Big River Research Articles

Shifted Flood and Ecology Regimes Due To Channel Bar Greening and Increased Flow Resistance in a Large Dammed River

AbstractDamming profoundly affects downstream flow‐sediment regimes, altering channel bar dynamics and thereby affecting floods and riverine biodiversity. Here, we investigate the response of bars to upstream damming by examining patterns, mechanisms, and impacts in the Middle Yangtze River (∼1,000 km). Over a decade of post‐damming observational data reveal substantial increases in bar revegetation and Leaf Area Index. Shorter flood duration and stable bar size collectively drive bar greening. Consequently, denser vegetation has slowed flow velocity by 17% ± 2% and increased flow resistance by 21% ± 5%, offsetting the water‐level decrease from channel expansion due to scouring and even causing a slight rise in floodwater levels. Furthermore, damming has markedly altered river connectivity, thermal regimes, and solute dynamics, detrimentally affecting fish habitats and aquatic life. These findings, along with refined river stage simulation considering flow‐sediment‐vegetation interactions, facilitate sustainable reservoir operation and river management in big river systems.

Submesoscale processes and their seasonality generated by freshwater discharge at the Yangtze estuary

As the intersection between land and sea, the estuary is a hotpot for natural and human-induced processes that affect its physical and chemical characteristics, as well as biodiversity and ecosystems. Due to a combination of freshwater discharge and the unique topography of river estuaries, submesoscales with a spatial scale of O(1) km can be easily generated due to the presence of strong salinity fronts at river estuaries. As the biggest river in Asia, the basically dynamical characteristics and their seasonal mechanisms of submesoscales at the Yangtze estuary remain unclear. Using a nested high-resolution (300 m) simulation established by the Coastal and Regional Ocean Community model (CROCO), the seasonal variability of submesoscales at the Yangtze estuary is investigated and the underlying generation mechanisms are analyzed based on the analysis of kinetic energy budget. The results of normalized relative vorticity, horizontal salinity gradient, and submesoscale kinetic energy (SMKE) show that submesoscale processes have a seasonal variation at the Yangtze estuary. This seasonality is tightly related to the freshwater input with a correlation coefficient of up to 0.66 (the confidence level >99%). To figure out the dominant energy sources that control the SMKE budget, five terms including the baroclinic term (BC), the barotropic term (BT), the advection of submesoscale kinetic energy term (ADK), the pressure work term (PW), and vertical mixing term (VM) are diagnosed. The results suggest that BC, BT, and PW are the source producing SMKE, while ADK and VM tend to dissipate SMKE. This work suggests the important role of submesoscale activities in the energy cascade and enhancing the transports of tracers at the estuary.

Fluvial fan sedimentary characteristics of distributive fluvial system

The characteristics of fan sediment in the distributive fluvial system are evaluated based on a thorough analysis of modern silt in the Guertu river distributive fluvial system, as well as data obtained from UAV aerial photography and satellite remote sensing. The Guertu River Distributive Fluvial System (DFS) is classified into three stages, namely "proximal," "middle," and "distal," based on the examination of river morphology, sediment variations, sedimentary attributes, and other relevant aspects throughout different sections of its tributaries, from the source to the mouth. At the upstream section of the downstream fining sequence, the slope is the steepest and the hydrodynamic conditions are intense, resulting in the formation of a predominantly big gravel braided river. The river bed section has a morphology resembling a combination of a "V" and a "U" shape. It is characterized by a narrow and deep configuration, with a relatively short breadth. The sediment primarily consists of medium to large-sized gravel with minimal sand content. The gravel exhibits good roundness and displays a considerable degree of orientation. The primary microfacies present are braided channel and flood plain. The slope of the central area is decreased in comparison to the nearby end, primarily due to the presence of extensive braided rivers. The river bed has a greater width, with minor eolian dunes visible in the river channel. The gravel particles are predominantly fine to medium in size, and there is an increased amount of sand present. The predominant microfacies are braided channels, floodplains, and eolian dunes. At the distal end, the slope is minimal, the landscape is level, the braided river transitions into a meandering river, the sediment consists primarily of sand, and the signs of bioturbation are clearly visible. The primary microfacies consist of braided channels, meandering channels, floodplains, eolian dunes, lakes, and swamps.

Karyotypic description and comparison of Litoria (L.) paraewingi (Watson et al., 1971), L.ewingii (Duméril et Bibron, 1841) and L.jervisiensis (Duméril et Bibron, 1841) (Amphibia, Anura).

The karyotype of Litoria (L.) paraewingi (Watson et al., 1971) (Big River State Forest, Victoria) is described here for the first time. It is prepared following tissue culture of toe clipping macerates, cryopreservation, reculture and conventional 4',6-diamidino-2-phenylindole (DAPI) staining. The L.paraewingi karyotype is then compared to similarly processed IUCN (International Union for the Conservation of Nature) least concern members L.ewingii (Duméril et Bibron, 1841) (southern Victoria) and L.jervisiensis (Duméril et Bibron, 1841) (Myall Lakes National Park, New South Wales), all members of the same L.ewingii complex/group. The L.paraewingi diploid number is 2n = 26, the same as for the other two species. Litoriaparaewingi chromosomes 1, 2, 6 and 7 are submetacentric, chromosomes 3 and 5 are subtelocentric and the remainder are metacentric. No secondary constriction or putative nucleolus organiser region (NOR) was readily identifiable following conventional DAPI staining in any scored L.paraewingi metaphase spread. Conversely, a putative NOR was readily identifiable on the long arm of chromosome 1 in all examined metaphase spreads for the other two species. The karyotypes of L.ewingii and L.jervisiensis here further differ from L.paraewingi with chromosome 1 being metacentric and chromosomes 8 and 10 being submetacentric for both former species. The L.jervisiensis karyotype differs from those of L.ewingii and L.paraewingi by DAPI staining with: (i) apparent relative length inversion of subtelocentric chromosome 3 and metacentric chromosome 4 and (ii) chromosome 6 being metacentric rather than submetacentric. All three species have a highly conserved chromosome morphology with respect to chromosomes 2, 5, 7, 9, 11, 12 and 13. The greatest gross morphological difference karyotypically is observed between L.paraewingi and L.jervisiensis. These karyotype data support the previous phylogenetic separation of these three species based upon genetic compatibility and behavioural, biochemical and molecular genetic analyses.

Box Type Minor Bridge on Small Rivers in Alluvial Region

Since time immemorial, humankind has been using various techniques to cross the rivers, streams or any depression without closing or obstructing the original flow through a structure called bridge. With the span of time and advancements in civil engineering, several types of bridges have come into existence like wooden, steel, masonry arches, RCC and pre stressed concrete bridges. Indian Roads Congress categorizes three types of the bridges on the basis of length i.e. culverts up to 6.0 m, minor bridges above 6.0 m to maximum 60.0 m length and major bridges above 60.0 m. In present scenario, minor bridges over small rivers has become necessary for development and prosperity of nation as most of the roads have to cross small rivers at several places to connect remotest corner of the country. Bridges, though a manmade structure, over a period become an important part of environment because in most of the cases water flowing below is used for drinking, irrigation and underground recharging. The alluvial region of India spread from Punjab to West Bengal has a peculiar nature because soil is almost soft in nature consisting of mainly sand, clay and silt which is fertile for vegetation. Water retention and its movement condition are high throughout the year. Several type of water bodies which exists in this type of region are pond, small drain, small and medium rivers which drains into the big rivers like Ganga, Yamuna, Ghaghara, Gomati and Sai etc. Since long time, road system on the earthen track and pucca has been introduced for traffic like chart, chariot and motorized vehicle. There were little number of bridges over major rivers i.e. bridge alone to cross over the river Ganga except in few places like Allahabad, Kanpur and Varanasi and over the Ghaghra Algine bridge, Maghighat, Bhatni. Some bridges were constructed over small and medium rivers in medevial period by local rulers and businesspersons, which have now become obsolete. It is found that most of the bridges are of masonry arches wooden and trusses having insufficient water and carriageway. After independence, the road network system has been improved to meet out socio economic needs of people. The new bridges have been constructed with standard road width and sufficient waterway. Study has been conducted for existing new constructed bridge system over small river and alluvial region of Uttar Pradesh to set guidance for future course of action in replacing and providing new bridges to optimize the needs of the people. Bridge system being provided over small & minor rivers for the road network for new and replacement of older bridge at different site is varying from place to place. For this purpose, study has been conducted for sustainable option of minor bridges over small rivers discharge up to 300 m3 /s. It is found that the box type minor bridges are best option on small & minor rivers.

Predicting flood stages in watersheds with different scales using hourly rainfall dataset: A high-volume rainfall features empowered machine learning approach

Accurate prediction of instantaneous high lake water levels and flood flows (flood stages) from micro-catchments to big river basins are critical for flood forecasting. Lake Carl Blackwell, a small-watershed reservoir in the south-central USA, served as a primary case study due to its rich historical dataset. Bearing knowledge that both current and previous rainfall contributes to the reservoirs' water body, a series of hourly rainfall features were created to maximize predicting power, which include total rainfall amounts in the current hour, the past 2 h, 3 h, …, 600 h in addition to previous-day lake levels. Notedly, the rainfall features are the accumulated rainfall amounts from present to previous hours rather than the rainfall amount in any specific hour. Random Forest Regression (RFR) was used to score the features' importance and predict the flood stages along with Neural Network – Multi-layer Perceptron Regression (NN-MLP), Support Vector Regression (SVR), Extreme Gradient Boosting (XGBoost), and the ordinary multi-variant linear regression (MLR) together with dimension reduced linear models of Principal Component Regression (PCR) and Partial Least Square Regression (PLSR). The prediction accuracy for the lake flood stages can be as high as 0.95 in R2, 0.11 ft. in mean absolute error (MAE), and 0.21 ft. in root mean square error (RMSE) for the testing dataset by the RFR (NN-MLP performed equally well), with small accuracy decreases by the other two non-linear algorithms of XGBoost and SVR. The linear regressions with dimension reductions had the lowest accuracy. Furthermore, our approach demonstrated high accuracy and broad applicability for surface runoff and streamflow predictions across three different-sized watersheds from micro-catchment to big river basins in the region, with increases of predicting power from earlier rainfall for larger watersheds and vice versa.

Identifying Temporal Change in Urban Water Bodies Using OpenStreetMap and Landsat Imagery: A Study of Hangzhou City

As one of the most important ecosystems, the water body is losing water during the rapid development of the city. To understand the impacts on water body change during the rapid urbanization period, this study combines data from the OpenStreetMap platform with Landsat 5/Thematic Mapper images to effectively and accurately identify small urban water bodies. The findings indicate that the trained U-net convolutional neural network (U-Net) water body extraction model and loss function combining Focal Loss and Dice Loss adopted in this study demonstrate high precision in identifying water bodies within the main urban area of Hangzhou, with an accuracy rate of 94.3%. Trends of decrease in water areas with a continuous increase in landscape fragmentation, particularly for the plain river network, were observed from 1985 to 2010, indicating a weaker connection between water bodies resulting from rapid urbanization. Large patches of water bodies, such as natural lakes and big rivers, located at divisions at the edge of the city are susceptible to disappearing during the rapid outward expansion. However, due to the limitations and strict control of development, water bodies, referring to as wetland, slender canals, and plain river networks, in the traditional center division of the city, are preserved well. Combined with the random forest classification method and the U-Net water body extraction model, land use changes from 1985 to 2010 are calculated. Reclamation along the Qiantang River accounts for the largest conversion area between water bodies and cultivated land, constituting more than 90% of the total land use change area, followed by the conversion of water bodies into construction land, particularly in the northeast of Xixi Wetland. Notably, the conversion of various land use types within Xixi Wetland into construction land plays a significant role in the rise of the carbon footprint.

Towards an integrative understanding of British Columbia’s Nechako Watershed: Connecting knowledge systems to strengthen understanding of climate change, watershed security, health and well-being

Understanding of upstream and downstream dynamics of continental river basins demands attention to the influence of important tributaries and watersheds. This is exemplified by the 47,200 km2 Nechako Watershed, the second largest sub-watershed of British Columbia’s Fraser River Basin. Although the Nechako (derived from the Indigenous Dakelh word meaning “big river”) is recognised for its ecological, societal and cultural importance, attention to this sub-watershed has often been overshadowed by a focus on the iconic Fraser River. This paper examines insights from a purposeful response to this gap, whereby a team of researchers has worked together to strengthen understanding of cumulative stressors and changes in the Nechako, focusing on climate change and water security, sediment sources and quality, and health and well-being dynamics within the Nechako Watershed. Lessons learned from a decade of this collaboration are presented, reflecting on the Nechako Watershed’s past, present, and future through the lens of a unique case study of interdisciplinary research. Emerging research and knowledge exchange partnerships are highlighted along with growing concerns for the Nechako’s keystone aquatic species including three species of Pacific salmon and the endangered Nechako white sturgeon. Drawing on the natural, social and health sciences, we examine strengths and challenges of connecting research across interrelated watershed security issues ranging from climate change, landcover disturbances (e.g., wildfires, mountain pine beetle outbreaks and forest harvesting), land use changes (e.g., expansion of Vanderhoof’s agricultural belt), and the far-reaching impacts of the damming of the Nechako River mainstem in the 1950’s. Our paper brings necessary attention to these and other influences on waterways, landscapes and communities of the Nechako Watershed, highlighting new research opportunities arising among diverse knowledges and disciplines, and the ongoing collaborative effort required to address emerging challenges for the Nechako and wider Fraser River Basin, with consequences for current and future generations.

Big river channel formation and deformation in the intermountain basin (case study of the Yana River within the Kular mountain massif)

The incised pebble-boulder channels of large mountain rivers (including the Yana in its mountainous area), their morphology and history of formation are well studied. However, local conditions within the intermountain depressions lead to the emergence of specific features of the channel development and its morphology — in this case, the formation of finger-shaped meander. The paper analyzes the historical and modern features of the formation of the Yana riverbed in the “Porogi” section located in the depression inside Kular range, and describes the negative impact of channel processes on navigation. Using this case study, we consider the characteristic features of the channel development of a large river under the influence of a complex of factors — the regional geological conditions (which caused active incision of the channel), discharge, and channel sediment composition. Characteristics of lateral migration and curvature development of meander controlled by bedrock and narrowing of the valley are presented. The discharge conditions under which the displacement of riffles is possible are calculated. The forecast of the further channel development and recommendations for sustainable navigation are given.

Hotspots of the Habitats Directive species in the Carpathians

Knowledge of species distribution is crucial for their protection, and this was our motivation to identify hotspots of the Habitats Directive (HD) species in the Carpathians. As a data source we used reports and species distribution maps submitted by the EU Member States according to the Habitats Directive Article 17 in 2019.The highest HD species richness areas are in the south-eastern part of the Western Carpathians and in the south-west outcrops of the Carpathians at the SK/AT and CZ/AT borders. The south-eastern part of the Western Carpathians is important for all studied species groups, specific patterns of distribution exhibit fish (distribution along big rivers), amphibians (high diversity also in the outer Western Carpathians and Transylvanian Basin) and partially plant species (besides SE Western Carpathians, quite high diversity also in other parts of the Western Carpathians).We analysed the relation between species richness, proportion of species groups, and concentration of rare species. Mammals are the dominant taxonomical group, especially in species-poor grid cells. The proportion of invertebrates increases with increased species richness. The widespread species prevail in species-poor grid cells and their proportion decreases with increasing species richness.We also identified areas with low Natura 2000 coverage, but with high biodiversity or a high number of rare species. These areas have high potential to improve protection of the HD species by designating new Natura 2000 sites or enlarging existing ones.

Human interventions alter morphodynamics of meandering channels: Insights from decadal to pre-industrial observations in the Yangtze River

Human activities, such as reservoir construction and bank revetment, significantly alter downstream flow and sediment regimes and river channel changes, impacting river ecosystem services. However, our understanding of how intense human activities affect morphodynamics of meandering channels in big river systems remains incomplete due to the lack of high-resolution in-situ data. Here, we use comprehensive data encompassing hydrology and sediment, historical channel maps, and high-resolution river bathymetry to investigate the evolution of meandering bends in the Middle Yangtze River (MYR) across three distinct phases: the natural period (1490–1975), the bank revetment period (1975–2002), and the post-dam period (2003–2018). The study revealed that, in the absence of human intervention, the meandering channels of the MYR naturally experienced inner bank deposition and outer bank erosion, largely governed by curvature-induced secondary flow patterns in flow and sediment transport mode. In 1975–2002, outer-bank revetments reduced erodibility, stabilizing outer banks, while inner banks continued to experience lateral and vertical deposition, causing a narrower and deeper channel hydraulic geometry. Conversely, meandering bends had exhibited an unusual pattern of ‘outer bank deposition and inner bank erosion’ in 2003–2018. Channel morphological changes characterized by channel incision and widening were driven by changes from erodible bank boundaries to solidified bank boundaries, substantial reduction in suspended sediment concentration, and an altered and extended effective flow range (10,000–25,000 m3/s). Our findings highlight that human interventions such as damming and bank revetments can alter the conventional erosion–deposition morphodynamics of meandering bends in large river systems, carrying vital implications for sustainable river management in the Anthropocene.

Spatial and Temporal Characteristics of Channel Disturbance Zones in Big River, Southeast Missouri (1937–2018)

abstract: Ozarks watersheds have responded to land clearing and settlement disturbances by transporting large amounts of gravel and sediment to main valleys of medium-large river systems. Historical gravel and sediment accumulate in disturbance zones, which are areas of excessive channel activity that can be detected over time using historical aerial photographs. This project uses a series of aerial photos from 1937–2018 to identify disturbance zones in the Big River of southeast Missouri, which has a history of lead mining and ore processing that has caused widespread contamination of the channel and floodplain deposits. Variations in active areas of the historical meander belt show that disturbance zones account for 24 percent of the channel length at an interval of one per 2.5 km of channel. Megabars and extensions are the most prominent types of disturbance zones, but translations and cutoffs are larger with higher potential for sediment storage. From 1937 to 1976, areas of channel activity have cycled between expansion and contraction. However, after a period of recovery prior to 1976, disturbance zone areas have been expanding over the last 40 years likely in response to an increase in flood magnitude and frequency from more high intensity rainfall events since 1973.

Усложняя картину мира

The article, which dedicated to the jubilee of Galina Yankovskaya could be characterized as a collage consisted of fragments of different styles and compositions. Three authors use a date in a historian’s biography as a reason for thinking about interdisciplinary trends in modern historical science and play with the genres of historical narratives. E.Yu. Zubkova shares her vision of the situation in the historiography of late Stalinism and highlights the intersections of her own interpretations of this period with the works of G. Yankovskaya. I.V. Narsky imagined a conversation that could take place between him and the hero of the day about the key issues of visual historical research and new cultural history. Based on the the 2007-2008 monographs on Soviet artists of the Stalinist era and on private photographic practice in the USSR, participants in the imaginary discussion will address a range of issues of concern to them. Two books and their reviews are used as material for a virtual discussion on key issues of visual historical research and new cultural history. These include the impact of the country's development in the 1990s on the research interests of young historians, the origins of the 'visual turn' and its relationship to the shift in interest of Russian historians from events, structures and processes to 'ordinary' people, and the prospects and difficulties of working with the image as a historical source. G.A. Orlova in the first part of her section raises the question of the screen nature of a jubilee. The hero of the day’s statement, that a professional historian should enhance the complexity of the world picture, is contextualized and problematized. In the second part, the results of curating a biographical conversation with Galina Yankovskaya are presented in the form of nine screen-shorts. The life on the big river under late socialism and the river as a frame for the temporal experience of the historian are in focus.

Usage of ring-recovery data for the background for the Migration Atlas of the European Anseriform birds

The atlas was prepared from the data on ring-recovery database of the Bird Ringing Centre of Russia (Institute of Ecology and Evolution of the Russian Academy of Sciences). We plan to publish an extended version of the atlas on the base of bird ring-recovery data. The Atlas will consist not only description of the migratory routes but a consideration of several population parameters of the focal species, as well as, the spatial distribution characteristics of recoveries and even probable practical use of the obtained population parameters values. More than 42000 ring recoveries of 36 European waterfowl species were used. Besides the standard description of the migratory routes, monthly distribution of recoveries, maps of direct and indirect recoveries, etc., the Atlas contains some additional information. In particular, the population structure of species: geographical populations were revealed. It is known that these populations served as a basement of the flyway conception. Then we elaborated math model allows calculating mean yearly mortality rate for each species, in different periods, males and females, etc. Ring-recovery data of a number of species shows the influence of the global warming on the waterfowl. Wintering sites usually are permanent; however breeding places shift more and more to the north. Therefore, mean distance between wintering and breeding places progressively increasing during 20th and the beginning of the 21th century. In addition, the distribution of recoveries in relation to each other along the area was described: 1) it was possible to calculate the degree of aggregation of recoveries (aggregation) for the species with the most numerous recoveries, specifically – to calculate the mean distance from each recovery to its nearest neighbour (mean minimal distance between recoveries); 2) degree of recovery concentration in groups (concentration) with different number of recoveries that located at not more than some distance (might be called as “key distance”) from each other. The distance between recoveries within such groups is less than the distance between groups (clusters). The distribution of recoveries in connection with ecological capacities of the area where these recoveries are located is described for the first time. The distribution of recoveries by their proximity to the different waterbodies is compared: to small and big rivers, lakes, and to the seashore. The exploratory analysis of the separate and mutual numbers dynamics in the two systematically close waterfowl species was performed.

A Comparative Assessment and Decision-Making Approach of Water Quality Evaluation of Mahanadi Basin, Odisha

The Mahanadi River is one of Odisha's biggest rivers and is vital to the region's ecosystem and economy. Rapid water use, however, causes significant water contamination. However, the primary goal of this study is to assess surface water using the Critic Water Quality Index (CWQI), with a goal of collecting 20 samples from 19 monitoring stations over the course of a year (2021-2022). Inverted Distance Weighted (IDW) in ArcGIS 10.5 was used to create the spatial distribution maps. Multi-criteria decision-making methods (MCDMs), such as MOORA, were developed to offer a reliable and impartial portrayal of the cumulative pollution levels of each sample location. The physicochemical results were categorized in accordance with WHO drinking water threshold levels. The range of the CWQI value for surface water quality, which represents the excellent to very poor categories, was determined to be 36 to 290.8. It demonstrates that 84.21% of samples fit into the best drinking groups. Using the MOORA-recommended assessment scores, the Paradeep (St. 9) was discovered to be the most polluting site in contrast to other places, followed by 2nd (Cuttack D/s) and 3rd (Choudwar D/s). The factors responsible of the decline in water quality at St. 8, 9 and 19, respectively, were found to be runoff from waste material, unprocessed effluents, and several other anthropogenic factors. The paper's detailed discussion of water quality methods can also give readers a general understanding of indexing for further study.

First records of two mackerel shark species (Carcharodon planus comb. nov. and Carcharodon hubbelli; Lamnidae) from New Zealand

ABSTRACT The fossil record of the genus Carcharodon (Lamniformes: Lamnidae) dates to the late Oligocene and has a near global distribution. Today the genus is represented by a single species, the white shark Carcharodon carcharias. However, multiple extinct species are recognised in the Cenozoic including Carcharodon hastalis, Carcharodon hubbelli and Carcharodon planus comb. nov. Here we present the first occurrences of Carcharodon hubbelli and Carcharodon planus from New Zealand/Aotearoa, from the South Island/Te Waipounamu. Carcharodon hubbelli is previously reported from late Miocene deposits in the Pacific basin of North and South America, Asia, and Australia. Whereas Carcharodon planus has been reported from the Miocene of North America and Asia. One tooth from Carcharodon hubbelli is reported from the presumed late Miocene of Motunau Beach, North Canterbury, while one upper early Miocene tooth recovered from the Kakahu River, South Canterbury and an earliest Miocene tooth from the Big River mouth, Tasman District are referred to Carcharodon planus. In addition to being the first reported occurrences of these two species in New Zealand, the teeth of Carcharodon planus represent some of the earliest occurrences of the taxon as well as its southernmost occurrence.

Why river islands are formed after every big city

The perennial rivers have high and wide catchment areas that supply water continuously to the rivers. So, all through the year, they get water for their activities. Large cities emerge around such rivers and congregate as huge urban clusters like Delhi, Varanasi, and Patna. It was quite interesting to note that in all the big rivers like the Ganges, after crossing all big cities are invariably present, big river islands. The perceived cause of this is the heavy deposits by the people, or the slowing down of the river as it flattens up. The cause of the river islands is only partly the dirt thrown into the river by the people but largely because of the soap detergents and acids that produce large amounts of salts leading to precipitate and coagulation through a process called Cataphoresis of the colloidal impurities while crossing the cities. Since the river is slender in the cities due to concertized/solid embankment the flow is fairly fast. So, the whole material is pushed beyond the precincts of the cities. But as the river meanders beyond the city's ambit it spreads wider and slows down. So it gives enough opportunity to the colloids to settle down over some time the same enlarges to form River Island.

Analysis of coupling coordination and obstacle factors between tourism development and ecosystem services value: A case study of the Yellow River Basin, China

The rapid development of tourism has caused a series of impacts on the ecosystem. Although studies on the relationship between tourism development (TD) and the ecological environment are rich, few scholars have focused on the coupling coordination between them from the perspective of ecosystem services value (ESV). Given this research gap, we evaluated the levels of TD and ESV in 78 cities of the Yellow River Basin (YRB), China based on statistical and land-use data. Then, the coupling coordination degree (CCD) model, exploratory spatial data analysis (ESDA), the spatial variogram model, and the obstacle degree model were used to analyze the spatiotemporal evolution of coupling coordination between TD and ESV and its obstacle factors. The results show the following: (1) The comprehensive TD level shows an upward trend and presents significant spatial differentiation characteristics. The total ESV of the YRB shows a fluctuating upward trend, and the average ESV presents the spatial pattern of uplift in the middle reaches. (2) The comprehensive CCD of the YRB has gradually improved, but the gap between cities has widened. The global spatial autocorrelation of CCD is significantly positive, and the spatial variability has gradually increased. An “uplift area” in southern Shaanxi always exists and has gradually expanded to Shanxi and western Henan, while eastern Henan and western Shandong become a “subsidence area”. The coupling coordination level has changed from uncoordinated to coordinated in most counties, but the problem of TD and ESV imbalance generally exists. (3) For the whole basin, TD is always the main obstacle factor at the system layer, and tourism scale and tourism economic benefit are the most significant obstacles at the category layer. At the city level, the proportion of cities where TD is the main obstacle factor exceeds 80% by 2019. Specifically, insufficient tourism scale and low tourism economic efficiency restrict the improvement of CCD in most cities. This research provides valuable references for studying the coupling coordination relationship between TU and ESV in big river basins worldwide.

Spatial and Temporal Characteristics of Channel Disturbance Zones in Big River, Southeast Missouri (1937-2018)

Ozarks watersheds have responded to land clearing and settlement disturbances by transporting large amounts of gravel and sediment to main valleys of medium-large river systems. Historical gravel and sediment accumulate in disturbance zones, which are areas of excessive channel activity that can be detected over time using historical aerial photographs. This project uses a series of aerial photos from 1937-2018 to identify disturbance zones in the Big River of southeast Missouri, which has a history of lead mining and ore processing that has caused widespread contamination of the channel and floodplain deposits. Variations in active areas of the historical meander belt show that disturbance zones account for 24 percent of the channel length at an interval of one per 2.5 km of channel. Megabars and extensions are the most prominent types of disturbance zones, but translations and cutoffs are larger with higher potential for sediment storage. From 1937 to 1976, areas of channel activity have cycled between expansion and contraction. However, after a period of recovery prior to 1976, disturbance zone areas have been expanding over the last 40 years likely in response to an increase in flood magnitude and frequency from more high intensity rainfall events since 1973.

Assessing hydrological and water quality parameters in the Hathmati Watershed using the SWAT (Soil and Water Assessment Tool)

Abstract The study is conducted on the Hathmati River, which is the principal tributary of the Sabarmati River, one of Gujarat's biggest rivers. Indicators of water quality such organic N, organic P, NO3, NH4, NO2, total N, and total P were compared between the observed values in the watershed and the streamflow models. For monthly streamflow and monthly nitrate during the calibration period of 1999–2012, and for 0.87 and 0.56 for the validation period of 2013–2020, respectively, the Nash–Sutcliffe efficiency was 0.89 and 0.79. The measured water quality data at three locations in the watershed were largely compatible with their corresponding modeled values, while the agreement varied by nutrients. Using the parameters used to forecast the hydrological and water quality responses in the watershed region, the Soil and Water Assessment Tool model faithfully duplicated the hydrological and water quality conditions in this agricultural watershed. The results of the modeling indicated that nutrients are one of the key determinants with regard to the quality of the water, in accordance with the current land use and management practices in the watershed. Management practices should be implemented in order to reduce the nutrient load and meet the watershed's requisite water quality standards.