, respectively. There has been rapid growth and intensive development in the Houston area in recent decades that continues to this day, and land cover change has been significant as 12.6% of Harris County changed to one of four National Land Cover Database (NLCD) Urban classes (e.g., developed: barren, low intensity, medium intensity, high intensity). This confirms that urbanization has continued to increase while total vegetative and wetland coverage has decreased. The findings of this study provide essential guidance for city and state planners and engineers.

Major Floods and Tropical Cyclones over Bangladesh: Clustering from ENSO Timescales

The present study analyzed major floods and tropical cyclones (TCs) over Bangladesh on El Niño-Southern Oscillation (ENSO) timescales. The geographical location, low and almost flat topography have introduced Bangladesh as one of the most vulnerable countries of the world. Bangladesh is highly vulnerable to the extreme hazard events like floods and cyclones which are impacted by ENSO. ENSO is mainly a tropical event, but its impact is global. El Niño (La Niña) represents the warm (cold) phase of the ENSO cycle. Rainfall and cyclonic disturbances data have been used for the period of 70 years (1948–2017) and compared with the corresponding observations of the Southern Oscillation Index. Result shows that major flood events occurred during the monsoon period, and most of them are during the La Niña condition, consistent with the historical archives of flood events in Bangladesh. Synoptic conditions of these events are well matched during La Niña condition. On the other hand, the major TC cases are in the period of either pre-monsoon or post-monsoon season. The pre-monsoon cases are under neutral (developing La Niña) or El Niño and the post-monsoon cases are under La Niña, consistent with climatology studies that La Niña is favorable to have more intense TCs over the Bay of Bengal.

Finding voices in the floods of Freedom Hill: innovating solutions in Princeville, North Carolina.

Princeville, NC, is the oldest town chartered by Blacks in America. Founded as Freedom Hill in 1865 and incorporated as Princeville in 1885, the town continues to be predominantly African American today. Built on the unwanted and flood-prone lands adjacent to the Tar River, Princeville has flooded multiple times throughout its history, including after Hurricane Floyd in 1999 and Hurricane Matthew in 2016. Because of the town’s historical significance, residents and town officials alike have been reluctant to accept offers for widespread buyouts from the government. Despite having limited financial resources and political clout, the town has developed a unique approach to managed retreat while rebuilding from Matthew—one that emphasizes the importance of historical sites while also recognizing the need to relocate residents out of harm’s way from future floods. This manuscript uses a historical and narrative approach to examine how Princeville’s unique history, and the relationship between the town and the Tar River, play important roles in the town’s decisions regarding retreat and redevelopment in the aftermath of major flooding events. We highlight the voices of current residents, including leaders, as well as the structural and cultural conditions that both constrain and enable the town’s collective agency. While focused on the present day, this case study is historically informed, using oral histories and archival documents.

Investigating the flood damages in Lower Indus Basin since 2000: Spatiotemporal analyses of the major flood events

Investigating the flood damages in Lower Indus Basin since 2000: Spatiotemporal analyses of the major flood events

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

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

Performance of Multi-Radar Multi-Sensor (MRMS) product in monitoring precipitation under extreme events in Harris County, Texas

With an increase in intensity and frequency of extreme precipitations as a result of climate change, it is necessary to develop effective strategies for emergency flood management plan. It is critical to integrate the use of high-resolution hydro-meteorological data (e.g., precipitation) as input for hydrologic modeling to accurately predict and reduce the negative impact of floods. The Multi-Radar Multi-Sensor (MRMS) system has been developed by the National Severe Storms Laboratory (NSSL)to produce high-resolution spatio-temporal precipitation data. While the MRMS data are available at relatively high spatial (1 km) and temporal (2 min) resolutions across the continental United States (CONUS), MRMS’s accuracy in measuring actual precipitation needs to be investigated across some urban areas such as Harris County, TX. Therefore, the objectives of this study are to evaluate i) the performance of the MRMS system compared to other precipitation products (rain gauge network, Multisensor Precipitation Estimator (MPE)) at different spatial (5, 10, 15, 30 km) and temporal aggregations (5, 10,15, 30, 60 min) during four major flooding events of May 2015 (Memorial Day flood), April 2016 (Tax Day Flood), August 2017 (Hurricane Harvey), and September 2019 (Tropical Storm Imelda) in Harris County, Texas; and ii) the effects of temporal and spatial aggregation scales on the performance of the MRMS system using a suite of statistical parameters. Point-to-grid comparisons were conducted between 142 rain gauges and MRMS system data during four extreme flood events. Overall, the MRMS system captured precipitation reasonably well with a coefficient of determination (R2) of 0.78, correlation coefficient (CC) of 0.88, root mean square error (RMSE) of 1.21 mm, critical success index (CSI) of 0.65, probability of detection (POD) of 0.98, and false alarm ratio (FAR) of 0.34 over Harris County at 15 min and 15 km temporal and spatial resolutions. The results indicate that MRMS product tends to underestimate higher precipitation rates and overestimate light precipitation. Coarser temporal resolutions from 5 min to 1 h resolved some of the overestimation issues. Temporal aggregation increased R2, CC, CSI, and error variances and decreased FAR. However, increasing spatial resolution from 1 to 30 km increased R2, CC, and CSI and reduced RMSE and FAR. A comparison of MPE QPE and MRMS products at hourly temporal resolution with gauge observations showed that both products estimate rainfall accurately for the four events. Still, on average, MRMS product has a slightly better agreement with rain gauge observations at 1-hr temporal resolution.

Evaluation of the subseasonal forecast skill of floods associated with atmospheric rivers in coastal Western U.S. watersheds

AbstractAtmospheric rivers (ARs) are responsible for up to 90% of major flood events along the U.S. West Coast. The timescale of subseasonal forecasting (two weeks to one month) is a critical lead time for proactive mitigation of flood disasters. The NOAA/Climate Testbed Subseasonal Experiment (SubX) is a research-to-operations project with almost immediate availability of forecasts. It has produced a reforecast database that facilitates evaluation of flood forecasts at these subseasonal lead times. Here, we examine the SubX driven forecast skill of AR-related flooding out to 4-week lead using the Distributed Hydrology Soil Vegetation Model (DHSVM), with particular attention to the role of antecedent soil moisture (ASM), which modulates the relationship between meteorological and hydrological forecast skill. We study three watersheds along a transect of the U.S. West Coast: the Chehalis River basin in Washington, the Russian River basin in Northern California, and the Santa Margarita River basin in Southern California. We find that the SubX driven flood forecast skill drops quickly after week 1, during which there is relatively high deterministic forecast skill. We find some probabilistic forecast skill relative to climatology as well as ensemble streamflow prediction (ESP) in week 2, but minimal skill in weeks 3-4, especially for annual maximum floods, notwithstanding some probabilistic skill for smaller floods in week 3. Using ESP and reverse-ESP experiments to consider the relative influence of ASM and SubX reforecast skill, we find that ASM dominates probabilistic forecast skill only for small flood events at week 1, while SubX reforecast skill dominates for large flood events at all lead times.

Disaster Tales as Communication Tool for Increasing Risk Resilience

Agencies in charge of flood management use disaster reports (DRs) as the preferred source of information on past flooding events. A systematic survey of DRs prepared by Italian agencies suggests that DRs could be widely enhanced in view of targeting more effective communication to citizens, reinforcing the communication pillar in civil protection planning and management, and improving the resilience of the population to extreme events. Without loss of the rigor and details required for all the usual technical uses of DRs, we suggest recompiling them in the form of “disaster tales” (DTs), as tools that offer wider knowledge of the events to improve people’s preparedness and self-protection behavior. Recent major flooding events have demonstrated the communication potential that videos and pictures taken by citizens have for risk perception and disaster preparedness. By watching and listening to what has happened the communication recipient can better understand the feelings of the people experiencing an emergency. The structure of the improved reports, we suggest, will finally integrate data, graphs, and maps with interactive tools and be able to present handier multimedia views of the events. Application to three case studies of flooding in Italy illustrates how to concretely implement the suggested disaster reports to create more readily accessible disaster tales.

Flash floods controlling Cu, Pb, As and Hg variations in fluvial sediments of a river impacted by metal mining in the Atacama Desert

Solid mine wastes can be dispersed in river systems by fluvial processes contaminating distant areas. This process has been previously reported in rivers of the Atacama Desert impacted by mining. The removal of waste in these rivers is a complex environmental scenario that involves (i) mining operation plans, (ii) the spatio-temporal variability of precipitation events and, (iii) the sediment-transport pathways within the drainage network. This work presents how flash floods triggered by extreme storm events determine the redistribution and the variation of elemental concentrations of the suspended load fraction in a river with several historical and actual mine wastes situated in the Atacama Desert. The concentrations of Cu, Pb, As and Hg measured in two sampling stations of a mining segment of the Copiapó River after flash floods are lower compared to the concentrations measured in the period before these hydrometeorological events. However, the concentrations of these metals and metalloids increased in areas distant from the mine clusters, where the values observed before the flash floods were lower. The redistributions of the element concentrations can be explained by the occurrence of two major flood events triggered by the extreme storm events of March 2015 and May 2017. The combination of the element concentrations with calculated geo-accumulation indexes shows the potential source of geochemical anomalies for these elements. Cu and Hg anomalies are induced by historical mining activities in the Copiapó River while Pb and As concentrations agree with the regional background. Some Pb and As anomalies would be associated with the geology of the zone where the main cluster of mine exploitations are present. The fact that flash floods result in Cu, Pb, As and Hg concentrations in sediment load more in line with the local background, suggests that this type of hydrometeorological events probably represent the natural processes of geochemical recovery of arid river impacted by metal mining.

Land Subsidence in Wuhan Revealed Using a Non-Linear PSInSAR Approach with Long Time Series of COSMO-SkyMed SAR Data

Wuhan is an important city in central China, with a rapid development that has led to increasingly serious land subsidence over the last decades. Most of the existing Interferometric Synthetic Aperture Radar (InSAR) subsidence monitoring studies in Wuhan are either short-term investigations—and thus can only detect this process within limited time periods—or combinations of different Synthetic Aperture Radar (SAR) datasets with temporal gaps in between. To overcome these constraints, we exploited nearly 300 high-resolution COSMO-SkyMed StripMap HIMAGE scenes acquired between 2012 and 2019 to monitor the long-term subsidence process affecting Wuhan and to reveal its spatiotemporal variations. The results from the Persistent Scatterer Interferometric SAR (PSInSAR) processing highlight several clearly observable subsidence zones. Three of them (i.e., Houhu, Xinrong, and Guanggu) are affected by serious subsidence rates and non-linear temporal behavior, and are investigated in this paper in more detail. The subsidence in Houhu is caused by soft soil consolidation and compression. Soil mechanics are therefore used to estimate when the subsidence is expected to finish and to calculate the degree of consolidation for each year. The COSMO-SkyMed PSInSAR results indicate that the area has entered the late stage of consolidation and compression and is gradually stabilizing. The subsidence curve found for the area around Xinrong shows that the construction of an underground tract of the subway Line 21 caused large-scale settlement in this area. The temporal granularity of the PSInSAR time series also allows precise detection of a rebound phase following a major flooding event in 2016. In the southern industrial park of Guanggu, newly detected subsidence was found. The combination of the subsidence curve with an optical time-series image analysis indicates that urban construction is the main trigger of deformation in this area. While this study unveils previously unknown characters of land subsidence in Wuhan and clarifies the relationship with the urban causative factors, it also proves the benefits of non-linear PSInSAR in the analysis of the temporal evolution of such processes in dynamic and expanding cities.

Meteorological observations collected during the Storms and Precipitation Across the continental Divide Experiment (SPADE), April–June 2019

Abstract. The continental divide along the spine of the Canadian Rockies in southwestern Canada is a critical headwater region for hydrological drainages to the Pacific, Arctic, and Atlantic oceans. Major flooding events are typically attributed to heavy precipitation on its eastern side due to upslope (easterly) flows. Precipitation can also occur on the western side of the divide when moisture originating from the Pacific Ocean encounters the west-facing slopes of the Canadian Rockies. Often, storms propagating across the divide result in significant precipitation on both sides. Meteorological data over this critical region are sparse, with few stations located at high elevations. Given the importance of all these types of events, the Storms and Precipitation Across the continental Divide Experiment (SPADE) was initiated to enhance our knowledge of the atmospheric processes leading to storms and precipitation on either side of the continental divide. This was accomplished by installing specialized meteorological instrumentation on both sides of the continental divide and carrying out manual observations during an intensive field campaign from 24 April–26 June 2019. On the eastern side, there were two field sites: (i) at Fortress Mountain Powerline (2076 m a.s.l.) and (ii) at Fortress Junction Service, located in a high-elevation valley (1580 m a.s.l.). On the western side, Nipika Mountain Resort, also located in a valley (1087 m a.s.l.), was chosen as a field site. Various meteorological instruments were deployed including two Doppler light detection and ranging instruments (lidars), three vertically pointing micro rain radars, and three optical disdrometers. The three main sites were nearly identically instrumented, and observers were on site at Fortress Mountain Powerline and Nipika Mountain Resort during precipitation events to take manual observations of precipitation type and microphotographs of solid particles. The objective of the field campaign was to gather high-temporal-frequency meteorological data and to compare the different conditions on either side of the divide to study the precipitation processes that can lead to catastrophic flooding in the region. Details on field sites, instrumentation used, and collection methods are discussed. Data from the study are publicly accessible from the Federated Research Data Repository at https://doi.org/10.20383/101.0221 (Thériault et al., 2020). This dataset will be used to study atmospheric conditions associated with precipitation events documented simultaneously on either side of a continental divide. This paper also provides a sample of the data gathered during a precipitation event.

Assessing the spatiotemporal socioeconomic flood vulnerability of agricultural communities in the Potomac River Watershed

Flood events are one of the most destructive and yet increasingly frequent natural hazards causing a considerable amount of economic losses in the United States (US). The agricultural sector is particularly vulnerable to flood hazards. The representation of spatiotemporal distributions of the agricultural damage and the vulnerability of the agricultural communities are essential for flood risk management. Therefore, this study investigates spatiotemporal Socioeconomic flood vulnerability of the agricultural communities in the Potomac River Watershed (PRW), where corn and soybeans cultivation are one of the important agricultural activities. In this context, a combination of the widely used flood damage estimation tool HAZUS-MH and the county-based Social Vulnerability Index (SOVI) were utilized for the vulnerability assessment. The spatial distribution of agricultural communities vulnerable to flood was evaluated for the extreme and average damage conditions for 365 days along with the monthly average damage from a 100-year flood event. The maximum crop damage and most likely months to experience major flood events were found in the same temporal periods. The spatial distributions of damage and SOVI assessments suggested that the most vulnerable agricultural communities (Highland (VA) and Prince George’s (MD)) did not experience high flood damages in any scenario. The agricultural community in Shenandoah County was the most vulnerable in September and October, which has the highest flood probability. This high risk that is spatiotemporally highlighted can aid decision-makers regarding the resource allocation for mitigation efforts in the PRW. Our method can potentially be replicated throughout the country, thus protecting vulnerable agricultural communities.

Quantifying Debris Flood Deposits in an Alaskan Fjord Using Multitemporal Digital Elevation Models.

Six DEMs over a 10-year period were used to estimate flood-related sedimentation in the Japanese Creek drainage located in Seward, Alaska. We analyze two existing LiDAR DEMs and one GNSS-derived DEM along with three additional DEMs that we generated using differential Global Navigation Satellite System (dGNSS) and Structure from Motion (SfM) techniques. Uncertainties in each DEM were accounted for, and a DEMs of Difference (DoD) technique was used to quantify the amount and pattern of sediment introduced, redistributed, or exiting the system. Through correlating the changes in sediment budget with rainfall data and flood events, the study demonstrates that the major flood events in 2006 and 2012—the 7th and 5th highest precipitation events on record—resulted in an increased sedimentation in the drainage as a whole. At a minimum the 2006 and 2012 events increased the sediment in the lower reaches by 70,100 and 53,900 cubic meters, respectively. The study shows that the DoD method and using multiple technologies to create DEMs is effective in quantifying the volumetric change and general spatial patterns of sediment redistribution between the acquisition of DEMs.

Impacts of climate change and sea level rise on catchment management: A multi-model ensemble analysis of the Nerang River catchment, Australia

Estimating the most likely impacts of climate change on the hydrological conditions of catchments is essential for efficient future water management. This is particularly important in Southeast Queensland, Australia, which is projected to be significantly impacted by climate change. We have developed an integrated catchment modelling framework for the Nerang River catchment that combines a hydrologic model, a reservoir operation model, and a hydrodynamic river model. The multi-model ensemble is used to investigate eight General Circulation Models (GCMs) of the Coupled Model Intercomparison Project Phase 5 (CMIP5) under two representative concentration pathway scenarios (RCP 4.5 and RCP 8.5) over the baseline period (2000–2009) and one future period (2075–2084). Additionally, the tidal section of the Lower Nerang River was studied under coupled impacts of the RCP scenarios and sea level rise by 0.80 m. The ensemble projections over the future period present slight decreasing tendencies in the median of monthly long-term daily inflow to Hinze Dam in the upper Nerang River. Additionally, the average environmental releases of 7.25 ML/day are expected to reduce over the future period by 6.02% and 5.37% under RCP 4.5 and RCP 8.5, respectively compared to the baseline period. The hydrodynamic model results revealed that sea level rise is projected to have significant impact on water level variations at two river flooding alert sites, Carrara Alert and Evandale Alert. As a result, a 0.80 m sea level rise can increase ensemble water level projections by almost 0.75 m and 0.80 m at Carrara Alert and Evandale Alert sites, respectively, which will cause minor to major flooding events at Evandale Alert site. The outcomes of the present paper can assist the decision-makers and the community of the Nerang River catchment with a robust tool to evaluate climate change scenarios for sustainable future water resources management and allocation. • • An integrated catchment modelling framework was developed for SEQ, Australia. • • A hydrologic, reservoir, and a hydrodynamic river models were combined. • • Outputs from eight CMIP5 models and two RCPs were used for future projections. • • Slight decreases in dam inflow are projected in the future. • • Decreasing trends in environmental flow release are expected under climate change.

Drought and Flood Characterization and Connection to Climate Variability in the Pearl River Basin in Southern China Using Long-Term GRACE and Reanalysis Data

AbstractDrought and flood are investigated in the Pearl River basin (PRB) using long-term terrestrial water storage anomaly (TWSA) data from the mascon (mass concentration) solutions based on Gravity Recovery and Climate Experiment (GRACE) satellite measurements (2002–19) and reanalysis data (1980–2019). The GRACE mascon solutions capture two major drought periods (2003–06 and 2009–12) with similar onsets and endings over the last two decades, but show considerable differences in quantifying total drought severity. The reanalysis data significantly overestimate drought duration and severity during 1980–2000 owing to overestimated negative TWSA forced by underestimated precipitation. The GRACE mascon solutions identify four major flood events in August 2002, June 2008, and July in 2006 and 2019. The flood potential is influenced by the precipitation in both the current and antecedent months. The flood potential index of the most recent flood in 2008 showed a similar spatial pattern compared to precipitation at monthly and subbasin scales. The precipitation and TWSA in the PRB are mainly influenced by El Niño–Southern Oscillation (ENSO). TWSA exhibits a lag of 1–3 months responding to ENSO during 1980–2019. This study emphasizes the significance of removing water storage changes in new large reservoirs before long-term drought and flood characterization. The inclusion of reservoir water storage would expand (shrink) the drought duration and overestimate (underestimate) drought severity for the period before (after) reservoir impoundment and overestimate flood potential for the period after reservoir impoundment. This study highlights the intensifying drought conditions in the PRB over the last four decades under the circumstances of more frequent human activities (reservoir construction and regulation) and the complex changing climate system.