Increase In Frequency Of Floods Research Articles

Growth conditions of tree species relative to climate change and sea level rise in low-lying Mid Atlantic coastal forests

IntroductionCoastal forests occupy low-lying elevations, typically adjacent to tidal salt marshes. Exposed to increased flooding with sea level rise, coastal forests have retreated as salt marshes advance upslope. Coastal forests likely currently experience periodic tidal flooding, but whether they temporarily accommodate or quickly succumb to rising sea level under changing climatic conditions remains a complex question. Disentangling how tidal flooding and climate affect tree growth is important for gauging which coastal forests are most at risk of loss with increasing sea levels.MethodsHere, dendrochronology was used to study tree growth relative to climate variables and tidal flooding. Specifically, gradients in environmental conditions were compared to species-specific (Pinus taeda, Pinus rigida, Ilex opaca) growth in coastal forests of two estuaries (Delaware and Barnegat Bays). Gradient boosted linear regression, a machine learning approach, was used to investigate tree growth responses across gradients in temperature, precipitation, and tidal water levels. Whether tree ring widths increased or decreased with changes in each parameter was compared to predictions for seasonal climate and mean high water level to identify potential vulnerabilities.ResultsThese comparisons suggested that climate change as well as increased flood frequency will have mixed, and often non-linear, effects on coastal forests. Variation in responses was observed across sites and within species, supporting that site-specific conditions have a strong influence on coastal forest response to environmental change.DiscussionSite- and species-specific factors will be important considerations for managing coastal forests given increasing tidal flood frequencies and climatic changes.

Effects of Deforestation and Anthropogenic Aspects on Streamflow in the Mau Forest Catchments in Kenya: Hydrological Modelling of Surface Water Yields from Sondu River Basin

Climatic factors determine the amount and distribution of atmospheric water received at the land surface while the land cover conditions determine the partitioning of this water into different hydrological components and ultimately the catchment surface water yields. This study assessed the effects of deforestation of a tropical catchment on surface water yields to address fluctuating flows of the rivers emanating from Mau Forest, the largest water tower in Kenya. Sondu basin traverses Southwest Mau Forest covering an area of 3500 km2. The main channel in the basin flows in a southwest direction into Lake Victoria in an altitudinal range of 2900 to 1130 m a.s.l over a length of 173 km. Different deforestation scenarios over the basin were integrated with climate data to form inputs to a hydrologic model, Soil and Water Assessment Tool (SWAT). Using model outputs, the effects of deforestation on annual and seasonal surface water yields, represented by changes in streamflow volumes under different deforestation scenarios, were evaluated. Deforestation scenarios were derived from a supervised classification scheme of time series of LANDSAT images (1970-2020) to show deforestation trends. Effects of deforestation on the catchment water-yielding capacity were estimated as the ratio of the difference between simulated yields under different deforestation scenarios and those simulated under the pre-deforestation scenario of the 1970s decade. Results show that forest cover declined by 21% and a corresponding growth in land under agriculture by 26% in the period 1970-2020. The decline in forest coverage resulted in an increase in the annual surface water yields of about 23% (from 152 to 187 MCM/year) throughout the period of study. This implies that there is less recharge of groundwater due to decreased infiltration and subsequent storage leading to lower flows during the dry seasons and increased flood frequencies in the basin during the wet seasons. The study has therefore, demonstrated that deforestation has reduced the stability of Mau Forest as a water tower and conservation of the forest will enhance its water-holding capacity thereby ensuring a stable water supply to rivers emanating from it as a way of combating floods and low flows in the basin. The resultant impacts on environment and society are displacements from floods and destruction of properties.

Increasing Occurrence of Sudden Turns From Drought to Flood Over China

AbstractThis study focuses on a new compounding concern, the sudden turn from drought to flood (STDF), that is becoming increasingly prominent. This study investigates the long‐term trends and variability of STDFs in China during 1961–2020. The findings indicate that STDFs are prevalent in north and northeast China, and the Yangtze River Delta (YRD). The probability of a drought being followed by a severe flood is approaching 35% in northern and northeastern China. Since 1961, the number of STDFs in China has increased at a rate of average 2.8 events per decade. This increase mainly has occurred in late spring and early summer. The likelihood that a drought being followed by a significant pluvial is also increasing. The increasing STDF in northern China is mainly attributable to the increasing flood frequency and volatility of precipitation. Changes in the STDF trend is more dependent on the drought frequency in the YRD.

Catchment-scale hydrology limits the benefits of geomorphic complexity for instream vegetation communities

Improving instream habitat complexity is a common stream restoration approach despite often limited improvements to stream biota with catchment-scale stressors such as altered hydrology thought to be more important. Instream vegetation is a critical component of lowland stream ecosystems, providing multiple ecological benefits. Thus, we asked: How does instream vegetation respond to (1) geomorphic complexity; (2) different flow regime components; and (3) what is the relationship between geomorphic complexity and flow in driving instream vegetation?We surveyed instream vegetation and geomorphology along 23 lowland stream reaches. We investigated associations between six measures of geomorphic complexity, six flow metrics, and amphibious and aquatic vegetation richness, Shannon diversity and cover.Amphibious vegetation was negatively associated with simplified channels and increasing flood frequency. Increasing depth and width variation, and Julian day low flow variability, were positively associated with aquatic vegetation. Considering sites with complex (stable) or simplified (unstable) geomorphology separately, only vegetation at stable sites showed strong relationships to flow regime components, with variables related to flow flashiness negatively associated with both amphibious and aquatic vegetation, and Julian day low flow variability positively associated with aquatic vegetation.We identified channel complexity, variables related to flow flashiness and variation in low flow timing, as key geomorphic and flow drivers of instream vegetation, respectively. Importantly, our results suggest that instream vegetation benefits from improving geomorphic complexity are likely to be limited without also addressing altered flow regimes.

Palynological and sedimentological evidence for early mid-Holocene hydroclimatic variability in the Ningshao Plain, East China

The southeastern coastal areas of China represent one of the most populous and economically developed regions in China, but they are often severely affected by flood hazards. Therefore, studying the phenomenon and mechanisms behind extreme rainfall changes in this region is of great significance for economic and social development. In this study, we present high-resolution pollen and grain-size records from the Shanglin Lake located in Zhejiang, eastern China, based which changes in the frequency of paleo-flood events were reconstructed and the climatic context was inferred. Our pollen records show that the content of evergreen broadleaf trees gradually increased during 8000–7000 cal. yr BP, reflecting the gradually increasing temperature in the growing season. The content of Altingia increased substantially during the periods of 7960–7860, 7600–7500, and 7200–7100 cal. yr BP, especially in the first and last periods, indicating the prevalence of an El Niño-like condition in the study area during the early mid-Holocene warm period. Grain-size record shows that the prolonged El Niño condition facilitated a significant increase in flood frequency. Our results suggest that, similar to that of today, the early mid-Holocene warm climate was the most important factor controlling extreme hydroclimatic changes in the middle and lower reaches of the Yangtze River.

A flooded future for River Chub? Future impacts of climate change and urbanization on reproduction of a keystone native fish species

AbstractObjectivePredicted impacts of climate change in the eastern United States are pervasive and complex, including increased precipitation, increased frequency of heavy precipitation events, and altered seasonality of rainfall. This will potentially lead to increased flooding frequency and severity. The River Chub Nocomis micropogon is an important keystone and engineer species in the eastern United States, primarily through its construction of nesting habitat, which is shared with other species (“nest associates”) in a mutualistic relationship. River Chub nests are vulnerable to high flows caused by excessive precipitation and by urbanization of watersheds. Using predictions of climate change models, we examined the potential for increased River Chub nest disruption under two climate change scenarios.MethodsPublished thresholds linking River Chub nest disruption with stream discharge were used to interpret fine‐scale predictions of a downscaled climate prediction model (HadGEM2‐ES) using a stochastic weather generator (LARS‐WG6) calibrated to two climate change scenarios. This was examined for a case study watershed (Big Elk Creek, Maryland). The amount of River Chub nest disruption was compared between present‐day stream discharge observations (1995–2021) and simulated data for 2061–2080 under the “worst case” (RCP85) and “probable‐case” (RCP45) scenarios. Potential nest disruption in an urbanized stream that lost its River Chub (Gwynns Falls, Maryland) was also evaluated for comparison with Big Elk Creek scenarios.ResultSignificantly elevated nest disruption under both RCP45 and RCP85 relative to observed current conditions was found under status quo watershed characteristics in the form of more disruptive events, more disrupted days, and shorter periods of disruption‐free days during the River Chub nesting season. Potential nest disruption in the urbanized case study stream was far greater than that observed for any scenario.ConclusionIncreased nest disruption projected by the downscaled HadGEM2‐ES climate prediction model was moderate and far below the level of nest disruption observed in flashy urbanized streams that have lost or may have lost River Chub populations in the region. The moderate impacts of increased flooding from climate change will interact with projected population growth and urbanization for the Big Elk Creek watershed. Mechanistic modeling of fine‐scale processes by using stochastic weather generators shows promise for modeling the responses of ecosystems to changing conditions.

Hyperspectral imaging sediment core scanning tracks high-resolution Holocene variations in (an)oxygenic phototrophic communities at Lake Cadagno, Swiss Alps

Abstract. Pigments produced by anoxygenic phototrophic bacteria are valuable proxies of past anoxia in lacustrine and marine environments. Pigment measurement typically requires time-consuming and costly chemical extractions and chromatographic analyses, which limits the temporal resolution of paleoenvironmental reconstructions based on sedimentary pigments. Here, we evaluate the potential of in situ hyperspectral imaging (HSI) core scanning as a rapid, non-destructive method to document high-resolution changes in oxygenic and anoxygenic phototrophic communities at meromictic Lake Cadagno, Switzerland. Three distinct groups of pigments can be detected with the HSI method in the sediments of Lake Cadagno; each pigment group represents a different phototrophic community. Oxygenic phototrophs are indicated by total chloropigments (TChl; chlorophyll a, b, and derivatives). Two types of anoxygenic phototrophs were distinguished – purple sulfur bacteria (PSB), represented by bacteriochlorophyll a, and green sulfur bacteria (GSB), represented by bacteriochlorophyll c, d, and e. HSI pigment indices were validated by pigment measurements performed on extracted samples using spectrophotometer and high-performance liquid chromatography (HPLC). Bacteriochlorophylls were present throughout the past 10 kyr, confirming geochemical evidence of nearly continuous stratification and sulfidic conditions at Lake Cadagno. Major shifts in the anoxygenic phototropic communities are recorded at decadal to millennial scales. GSB and PSB communities coexisted from 10.2–8.8 kyr BP. Dominance of PSB over GSB from 8.8–3.4 kyr BP indicates strongly stratified conditions in the lake and strong light radiation at the chemocline. From 3.4–1.3 kyr BP, PSB were mostly absent, and GSB became dominant, implying lower light intensity at the chemocline due to a combination of factors including deforestation in the lake surroundings, increased flood frequency, cooler climatic conditions, and changes in groundwater solute concentrations. The high-resolution HSI data show that frequent flood events and mass movements disturbed the chemocline and the anoxygenic bacterial communities and that the PSB were particularly sensitive and slow to recover following these disturbance events. This study demonstrates for the first time that HSI can detect GSB-related pigments, making the method uniquely valuable as a rapid tool to study samples containing pigments of both oxygenic and anoxygenic phototrophs.

Human disturbances dominated the unprecedentedly high frequency of Yellow River flood over the last millennium.

A warming climate may increase flood hazard through boosting the global hydrological cycle. However, human impact through modifications to the river and its catchment is not well quantified. Here, we show a 12,000-year-long record of Yellow River flood events by synthesizing sedimentary and documentary data of levee overtops and breaches. Our result reveals that flood events in the Yellow River basin became almost an order of magnitude more frequent during the last millennium than the middle Holocene and 81±6% of the increased flood frequency can be ascribed to anthropogenic disturbances. Our findings not only shed light on the long-term dynamics of flood hazards in this world's most sediment-laden river but also inform policy of sustainable management of large rivers under anthropogenic stress elsewhere.

Increasing tidal inundation corresponds to rising porewater nutrient concentrations in a southeastern U.S. salt marsh.

Salt marshes are ecologically and economically important features of coastal environments that are vulnerable to sea level rise, the rate of which has accelerated in recent decades along the southeastern US Atlantic coast. Increased flooding frequency and duration across the marsh platform is predicted to impact vegetation community structure and overall marsh persistence, but the effect of changing inundation patterns on biogeochemical processes in marsh sediments remains largely unexplored. As part of a long-term monitoring effort to assess how marshes are responding to sea level rise in North Inlet estuary (South Carolina, USA), we collected data on porewater nutrient concentrations from a series of permanent monitoring plots across multiple transects spanning the marsh elevation gradient during the growing season from 2009 to 2019. Additionally, we calculated time inundated for each plot using local water level data and high-resolution elevation measurements to assess the change in time flooded at each plot. Our results indicate that both NH4 and PO4 nutrient concentrations have increased in most permanent plots over the 11-year study period and that nutrient concentrations are higher with increasing proximity to the creek. Spatial patterns in nutrient increases through time are coincident with considerable increases in tidal inundation observed over the marsh platform. Across plots located in the low marsh, porewater NH4 and PO4 concentrations have risen at average rates of 8.96 μM/year and 0.86 μM/year, respectively, and have reached rates as high as 27.25 μM/year and 3.13 μM/year. We suggest that increased inundation time due to rising sea level has altered biogeochemical conditions influencing nutrient availability in marsh porewater, resulting in increases that likely have relevance for larger scale nutrient cycles as well as marsh ecosystem stability and function.

Changes in flooding in the alpine catchments of the Tarim River Basin, Central Asia

AbstractFloods are one of the most affective climate‐related disasters, and climate change has altered their intensity and frequency worldwide. This study examined long‐term changes in flood characteristics (including magnitude, frequency, and timing) in 30 alpine headwaters of the large endorheic Tarim River Basin, Central Asia. The contributions of climatic factors to flood (magnitude and timing) changes were investigated using numerical experiments in combination with the random forest approach. The following results were obtained: (1) Annual maximum flood peaks increased at most stations (89% stations) during 1961–2015 with increased flood frequency. Earlier flood peaks were observed in spring with a rate of 1.38 day per decade; for other seasons, changes in the occurrence time of flood peaks showed strong spatial variability. (2) Precipitation was the dominant factor for the increased flood magnitude in most catchments of the southern slope of the Tianshan Mountains, and temperature played a greater role in the northern Kunlun Mountains. (3) For flood timing changes, melt level height and precipitation were the most influential factors in the alpine catchments in the Tarim River Basin. The results provide information on the spatiotemporal variations of floods and their driving factors in this alpine basin under climate change.

Stream flow prediction using TIGGE ensemble precipitation forecast data for Sabarmati river basin

Abstract Flooding is the most prevalent natural disaster globally. Increasing flood frequency affects developing nations as these countries lack strong forecasting systems. The most flood-prone urban regions are near the coast or riverbanks. Using The International Grand Global Ensemble (TIGGE) data, a coupled atmospheric-hydrologic ensemble flood forecasting model for the Sabarmati river was developed. Incorporating numerical weather prediction (NWP) information into flood forecasting systems can increase lead times from hours to days. When predicting the weather, we employed numerous NWP models from various prediction centers. European Center for Medium Range Weather Forecasts (ECMWF), United Kingdom Meteorological Office (UKMO) and National Centers for Environmental Prediction (NCEP) data with a 5-day advance time are coupled with the HEC-HMS model to provide ensemble stream flow predictions. The ensemble flood forecasting model uses the 2015 flood season as a test scenario. In this research, we discovered that TIGGE ensemble prediction data can be useful for prediction of stream flow and results showed effective flood forecasting for Sabarmati river. HEC-HMS, a semi-distributed hydrologic model, uses ECMWF, NCEP, and UKMO precipitation ensembles. ECMWF shows that 90% of the correlation with observed data and peak time and peak discharge is also match with the observed discharge with a peak on 29 July 2015 with 9,300 cumecs. Danger probability may be accurately predicted based on peak time and flood warning probability distributions.

Spatiotemporal Characteristics of US Floods: Current Status and Forecast Under a Future Warmer Climate

AbstractFloods in the US exhibit strong spatiotemporal variability, mainly controlled by precipitation types and catchment attributes. In a future warmer climate, it remains largely unclear how such features change, relative to the current climate. Global Climate Models at coarse resolution cannot resolve convective‐scale storms which is one of the major weather systems causing devastating floods in the US. Alternatively, coupled, high‐resolution and continental‐scale climate and flood simulations can advance our understanding. In this study, we couple a 4‐km convection‐permitting climate simulation model with a 1‐km hydrologic model to simulate the spatiotemporal variability of rainfall and flooding over the contiguous US. In particular, changes in rainfall and flood frequency, spatial scale, and seasonality are explored in major climate divisions. We found: (a) an overall increase in flood frequency (+101.7%) and spatial extent (+44.9%), mainly attributed to more extreme rainfall and variability in the future; (b) weakening rainfall and flood seasonality, resulting in more random and unpredictable events throughout the year; (c) earlier flooding season onsets in the West and snow‐dominated regions while delayed onsets in the East driven by drier antecedent soil moisture; (d) correlation between extreme rainfall and flood onsets is becoming stronger in the West yet weaker in the East in the future. Findings in this study can potentially serve as a basis for future flood exposure and risk assessments, as well as more scientific understanding of changing flood‐generating mechanisms across the CONUS.

Multi-source remote sensing data reveals complex topsoil organic carbon dynamics in coastal wetlands

• UAV data accurately predicted SOC concentrations (RMSE < 2.44 %) • Radar data characterized spatial patterns of flood frequency in coastal areas. • The effect of flood frequency on SOC was highest at pioneer and seaward communities. • AGB showed a larger explanatory power than flood frequency in SOC predictions. • UAV-SAR fusion unveils site-specific fine-scale patterns of SOC in coastal meadows. Coastal wetlands are considered important stores of blue carbon, containing some of the largest stores of pedologic and biotic carbon per unit area on the planet. These ecosystems are however highly sensitive to Climate Change and changes in the management practices. It is of utmost importance to address relevant ecosystem scales in order to fully understand carbon dynamics in coastal wetlands. In this regard, Unoccupied Aerial Vehicles (UAVs) can provide spatial scales detailed enough to address the fine scale patters of topsoil organic carbon accumulation in coastal wetlands. This study demonstrates the use of multispectral and photogrammetric data derived from UAVs to accurately map plant communities and topsoil organic carbon concentration in coastal wetlands. The overall accuracies from the classification of plant communities ranged from 88% to 97% whereas RMSE for topsoil organic carbon concentration ranged from 2.44% to 0.74%. By combining both models, site-specific variations in topsoil carbon concentrations among plant communities were unveiled. Open pioneer communities consistently showed the lowest topsoil organic carbon concentration, while the concentrations vary considerably across plant communities characterized by denser vegetation coverage. Furthermore, Sentinel-1 radar data was used to assess the spatial patterns of flood frequency. GAMs were used to combine flood frequency with the plant communities and topsoil organic carbon models, as well as an aboveground biomass (AGB) model from a previous study. GAMs revealed a stronger effect than flood frequency on topsoil organic carbon. Regarding flooding, increased flood frequency generally led decreased topsoil organic concentrations across communities and sites. However, the relative contribution of flood frequency to topsoil organic carbon concentration in Baltic coastal wetlands depends strongly on the location of the wetland and the nature of the floods. Higher flood frequencies could lead to increased topsoil organic carbon in wetlands subject to the input of estuarine sediments. Lastly, the integration of remote sensing platforms constitutes an effective tool for revealing spatial heterogeneity of carbon storage in coastal wetlands.

Climate Change Impacts on the Water Resources and Vegetation Dynamics of a Forested Sardinian Basin through a Distributed Ecohydrological Model

Climate change is impacting Mediterranean basins, bringing warmer climate conditions. The Marganai forest is a natural forest protected under the European Site of Community Importance (Natura 2000), located in Sardinia, an island in the western Mediterranean basin, which is part of the Fluminimaggiore basin. Recent droughts have strained the forest′s resilience. A long-term hydrological database collected from 1922 to 2021 shows that the Sardinian forested basin has been affected by climate change since the middle of the last century, associated with a decrease in winter precipitation and annual runoff, reduced by half in the last century, and an increase of ~1 °C in the mean annual air temperature. A simplified model that couples a hydrological model and a vegetation dynamics model for long-term ecohydrological predictions in water-limited basins is proposed. The model well predicted almost one century of runoff observations. Trees have suffered from the recent warmer climate conditions, with a tree leaf area index (LAI) decreasing systematically due to the air temperature and a vapor pressure deficit (VPD) rise at a rate of 0.1 hPa per decade. Future climate scenarios of the HadGEM2-AO climate model are predicting even warmer conditions in the Sardinian forested basin, with less annual precipitation and higher air temperatures and VPD. Using these climate scenarios, we predicted a further decrease in runoff and tree transpiration and LAI in the basin, with a reduction of tree LAI by half in the next century. Although the annual runoff decreases drastically in the worst scenarios (up to 26%), runoff extremes will increase in severity, outlining future scenarios that are drier and warmer but, at the same time, with an increased flood frequency. The future climate conditions undermine the forest’s sustainability and need to be properly considered in water resources and forest management plans.

Increasing Arctic Tundra Flooding Threatens Wildlife Habitat and Survival: Impacts on the Critically Endangered Siberian Crane (Grus leucogeranus)

Climate change is causing Arctic temperatures to increase at least twice as fast as the planet on average. Temperature and precipitation are predicted to continue increasing, such that flooding might become more prevalent in the new Arctic. Increased flooding frequency and extreme flooding events may pose new threats to Arctic biodiversity through habitat disturbance and decreased survival. We used the Siberian crane (Grus leucogeranus) as a model organism to investigate how flooding influences nesting habitat availability and juvenile counts. When spring flooding destroys eggs, adults either do not raise any chicks or have reduced time to prepare them for their long migration to China, thus years with extensive flooding could negatively impact future crane generations. We used nest site observation data from 14 surveys between 1995 and 2019, habitat mapping based on Landsat 8 imagery, and species distribution modeling to predict Siberian crane potential nesting habitat. Nesting habitat loss due to extreme flooding was calculated by overlaying this potential nesting habitat with Global Surface Water data. The percent of potential flooded nest sites varied between 6.7–55% across years, with a significant increase between 2001 and 2018. Extreme flood events, as experienced in 2017 and 2018, eliminated almost half of the potential nesting habitat. Importantly, we found that the percentage of flooded nest sites across years was negatively correlated with the number of observed juveniles. The Arctic lowlands are exposed to seasonal water level fluctuations that species have evolved with and adapted to. Siberian cranes and other species depending on Arctic ecosystems are expected to continue adapting to changing flood conditions, but extreme flood events further threaten the long-term survival of critically endangered species. It is imperative to assess how ecosystems and species respond to climatic extremes to support Arctic conservation strategies.

Soil Organic Carbon Storage, Active Component Contents, and Stability Along a Flooding Gradient in the Tidal Wetland of the Jiulong River Estuary

Flooding is one of the key environmental factors affecting the carbon sequestration potential of estuarine tidal flat wetlands. In order to reveal the effect of flooding on soil carbon (C) sinks in estuarine tidal wetlands, we investigated and analyzed the soil organic carbon (SOC) storage, the contents of active SOC components, and SOC stability indicators across a tidal flat in the Jiulong River estuary in southeast China. The results showed that the SOC storage gradually decreased by 54% with the increase in flooding frequency. The change pattern of microbial biomass carbon (MBC), dissolved organic carbon (DOC), and liable organic carbon (LOC) followed the change pattern of the SOC storage. With the increase in flooding frequency, DOC/SOC and LOC/SOC increased by 80% and 26%, respectively, whereas MBC/SOC decreased by 29%. As flooding frequency increased, particulate organic carbon (POC) and mineral-associated organic carbon (MAOC) contents decreased by 81% and 35%, respectively. The decreases in POC contents were correlated with the increases in soil pH, whereas the decreases in MAOC contents were associated with the decline in clay contents. Soil carbon stability index (CSI) increased by 246% with increasing flooding frequency. These combined results indicated that SOC storage decreased, but SOC stability increased, with the increased flooding frequency. Mineral-bound organic carbon was the main protection mechanism for the SOC stability, which was of great significance to the soil C sink of the estuarine tidal wetlands.

Drought and flood dynamics of Godavari basin, India: A geospatial perspective

Assessing incidence and trends of droughts and floods can provide essential information for better water resource management, particularly in the context of ongoing climate change. The present study has examined the prevalence of drought and flood events of Godavari basin, India, for the last four decades using the Standardized Precipitation Evapotranspiration Index (SPEI) 3 months and 9 months, and their trends using Mann–Kendall’s test and Sen’s slope. The spatial distribution, frequency, and intensity of drought and flood episodes in the basin are not uniform. A 20-year breakdown, 1980–1999 and 2000–2019, shows a drastic increase in drought frequency in Manjra and Pranhita sub-basins, while Godavari Upper, Indravati, and northern part of Weinganga have registered increased flood frequency. The monthly trend of SPEI-3 shows that most of the sub-basins have registered a negative trend (increasing dryness) only during the winter months, while under the SPEI-9 scenario both Manjra and Pranhita registered strong negative trend throughout the year. Sen’s slope estimations detected an increasing trend in severity from SPEI-3 to SPEI-9. Dryness severity trend is highest in Pranhita, followed by Manjra, Wardah, and Lower Godavari sub-basins, and the increasing wetness severity trend is in Upper Godavari, while rest of the sub-basins do not show any significant trend. The interior districts of the basin are more prone to the high drought conditions in near future if the current trends persist. To sustain the future climate change challenges, the vulnerable districts need urgent structural and non-structural changes in their current water resource management practices.Supplementary InformationThe online version contains supplementary material available at 10.1007/s12517-022-10041-5.

Geomorphic responses of fluvial systems to climate change: A habitat perspective

AbstractFluvial systems provide a variety of habitats that support thousands of species including many that are threatened or endangered. Moreover, these habitats, which range from aquatic and riparian to floodplain, are important for the variety of ecosystem services they provide. In addition to water temperature and streamflow change, geomorphic change is important and warrants consideration as one of the several potential threats to these habitats posed by climate change. The geomorphic response of fluvial systems to global warming in temperate environments, for example, caused by an increase in the frequency and magnitude of floods, is important because geomorphology is a primary determinant of habitat availability and quality. Possible geomorphic responses include increased erosion and (or) deposition in the river channel, riparian zone, and floodplain with associated habitat implications. Geomorphic changes caused by global warming can be beneficial (e.g., increased habitat complexity) or detrimental (e.g., mortality caused by scour or burial) to biota. The ability of a species to respond to and survive disturbances, including geomorphic changes, will depend on the nature of the disturbances and the sensitivity and adaptive capabilities of the species. Post‐flood recovery often is rapid; however, for certain species (e.g., periphyton, macroinvertebrates), changes in community composition may persist. Increased flood frequency, sediment mobility, and associated geomorphic changes potentially will result in more frequent and persistent changes in habitat and community composition in the affected fluvial systems.

An era of Sentinels in flood management: Potential of Sentinel-1, -2, and -3 satellites for effective flood management

AbstractThe repetitive and destructive nature of floods across the globe causes significant economic damage, loss of human lives, and leaves the people living in flood-prone areas with fear and insecurity. With enough literature projecting an increase in flood frequency, severity, and magnitude in the future, there is a clear need for effective flood management strategies and timely implementation. The earth observatory satellites of the European Space Agency’s Sentinel series, Sentinel-1, Sentinel-2, and Sentinel-3, have a great potential to combat these disastrous floods by their peerless surveillance capabilities that could assist in various phases of flood management. In this article, the technical specifications and operations of the microwave synthetic aperture radar (SAR) onboard Sentinel-1, optical sensors onboard Sentinel-2 (Multispectral Instrument) and Sentinel-3 (Ocean and Land Color Instrument), and SAR altimeter onboard Sentinel-3 are described. Moreover, the observational capabilities of these three satellites and how these observations can meet the needs of researchers and flood disaster managers are discussed in detail. Furthermore, we reviewed how these satellites carrying a range of technologies that provide a broad spectrum of earth observations stand out among their predecessors and have bought a step-change in flood monitoring, understanding, and management to mitigate their adverse effects. Finally, the study is concluded by highlighting the revolution this fleet of Sentinel satellites has brought in the flood management studies and applications.

Field observations to establish the impact of fluvial flooding on potentially toxic element (PTE) mobility in floodplain soils

Inundation of river water during flooding deposits contaminated sediments onto floodplain topsoil. Historically, floodplains were considered an important sink for potentially toxic elements (PTEs). With increasing flood frequency and duration, due to climate change and land use change, it is important to understand the impact that further flooding may have on this legacy contamination. In this study a field-based approach was taken, extracting soil pore waters by centrifugation of soils sampled on multiple occasions from multiple locations across a floodplain site, which lies adjacent to the River Loddon in southeast England. Flooding generally decreased pore water PTE concentrations and significantly lower pore water concentrations of Cd, Cu, and Cr were found post-flood compared to pre-flood. The dominant process responsible for this observation was precipitation with sulphides resulting in PTE removal from the pore water post-flood. The changes in pH were found to be associated with the decreased pore water concentration of Cu, which suggests the pH rise may have aided adsorption mechanisms or precipitation with phosphates. The impact of flooding on the release and retention of PTEs in floodplain soils is the net effect of several key processes occurring concurrently. It is important to understand the dominant processes that drive mobility of individual PTEs on specific floodplains so that site-specific predictions can determine the impact of future floods on the environmental fate of legacy contaminants.