Artificial Flooding Research Articles

Implementation of Controlled Floods for Sediment Management on the Colorado River in Grand Canyon Under Aridification

ABSTRACTIn addition to supplying water for agriculture, cities, and industry, the Colorado River traverses the Colorado Plateau, including several of the most unique and valued National Parks and Recreation Areas in the United States. Although the water needs of these landscapes were not considered at the time water allocations were first negotiated, these needs were recognized in subsequent legislation and policy. Management goals address a range of aquatic and riparian resources, including fine sediment (sand, silt, and clay) which, in Grand Canyon, is important for ecological, cultural, and recreational resources. Over ~30 years, stakeholders, resource managers, and scientists collectively developed operational strategies for sediment management to meet goals outlined by an adaptive management program. However, prolonged drought, or “aridification,” resulting in declining runoff and the lowest reservoir storage elevations in decades has challenged those strategies. The paradigm for sustainable sediment management relies on (1) sand accumulation on the bed of the Colorado River during periods of sediment‐rich tributary floods from summer/fall thunderstorms, and (2) dam‐released controlled (artificial) floods, referred to as High‐Flow Experiments (HFEs), to redistribute the accumulated sand to rebuild eroded bar and floodplain deposits. The management protocol, which specifies narrowly defined sand accumulation periods and HFE implementation windows, is based on implementing HFEs in late fall during the period of greatest sediment enrichment, before higher winter releases for hydropower erode the accumulated sand from the riverbed. Low dam releases associated with drought, however, have changed the pattern of sand accumulation and low reservoir elevations have prevented HFE implementation in the defined window. An alternative strategy for HFE planning and implementation was tested opportunistically in April 2023 following lower‐than‐normal winter dam releases. We present findings from this HFE indicating that sand enrichment and sandbar building equaled or exceeded that of HFEs conducted under the established management protocol. These findings show that management goals for sediment under conditions of prolonged drought may be achievable but will likely require substantial changes in dam management strategies.

Artificial river flow regulation triggered spatio-temporal changes in marine macrobenthos of the Yellow River Estuary

The Water Sediment Discharge Regulation (WSR) in the Yellow River transports a vast quantity of freshwater and materials to the Bohai Sea within 20 days, significantly altering the ambient environment of the estuary. To elucidate the ecological impacts of this typically artificial flood event, we investigated the benthic habitats and macrobenthic biodiversity within the Affected Core Area (ACA) influenced by this discharge. Our results show that: (1) The discharge created an area with extreme environmental conditions, extending from the southern estuary to Laizhou Bay. This led to a rapid transformation of the habitat, as evidenced by a significant increase in turbidity, ammonium, and silicate levels. Among these factors, nitrogen nutrients and pH were the dominant drivers of environmental filtration, shaping the macrobenthos community structure; (2) The changing habitat triggered spatial shifts in macrobenthos abundance based on the distance from the estuary. Compared to the northern estuary, species composition and C-diversity in the southern area decreased significantly. These changes collectively established a short-term biodiversity front in the estuary region; (3) Community stability declined, as evidenced by a 24.20% reduction in niche width for generalist species and a 90.91% shift in specialist species. Furthermore, the connectivity between species decreased, and the average path length of the network increased, resulting in a more fragmented community structure. Notably, some ecological patches dominated by generalist species (e.g. Alpheus distinguendus) emerged. These findings enhance our understanding of marine ecological responses to artificial flood events within the context of global environmental changes.

Effects of inlet height of detention basins on fish movement to refuges during floods

AbstractDetention basins, typically installed adjacent to rivers, prevent the rise in water levels downstream by temporarily storing river water. Furthermore, these basins potentially promote biodiversity by creating floodplains as refuges during floods. The heights of the inlet dikes, which divert river water into the basins during floods, are designed just below the flood elevation to maximise disaster prevention. However, the accessibility of these artificial basins to organisms during floods is uncertain, primarily due to the design of the inlet dikes. Herein, we experimentally examined the effect of the height of these inlets on fish entering the detention basins during floods. The Aqua Restoration Research Center created small‐scale detention basins next to the experimental streams to induce artificial flooding using movable water gates. We controlled the height of the inlet boards to simulate an inlet dike and recorded the number of fishes that entered these basins during an experimental flood. The number of individuals moving into the basins increased as the height of the inlet board decreased. No fish were captured in the basins with the highest inlet board, which was set just below the experimental flood level. While the detention basin needs to be of a certain height of the inlet for effective flood control, we suggest a solution that may be possible to achieve both objectives, disaster prevention and biodiversity conservation, by altering the inlet location, with reference to a Japanese traditional flood reduction installation, the Kasumi‐tei.

Assessing leaf physiological traits in response to flooding among dominant riparian herbs along the Three Gorges Dam inChina.

Dams worldwide have significantly altered the composition of riparian forests. However, research on the functional traits of dominant herbs experiencing flooding stress due to dam impoundment remains limited. Given the high plasticity of leaf traits and their susceptibility to environmental influences, this study focuses on riparian herbs along the Three Gorges Hydro-Fluctuation Zone (TGHFZ). Specifically, it investigates how six leaf physiological traits of leading herbs-carbon, nitrogen, phosphorus, and their stoichiometric ratios-adapt to periodic flooding in the TGHFZ using cluster analysis, one-way analysis of variance (ANOVA), multiple comparisons, Pearson correlation analysis, and principal component analysis (PCA). We categorized 25 dominant herb species into three plant functional types (PFTs), noting that species from the same family tended to fall into the same PFT. Notably, leaf carbon content (LCC) exhibited no significant differences across various PFTs or altitudes. Within riparian forests, different PFTs employ distinct adaptation strategies: PFT-I herbs invest in structural components to enhance stress resistance; PFT-II, mostly comprising gramineous plants, responds to prolonged flooding by rapid growth above the water; and PFT-III, encompassing nearly all Compositae and annual plants, responds to prolonged flooding with vigorous rhizome growth and seed production. Soil water content (SWC) emerges as the primary environmental factor influencing dominant herb growth in the TGHFZ. By studying the response of leaf physiological traits in dominant plants to artificial flooding, we intend to reveal the survival mechanisms of plants under adverse conditions and lay the foundation for vegetation restoration in the TGHFZ.

Evaluation of the Offsets of Artificial Recharge on the Extra Run-Off Induced by Urbanization and Extreme Storms Based on an Enhanced Semi-Distributed Hydrologic Model with an Infiltration Basin Module

Urbanization and climate change exacerbate groundwater overexploitation and urban flooding. The infiltration basin plays a significant role in protecting groundwater resources because it is a prevalent technology of managed aquifer recharge. It could also be utilized as a retention pond to mitigate city waterlogging. The goal of this study was to explore the offsets of artificial recharge on the extra runoff induced by urbanization and extreme storms via infiltration basins. To achieve this objective, a lumped infiltration basin module was developed and integrated into a semi-distributed hydrologic model. Then, the enhanced model was applied to an agriculture watershed with urban areas. Finally, the functionalities of the infiltration basins were evaluated under the scenarios of the predicted urbanization and extreme storms. The results demonstrated the capability of the infiltration basins to influence both artificial recharge and flood mitigation. To mitigate floods, especially peak flows, larger areas are needed for infiltration basins than for artificial recharge purposes only. Based on different demands, the intermittent regulation of infiltration basins according to different hydrologic periods is recommended. The offsets of artificial recharge on the extra surface runoff provide insight into the comprehensive preservation and management of surface water resources and groundwater resources.

Linking marsh sustainability to event-based sedimentary processes: Impulsive river floods initiated lateral erosion of deltaic marshes

Salt marshes providing valuable services in buffering flooding risks are regarded as cost-effective coastal defense solutions. Given that eroding marsh cliffs will threaten the sustainability of these protective functions, there is a need for mechanistic understanding of cliff formation. Based on short-term field measurements together with satellite-derived dataset and a morphodynamic model, we determined the response of marsh lateral dynamics to event-based sedimentary processes in the Yellow River Delta, China. It was found that the Eastern Marsh with a cliff of ∼1.2 m in height significantly differed from the gentle Western Marsh in accretion pattern and lateral dynamics. Attributed to an artificial flood lasting ∼20 days in 2022, the Eastern Marsh platform experienced average vertical accretion of 23.3 mm, ∼5 times higher than the Western Marsh barely impacted by fluvial sediment supply. Although the accretion pattern ensured the overall vertical adaptability, Eastern Marsh has translated from a phase of rapid expansion to lateral retreat of ∼60 m/yr since 2018, whereas Western Marsh was relatively stable in recent decade. With a validated delta-marsh model, we showed that the observed disparities were attributed to different marsh edge morphodynamic responses to river flood sediment supplies. When Spartina alterniflora initially colonized, the Eastern Marsh platform was lower and the trapping efficiency could rise by ∼3 times than the present. Integrating with ten-fold increases in sediment loads, it was estimated that the large artificial floods in 2018 could contribute to a vertical growth approximating 30 cm at Eastern Marsh. Such episodic but rapid marsh accretion played a crucial role in initiating the development of marsh cliff. Driven by positive feedbacks between platform elevations and cumulative wave thrust, a series of event-based marsh sedimentation will promote long-term marsh loss caused by lateral retreat at sediment-starved systems. This study provides insights in predicting marsh sustainability and long-term evolutions under episodic sedimentary events.

Ecological problems and ecological restoration zoning of the Aral Sea

The Aral Sea was the fourth largest lake in the world but it has shrunk dramatically as a result of irrational human activities, triggering the “Aral Sea ecological crisis”. The ecological problems of the Aral Sea have attracted widespread attention, and the alleviation of the Aral Sea ecological crisis has reached a consensus among the five Central Asian countries (Kazakhstan, Uzbekistan, Tajikistan, Kyrgyzstan, and Turkmenistan). In the past decades, many ecological management measures have been implemented for the ecological restoration of the Aral Sea. However, due to the lack of regional planning and zoning, the results are not ideal. In this study, we mapped the ecological zoning of the Aral Sea from the perspective of ecological restoration based on soil type, soil salinity, surface water, groundwater table, Normalized Difference Vegetation Index (NDVI), land cover, and aerosol optical depth (AOD) data. Soil salinization and salt dust are the most prominent ecological problems in the Aral Sea. The Aral Sea was divided into seven first-level ecological restoration subregions (North Aral Sea catchment area in the downstream of the Syr Darya River (Subregion I); artificial flood overflow areas downstream of the Aral Sea (Subregion II); physical/chemical remediation area of the salt dust source area in the eastern part of the South Aral Sea (Subregion III); physical/chemical remediation areas of severe salinization in the central part of the South Aral Sea (Subregion IV); existing water surface and potential restoration areas of the South Aral Sea (Subregion V); Aral Sea vegetation natural recovery area (Subregion VI); and vegetation planting areas with light salinity in the South Aral Sea (Subregion VII)) and 14 second-level ecological restoration subregions according to the ecological zoning principles. Implementable measures are proposed for each ecological restoration subregion. For Subregion I and Subregion II with lower elevations, artificial flooding should be carried out to restore the surface of the Aral Sea. Subregion III and Subregion IV have severe soil salinization, making it difficult for vegetation to grow. In these subregions, it is recommended to cover and pave the areas with green biomatrix coverings and environmentally sustainable bonding materials. In Subregion V located in the central and western parts of the South Aral Sea, surface water recharge should be increased to ensure that this subregion can maintain normal water levels. In Subregion VI and Subregion VII where natural conditions are suitable for vegetation growth, measures such as afforestation and buffer zones should be implemented to protect vegetation. This study could provide a reference basis for future comprehensive ecological management and restoration of the Aral Sea.

Accumulation and migration of particulate trace metals by artificial flood event of the Yellow River: From Xiaolangdi reservoir to estuary

Reservoir construction increasingly alters the natural transport of riverine water and sediment to the sea, including the trace metals and other pollutants. In 2018, an intensive flood event and 412 million tons of sediment were released from the Xiaolangdi dam during the water-sediment regulation of Yellow River, one of the world's largest sediment releases. During the artificial flood event, the surface sediments in Xiaolangdi Reservoir (XLD) and the Yellow River estuary, suspended sediments at Lijin Station were collected. The concentration and speciation of particulate Cr, Ni, Cu, Zn, Cd and Pb, as well as the major geochemical composition were analyzed, to characterize the behaviors of the metals from the reservoir to estuary mixing zone, and elucidate the controlling mechanisms. The results showed that for exogenous phases, Cr, Ni, Cu and Zn were likely bound to the FeMn oxides, whereas Pb and Cd were mainly adsorbed in the carbonates. The trace metals in XLD were stably combined with fine-grained bottom sediments at high concentrations before dam release. During the delivery from reservoir to downstream channel, the binding of Cr, Ni and Cu with FeMn oxides was markedly enhanced. Pb and Cu showed obvious migration from carbonates to FeMn oxides, and Cd and Pb were even released into the water. The accumulation and migration of trace metals were controlled by the adsorption of fine-grained components, especially FeMn oxides and carbonates, and influenced by the oxidizing processes. After entering the estuary, the trace metals were greatly scavenged by reservoir-sourced fine particles, tended to bound to organic matter affected by the reducing environment. Our results suggest that dam regulation and artificial flood events will likely alter the existing forms and redox state of trace metals and the potential environmental effects should be considered.

Mechanistic Study and Optimization of High Water Cut Phase Management Strategies in Fracture-Vuggy Carbonate Reservoirs with Bottom Water

Fracture-vuggy carbonate reservoirs commonly exhibit sufficient bottom water energy and are characterized by fractures or other interconnected channels with bottom water, which can easily cause high water cut in oil wells during production. The main reasons are as follows: firstly, bottom water coning leads to water flooding. Secondly, artificial water injection flooding fails and shows high water cut in oil production. This paper further clarifies the causes of high water cut in fractured-vuggy carbonate reservoirs and explores rational and feasible management strategies to improve the current water flooding situation and reduce the comprehensive water cut in oil wells. In this paper, numerical simulation technology is used to establish a mechanism model based on the actual reservoir conditions. By comparing the development effects of four bottom water suppression measures, including the adjustment of flow channel, artificial barriers, adjustment of flow potential and gas injection, the optimal measure is selected and the relevant parameters are optimized. Building upon this, further optimization of water injection methods is conducted to explore comprehensive management strategies for enhancing the water flooding effect during high water cut periods. The research demonstrates that bottom water can be effectively inhibited by artificial barriers, leading to an expansion of the swept volume of water injection and achieving the goal of improving the high water cut condition in carbonate reservoirs. Optimal implementation of artificial barriers occurs when the water cut reaches around 80%. Specifically, positioning barriers at the bottom of perforations and setting the barrier radius at 0.15–0.2 times the well spacing obtain the most favorable results. Additionally, short-term injection with long-term shut-in, identified through cyclic water injection simulations, exhibits superior oil recovery enhancement. Validation conducted in a practical field of a fractured carbonate reservoir over a five-year period has led to a substantial increase in oil production by 5.6 × 104 t and a 12% reduction in water cut. The research approach and methodology presented in this paper can provide valuable insights and serve as a reference for the development of high water cut periods in fractured-vuggy carbonate reservoirs.

Improving blank ocean satellite data through machine learning: Case study and application in the Bohai Sea, China

Ocean satellites provide accurate and precise data across various scales, making them a vital tool for investigating the association between global change and ocean processes. However, low-quality data creates unavoidable gaps in satellite data, diminishing its usefulness and continuity. These deficiencies can be resolved by implementing machine learning techniques as valuable tools. This paper details a new satellite data prediction tool titled “SatelliteFixer”. The SatelliteFixer model, utilizing a custom-built random forest structure, can generate dependable data with enhanced temporal-spatial continuity. This model has demonstrated feasibility with diverse satellite data sources and light bands, and outperforms the basic machine learning approach. The juxtaposition of model data with in-situ cruise sampling results allows for widespread analysis of the movement and dispersion of suspended sediment. The above entails the inversion of long-term events and the observation of short-term events, which enables accurate seasonal analysis using continuous data without the influence of uneven data volume distribution and outliers, and is also the first-time satellite data has tracked the entire process of pulsed artificial flooding. SatelliteFixer provides a fresh outlook for detailing the varying trends on consecutive timescales and successional spaces among ocean processes.

Гидрохимические особенности озёр Большое и Малое Турали по результатам исследований в 2018 и 2021 годах

In the summer months of 2018 and 2021, concentrations of major ions, dry residue, pH and temperature were determined in the water of the Maloe and Bolshoe Turali lakes; in various horizons (up to 20 cm) of bottom sediments, in addition to concentrations of methane and total hydrogen sulfide, Eh and pH values, humidity and density were determined. The mineralization of the waters of the Bolshoe and Maloe Turali lakes in 2018 was 275.8 and 19.1 g/dm3, respectively. According to the chemical composition, the class of waters in lakes is chloride, the sodium group, the second type. In 2021, the mineralization of lakes decreased, especially strongly in the lake Bolshoe Turali. It is shown that the significant salinization of its waters is not associated with precipitation, but is caused by artificial flooding of the feeding channel with water. Lake sediments are characterized by a neutral or slightly alkaline environment (pH from 7.01 to 7.88) and strong variability of redox conditions (Eh from -213.8 to 177.1 mV). The concentrations of CH4 in the sediments of the Maloe and Bolshoe Turali lakes varied in the range of 0.006–0.070 μg/g of wet sediment and 0.011–0.12 μg/g, respectively. The concentrations of ΣH2S varied from <0.005 to 0.241 mg/g in the lake of Maloe Turali and from <0.005 to 1.47 mg/g in the lake of Bolshoe Turali. The relationship between CH4 and ΣH2S is weakly manifested, which is due to their insignificant concentrations associated with Eh not low enough for intensive anaerobic processes in most sediment horizons.

Limnology for the ornithologist: effects of Lake Maggiore water level on migratory flows

Wetlands are widely recognised as the most critical stop-over locations along migration flyways. Wetland ecology is mostly influenced by water levels and water regimes. This research focuses on Bolle di Magadino (Switzerland), an important stop-over site on Lake Maggiore, artificially regulated by a dam. In this work we examined how the artificial flooding of a wetland affects the use of this stop-over site by migrating passerines during spring. Bird presence in the area was evaluated using both data collected at the ringing station located in the wetlands and the bird traffic rate (BTR) supplied by the BirdScan MR1, an avian verticallooking radar (VLR) capable of automatically detecting and classifying birds in flight. In an attempt to shed light on the effect of lake level on stop-over quality, we i) simulated with GIS the extent of the flooded area and of the different habitat categories as the lake level changes; ii) calculated the relationship between lake level and the ability of stop-overing birds to acquire trophic resources; iii) verified that the flux of passerines below 500 m above ground level measured by radar could be used as a proxy for the number of stop-overing birds; iv) calculated the relationship between the number of birds leaving the stop-over and the lake level. While the number of ringed passerines has proven to be representative of the migratory flow below 500 meters of altitude at the site of interest, a high lake level seems to have a negative impact on the use by some species of the Bolle di Magadino area as a stop-over site during spring. In particular, two of the target species -the blackcap and the reed bunting- have proven to be sensitive to higher water levels. While taking into account the limitations and the relative nature of the results, could be necessary for the competent authorities to take these results into consideration in order to safeguard the Bolle di Magadino’s role as an important stop-over area during spring.

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.

Prevalence and genetic diversity of avian haemosporidian parasites in islands within a mega hydroelectric dam in the Brazilian Amazon.

The Brazilian Amazon supports an extremely diverse avifauna and serves as the diversification center for avian malaria parasites in South America. Construction of hydroelectric dams can drive biodiversity loss by creating islands incapable of sustaining the bird communities found in intact forest sites. Besides anthropogenic actions, the presence of parasites can also influence the dynamics and structure of bird communities. Avian malaria (Plasmodium) and related haemosporidian parasites (Haemoproteus and Leucocytozoon) are a globally distributed group of protozoan parasites recovered from all major bird groups. However, no study to date has analyzed the presence of avian haemosporidian parasites in fragmented areas such as land bridge islands formed during artificial flooding following the construction of hydroelectric dams. The aim of this study is to assess the prevalence and molecular diversity of haemosporidians in bird communities inhabiting artificial islands in the area of the Balbina Hydroelectric Dam. The reservoir area covers 443,700 ha with 3546 islands on the left bank of the Uatumã River known to contain more than 400 bird species. We surveyed haemosporidian infections in blood samples collected from 445 understory birds, belonging to 53 species, 24 families, and 8 orders. Passeriformes represented 95.5% of all analyzed samples. We found a low overall Plasmodium prevalence (2.9%), with 13 positive samples (two Plasmodium elongatum and 11 Plasmodium sp.) belonging to eight lineages. Six of these lineages were previously recorded in the Amazon, whereas two of them are new. Hypocnemis cantator, the Guianan Warbling Antbird, represented 38.5% of all infected individuals, even though it represents only 5.6% of the sampled individuals. Since comparison with Plasmodium prevalence data prior to construction of Balbina is not possible, other studies in artificially flooded areas are imperative to test if anthropogenic flooding may disrupt vector-parasite relationships leading to low Plasmodium prevalence.

A STUDY ON THE APPLICATION OF ARTIFICIAL NEURAL NETWORK TO PREDICT EXTREME RAINFALL AND FLOOD RISK IN NIGERIA

A STUDY ON THE APPLICATION OF ARTIFICIAL NEURAL NETWORK TO PREDICT EXTREME RAINFALL AND FLOOD RISK IN NIGERIA

Body mass dynamics in wintering mallards (Anas platyrhynchos) in the Lower Mississippi Alluvial Valley

Body mass in overwintering waterfowl is an important fitness attribute as it affects winter survival, timing of spring migration, and subsequent reproductive success. Recent research in Europe and the western United States indicates body mass of mallards (Anas platyrhynchos) has increased from the late 1960s to early 2000s. The underlying mechanism is currently unknown; however, researchers hypothesize that increases are due to a more benign winter climate, increased food availability through natural and artificial flooding, introgression of wild mallard populations by game-farm mallards, or shifting of wintering distributions northward. Further investigation of factors related to winter mallard body mass increases and whether this phenomenon is occurring in other major flyways could increase understanding of intrinsic and extrinsic variables influencing waterfowl fitness. Here, we analyzed mallard body mass in the Lower Mississippi Alluvial Valley from 1979-2021 to determine sources of temporal variation. We measured hunter-harvested mallards from private hunting clubs, public hunting areas, and duck-plucking businesses. Mallard body mass increased by approximately 6% among all age-sex classes from 1979-2021. Average mallard mass increased by about 1.5% per decade but varied substantially among years. Within years, body mass was related to rainfall and river gage height; mallards had greater mass after periods of increased rainfall or river flooding, likely due to increased food availability. Mallard body mass had a marginal negative relationship with severe cold weather (derived using a weather severity index [WSI]). While body mass increased after wet periods within years, there was no relationship of mallard body mass with wet vs dry years, low vs high flood years, or hot vs cold years. Additionally, there was no detectable change in rainfall, river discharge, or temperature from 1979-2021. This indicates that rainfall and river height may influence mallard body mass within years, but may not be the primary factor responsible for mass increases over time. Our research confirms changes in mallard body mass are widespread and within-season precipitation and flooding account for much of the observed annual variation. Future research investigating specific mechanisms, such as introgression of game-farm mallard DNA and climate change, may clarify their contribution to mallard body mass change over time.

Forest composition and red oak (Quercus sp.) response to elevation gradients across greentree reservoirs

Elevation gradients within forested wetlands have long been recognized for their role in defining species composition through factors such as hydrology and soil characteristics. Greentree reservoirs (GTRs) are levee-impounded tracts of bottomland hardwood forest flooded throughout the winter months to provide habitat for overwintering waterfowl. Artificial flooding of GTRs alters the forest composition due to flood frequency, depth, and duration in combination with slight changes in topography. To evaluate the effect of elevation gradients, soil properties, and management techniques in the overstory species composition and red oak (Quercus spp.) species abundance, we inventoried 662 plots across 12 independent GTRs in eastern Arkansas. In the lower elevations ranging from 50.98 to 54.99 ​m above sea level, the importance value index (IVI) was highest for nuttall oak (Quercus texana) and overcup oak (Quercus lyrata), whereas IVI shifted to cherrybark oak (Quercus pagoda) in the higher elevations ranging from 54.99 to 58.00 ​m. Alpha diversity did not differ by elevation gradient, soil property, or management technique within GTRs. Beta diversity, using non-metric multi-dimensional scaling (NMDS) analysis, indicated site-specific variability significantly correlated with the environmental predictors, including elevation (R2 = ​0.57), easting (R2 = ​0.47), soil texture (R2 = ​0.21), and pH (R2 = ​0.12). Red oak species-specific mixed-effects modeling of abundance response using Poisson distribution suggested an inverse correlation of nuttall oak and a direct correlation of cherrybark oak abundance with elevation. However, willow oak (Quercus phellos) abundance was not significantly affected by elevation but was by silt loam soil texture and restoration management techniques. These findings will aid management efforts to reduce the dominance of less desirable species that are prominent under specific environmental conditions and promote the dominance of more desirable species. Ultimately GTR sustainability is increasingly important amid the unpredictable impacts of climate change on the preferred red oak species that are economically, ecologically, and environmentally valuable to the sustaining economy of the local community and managing habitats for wildlife.

Socio-economic Impact and Adapting Strategies of Inter Basin Transfer by Kulekhani Hydro-electricity Project Nepal

This paper tries to assess the changes in socio-economic conditions in downstream dewatered area from Kulekhani dam after inter-basin transfer of river water from Kulekhani basin to Rapti basin since 1982. After decline in crop productivity because of decline in irrigation particularly during winter season, livelihood options are affected. Downstream people are depending for water on different resources such as natural springs; tap etc. Traditional water mills are either non-functioning or its efficiency is declined due to decline in water availability. Out of 16, 9 water mills have been closed, remaining are hardly conducting. Almost 90% fishes have decreased and some species of fishes have disappeared from the river therefore, Fishermen who were economically dependent on fishing activities have forced to replace their traditional fishing occupation. People have felt new experiences such as temperature increased and appearance of mosquitoes. Upper reach has almost completely dried but lower reach has little water available in the river because of its tributaries thus upper reach is more effected than lower reach. The risk of artificial uncertain flood due to high dam may burst by natural or unnatural forces and during the period of opening dam gates due to overflow, as there are no enough early warning systems developed particularly at the time of opening the dam gates, the unexpected risk has increased in downstream area.

Flood risk assessment of artificial islands under compound rain-tide-wind effects during tropical cyclones

Tropical cyclones are often accompanied by heavy rainfall, high tides, and strong wind speeds, which can induce serious compound floods resulting in immeasurable losses to coastal areas. Studies on flood risk for ocean engineering by compound impacts of rain, tide, and wind are still limited to date. The west artificial island of Hong Kong-Zhuhai-Macao Bridge is a vital link between the immersed tunnel and the bridge. The flooding on the artificial island under the compound effects of rain-tide-wind and the flood risk of cars were analyzed in this study. We propose rain-tide-wind joint probabilities for different compound scenarios based on historical observational data of tropical cyclones. The artificial island hydrodynamic model was created to evaluate flood disasters induced by rainfall and wave overtopping. The 24-hour flood process and maximum flood depth distribution of each scenario are presented. The car damage in floods by the compound effects was assessed to derive the probability-car damage curve for risk assessment. The study provides technical support for artificial island flood prevention and disaster risk reduction.

Artificial Intelligence-Based Regional Flood Frequency Analysis Methods: A Scoping Review

Flood is one of the most destructive natural disasters, causing significant economic damage and loss of lives. Numerous methods have been introduced to estimate design floods, which include linear and non-linear techniques. Since flood generation is a non-linear process, the use of linear techniques has inherent weaknesses. To overcome these, artificial intelligence (AI)-based non-linear regional flood frequency analysis (RFFA) techniques have been introduced over the last two decades. There are limited articles available in the literature discussing the relative merits/demerits of these AI-based RFFA techniques. To fill this knowledge gap, a scoping review on the AI-based RFFA techniques is presented. Based on the Scopus database, more than 1000 articles were initially selected, which were then screened manually to select the most relevant articles. The accuracy and efficiency of the selected RFFA techniques based on a set of evaluation statistics were compared. Furthermore, the relationships among countries and researchers focusing on AI-based RFFA techniques are illustrated. In terms of performance, artificial neural networks (ANN) are found to be the best performing techniques among all the selected AI-based RFFA techniques. It is also found that Australia, Canada, and Iran have published the highest number of articles in this research field, followed by Turkey, the United Arab Emirates (UAE), India, and China. Future research should be directed towards identification of the impacts of data quantity and quality, model uncertainty and climate change on the AI-based RFFA techniques.