Major Flood Events Research Articles

Tropical cyclone—Induced heavy rainfall and flow in Colima, Western Mexico

AbstractTropical cyclone (TC) landfall is often accompanied by storm surges, strong winds, and heavy rain that cause destructive flash floods, especially in mountainous regions. However, there is limited understanding of the contribution of TCs to major flood events, especially in Western Mexico. In this study, we assess the contribution of TCs to the annual rainfall, extreme rainfall and stream flow in the mountainous region of Colima, one of the most TC‐exposed areas in Western Mexico. The top 1% of daily rainfall and stream flow, annual maximum rainfall and the highest 20 stream flow events from 1970 to 2015 are examined for their association to TCs. Results indicate that the relative contribution of TCs to the average annual rainfall can exceed 25% in the coastal area of Colima. Over 25–35% of heavy daily rainfall (top 1% rainfall) recorded in the coastal rain gauges is found to be associated with TCs. In terms of high flow, approximately 20–24% of the top 1% flow events and 28–35% (~7 events) of the top 20 flow events are driven by TCs. The heaviest precipitation and high flow events occur typically in the late TC season (September and October). Our results provide insights on the role of TCs in inducing rainfall and stream flow relevant for water and flood risk management.

Sand dunes and valley fills from Preboreal glacial‐lake outburst floods in south‐eastern Norway – beyond the aeolian paradigm

AbstractA major glacial‐lake outburst flood in the Glomma valley, south‐eastern Norway, took place during the final decay of the Scandinavian Ice Sheet. A combined morphological, geophysical and sedimentological study provides new insight into the variety of processes and deposits of the flood. The studied succession, some tens of metres in thickness, comprises the fill of a major flood basin that developed during hydraulic ponding. Large‐scale sand dunes and bars accumulated downstream of locations with expanding flow. Most notable are 10 m high, concentric dune ridges that accumulated downstream of a topographical constriction hosting a high‐velocity flow. Flow expansion at the outlet generated intense turbulence and scouring. The sand‐loaded eddies helped feeding the semi‐stationary dune ridges that grew vertically and downflow under high aggradation rates. Internal structures vary but reflect an overall shift in sedimentation from prevailing supercritical flow to overall subcritical flow conditions at high flood levels. Loading by water and sediment caused large‐scale, synsedimentary deformation, increasing local accommodation space. Fast‐falling flood levels caused stronger flow locally, while mud and fine sand settled in stagnant pools. The fall caused a significant drop in hydrostatic pressure. This triggered a release of excess pore pressure causing massive dewatering and fluidisation. Water‐escape structures include numerous (sub)vertical pipes. The present study shows that outburst flood‐generated, large‐scale dunes can develop in well‐sorted, fine sand and are thereby easily confused with aeolian deposits. Several dune fields in south‐eastern Norway are here reinterpreted as the product of at least two major flood events. Sandy dune fields with similar characteristics elsewhere in Scandinavia should likely also be reinterpreted, and the role of outburst floods during the final deglaciation of Scandinavia has seemingly been underestimated. The study emphasises the importance of ponding, flow expansion, sorting, rapidly changing pressure conditions and deformation for outburst flood‐related sedimentation.

Selfies Save Lives (Digital Strategies for Flood Response in Indonesia)

Flooding is very serious problem for cities in Asia; according to Dartmouth Flood Observatory, of the 20 megacities in East and Southeast Asia, 14 are sitting on river deltas and 18 have experienced major flood events in the past decade. In Indonesia, there are millions people exposed to flooding conditions during the monsoon season. There are also millions of residents who are connected to the internet, and one another, through their mobile devices. During flood situations, Indonesians are especially active on the social media; they share crucial information with each other through social media and instant messaging platforms. By sharing local information about their neighbourhood during the flood, others use this real-time information as to make decisions, reduce risk, and improve safety.Though the local government has received some support from NGOs, private companies, and other agencies in terms of collecting information from the field during disaster events, this information is usually not well-integrated with their operational system, which can cause problems during emergency situation. By beginning from the chaotic reality experienced by residents and first responders during flood events, PetaBencana.id team created a design brief for their platform that made sure it would easily collect disaster reports from social media and integrate with real-time updates from governmental agencies. In the same time, the platform was designed to support peer-to-peer sharing and to democratize decision support by allowing residents with internet access to freely use the platform. PetaBencana.id also runs on free and open source software, which is a key to maintain public transparency and make the project sustainable.

Flood Frequency Analysis Using Participatory GIS and Rainfall Data for Two Stations in Narok Town, Kenya

Flood management requires in-depth computational modelling through assessment of flood return period and river flow data in order to effectively analyze catchment response. The participatory geographic information system (PGIS) is a tool which is increasingly used for collecting data and decision making on environmental issues. This study sought to determine the return periods of major floods that happened in Narok Town, Kenya, using rainfall frequency analysis and PGIS. For this purpose, a number of statistical distribution functions were applied to daily rainfall data from two stations: Narok water supply (WS) station and Narok meteorological station (MS). The first station has a dataset of thirty years and the second one has a dataset of fifty-nine (59) years. The parameters obtained from the Kolmogorov–Smirnov (K–S) test and chi-square test helped to select the appropriate distribution. The best-fitted distribution for WS station were Gumbel L-moment, Pareto L-moment, and Weibull distribution for maximum one day, two days, and three days rainfall, respectively. However, the best-fitted distribution was found to be generalized extreme value L-moment, Gumbel and gamma distribution for maximum one day, two days, and three days, respectively for the meteorological station data. Each of the selected best-fitted distribution was used to compute the corresponding rainfall intensity for 5, 10, 25, 50, and 100 years return period, as well as the return period of the significant flood that happened in the town. The January 1993 flood was found to have a return period of six years, while the April 2013, March 2013, and April 2015 floods had a return period of one year each. This study helped to establish the return period of major flood events that occurred in Narok, and highlights the importance of population in disaster management. The study’s results would be useful in developing flood hazard maps of Narok Town for different return periods.

Mapping Impact of Tidal Flooding on Solar Salt Farming in Northern Java using a Hydrodynamic Model

The number of tidal flood events has been increasing in Indonesia in the last decade, especially along the north coast of Java. Hydrodynamic models in combination with Geographic Information System applications are used to assess the impact of high tide events upon the salt production in Cirebon, West Java. Two major flood events in June 2016 and May 2018 were selected for the simulation within inputs of tidal height records, national seamless digital elevation dataset of Indonesia (DEMNAS), Indonesian gridded national bathymetry (BATNAS), and wind data from OGIMET. We used a finite method on MIKE 21 to determine peak water levels, and validation for the velocity component using TPXO9 and Tidal Model Driver (TMD). The benchmark of the inundation is taken from the maximum water level of the simulation. This study utilized ArcGIS for the spatial analysis of tidal flood distribution upon solar salt production area, particularly where the tides are dominated by local factors. The results indicated that during the peak events in June 2016 and May 2018, about 83% to 84% of salt ponds were being inundated, respectively. The accurate identification of flooded areas also provided valuable information for tidal flood assessment of marginal agriculture in data-scarce region.

Systematic Hydrological Evaluation of the Noah-MP Land Surface Model over China

We evaluate water budget components—namely, soil moisture, runoff, evapotranspiration, and terrestrial water storage (TWS)—simulated by the Noah land surface model with multi-parameterization options (Noah-MP) in China, a large geographic domain challenging for hydrological modeling due to poor observational data and a lack of one single parameterization that can fit for complex hydrological processes. By comparing the model simulations with multi-source reference data, we show that Noah-MP can generally reproduce the overall spatiotemporal patterns of runoff and evapotranspiration over six major river basins, with the annual correlation coefficients generally greater than 0.8 and the Nash-Sutcliffe model efficiency coefficient exceeding 0.5. Among the six basins evaluated, the best model performance is seen over the Huaihe River basin. The temporal trend of the modeled TWS anomalies agrees well with GRACE (Gravity Recovery and Climate Experiment) observations, capturing major flood and drought events in different basins. Experiments with 12 selected physical parameterization options show that the runoff parameterization has a stronger impact on the simulated soil moisture-runoff-evapotranspiration relationships than the soil moisture factor for stomatal resistance schemes, a result consistent with previous studies. Overall, Noah-MP driven by GLDAS forcing simulates the hydrological variables well, except for the Songliao basin in northeastern China, likely because this is a transitional region with extensive freeze-thaw activity, while representations of human activities may also help improve the model performance.

Major flood events recorded in the Holocene sedimentary sequence of the uplifted Ladiko and Makrisia basins near ancient Olympia (western Peloponnese, Greece)

Detailed palaeoenvironmental studies were conducted in the Ladiko and Makrisia basins near the Alpheios River and ancient Olympia (western Peloponnese, Greece) to assess major landscape changes during the Holocene. Previous studies and literature data document that the area experienced crust uplift of minimum 13 m to 30 m since the mid-Holocene. Geological archives were sampled along a vibracore transect connecting the Ladiko and Makrisia basins. Sediment cores were analyzed using sedimento-logical, geochemical and micropalaeontological methods. Geochronological reconstruction of major landscape changes is based on a set of 24 radiocarbon dates. Geophysical studies were carried out using electrical resistivity tomography (ERT) and Direct Push-Electrical Conductivity (DP-EC) measurements to detect stratigraphic changes and subsurface bedrock structures. The stratigraphic record of the uplifted lake basins of Ladiko and Makrisia revealed two major lithostratigraphic units. Unit I, predominantly composed of clay, silt and silty fine sand, reflects prevailing low-energy sedimentary conditions typical of quiescent (fluvio-)limnic waterbodies. Unit II is made out of fine to coarse sand and documents repeated interferences of unit I associated with abrupt and temporary high-energy flood type (= heft) events. We found signals of four different heft events (H1 to H4) showing strong stratigraphic and geochronological consistencies along the vibracore transect. The following age ranges were determined: H1 – between 4360 – 4330 cal BC and 4320 – 4080 cal BC; H2 – be- tween 2830 – 2500 cal BC and 2270 – 2140 cal BC; H3 – between 1220 –1280 cal AD and 1290 –1390 cal AD; H4 – between 1640 –1800 cal AD and 1650 –1800 cal AD. Different hypotheses concerning the characteristics, potential trigger mechanisms and causes of the flood events were tested against the background of strong Holocene crust uplift and using a variety of different methodological approaches: Geomorphological and granulometric aspects, micropalaeontological contexts, geochronological data sets, numerical simulation of flooding events, local tectonic uplift, and the palaeoclimate background were taken into account. We hypothesize that, during the mid-Holocene, the study area was affected by tsunami events, namely between 4360 – 4330 cal BC and 4320 – 4080 cal BC (H1) and between 2830 – 2500 cal BC and 2270 – 2140 cal BC (H2). These ages are very well consistent with the supra-regional and regional tsunami event signal retrieved from many coastal archives in large parts of western Greece. The timing of flood events H1 and H2 is highly consistent with ages of (supra-)regional tectonic events known from literature and is not consistent with increased flood indices of palaeoclimate data available for western Greece. Tsunami inundation scenarios based on numerical simulation are highly consistent with vibracoring and geophysical (ERT, DP-EC) data. In contrast, heft events H3 and H4 are possibly related to phases of increased precipi- tation and flooding activity in the Mediterranean or to land-based geomorphological processes triggered by regional tectonic events (RTE). Neolithic, Chalcolithic as well as Early and Middle Helladic human activities documented at ancient Olympia were most probably affected by tsunami heft events H1 and H2. Sandy deposits of tsunami event H2, covering the prehistorical tumulus, seem to have been used as a higher and dry base to construct the apsidal houses in the center of the later sanctuary at Olympia. The site, already abandoned, must have again been subject to major flood events during the 13/14th cent. AD and the 17–19th cent. AD associated with heft events H3 and H4.

EXTENT MAPPING OF A MAJOR FLOODING EVENT ON THE ISLAND OF TRINIDAD USING SPACE-BORNE SYNTHETIC APERTURE RADAR

Abstract. Flooding events around the world have been increasing both in their occurrence and their intensities within recent decades. Studies have shown that this is most likely linked to climate change effects and anthropogenic activities that lead to pollution. Irrespective of the cause, floods incur massive economic and human losses. Synoptic data on flooding events help to support the planning and management efforts during this disaster event. Remotely sensed data, particularly from satellites is useful for mapping and monitoring large scale flooding events. More specifically, synthetic aperture radar (SAR) allows for data acquisition despite the interference of clouds and other atmospheric elements such as fog, light rain and mist. This study utilized SAR data from the Sentinel–1 satellite to map a major flooding event on the island of Trinidad which occurred during October 18–21, 2018. The peak of the flooding was estimated to have occurred on October 20, 2018. The SAR images were first calibrated then geometrically corrected and filtered. A threshold method was then applied to extract the inundated areas. A proprietary algorithm implemented by Geospatial Enabling Technologies (GET) and based on SNAP software, was used for processing Sentinel-1 imagery to separate the open water and non-water (land) areas from the images. Outputs were then integrated into ArcGIS 10.6 mapping software and the extents of the flooded areas were delineated based on the available data. By applying this method to a Sentinel–1 image captured on October 19, 2018 it was revealed that the total flooded area on that date was 9.94 square kilometres. This study provides a brief illustration of the value of SAR data for flood delineation and mapping but also highlights some of the limitations that can be involved when using such technology.

Effects of hydraulic engineering restoration measures on invasive gobies in a large river (Danube, Austria)

Invasive gobies can have severe detrimental effects on local fish communities, however, direct methods for population control are often insufficient (i.e. fishing) or not feasible (i.e. poisoning). Indirect methods, such as habitat modifications in the course of restoration programs, appear promising but are poorly studied. In this study, we investigate the effects of different restoration measures on the abundance and occurrence of non-native gobies in the main stem of a free-flowing section of the Danube and attempt to disentangle these measures from general large-scale trends by applying a Before-After-Control-Impact design. We found three invasive goby species (racer, bighead, and round goby) in the sampling area, partly with very high abundances. Four to six years after the installation, the measures had negative (riprap removal), neutral (side arm reconnection), or positive (groyne field adaptations) effects on goby abundances. We conclude that the impact of the measures depends on the type of intervention, is species-specific, and is largely related to substrate composition. Independent from the effect of the measures, abundances of bighead and round goby dropped in the project and reference sections after the pre-survey. This general decline probably indicates a stabilization phase of the goby populations on a lower level, but may also be influenced by a major flood event. Nevertheless, our results indicate a high potential of shoreline modifications for invasive species control, calling for considering and incorporating them in river restoration programs.

Increasing Synchrony of Annual River‐Flood Peaks and Growing Season in Europe

AbstractIn a changing climate, time sensitive ecological interactions such as pollination and predation are vulnerable to temporal mismatch with direct consequences for ecosystem functioning. It is not known if synchrony and asynchrony of ecological and physical processes such as flood disturbance and plant phenology may similarly be affected by climate change. Here, by spatially merging temperature and flood peak data, we show for the first time that in Central and Eastern Europe, annual river flood peaks increasingly occur within the thermal growing season. This is due to the combined effect of earlier spring onsets and later flood peaks. Such increased physical‐phenological synchrony may especially impact river biogeomorphology and riparian floodplain ecosystem functioning through uprooting of seedlings and increased hydraulic roughness during major flood events.

Comparison of Satellite Passive Microwave With Modeled Snow Water Equivalent Estimates in the Red River of the North Basin

The Red River of the North basin (RRB) is vulnerable to spring snowmelt flooding because of its flat terrain, low permeability soils, and the presence of river ice jams resulting from the river's northward flow direction. The onset and magnitude of major flood events in the RRB have been very difficult to forecast, in part due to limited field observations of snow water equivalent (SWE). Coarse-resolution (25-km) passive microwave observations from satellite instruments are well suited for the monitoring of SWE. Despite routine use in the Earth sciences community to document the impacts of climate change, the use of passive microwave observations in operational flood forecasting is rare. This paper compares daily satellite passive microwave SWE observations from special sensor microwave/imager (SSM/I) and special sensor microwave imager/sounder (SSMIS), advanced microwave scanning radiometer for earth observing system (AMSR-E), and advanced microwave scanning radiometer 2 (AMSR2) from 2003 to 2016 to modeled output from the SNOw Data Assimilation System (SNODAS) and Global Snow Monitoring for Climate Research -2 (GlobSnow-2) in the RRB to determine the differences between the remotely sensed SWE estimates and the model products currently used in flood forecasting. Results show statistically significant differences between the satellite observations and SNODAS in the northern region of the basin that were not evident in the southern region. Satellite estimates of peak SWE in the forecast subbasins in the northern region were 40–125% higher than the model results which points to the lack of ground observations used to constrain the model simulations. This paper recommends that satellite SWE observations should be considered for improving operational snowmelt forecasting in the RRB.

Water Pathways for the Hindu-Kush-Himalaya and an Analysis of Three Flood Events

The climatology of major sources and pathways of moisture for three locales along the Hindu-Kush-Himalayan region are examined, by use of Lagrangian methods applied to the ERA-Interim dataset, over the period from 1980 to 2016 for both summer (JJA) and winter (NDJ) periods. We also investigate the major flooding events of 2010, 2013, and 2017 in Pakistan, Uttarakhand, and Kathmandu, respectively, and analyse a subset of the climatology associated with the 20 most significant rainfall events over each region of interest. A comparison is made between the climatology and extreme events, in the three regions of interest, during the summer monsoon period. For Northern Pakistan and Uttarakhand, the Indus basin plays the largest role in moisture uptake. Moisture is also gathered from Eastern Europe and Russia. Extreme events display an increased influence of sub-tropical weather systems, which manifest themselves through low-level moisture transport; predominantly from the Arabian sea and along the Gangetic plain. In the Kathmandu region, it is found that the major moisture sources come from the Gangetic plain, Arabian Sea, Red Sea, Bay of Bengal, and the Indus basin. In this case, extreme event pathways largely match those of the climatology, although an increased number of parcels originate from the western end of the Gangetic plain. These results provide insights into the rather significant influence of mid-latitudinal weather systems, even during the monsoon season, in defining the climatology of the Hindu-Kush-Himalaya region, as well as how extreme precipitation events in this region represent atypical moisture pathways. We propose a detailed investigation of how such water pathways are represented in climate models for the present climate conditions and in future climate scenarios, as this may be extremely relevant for understanding the impacts of climate change on the cryosphere and hydrosphere of the region.

Reconstructing the man-made Yellow River flood of Kaifeng City in 1642 AD using documentary sources

The Yellow River flood of September 1642 AD was one of the most extreme events inflicted on Kaifeng city which also had ramifications across the wider Yellow River region. Using all the available and predominantly non-instrumental data, this paper presents a geographical reconstruction of the 1642 AD flood. Through this reconstruction of the 1642 AD flood, a flood that resulted in the worst urban disaster in Yellow River history, reveals the series disaster spatial processes associated with the actual flood event. After introducing the disaster scene, this paper then goes on to help develop an understanding of the relationships between the geographical situation, climate factors, military purposes, people and the Yellow River at that time. The results show that reconstructing flood processes, is a very effective method for improving our understanding of major flood events, including natural and humanity effects of such events. Furthermore, the analysis of historical documents and archaeological findings may significantly contribute to a better and more detailed understanding of the space and time relationships involved in flood processes and the consequential impact of such floods.

Developing flood mitigation measures for the northern part of Nicosia

This study aims to examine a set of alternatives as remedial measures for the flood management purposes in order to protect the northern part of Nicosia which has been affected by major flooding events in recent years. In this context, at first, in order to obtain the run-off hydrographs at the entrance of reservoirs, the hydrological modelling of the ungauged catchments of Kanlikoy and Gonyeli Reservoirs which are located at the upstream part of the city was performed. In the simulation of these rainfall–run-off processes for different extreme precipitation events, the HEC-HMS software was employed using Soil Conservation Service Unit Hydrograph approach. In hydraulic modelling, the branches of Pedieos (Kanlidere) River and its urbanized floodplain were modelled by coupling the models of one-dimensional (1D) MIKE 11 and two-dimensional (2D) MIKE 21 using MIKE FLOOD tool. The calibration of the coupled hydrodynamic model was carried out by locally modifying the Manning’s roughness coefficients of the floodplains to match with the observed flood inundation extent of 2010 Flood. Consequently, the calibrated model showed nearly 94% similarity in terms of simulating the flood extent areas. Amongst different alternatives, the final proposed solution consisting of implementation of a new nearby upstream reservoir in Kanlikoy, dredging Gonyeli Reservoir and raising the crest elevations of its embankment and spillway, and restoration of possible channels sufficiently contributed to the mitigation of inundation problem and protected the northern part of Nicosia against the flooding events up to 500-year return period.

Reconstructing the channel shifting pattern of the Torsa River on the Himalayan Foreland Basin over the last 250 years

Abstract The varied physiography, incidences of high seasonal discharge, influences of neo-tectonic activity and the young geological foundation with less consolidated cohesive and non-cohesive sediment have left the Himalayan foreland basin a formidable ground, where silt-laden rivers tend to migrate frequently. A set of maps prepared after 1764, space photographs captured in 1970 and current satellite images from 2015 and 2017 were studied to reconstruct the fluvial dynamics of the Torsa River on the foreland basin of Sikkim-Bhutan Himalaya considering a time span of nearly 250 years. Evidence collected from colonial literature, the above-mentioned satellite images and a field survey, were combined to verify results taken from the old maps used as the base of the study. The application of satellite remote sensing and analysis of the topographic signatures of the palaeo-courses in the form of the palaeo-levee, abandoned courses and ox-bow lakes were the major operational attributes in this study. As a consequence of the channel migration of Torsa River since 1764, the historical floodplain of Torsa has been topographically marked by beheaded old distributaries, a misfit channel system and the presence of abandoned segments. Morphometric changes in the old courses, major flood events and neo-tectonic activity guided an overall trend of channel migration eastwards and has led to a couple of channel oscillation events in the Torsa River over the last 250 years. The mechanism of the avulsion events was thoroughly driven by sedimentation-induced channel morphometric changes and occasional high discharge.

Challenges and Future Directions in Ocean Wave Modeling — A Review

An increasing number of instances in extreme weather events over the global oceans have deepened the concerns on the impact of climate change. The frequency of extreme weather events is also seen to increase attributes to climate change across the globe. In the Indian context, there has been about 285 reported flooding events over the period from 1950 to 2017 that affected nearly 850 million people with many causalities. As the global oceans become stormier, the effects are seen in rising sea level and infrastructural facilities. Major flooding events are caused by tropical cyclone-induced storm surge and associated breaking waves. These extreme weather events coupled with sea level rise have serious repercussions on the coastal vulnerability. Also recently, there is an upsurge in the intensity and tropical cyclone size that forms over the North Indian Ocean region that brought attention among the scientific community. The worst possible scenario of extreme water level can occur when the time of storm surge occurrence coincides with the astronomical high water. This review paper provides a comprehensive overview on the research developments and efforts made in ocean wave modeling in particular for the Indian seas. As per the Fifth Assessment Report of Intergovernmental Panel on Climate Change (IPCC), the role and influence of ocean surface gravity wave in the climate system are considered to be very important. At present, numerical models are widely used and that can be used to hindcast and forecast the wave characteristics over both regional and global ocean basin scales. A detailed overview on the observational techniques is listed along with the historical perspective and recent developments in wind-wave modeling for the Indian seas. Recent developments in computing technology and advanced numerical techniques have made it possible to solve the complex problems in coastal science and engineering using state-of-the-art numerical models providing realistic estimates, cost effective and having immense potential in operational weather centers. This review also deals with some of the important issues and future directions in wind-wave modeling studies such as improvements required in momentum transfer, bottom dissipation, and rain–wave interaction effects that require detailed understanding and concentrated efforts.

Quantifying bed‐related suspended load in gravel bed rivers through an analysis of the bedload‐suspended load relationship

AbstractSuspended load transport can strongly impact ecosystems, dam filling and water resources. However, contrary to bedload, the use of physically based predicting equations is very challenging because of the complexity of interactions between suspended load and the river system. Through the analysis of extensive data sets, we investigated extent to which one or several river bed or flow parameters could be used as a proxy for quantifying suspended fluxes in gravel bed rivers. For this purpose, we gathered in the literature nearly 2400 instantaneous field measurements collected in 56 gravel bed rivers. Among all standard dimensionless parameters tested, the strongest correlation was observed between the suspended sediment concentration and the dimensionless bedload rate. An empirical relation between these two parameters was calibrated. Used with a reach average bedload transport formula, the approach allowed to successfully reproduce suspended fluxes measured during major flood events in seven gravel bed alpine rivers, morphodynamically active and distant from hillslope sources. These results are discussed in light of the complexity of the processes potentially influencing suspended load in a mountainous context. The approach proposed in this paper will never replace direct field measurements, which can be considered the only confident method to assess sediment fluxes in alpine streams; however, it can increment existing panel tools that help river managers to estimate even rough but not unrealistic suspended fluxes when measurements are totally absent. © 2019 John Wiley & Sons, Ltd.

Culture-Documented Invasive Mold Infections at MD Anderson Cancer Center in Houston, Texas, Pre– and Post–Hurricane Harvey

BackgroundExtensive floodwater damage following hurricane Harvey raised concerns of excess mold infections in immunocompromised patients. This study sought to evaluate the impact of hurricane Harvey on the incidence of culture-positive invasive mold infections (cIMIs) in patients treated at MD Anderson Cancer Center (MDACC; Houston, TX).MethodsAll mold-positive culture results in the Microbiology Laboratory at MDACC in a 12-month period before and after hurricane Harvey were reviewed. cIMI cases were defined according to European Organization for Research and Treatment of Cancer/Invasive Fungal Infections Cooperative Group and the National Institute of Allergy and Infectious Diseases Mycoses Study Group criteria. Rates and causative agents of cIMIs pre- and post-Harvey were compared. In addition, we evaluated institution-wide trends in the use of systemically administered mold-active antifungal agents by segmented regression analysis.ResultsInpatient cIMI rates per 1000 patient-days were comparable in the pre- and post-Harvey observation period (0.17 vs 0.21, P = .36). During both surveillance periods, the vast majority of cIMI cases were due to Aspergillus spp., Fusarium spp., or Mucorales. No emergence of unusual mold infections was seen, and the relative frequencies of mold genera recovered from cultures at the MDACC Microbiology Laboratory remained largely unaltered. The overall use of posaconazole was significantly higher in the post-Harvey period and the use of both voriconazole and liposomal amphotericin B began to increase significantly immediately after Harvey.ConclusionsOur monocentric study employing stringent culture-based definitions of mold infections found no excess cases of IMIs in MDACC’s immunosuppressed patient population in the aftermath of a major flooding event. Increased use of some mold-active antifungals in the aftermath of hurricane Harvey was observed institutionally.

Flooding in Townsville, North Queensland, Australia, in February 2019 and Its Effects on Mosquito-Borne Diseases.

In February 2019, a major flooding event occurred in Townsville, North Queensland, Australia. Here we present a prediction of the occurrence of mosquito-borne diseases (MBDs) after the flooding. We used a mathematical modelling approach based on mosquito population abundance, survival, and size as well as current infectiousness to predict the changes in the occurrences of MBDs due to flooding in the study area. Based on 2019 year-to-date number of notifiable MBDs, we predicted an increase in number of cases, with a peak at 104 by one-half month after the flood receded. The findings in this study indicate that Townsville may see an upsurge in the cases of MBDs in the coming days. However, the burden of diseases will go down again if the mosquito control program being implemented by the City Council continues. As our predictions focus on the near future, longer term effects of flooding on the occurrence of mosquito-borne diseases need to be studied further.

Using spectrocolourimetry to trace sediment source dynamics in coastal catchments draining the main Fukushima radioactive pollution plume (2011–2017)

Spectrocolourimetric measurements provide a relatively inexpensive, quick and non-destructive alternative to the analysis of geochemical and organic matter properties. When used in the analysis of sediments and their potential sources, these colour parameters may provide important information on the dominant processes (i.e. erosion) occurring in the Critical Zone. Here, they are used to investigate whether eroded sediment is derived from forest (i.e. natural), cultivated (i.e. anthropogenic) or subsoil sources in order to assess their potential to monitor the effect of decontamination in regions impacted by fallout from the Fukushima Dai-ichi Nuclear Power Plant (FDNPP) accident. Fifteen spectrocolourimetric properties (L*, a*, b*, C*, h, x, y, z, L, a, b, u*, v*, u’, v’) were measured in potential source (n = 37) and sediment (n = 400) samples collected during 13 campaigns from 2011 to 2017 after major flood events in two catchments (total surface area of 450 km2) draining the main FDNPP radioactive pollution plume. Potential sources included topsoil from forest and cultivated sources along with subsoil material originating from landslides, channel banks and the decontamination of cultivated areas. The optimum set of parameters used in the mixed linear model to calculate the sediment source contributions was obtained through the use of a range test, the Kruskal–Wallis H test and a linear discriminant analysis. Nine selected colour parameters correctly classified 100% of the source samples (i.e. forest, subsoil and cultivated sources). The results illustrate that cultivated landscapes were the main source of sediment to these river systems (mean 56%, SD 34%) followed by subsoil (mean 26%, SD 16%) and forest sources (mean 21%, SD 24%). However, these contributions varied strongly over time, with a peak of subsoil contributions (mean 57%, SD 17%) in Fall 2015, coinciding with the occurrence of a typhoon after the remediation works. These results were consistent with monitoring studies conducted in the same area that showed the major impact of typhoon Etau in September 2015 on sediment and radiocaesium fluxes. These original results demonstrate that spectrocolourimetric measurements may contribute to the routine monitoring of the effectiveness of remediation works in this post-accidental context. Owing to the inexpensive, rapid and non-destructive analyses, spectrocolourimetric-based tracing methods have significant potential to provide information on the dominant erosion processes occurring in the Critical Zone.