Flood Conditions Research Articles

Efforts of Community Adaptation to Deal with Rob Floods on The Meulaboh Coastline

Most of Indonesia's territory is geographically located in the coastal area. One of the areas located in the coastal area is the city of Meulaboh, West Aceh Regency. The coastal area of Meulaboh often experiences tidal flooding, especially the coastal area of Gampong Pasir and has a quite severe impact compared to other areas on the coast of Meulaboh. Based on this background, this study aims to identify community adaptation to the tidal flood event based on community responses in the coastal area and identify efforts to mitigate the impact of tidal floods that have been carried out by the community and the government. The analytical methods used are descriptive quantitative and qualitative analysis methods, as well as cross-tabulation analysis related to community adaptation variables, which include community characteristics, the impact of tidal floods on the residential environment, identification of tidal flood conditions and efforts to mitigate the impact of tidal floods, carried out by the community and the government. The results showed that the people of the coastal area of Meulaboh were able to make efforts to deal with tidal floods in the form of repairing road networks, residential houses, drainage channels, places of worship (mosques), village offices, and clean water and sanitation systems. The government's efforts to deal with tidal floods are carried out by making barriers to protect the coast through tetrapod. These results are important to take future action to deal with tidal floods.

Carbon nano dots mixed rice bran oil as a cutting fluid for enhanced lubrication/cooling in milling of additively manufactured 316 stainless steel

Nanofluids, which have improved thermal conductivity compared to regular lubricants, can assist in the dissipation of heat while cutting materials. A colloidal suspension can be formed by dispersing nanoparticles within a base fluid. Their high thermal conductivity and viscosity make them a promising heat transfer fluid option; by using nano-additives, their cooling and lubricating capabilities may be further improved. Recently, carbon nanodots have grabbed the attention due to their many desirable characteristics, including their high solubility, chemical inertness, and low toxicity. Therefore, in this perspective, the thermophysical properties of rice bran oil enriched with carbon nanodots and their considerable impact on the machinability of 316 stainless steel produced additively has been examined. The different wt.% (0–1.25) of carbon nanodots are dispersed in rice bran oil to test the wettability, thermal conductivity, and dynamic viscosity. After that, milling tests are conducted under dry, flood, minimum quantity lubrication, and nano-minimum quantity lubrication conditions. The findings admit that the inclusion of nanoparticles in rice bran oil at 1 wt.% results in lower contact angle, higher thermal conductivity, and higher viscosity. In addition, the employment of nanoparticles in minimum quantity lubrication reduced the roughness by 60–63 %, 40–43 %, and 22–25 % in relation to dry, flood, and MQL conditions, respectively. The reduction in roughness has a direct influence on tool wear.

Regulation of straw decomposition and its effect on soil function by the amount of returned straw in a cool zone rice crop system

The degradation process of returned straw in rice fields can improve soil organic matter and promote sustainable agriculture. The degradation process of returned straw is a humification process as well as a mineralization process involving microorganisms and enzymes. However, the degradation process of returned straw, the effect on straw decomposing microorganisms and the regulatory mechanism on potential functionality under cool climate flooding conditions are currently unknown.For this purpose, we investigated the biodegradation of straw from a biodegradation point of view at 20, 40, 71, 104, and 137 d after return under conventional (130 kg hm−2), 1/3 straw return (2933 kg hm−2), 2/3 straw return (5866 kg hm−2), and full straw return (8800 kg hm−2) applications in cool climate rice fields.. The test found Paludibacteraceae and Archaeaceae were the dominant bacteria for straw degradation, and their relative abundance was highest when 2/3 of straw was returned to the field. The straw degradation extracellular enzyme activity was higher in the late return period (104 d). At this time, the potential functionality of the soil differed significantly among the different return amounts, with the best extracellular enzyme activity and potential functionality at the 2/3 straw return amount. Therefore, the optimal amount of rice straw returned to the field is 5866 kg hm−2 at the current conventional N application rate (130 kg hm−2) in the cold zone.

Integrating Non-photochemical Quenching (NPQ) Measurements for Identifying Flood-Tolerant Soybean Genotypes in the Era of Climate Change

Climate change has negatively affected agriculture worldwide, including soybean production. Studies have shown that rising temperatures and extreme weather events like droughts and floods significantly reduce soybean yields. Developing flood-tolerant soybean genotypes is crucial for ensuring food security. Conventional breeding programs are limited by laborious and imprecise visual rating methods for flooding tolerance identification. High-throughput platforms for plant phenotyping using imaging techniques offer potential solutions, but they lack information on underlying physiological mechanisms. Non-photochemical quenching (NPQ) is a molecular adaptation in photosynthesis that dissipates excess light energy, protecting plants from damage. This study aimed to integrate NPQ measurements into high-throughput phenotyping procedures to identify flooding-tolerant soybean genotypes. The study evaluated 160 soybean genotypes for flooding tolerance, identifying those with higher grain yield potential. Subsequently, ten genotypes were selected for monitoring NPQ responses under flooded conditions. Results showed that genotypes with higher grain yields also exhibited superior NPQ performance, suggesting a positive correlation between flooding tolerance and energy dissipation capacity. Among these genotypes, 58I60 RSF IPRO, 64HO130 I2X and BRS 525 displayed superior potential and could be further exploited in breeding efforts, considering their grain yield capacity, plant leaf area, and photoprotective capacity under flooding conditions. These findings suggest that integrating NPQ measurements into high-throughput phenotyping platforms can aid in identifying flood-tolerant soybean genotypes for breeding programs, leading to more resilient crops in the face of climate change. Further field studies are warranted to validate these hypotheses and improve crop models for future climate scenarios.

Root-hypoxia tolerance in soybean sister-lines plants indicates a better balance in energy use/dissipation and oxidative stress control

Climatic changes are leading to an increased number of flooding year by year which impacts negatively the metabolism of roots and influences the shoot metabolism which leads to a decline in soybean productivity. This can be more drastic when it is cultivated in lowland soils. Our group hypothesized that tolerant sister-line plants have more capacity to cope with oxidative stress due to better management of energy use and dissipation on photosynthesis machinery during root-flooding and recovery conditions, while in sensitive soybean sister-line the impairment of the photosynthetic use and dissipation of energy lead to an unbalanced redox state response. For that, soybean seeds from the same parents, PELBR15- 7015C (flooding tolerant) and PELBR15-7060 (flooding sensitive) were sowed and cultivated in 500 L capacity plastic containers with lowland soil simulating the field management process. At the reproductive stage, the roots were subjected to flooding for 11 days, then drained to analyze reoxygenation (3 d) and recovery (10 d). Tolerant plants have a greater ability to manage root flooding conditions compared to sensitive ones. The ability includes efficient energy use and dissipation, which minimizes the production of reactive oxygen species (ROS) and subsequent cell damage. Conversely, in sensitive sister lines, impaired electron transport chains lead to increased ROS production and damage. Upon reoxygenation and recovery, the tolerant sister lines exhibit a faster metabolism turnover, allowing them to cope more effectively with the stress on leaves and roots. While both sister lines are capable of detoxifying ROS, the tolerant sister line's superior ability to manage energy use and dissipation allows for more stable and rapid control of oxidative stress.

Temporal evolution of lake level fluctuations under flood conditions and impacts on the littoral ecosystems

Lake levels fluctuations are conditioned by seasonal variability, water resources management and climate change. Recent studies have shown that global warming potentially affects the risk of flooding and that the decisive factor for flood events is not temperature, but precipitation characteristics and hydrological conditions. Flood events have numerous impacts on social, economic and environmental aspects depending on how humans have altered lands, natural rivers and lake dynamics. Flood protection measures can cause conflicts with conservation measures and with ecosystem services because natural capital is not considered able to control floods and to contribute control floods and that it can contribute to human health and safety. In this paper we analysed the flood events in Lake Maggiore for return time periods of 3 – 5 – 10 – 25 – 50 – 100 – 250 – 500 years, considering the flood frequency in the last ten years using 1868-2021 as a reference period. We discussed the probability distribution of flood peaks, the correlation and linear regression between the lake level fluctuations and macroinvertebrates occurrence. We also presented lake coasts flood hazard mapping. The probability distribution that better describes the annual peak level is the Gumbel function, while for spring and autumn flood events the better distribution is the Log-Pearson type III. One of the historical flood events in terms of magnitude was in 2000, characterized by a return time of about 50 years. The last flood event in 2020, was characterized by a return period of about 10 years. Considering the seasonal frequency of flood, the autumn magnitude was higher than the spring one, and the differences between seasonal flood events progressively increased. The results suggested a high probability of a flood event every three years and also a forecast of a flood of about 197 m asl (3.14 m above the average lake level) every 10 years. Raising the lake level will affect the reed bed area from 193 m asl, and it will be more effective at 194.5 m (up to a 10% reduction). During flood events, the whole reed bed area is submerged. As regard macroinvertebrates composition and abundance, the first results show significant negative relationships between all sampling stations altogether vs the abundance of Cladotanytarsus sp. (Chironominae) and nearly significant positive relationships between water levels at Magadino vs Pscectrocladius sordidellus (Orthocladiinae) abundances. These few results are perhaps due to the current limited data availability.

Forecasting of Flood Flow of Panam River Basin using Adaptive Neuro-Fuzzy Inference System (ANFIS) and ANN with Comparative Study

Flood forecasting is one of the most important issues in the hydrology due to its indispensable contribution in lowering monetary and life losses. In recent years reliability of flood forecasting using various modelling tools has improved to a great extent due to hydrologic modelling, development in expertise and knowledge, and advancement in the collection of data and algorithms for evaluation. The current study presents the use of the Adaptive Neuro Fussy Inference System (ANFIS) in forecasting floods for the Panam River basin system. ANFIS combines neural network algorithms and fuzzy reasoning to map an input space to an output space. This paper includes the development of ANFIS models using various membership function and their comparison for forecasting the inflow rate into the Panam dam, which creates flooding conditions on the downstream side. The different evaluation parameters like Root Mean Square Error (RMSE), Correlation Coefficient (R), Coefficient of Determination (R2) and Discrepancy Ratio (D) are used to evaluate the results of each model. From all the developed ANFIS models, the best ANFIS model is selected, having RMSE as 271.91, R as 0.98, R2 as 0.96, and D as 1.00 for training the model, and RMSE as 2000.74, R as 0.95, R2 as 0.90 and D as 1.12 for validating the model. Artificial Neural Network (ANN) model has also been developed for forecasting flood. In the Neural network there are total 3 types of transfer function in each layer i.e., LOGSIG, TANSIG and PURELIN. All the developed is evaluated with the coefficient of correlation (R) and Mean Squared Error (MSE). In the end, future headings for innovative research work are discussed.

GIS-based identification and analysis of suitable evacuation areas and routes in flood-prone zones of Nakhon Si Thammarat municipality

Floods are a significant issue across Southeast Asia, with Thailand, particularly the Nakhon Si Thammarat Municipality, being heavily affected due to its unique conditions such as heavy rainfall, rapid urbanization, and low-lying coastal position. This study utilizes Geographic Information Systems (GIS) to analyze the flood-prone areas of Nakhon Si Thammarat Municipality, assess its road networks, and identify optimal evacuation locations and routes. Various data layers such as slope angle, elevation, distance from roads, rainfall, TWI, NDVI, land use, soil texture, distance from rivers, stream density, and road density are integrated using the frequency ratio method. The findings reveal areas with very high flood susceptibility, which span 198.78 sq. km (56.74%) at the high frequency level, 299.43 sq. km (37.63%) at the low frequency level, and 284.62 sq. km (53.88%) at the moderate frequency level. During flood scenarios, travel times saw an average increase to 21.4 min, which is a fourfold surge compared to regular conditions, highlighting the impact of floods on evacuation strategies. Upon evaluating the road network under flood conditions and applying network analysis techniques, efficient and safe evacuation routes were determined. The results, which underscore a fourfold increase in travel time during flood scenarios, present valuable insights for emergency management authorities across Thailand and Southeast Asia to devise comprehensive evacuation plans, thereby enhancing regional resilience against future flood events. Furthermore, the methodologies and findings are adaptable and can be applied to other flood-prone regions within Southeast Asia, contributing to improved disaster preparedness and response.

Effect of nicotinic acid in defence of wheat plants against hypoxia under flooding stress

Aim. The aim of the research was to investigate the induction of the Triticum aestivum L. non-specific tolerance by nicotinic acid to hypoxia during the flooding stress. Methods. Winter wheat plants cv. Ladyzhynka were grown in laboratory conditions and had been treated by nicotinic acid solution then flooding stress started. The hydrogen peroxide content in leaves and morphometric parameters were measured during the experimental period. Results. It is shown that the influence of the nicotinic acid was essential during the first hour of the flooding stress. After 96 hours of flooding stress the nicotinic acid balanced the hydrogenous peroxide level in wheat leaves close to control. Conclusions. Nicotinic acid decreased the stress level in wheat plants under flooding conditions via regulation of hydrogen peroxide content in leaves. The regulation of the hydrogen peroxide level could influence on plant adaptation to flooding stress and conditions of high humidity, decrease the damage of tissues and prevent their loss under flooding. Nicotinic acid could be used as a perspective component for compound combinations to induce complex stimulation of plant tolerance and defense against plant biotic and abiotic stresses.

AN APPLICATION OF 1-D MODEL FOR ASSESSING SALINE INTRUSION IN THE COASTAL AREAS OF THE VIETNAMESE MEKONG DELTA

Many studies in present years have been conducted to predict the effects of changes in the upstream discharge, hydrodynamics, and saline intrusion in the coastal of the Vietnamese Mekong Delta (VMD) (Smajgl et al., 2015; T. Van et al., 2013); however, the models for the entire delta did not show detail for small areas such as the Ca Mau Peninsula, and other studies were only considered in upstream flooding condition such as the Long Xuyen Quadrangle (Nguyen et al., 2012; T. Van et al., 2013). Besides, several study were using hydraulic models for the whole VMD region; Nevertheless, these studies were only interested in major river systems that applied the Mike 11 salt simulation model for the VMD region. Some hydraulic studies were simulated in specific region such as Long Xuyen Quadrangle. However, a few studies have focused on a complex river system such as Quan Lo Phung Hiep (QLPH) area of the Ca Mau peninsula, which is characterized by a complex river system, inter-regional irrigation works, and a variety of water demands, including marine, brackish, and freshwater-based agriculture. However, coastal studies, particularly those of an inter-regional character with complicated river networks like the QLPH, have received little attention. As a result, this research was carried out to assess the hydrodynamics and saline intrusions of the interwoven river network's coastal area, a complex operating system in a large area affected by both tidal regimes in the West and East Sea, which is characteristic of the Mekong Delta.

SUITABLE BOUNDARY LOCATION IDENTIFCATION FOR RAINFALL-RUNOFF AND SURGE MODEL COUPLING TO EVALUATE COMPOUND FLOOD HAZARDS IN COASTAL REGIONS

Flooding in many coastal regions is exacerbated due to complex interactions of multiple flood drivers such as rainfall-runoff and coastal surge which can occur simultaneously or sequentially during storm events, leading to compound flooding hazards. The Texas Gulf Coasts (USA) are especially vulnerable from compound flooding due to frequent occurrence of tropical storms which bring strong winds to drive storm surge and heavy rainfall to generate inland flooding. Large scale studies {Coastal Texas Restoration and Protection Study (CTX, 2021), Texas General Land Office’s Texas River Basin Study, Base Level Engineering Study} are being conducted by state and federal agencies for flood hazard assessment and for development of mitigation and abatement strategies for reducing this risk and increasing community resilience. Traditionally, large scale storm surge models do not account for runoff contributions to water levels in the interior of their domain. Riverine models for their part use either normal depth or mean high water levels to assign downstream boundary conditions within tidally influenced area, thus ignoring effects of storm surge. In this Planning Assistance to States (PAS) study, located in the Lower Clear Creek and Dickinson Bayou watersheds (Texas, USA), we have evaluated rainfall-runoff and storm surge interactions to determine suitable locations to use as model boundary conditions for exchanging data between rainfall-runoff and surge models under compound flooding conditions.

Transcriptomic and Metabolomic Analyses of Seedlings of Two Grape Cultivars with Distinct Tolerance Responses to Flooding and Post-Flooding Stress Conditions

Grapes, an important and widespread fruit crop providing multiple products, face increasing flooding risks due to intense and frequent extreme rainfall. It is thus imperative to fully understand the flood-tolerance mechanisms of grapevines. Here, RNA-seq and LC-MS/MS technologies were used to analyze the transcriptome and metabolome changes in the roots of SO4 (tolerant to flooding) and Kyoho (sensitive to flooding) grapes under flooding and post-flooding conditions. The results showed that the abundance of many metabolites in the phenylpropanoids and polyketides, organic acids and their derivatives, and organic oxygen compounds superclasses changed in different patterns between the Kyoho and SO4 grapes under flooding and post-flooding conditions. Jasmonic acid and the ascorbic acid–glutathione cycle played a pivotal role in coping with both hypoxia stress and reoxygenation stress incurred during flooding and post-flooding treatments in the SO4 cultivar. Under flooding stress, the regulatory mechanistic shift from aerobic respiration to anaerobic fermentation under hypoxia is partly missing in the Kyoho cultivar. In the post-flooding stage, many genes related to ethylene, gibberellins, cytokinins, and brassinosteroids biosynthesis and brassinosteroids-responsive genes were significantly downregulated in the Kyoho cultivar, adversely affecting growth recovery; however, their expression was not reduced in the SO4 cultivar. These findings enhance our understanding of the flooding-tolerance mechanisms in grapes.

Flood Monitoring and Alerting System

Abstract: Floods pose significant threats to communities worldwide, necessitating the development of efficient monitoring and alerting systems. This abstract presents an IoT-based Flood Monitoring and Alerting System that leverages the power of LoRaWAN (Long Range Wide Area Network) technology to provide real-time flood detection, monitoring, and timely alerts. The system consists of strategically placed water level sensors that use ultrasonic or pressure-based technology to accurately measure water levels. The sensor data is wirelessly transmitted to a central gateway through the LoRaWAN network, known for its long-range and low-power capabilities. A cloud-based platform processes and analyzes the collected data, identifying abnormal water level patterns and potential flood conditions. In case of a flood, the system triggers alerts via mobile notifications, email, and SMS to relevant authorities and stakeholders. Users can access real-time flood information, historical data, and visualizations through a user-friendly web or mobile interface. The system offers cost-effectiveness, extended range, low power consumption, early flood detection, timely response, data-driven decision-making, and has a brighter potential for future enhancements

Coupled sink and flow accumulation analyses with single flow direction and multiple flow direction algorithms

Abstract A static flood analysis (SFA) toolset is implemented with the purpose of performing simplified, event-based flood inundation modeling. The simulation process is divided into two steps: a topographic sink analysis of the terrain followed by flow accumulation (FA) of runoff volumes. Both procedures are coupled to account for sink storage effects. The sink analysis procedure determines the morphology of present sinks that are utilized during FA to calculate the sink storage by solving a mass balance, whereby inflows are captured in each sink according to their capacity and overflows are routed further downstream. Each sink is enriched with a set of hydrological attributes such as the total inflow, overflow, and flood depth. The flood depth is then utilized to determine the flood extent and flood depths of each sink. Two main options are made available for the FA procedure: either a single flow direction (SFD) or a novel formulation of the multiple flow direction (MFD) algorithm. Both methods were compared in terms of their accuracy with results from the TELEMAC-2D finite-volume solver for an urban inundation model. Both methods showed good agreement when compared with the validation results, with the MFD method performing marginally better than the SFD method.

Potential soil organic carbon sequestration vis-a-vis methane emission in lowland rice agroecosystem.

Mitigating the atmospheric greenhouse effect while enhancing the inherent soil quality and productive capacity is possible through soil carbon (C) sequestration, which has a significant potential to counteract the adverse effects of agroecosystem level C emission through natural and anthropogenic means. Although rice is the most important food in India, feeding more than 60% of the country's population, it is commonly blamed for significant methane (CH4) emissions that accelerate climate change. Higher initial soil organic matter concentrations would create more CH4 under the flooded soil conditions, as reducible soil C is a prerequisite for CH4 generation. In India, rice is generally cultivated in lowlands under continuous flooding. Less extensive organic matter breakdown in lowland rice agroecosystems often significantly impacts the dynamics of soil active and passive C pools. Change from conventional to conservation agriculture might trap a significant quantity of SOC. The study aims to investigate the potential of rice-based soils to sequester C and reduce the accelerated greenhouse effects through modified farming practices, such as crop residue retention, crop rotation, organic farming, varietal selection, conservation agriculture, integrated nutrient management, and water management. Overall, lowland rice agroecosystems can sequester significant amounts of SOC, but this potential must be balanced against the potential for CH4 emissions. Management practices that reduce CH4 emissions while increasing soil C sequestration should be promoted and adopted to maximize the sustainability of rice agroecosystems. This review is important for understanding the effectiveness of the balance between SOC sequestration and CH4 emissions in lowland rice agroecosystems for adopting sustainable agricultural practices in the context of climate change.

Subrecent charophyte flora from the Pheneos palaeolake (Greece): Palaeoecological implications

Herein, the late Quaternary charophyte flora from the Pheneos palaeolake in north Peloponnese (Greece) is examined for the first time. The Pheneos palaeolake was located in the south region of the Pheneos polje, where late Quaternary relict shoreline segments are still preserved. These shorelines correspond to the fluctuation of the water level at different periods reflecting the polje’s successive flooding and draining. Sediment sampling was conducted at 4 levels representing ancient shorelines of the lake. Up to five charophyte taxa have been identified and illustrated based on parautochtonous oospores and gyrogonites i.e., Nitella cf. hyalina, Sphaerochara prolifera, Chara vulgaris, Chara sp. and Nitellopsis obtusa. The distribution of the flora within the four studied levels allows the distinction of three different palaeoenvironmental conditions that prevailed at the paleolake´s margins during the late Quaternary. The occurrence of S. prolifera in the lowest elevation level indicates the prevalence of ephemeral annual flooding conditions of the lake´s margin. N. obtusa has been recovered from both the lowest and the upper lowest levels reflecting permanent, oligohaline, oligotrophic, and cold-water conditions. Chara vulgaris and Chara sp. are present in the uppermost two levels reflecting less permanent and oligotrophic conditions. The distribution of the charophyte flora in the Pheneos palaeolake suggests major changes in the palaeoecological conditions of the lake ranging from permanent, cold and oligotrophic to ephemeral and more eutrophic.

Under flooding conditions, controlled-release fertiliser coated microplastics affect the growth and accumulation of cadmium in rice by increasing the fluidity of cadmium and interfering with metabolic pathways

The combined pollution of microplastics (MPs) and Cd can affect plant growth and development and Cd accumulation, with most studies focusing on dryland soil. However, the effects of polyurethane (PU) controlled-release fertiliser coated MPs (PU MPs), which widely exist in rice systems, coupled with Cd on plant growth and Cd accumulation under flooding conditions are still unknown. Therefore, in the present study, in situ techniques were used to systematically study the effects of PU MPs and Cd coupling on the physiological and biochemical performance, metabolomics characteristics, rhizosphere bacterial community, and Cd bioavailability of rice in different soil types (red soil/cinnamon soil). The results showed that the effects of PU MPs on rice growth and Cd accumulation were concentration-dependent, especially in red soil. High PU concentration (1 %) inhibited rice root growth significantly (44 %). The addition of PU MPs inhibited photosynthetically active radiation, net photosynthesis, and transpiration rate of rice, mainly with low concentration (0.1 %) in red soil and high concentration (1 %) in cinnamon soil. PU MPs can enhance the expression of Cd resistance genes (cadC and copA) in soil, enhance the mobility of Cd, and affect the metabolic pathways of metabolites in the rhizosphere soil (red soil: fatty acid metabolism; cinnamon soil: amino acid degradation, heterobiodegradation, and nucleotide metabolism) to promote Cd absorption in rice. Especially in red soil, Cd accumulation in the root and aboveground parts of rice after the addition of high concentration PU (1 %) was 1.7 times and 1.3 times, respectively, that of the control (p < 0.05). Simultaneously, microorganisms can affect rice growth and Cd bioavailability by affecting functional bacteria related to carbon, iron, sulfur, and manganese. The results of the present study provide novel insights into the potential effects of PU MPs coupled with Cd on plants, rhizosphere bacterial communities, and Cd bioavailability.

High-resolution sequence stratigraphy of clastic shelves IX: Methods for recognizing maximum flooding conditions in shallow-marine settings

Maximum flooding conditions in high-frequency sequences are associated with a condensed section, a generally cryptic maximum flooding surface, and with facies contacts marked by grain size changes, shell beds and bioturbation; i.e., the downlap surface and the local flooding surface. Conditions of maximum water depth usually occur above the condensed section, in the early highstand systems tract. Due to its importance in sequence stratigraphic analysis, the identification of the precise position of the maximum flooding surface, which separates the transgressive and highstand systems tracts, is critical. This is particularly true in high-resolution studies based on field and core data, where only facies contacts that are older and younger than the maximum flooding surface are recognizable. An integration of several criteria, including sedimentological (facies analysis), diagenetic, micropaleontological, geophysical and geochemical, represents the best approach to define a relatively thin uncertainty interval within high-frequency sequences, in which the cryptic MFS should lie. Among the available criteria, those sedimentological and diagenetic are the ones best suited to recognize facies contacts, whereas those micropaleontological are the most reliable ones to identify the position of the maximum flooding surface. Future studies on the integration of these methods with those geophysical and geochemical have the potential to improve the ability to identify the maximum flooding surface, and improve the available tools in the high-resolution sequence stratigraphic analysis.

The usefulness of ecotoxicological tools to improve the assessment of water bodies in a climate change reality

This study aimed to analyse the added value of using ecotoxicological tools to complement and improve the assessment of natural water bodies status, in situations of climate change, with a higher frequency of extreme events as floods or droughts.Four water bodies of streams in the Guadiana Basin (Álamos, Amieira, Lucefécit, Zebro) were studied in 2017 and 2018 and classified based on the Water Framework Directive (WFD) parameters: Biological Quality Element – Phytobenthos (diatoms), General chemical and physicochemical elements, Specific pollutants, and Priority Substances. Complementarily, bioassays (including lethal and sublethal parameters) were carried out with organisms of different trophic levels: (i) the bacteria Aliivibrio fischeri; (ii) the microalgae Pseudokirchneriella subcapitata; (iii) the crustaceans Daphnia magna, Thamnocephalus platyurus and Heterocypris incongruens. A classification system with 5 scores was developed, permitting to classify water bodies from non-toxic (EC50 > 100 %; growth and feeding rate > 80 %; blue) to highly toxic (EC50 < 10 %; growth and feeding rate < 10 %; red). The comparison between the classification based on the WFD parameters and on ecotoxicological endpoints showed similar results for 71 % of the samples, and significant positive Pearson correlations were detected between the diatom-based Specific Polluosensitivity Index (SPI) and EC50V.fisheri, the algae growth rate and Shannon diversity index. These results indicate that when the biological quality elements cannot be used (namely under drought or flooding conditions) the application of ecotoxicological bioassays may be a good alternative. Further, when ecotoxicological parameters were included, an increase of worse classifications (Bad and Poor) was observed, revealing an improvement in the sensitivity of the classification, mainly in presence of specific and priority substances. So, the ecotoxicological analysis appears to provide useful information regarding the potential presence of both known and unknown contaminants at concentrations that cause biological effects (even within the WFD limits), in agreement with several authors that have already suggested its use in biomonitoring.

Influence of channel geomorphic units on bedload transport and river morphology during low‐magnitude bed‐forming floods coupled with sediment augmentation

AbstractIn this study, we map different types of channel geomorphic units in a sediment‐starved, residual‐flow reach before and after an artificial flood. Bedload particles of a previous sediment augmentation measure are tracked with passive integrated transponder tags, and water depth and flow velocity are recorded across 10 cross‐sections. The analysis focuses on the influence of channel geomorphic units on bedload transport and river morphology. Our hypotheses are (i) that during low‐magnitude bed‐forming floods with sediment pulse migration, existing channel geomorphic units influence bedload transport, and more specifically, (ii) that their type influences the retention rate of bedload particles. Furthermore, we hypothesise that (iii) the density of channel geomorphic units is linked to the hydromorphological diversity of a river section. We provide evidence that supports the first two hypotheses and contradicts the third one. We consider our results to be transferable to similarly regulated reaches based on an analysis of site‐specific conditions and alternative explanatory factors. Further research is needed to transfer the results to varying flood and sediment supply conditions in unregulated reaches.