River Branches Research Articles

Sedimentary and geomorphological evolution of a young tidal flat in the northern part of the Po delta (Italy)

Due to anthropic activities of the last centuries, coastal wetlands worldwide lost wide portions of salt marshes. Since these ecosystems provide fundamental services and benefits to both natural and anthropic components, the natural restoration of these habitats is becoming one of the main objectives of these days, and the opening of new connections between land and sea is becoming a highly used technique to restore portions of intertidal areas. According to recent studies based on analysis of long-term satellite imagery datasets and bathymetric surveys, the Po River Delta (Northern Italy) is currently subjected to a positive sedimentation trend and a constructive process is ongoing at the main river branches. Following an evolution similar to restoration projects, new tidal flats are building up around the tip of the delta, where agricultural fields were inundated by strong floods in the 1950s and the 1960s. This study focuses on a young tidal flat of about 8 ha, located in the Southernmost part of the Barbamarco lagoon. Sediment granulometric distribution and sedimentary pattern were investigated between May 2019 and March 2021 through coring, sediment traps, and orthophotos. The results show that the system is undergoing a progradation and an extended crevasse splay is developing. This covers the central part of the flat and it has developed from the early 2000s, due to human intervention on levees as well as river floods. The levees of the eastern channel stabilized between 2008 and 2012 thanks to vegetation growth, allowing the floods to focus in the NW direction, leading to the development of this recent feature. The presence of the crevasse splay confirms the importance of the river floods on the tidal flat formation. The calculated depositional rates suggest that sedimentation is higher during summer (average 66.89 g/m2 per submersion event) and lower during winter (18.86–20.65 g/m2 per submersion event). These trends are opposite to the seasonal trends observed in the literature, showing that the deposition controlled by the tide is lower compared to the river influence and suggesting that the river is the dominant factor.

Settlement Suitability Analysis: The Case of Bursa City

Abstract: Nowadays, the existing built-up area texture in cities has started to shift towards areas that are not suitable for settlement. In this sense, settlement suitability analyses play a critical role in the realisation of sustainable development goals. Detailed analyses are required to formulate an effective settlement strategy in regions with large and diverse natural features such as Bursa. In this study, in order to determine the areas suitable for settlement in the study area, which covers the borders of Osmangazi, Nilüfer and Yıldırım districts, which are the central districts of Bursa city, a settlement suitability analysis was carried out with the Analytical Hierarchy Process (AHP) method using 9 parameters consisting of slope, elevation, lithology, land use, precipitation, temperature, distance to stream, distance to fault and erosion. The main underlying data used in the study are 10m resolution Digital Elevation Model (DEM), lithology, land use, erosion, precipitation, and temperature (WorldClim) data of Bursa city. As a result of the analysis, it was determined that 9% of the city is very suitable, 44% is less suitable and 47% is not suitable. The area where the city was established is in very suitable and moderate suitable class. It is observed that the settlements established in the study area, especially in the areas close to the fault line and the main river branch, are in the moderate suitability class. In addition, it has been determined that the erosion risk is in the low class, and the settlements far from the main river branch and fault line are in the very favourable class. While it is observed that Bursa city is located at appropriate values in terms of topography, it is seen that especially the southern part of the city is not sufficiently suitable in terms of distance to fault lines. The results obtained aim to contribute to sustainable settlement planning and to provide a guide for the methods and processes to be used in settlement suitability analysis.

Distribution and ecological health risk assessment of heavy metals in damietta branch of Nile River, Egypt

ABSTRACT The Nile River is one of the longest rivers in the world, serving as the lifeline of many countries. The river is subjected to significant anthropogenic pressures, and thus, understanding the magnitude of contamination and its possible consequences is needed. This research aimed to evaluate the presence of heavy metals in the surface water of an understudied region within the Nile River. The distribution and level of 18 elements along the Damietta branch were assessed, and their potential sources were estimated. Additionally, pollution indices and health risks were calculated. The results showed that most metals were within the acceptable levels of USEPA and WHO. However, Na, Mg, and Ca were higher than the permissible level of WHO, and K was higher than the permissible levels for irrigation. Furthermore, heavy metal pollution indicators, degree of contamination indices, heavy metal evaluation indices, Nemerow pollution indices, and water quality indices all pointed to very high standards for water quality. Also, the noncarcinogenic health risk index indicated a safe limit for dermal and oral exposure for adults and children. Overall, this study recommends management focus on anthropogenic activities in the Damietta branch of the Nile River.

Natural Processes in the Area of the Former Kakhovske Reservoir After the Destruction of the Kakhovka HPP

Abstract The results of the studies devoted to the consequences of the Kakhovka dam destruction on June 6, 2023 in the course of the Russia-Ukraine war are presented. After the accident, the Kakhovske reservoir, which was the largest by volume on the Dnipro River, practically disappeared. It has turned into the network of river branches and lakes that do not compare with the former reservoir. Currently, the conditions on the territory of the former reservoir have approached those observed in natural conditions. To some extent, they depend on the water discharge of the Dnipro River, more exactly, on the water discharge of the Dnipro HPP located upstream. In the conditions of large water runoff, the large part of the former Kakhovske reservoir is covered with water. An unusual natural phenomenon of the area of the former reservoir is very rapid overgrowth, primarily by willow. A year after the accident, its height in places which is rich in organic sediments exceeded 4 meters. At the same time, the size of the trees on the bottom covered by sands is much smaller. Today, a large area of the former reservoir looks like a dense forest.

The Impact of the Kakhovka Dam Destruction on the Water Temperature in the Lower Reaches of the Dnipro River and the Former Kakhovske Reservoir

Abstract The results of the studies devoted to the consequences of the Kakhovka dam destruction and the empting of the Kakhovske reservoir are presented. The water regime of the lower reaches of the Dnipro River was studied, in particular, the water temperature. The remote sensing data on spatial features of water temperature are given. Significant changes in water temperature are shown both in the lower reaches of the Dnipro River and in the former Kakhovske reservoir. In the first days after the destruction of the dam, due to the mixing, the surface water temperature at the mouth of the Dnipro River dropped significantly. Then the water temperature in the lower reaches of the river approached to that one observed before the destruction. In turn, the former Kakhovske reservoir became a network of river branches and lakes that cannot be compared with the former reservoir. The Dniprovske Reservoir, located upstream, affects the water temperature of this territory, especially the largest branch.

The Genetic Diversity of the Macrophyte Ceratophyllum demersum in Backwaters Reflects Differences in the Hydrological Connectivity and Water Flow Rate of Habitats.

Macrophytes often live in fluvial backwaters that have a variety of hydrological connections to a main river. Since the ability of these plants to adapt to changing environments may depend on the genetic diversity of the populations, it is important to know whether it can be influenced by habitat characteristics. We examined the microsatellite polymorphism of the submerged macrophyte Ceratophyllum demersum from various backwaters and showed that the genetic diversity of this plant clearly reflects habitat hydrological differences. The greatest genetic variability was found in a canal system where constant water flow maintained a direct connection between the habitats and the river. In contrast, an isolated backwater on the protected side of the river had the lowest plant genetic diversity. Oxbows permanently connected to the branch system with static or flowing water, and former river branches temporarily connected to the main bed contained populations with moderately high or low genetic variability. The results demonstrate that habitat fragmentation can be a result not only of the loss of direct water contact, but also of the lack of flowing water. Adverse hydrological changes can reduce the genetic diversity of populations and thus the ability of this macrophyte to adapt to changing environments.

Evaluation of genetic consequences of stocking on the southern-margin populations of white-spotted charr.

Coldwater-adapted freshwater fishes, especially their populations along warm-range margins, are most vulnerable to the climate oscillations associated with global warming. Stocking is a major strategy for avoiding the extinction of these species. However, while stocking can reverse the decline of isolated populations, it may also result in a loss of genetic diversity in the native local population due to the introgressive replacement of hatchery genes. To plan an adequate strategy for conserving locally adapted populations, the genetic impacts of stocking on native lineages should be evaluated from small river branches to wide-ranging drainage areas. We investigated the population genetic structure of white-spotted charr (Salvelinus leucomaenis) within its southern range (Lake Biwa basin, Japan). By applying genome-wide SNP analysis to the population's genetic structure, we assessed the extent of genetic introgression resulting from stocking. White-spotted charr in the Lake Biwa watershed constitutes a distinctive genetic group, within which apparent genetic differentiation was observed. The hatchery-reared fish line commonly used for supplementation stocking in the catchment was discernable from the native population, enabling us to analyze genetic introgression across the entire drainage area. Admixed individuals resulting from hatchery introgression were observed in most of the stocked sites that showed relatively high heterozygosity and nucleotide diversity. However, their genetic differentiation was much lower than that of native populations. The supplementation history as well as the road availability contributed substantially to the introgression of hatchery genes. Populations with the native genetic structure remained in the upstream regions of the tested rivers. However, their heterozygosity and nucleotide diversity were low when compared with that of the populations with hatchery supplementation. Our results shed light on the genetic impacts of stocking on isolated native populations and suggest that conventional supplementation methods cannot preserve a unique biodiversity in the distribution margin.

Evolution of wetlands in the northern part of the Po Delta: The experience of unmanaged realignments

AbstractIt is increasingly recognised that nature‐based solutions in coastal ecosystems provide significant services compared to hard engineering measures. Several restoration projects are now being conducted worldwide to protect coastlines against flood risk and improve the ecosystems' quality. In the case of river deltas, managed realignment through levee breaching is becoming a recognised strategy for coastal wetland restoration. This study focusses on the formation of new wetlands in the Po River Delta after several natural dyke failures that occurred during the last century, when a large part of the land was abandoned and became wetlands. An historical review was performed to quantify the variation of the marsh extent in time developed after natural levee breaching in the easternmost lagoons of the delta and to understand the processes that determined their evolution. The analyses were based on orthophotos from the 1950s to the present‐day integrated with tidal records, water and sediment discharge records, and GPS survey for vegetation distribution. The review indicated that, between the 1950s and 1980s, anthropisation and natural processes caused a strong decline in marsh extent, thus leading to the recent shape of the lagoons. Several breaches and inlets were developed because of a combination of human intervention and erosive processes, and new tidal systems were born. Three main depositional areas connecting the main river branches were identified in three separated lagoons of the delta. These lagoons presented a ‘crevasse splay’ type of deposition which allowed the development of new tidal flats and, in certain cases, of large freshwater marsh systems within less than 8 years after the breach. The newly formed wetland systems (>100 ha) demonstrate the ability of the Po River Delta to build new wetlands, also during periods of human‐induced sediment starvation and high rates of subsidence, suggesting that further levee breaching should be exploited to favour marsh recovery.

Evaluating Flood Mitigation at a Branch River Basin Considering Enhanced Rice Paddy Storage Functions

Evaluating Flood Mitigation at a Branch River Basin Considering Enhanced Rice Paddy Storage Functions

Evaluation of Sabo Infrastructure Using UAV/Drone Technology for Monitoring and Inspection Data (Case Study: Sabo Dam Bakalan, Cangkringan District, Sleman)

The sabo dam serves as a structure positioned along a river branch, intended to manage and contain sediment for either a temporary or permanent duration, functioning as a system to combat potential disasters caused by erosion and sedimentation. Given the significance of sabo infrastructure in mitigating sediment- related calamities, it is essential to uphold and advance these structures through continuous monitoring, necessitating timely access to detection data. However, the inspection and monitoring of sabo buildings present considerable challenges, including the extensive coverage area of the river and the difficulty in accessing various building locations.To address these challenges, alternative approaches are being employed for the inspection and monitoring of sabo buildings. One such approach involves the utilization of drone-based asset survey technology. This technology enables the recording of precise object geometries and the generation of structural information that can be validated on-site, particularly in the context of infrastructure conditions related to sabo dams. By integrating drone technology, it is anticipated that the process of inspecting and monitoring buildings and land areas surrounding sabo dams can be expedited, with increased precision and enhanced safety measures.

Morphometric Analysis Using Geographical Information System and the Relationship with Precipitation Quantiles of Major Dam Basins in South Korea

Geographic information system (GIS) and remote sensing (RS) technologies are potent tools for evaluating various aspects of basin hydrology. This study conducted a morphological analysis using GIS tools on seven major dam basins in Korea. Additionally, long-term RS-based precipitation data were obtained, the probability of precipitation was estimated, and their relationship was examined. The findings are summarized as follows. It was observed that most major dam basins in Korea, which were the focus of this study, had a broad radial shape, and due to the mountainous topography, there was a notable presence of numerous river branches. Through the estimation of probability precipitation and its comparison with morphological indices, it was noted that wider basins tend to have higher rainfall amounts and a relatively uniform spatial distribution. Furthermore, it was found that the more uniform the spatial distribution, the simpler the river network. This trend becomes more pronounced in relation to basin size for longer durations, and in spatial dispersion for shorter durations. However, it is crucial to acknowledge that the complexity of these relationships is also affected by other factors such as climate, altitude, and local geographical conditions.

Business Charity Movement of Aisyiyah Organization West Sumatra in 1968-2016

This article discussed the Aisyiyah group and the women's movement in West Sumatra from 1968 to 2016. Byutilizing a historical method that includes historiography, source critique, interpretation, and heuristic stages. According to the study's findings, the Aisyiyah Organization was initially founded in Yogyakarta and formed its Batang River branch. Prior to 1968, this Organization's branches and branches quickly expanded in a number of West Sumatra locales, including Padang Panjang, Bukittinggi, Simabur, Payakumbuh, and Pesisir Selatan. After 1968 the Aisyiyah organization was spread across 18 regencies and cities in West Sumatra. The Aisyiyah Organization movement is no longer in the form of resistance as in the previous colonial era, but in the form of awareness to catch up with women in the field of charity and business such as in the fields of education, health, social welfare and the economy. Aisyiyah's charitable business movement includes a number of initiatives, such as sending as many young children as possible to ABA Kindergartens and establishing a Teacher Education School (SPG) to support educated teachers, expanding Aisyiyah Islamic clinics as places for women to seek treatment and supporting Schools Health Nurses as educated midwives, and empowering girls to enroll in Aisyiyah.

Morphometric Analysis for Sustainable River Management: A Case Study of Ciujung Watershed, Banten, Indonesia

Ciujung watershed is located in Banten province, Indonesia. The Ciujung watershed is one of the watersheds that have a significant area coverage, such as Serang, Lebak, and the eastern part of Pandeglang. These areas are developing both in terms of population growth and infrastructure. Therefore, a more in-depth study of the Ciujung watershed, namely morphometric studies, is needed to optimize the utilization of the river's renewable natural resources and mitigate potential flood hazards in the watershed area. The method used is remote sensing based on DEMNAS satellite data using QGis software. The parameters analyzed were watershed shape, watershed area, river branch ratio, and river density. The results show that the Ciujung watershed is divided into 14 sub-watersheds. In general, the sub-watersheds have a bird feather shape, and some are radial and parallel, which causes some research areas to be very at risk of flooding. From the condition of river branching, most areas are unaffected by deformation. A small part of the deformed area occurs in the middle area of the Ciujung watershed. This is interpreted to be related to tectonic activity. The drainage density shows that the Ciujung watershed is based on resistant rocks and materials, so it is easily eroded and causes siltation of the river in the downstream area, which can trigger flooding.

Saving Walker Lake: A Pleistocene Terminal Lake in the Anthropocene

Abstract: Just to the east of the Sierra Nevada mountain range a series of Pleistocene terminal lakes are present in the Great Basin of the intermountain West between the Rockies and the Sierra. Among them is Walker Lake, fed by the branches of the Walker River that flow eastward from their snow-melt sources in the Sierra. The terminal lakes have no natural outlets. Water is lost from the lakes' surfaces by evaporation during the hot summer months in the high desert. Since the arrival of Euro-Americans in the nineteenth century, the diversion of water for agricultural, industrial, and domestic uses from the Walker River has reduced the level of the lake to a point where it no longer supports a once-thriving fishery of native cutthroat trout. In the past, western Nevada Paiute peoples relied on the lake's fish as a food source. In the twentieth century the inland anadromous trout drew sports fishing enthusiasts. Climate change has caused additional strains on the water supply for the lake to the point where many have declared Walker Lake a dead lake with only shrinking shorelines and increased salinization in its future. In response, Nevada's U.S. senator Harry Reid, members of the Walker River Indian Reservation, sport fishing organizations, as well as environmental organizations pushed for legislation from Congress to promote efforts to save the lake in the 1990s. These efforts have produced some promising results.

Detour canal, a civil engineering heritage created through historical struggle for water resources, now provides the habitats for a rare freshwater fish.

The Ariake catfish, Tachysurusaurantiacus, is a freshwater fish endemic to Kyushu Island, Japan. However, these catfish are now endangered owing to environmental changes. Despite their status, there is scant quantitative research on the Ariake catfish regarding their potential conservation. The Yabe River is a typical catfish habitat situated in the northern part of Kyushu Island (Ariake Area) and has a unique civil engineering heritage, as represented by the so-called 'detour canal'. The canals were created owing to competition by two Domains to divert additional water resources into their own territory for rice cultivation during the Edo Period (1603-1867). To fill the research gap on the Ariake catfish and assess the ecological value of detour canals, in this study, we conducted a survey of local catfish populations and nine environmental parameters that can affect them. We found that the population volume of the Ariake catfish was significantly higher in canals than in ordinary branch rivers. Although the detour canals were not originally constructed for biodiversity conservation, they nonetheless unintentionally provide catfish habitat at present. As these canals represent a remarkable example of a contribution by a civil engineering heritage structure to biodiversity conservation, our study should be used as a potential justification for preserving the canals, as well as conserving the aquatic species that utilise them as vital habitat.

Assessing the Effects of Alluvial Transport in the Kizilirmak River on Dams with Local, Photogrammetric and Remote Sensing Methods

Naturally transported sand, clay, and gravel-like blocks by rivers cause a decrease in water flow and flow velocity. Additionally, uncontrolled disposal of waste materials into the riverbed increases adverse effects and endangers natural life. Over time, the alluvium generated by natural and external factors in river and creek beds leads to flood risks that pose a significant threat to life and property. These sediments, known as alluvium, accumulate in favorable locations in valleys and form alluvial beds with spread movement to broader areas. In Turkey, interventions in river branches and creek beds, as well as insufficient preventive measures, have kept floods a hot topic. To eliminate these issues, it is crucial for every organization to take comprehensive measures and increase environmental awareness by addressing similar areas in large projections. The Kızılırmak River, originating from the Kızıldag slopes in the İmranlı district of Sivas province and passing through the Çorum province before reaching the Black Sea at Bafra Cape, also harbors alluvial risks and adverse effects. It holds significant importance for energy production with 12 dams and hydroelectric power plants (HES) on the river. Additionally, the Pirinçli Hydroelectric Power Plant, with a transmission structure of 13,756 meters between Dodurga district of Çorum province and Güvercinlik and Kumbaba Villages, plays a vital role in electricity production in the region. The Pirinçli HES is located downstream of the Obruk Dam constructed by the State Hydraulic Works (D.S.I.) on the Kızılırmak River. It is known that a significant portion of the sediment accumulation between Güvercinlik Dam and Kumbaba Dam occurred before the construction of the Obruk Dam. Hence, preventing risks that could lead to environmental adversities is of paramount importance. In this study, a combined fieldwork was conducted using different methods to determine the areas where sediments accumulated and the alluvial material being transported cuts off the flow velocity of the Kızılırmak River and causes accumulations between the Güvercinlik Dam and Kumbaba Dam. For this purpose, terrestrial measurements, photogrammetric and remote sensing methods were combined and evaluated together to ensure the integrity of the obtained data.

RAU-Net++: River Channel Extraction Methods for Remote Sensing Images of Cold and Arid Regions

Extracting river channels from remote sensing images is crucial for locating river water bodies and efficiently managing water resources, especially in cold and arid regions. The dynamic nature of river channels in these regions during the flood season necessitates a method that can finely delineate the edges of perennially changing river channels and accurately capture information about variable fine river branches. To address this need, we propose a river channel extraction method designed specifically for detecting fine river branches in remote sensing images within cold and arid regions. The method introduces a novel river attention U-shaped network structure (RAU-Net++), leveraging the rich convolutional features of VGG16 for effective feature extraction. For optimal feature extraction along channel edges and fine river branches, we incorporate a CBAM attention module into the upper sampling area at the end of the encoder. Additionally, a residual attention feature fusion module (RAFF) is embedded at each short jump connection in the dense jump connection. Dense skip connections play a crucial role in extracting detailed texture features from river channel features with varying receptive fields obtained during the downsampling process. The integration of the RAFF module mitigates the loss of river information, optimizing the extraction of lost river detail feature information in the original dense jump connection. This tightens the combination between the detailed texture features of the river and the high-level semantic features. To enhance network performance and reduce pixel-level segmentation errors in medium-resolution remote sensing imagery, we employ a weighted loss function comprising cross-entropy (CE) loss, dice loss, focal loss, and Jaccard loss. The RAU-Net++ demonstrates impressive performance metrics, with precision, IOU, recall, and F1 scores reaching 99.78%, 99.39%, 99.71%, and 99.75%, respectively. Meanwhile, both ED and ED′ of the RAU-Net++ are optimal, with values of 1.411 and 0.003, respectively. Moreover, its effectiveness has been validated on NWPU-RESISC45 datasets. Experimental results conclusively demonstrate the superiority of the proposed network over existing mainstream methods.

Predicting salinity intrusion for the coastal rice cultivation areas in the Mekong Delta ​

The Mekong Delta is one of the most vulnerable regions to the impacts of climate change (CC). Prolonged drought causes salinity intrusion, which has become more and more complicated and seriously affects agricultural production and residential daily life. Therefore, studies on salinity intrusion play a critical role in socio-economic development. This study applies the remote sensing techniques to predict salinity intrusion at the main estuaries across the Mekong Delta based on comparing with observed salinity data for the years 2014, 2016, and 2020, at 22 hydrology stations along the Tien River and the Hau River. The results show that salinity tends to decrease gradually, inland from the estuary; it gradually increases from January, peaking in February, March, or April, and then gradually decreases. The farthest salinity intrusion extended approximately 80 km inland, at the Ham Luong branch, and 56-61 km inland from the other branches. Overall, salinity intrusion penetrated the deepest at four main river branches in 2020. Salinity intrusion can be predicted through multiple regression models.

Salinity dynamics under different water management plans coupled with sea level rise scenarios in the Red River Delta, Vietnam

In recent years, saltwater intrusion in river estuaries has become more severe and frequent worldwide. The common reasons lie in increasing freshwater withdrawal, river flow regulation and sea level rise due to global warming. In particular, the Red River Delta in northern Vietnam is facing a strong population growth worsening the pressure on freshwater resources for drinking water and irrigation needs. During the dry season, increasing conflicts and constraints in freshwater availability have already been experienced. Adverse combinations of river flow regulations and high sea levels lead to severe upstream propagations of salinity. This study takes advantage of a statistical characterization of discharges released from Hoa Binh reservoir and observed at Son Tay station, the main river flow control upstream of the river delta, along with downscaled and updated sea level rise scenarios to estimate the future extents of saltwater intrusion under different options of water release from reservoirs in the dry season. To do so, a 1D hydraulic model of the river delta network was implemented using MIKE11 software. The hydraulic and the quality modules were calibrated and validated with respect to the present scenario by using water stages and salinity concentrations observed in estuary branches. Sea level rise projections for 2050 and 2100 referred to RCP4.5 and RCP8.5 AR5 emission scenarios were then considered. Results show that river flow regulation can provide an effective mitigation measure. A 20–30% increase in the discharge released from the Son Tay station would be beneficial to push downstream the saltwater intrusion in the main Red River branch during the dry season. For instance, in 2050 the 1‰ salt concentration front is expected to be pushed back at least 6 km when the exceeding probability of the discharge released by Son Tay station decreases from 95% to 25%.

Risk-based portfolio planning of dike reinforcements

A system of dikes in flood-prone areas continuously requires measures to mitigate changes such as ageing and climate change. Planning costly measures requires proper insight into system risk effects. Especially in a riverine dike system, the risk contributions of individual assets to the system flood risks are not independent, because reinforcement of a dike upstream increases the risks downstream. Tactical plans define the planning of consecutive measures to implement a flood risk reduction strategy, which may take decades. They may differ due to choices such as a prioritization metric, planning conditions and budget. In this study, a method is developed to compare different tactics to prioritize and plan measures in interdependent systems of dikes to reduce risks most effectively and efficiently. A case study meant as a proof of concept was carried out for the reinforcement of about 500 km of dikes along the Rhine River branches in the Netherlands. We studied the effects of 12 different tactical plans on the aggregated risks over time. The economic risks differ by up to about 40%, and the risks on victims differ by up to 70 %. We conclude that tactical planning and corresponding decisions are important for reduction of time-aggregated flood risks.