River Management Research Articles

Experimental Study of Bedform Development Characteristics and Their Effects on Sediment Transport

Bedforms are complex and varied features on riverbeds created by the interaction between flow and sediment particles. Bedform evolution is crucial for understanding sediment transport, bed resistance, and the ecological environment of rivers. In this study, a series of movable-bed dune experiments were conducted utilizing advanced 3D topographic laser scanning technology to precisely measure the 2D and 3D dune bedforms under various conditions. This enabled the detailed analysis of the bedform parameters, including the dune length and height, the crest height, and the trough depth. Furthermore, this study examined the relationship between bed resistance and dune morphology and investigated how the intensity of bedload transport affects bed resistance. The findings indicate that bedload mass transport on the riverbed significantly contributes to increased bed resistance. Given the limitations of the traditional bedload transport rate formulas for dune bedforms, this research introduces a new formula derived from the experimental data. The accuracy of this formula was confirmed using the nonlinear least squares method. Our study enhances the accuracy of sediment transport predictions and provides scientific support for river management and engineering practices.

The LTAR Croplands Common Experiment at the Gulf Atlantic Coastal Plain.

The Gulf Atlantic Coastal Plain (GACP) Long-Term Agroecosystem Research (LTAR) Network site is characterized by hot and humid summers with low gradient stream channels surrounded by wetland forests and croplands. Beneath its sandy soils, a confining layer stifles recharge to the deeper aquifer system, so a substantial proportion of streamflow is driven by shallow subsurface baseflow. Agricultural practices in the area consist of forage and livestock production, forestry, and rotational cropping systems dominated by cotton (Gossypium hirsutum) and peanut (Arachis hypogaea). Certain factors impose challenges to the viability of GACP agricultural systems, like changing economics and demographics, as well as pest and disease pressures. The GACP communicates with stakeholders from various backgrounds, who provide their perspectives as agricultural research service scientists execute their research plans. The GACP LTAR common experiment (CE) is carried out via plot- and field-scale studies. The plot-scale CE compares prevailing practices, determined from regional data, with an alternative treatment including winter covers, such as the biofuel feedstock carinata (Brassica carinata, A. Braun), to provide both economic and environmental benefits. The field-scale CE is observational; key variables are monitored for two farms where management practices largely emulate the prevailing treatment. Data collection efforts quantify vegetation, hydrology, soils, and climate data to produce datasets for modeling and statistical analysis. Research teams quantify relationships between land management, environment, and socioeconomic benefits. Ultimately, the GACP LTAR site works to facilitate agricultural system health and wellbeing at local, regional, and national scales by providing long-term science-based solutions.

Delineating the drought vulnerability zones in Bangladesh

The research aims to explore the vulnerability of Bangladesh to drought by considering a comprehensive set of twenty-four factors, classified into four major categories: meteorological, hydrological, agricultural, and socioeconomic vulnerability. To achieve this, the study utilized a knowledge-based multi-criteria method known as the Analytic Hierarchy Process (AHP) to delineate drought vulnerability zones across the country. Weight estimation was accomplished by creating pairwise comparison matrices for factors and different types of droughts, drawing on relevant literature, field experience, and expert opinions. Additionally, online-based interviews and group discussions were conducted with 30 national and foreign professionals, researchers, and academics specializing in drought-related issues in Bangladesh. Results from overall drought vulnerability map shows that the eastern hills region displays a notably high vulnerability rate of 56.85% and an extreme low vulnerability rate of 0.03%. The north central region shows substantial vulnerability at high levels (35.85%), while the north east exhibits a significant proportion (41.68%) classified as low vulnerability. The north west region stands out with a vulnerability rate of 40.39%, emphasizing its importance for drought management strategies. The River and Estuary region displays a modest vulnerability percentage (38.44%), suggesting a balanced susceptibility distribution. The south central and south east regions show significant vulnerabilities (18.99% and 39.60%, respectively), while the south west region exhibits notable vulnerability of 41.06%. The resulting model achieved an acceptable level of performance, as indicated by an area under the curve value of 0.819. Policymakers and administrators equipped with a comprehensive vulnerability map can utilize it to develop and implement effective drought mitigation strategies, thereby minimizing the losses associated with drought.

Mapping landforms of a hilly landscape using machine learning and high-resolution LiDAR topographic data

Landform maps are important tools in assessment of soil- and eco-hydrogeomorphic processes and hazards, hydrological modeling, and natural resources and land management. Traditional techniques of mapping landforms based on field surveys or from aerial photographs can be time and labor intensive, highlighting the importance of remote sensing products based automatic or semi-automatic approaches. In addition, the time-intensive manual labeling can also be subjective rather than an objective identification of the landform. Here we implemented such an objective approach applying a random forest machine learning algorithm to a set of observed landform data and 1m horizontal resolution bare-earth digital elevation model (DEM) developed from airborne light detection and ranging (LiDAR) data to rapidly map various landforms of a hilly landscape. The landform classification includes upland plateaus, ridges, convex slopes, planar slopes, concave slopes, stream channels, and valley bottoms, across a 400 km2 hilly landscape of the Ozark Mountains in northeastern Oklahoma. We used 4200 landform observations (600 per landform) and eight topographic indices derived from 2 m, 5 m and 10 m resolution LiDAR DEM in random forest algorithm to develop 2 m, 5 m and 10 m resolution landform models. We test the effectiveness of DEM resolution in mapping landforms via comparison of observed landforms with modeled landforms. Results showed that the approach mapped ∼84% of observed landforms when covariates were at 2 m resolution to ∼89% when they were at 10 m resolution. However, predicted maps showed that the 2 m resolution covariates performed better at capturing accurate landform boundaries and details of small-sized landforms such as stream channels and ridges. The approach presented here significantly reduces the time required for mapping landforms compared to traditional techniques using aerial imagery and field observations and allows incorporation of a wide variety of covariates. The landform map developed using this approach has several potential applications. It could be utilized in hydrological modeling, natural resource management, and characterizing soil-geomorphic processes and hazards in a hilly landscape.

Description of a relict aspen parkland-associated grassland in the Peace River region of British Columbia, Canada

The aspen parkland-associated grasslands of the Peace River region, British Columbia (BC), have been severely reduced in area, primarily because of agricultural and urban development. In this region, the species composition of plant communities is similar to that of prairie grasslands and is topographically influenced, occurring primarily on warm-aspect slopes along the Peace River and some of its tributaries. Historical records show that non-forested grass- and sedge-dominated plant communities occurred on flat and gently rolling terrain in a parkland ecosystem near what are now the communities of Dawson Creek and Fort St. John. The Peace grasslands are not represented in BC’s biogeoclimatic ecosystem classification, perhaps leading to their neglect in regional natural resource management and conservation planning. Here, I describe the vascular plant community of a level-terrain relict aspen parkland-associated grassland in the Peace River region. Its species composition differs from nearby warm-aspect grasslands and includes provincially listed plant species. Increased awareness of grassland communities may support conservation, ecosystem restoration, and climate change adaptation in the southern boreal region of BC.

The ecological operation of ChiTan hydropower station based on hydrological alteration using the PCA method

ABSTRACT Water infrastructure affects the quantity, quality, and environment of water. During reservoir construction, only the social-economic benefits were considered and the health of the downstream river was neglected. Due to the severe downstream river system, the operators and managers faced the challenge of the downstream ecosystem. Many scholars are concerned with the reservoir's optimum functioning, which considers social and economic advantages. Numerous significant opinions and research findings are being presented on ecological scheduling at the moment, both in China and overseas, which surely deepen the connotations of ecological scheduling and serve as the research basis and critical reference of this work. The influence of hydropower development on hydrological conditions, the categorization and calculation of environmental runoff, and the building and solution of ecological scheduling models are all discussed and researched in this work. The study examined how the ChiTan hydropower project influenced the Jinxi River's flow. The total hydrologic alteration calculated using RVA is 50.53%. The component analysis is also utilized to eliminate the statistical redundancy in the hydrologic indicators. The indicators’ monthly flow for July and August's mean minimum flow for 7 days are relevant indicators for the Jinxi River basin's hydrologic modification regime.

Analyzing the distribution patterns and dynamic niche of Magnolia grandiflora L. in the United States and China in response to climate change.

Magnolia grandiflora L. (southern magnolia) is native to the southeastern coastal areas of the United States, from North Carolina to eastern Texas (USDA Cold Hardiness Zone 8). It is currently widely cultivated in Zones 5-10 in the U.S. and in southern Yangtze River regions in China. Limited studies have examined the effects of climate change and human activities on the geographical distribution and adaptability of M. grandiflora during its introduction to China. We selected 127 occurrence points in the U.S. and 87 occurrence points in China, along with 43 environmental variables, to predict suitable habitat areas for M. grandiflora using present climate data (1970-2000) and projected future climate data (2050-2070) based on a complete niche ensemble model (EM) using the Biomod2 package. We also predicted the niche change of M. grandiflora in both countries using the 'ecospat' package in R. The ensemble models demonstrated high reliability, with an AUC of 0.993 and TSS of 0.932. Solar radiation in July, human impact index, and precipitation of the wettest month were identified as the most critical variables influencing M. grandiflora distribution. The species shows a similar trend of distribution expansion under climate change scenarios in both countries, with predicted expansions towards the northwest and northeast, and contractions in southern regions. Our study emphasizes a practical framework for predicting suitable habitats and migration of Magnoliaceae species under climate change scenarios. These findings provide valuable insights. for species conservation, introduction, management strategies, and sustainable utilization of M. grandiflora.

How Does the Tibetan Plateau Land Thermal Initial Condition Influence the Subseasonal Prediction of 2020 Record‐Breaking Mei‐Yu Rainfall

AbstractAccurate subseasonal prediction of heavy rainfall is helpful for disaster mitigation but challenging. The land thermal condition of Tibetan Plateau (TP), usually with climate memory ranging from weeks to seasons, has been seen as a potential predictability source for subseasonal prediction. Aiming at 2020 record‐breaking Mei‐yu rainfall, this study attempts to investigate whether and how the influence of initial TP surface thermal condition near late June influences the July rainfall prediction over the Middle and Lower Yangtze River Region (MLYR), based on two contrasting prediction experiments using a global climate ensemble prediction system. The results show that the most distinguishable change in the downstream prediction in July is the anomalous low‐tropospheric cyclone and the associated increased rainfall over MLYR corresponding to the warmer initial condition of surface TP. Influenced by the invasion of the positive potential vorticity (PV) center that generated over TP and propagated eastward, this low‐level cyclone anomaly over MLYR is formed within the first week of prediction, and persists for the next 3 weeks maintained by the positive feedback between the low‐level cyclone and middle‐tropospheric latent heating over MLYR in the prediction. This study confirmed the significant effect of TP initial thermal condition on downstream prediction ahead of 3 weeks during the Mei‐yu season (peak summer) with strong land–atmosphere coupling over TP.

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.

Fish Distribution Pattern and Management in the Tinau River, Palpa

For study direct observation, survey, questionnaire, interviews and discussion method are used to meet the objectives. The main objectives of the study were fish distribution pattern and fish management. The field work was performed between September 2016 to june 2017 of different five stations in Tinau river. Local fishermen were also used for the collection of fishes from sampling sites. Cast net, hook, Bhureli jal and Nets (Jhal) other locally available devices were used for the collection of fish sample. Altogether 5 orders, 9 families, 14 genera and 25 species were found in the study area. Among them 19 fish species from Station I, 16 fish Species from Station II and station III, 10 fish species from Station IV and 7 species from Station V were collected with the help of local fisherman. Fish species such as Channa punctatus, Puntius conchonius and Glyptothorax pectinopterus were found to be clumped in distribution while the rest of the fishes were uniformly distributed. Cyprinids were found to be the most common and dominant among all the species. The human impacts like construction of dam, bridges, riverbed extraction, bank erosion, illegal fishing and use of poisonous chemicals effects on the fish distribution and management directly of the Tinau river. For the management practices like implementation of strict rules and regulations, made ladder for fish passing, construction of fish barrier, plantation, control water pollution and awareness programmes should be done with the help of local people and other institutions. This study helps the local people to pay more attention towards the knowledge about indigenous or locally found fishes and proper management of the Tinau river.

Groundwater productivity analysis with geology in the Geumgang River region, Korea

Groundwater productivity analysis with geology in the Geumgang River region, Korea

High resolution (1-km) surface soil moisture generation from SMAP SSM by considering its difference between freezing and thawing periods in the source region of the Yellow River

Soil moisture (SM) is a critical component of the land surface hydrological cycle, significantly impacting various sectors such as hydrology, meteorology, and agriculture. Accurate, high-resolution SM data are essential for effective flood forecasting, water resource management, and understanding the soil freeze-thaw processes in cold regions. This study aims to generate 1 km resolution liquid surface SM (SSM) data with a twice-daily update frequency by downscaling SMAP Level-4 SSM data using random forest (RF) and multiple linear regression (MLR) in the source region of the Yellow River (SRYR), by considering the differences in SM changes between freezing and thawing periods. To obtain the SSM data, 16 downscaling schemes of both RF and MLR were designed for each of the three scenarios. In each downscaling process, both land surface temperature (LST) and normalized difference vegetation index (NDVI) were utilized in MLR and RF models, alongside various combinations of additional variables such as albedo, elevation, leaf area index (LAI), soil texture. Results showed that during the freezing period, RF produced superior SSM estimates when supplemented with NDVI, LST, albedo, elevation, LAI, and soil texture. MLR was more effective during the thawing period when paired with NDVI, LST, elevation, LAI, and soil texture. During the freezing period, the downscaled SMAP SSM exhibited average R, RMSE, ubRMSE of 0.76, 0.029 m3·m-3, and 0.023 m3·m-3, respectively, when compared with in-situ measurements. During the thawing period, the average R, MAE, RMSE, and ubRMSE between the downscaled SMAP SSM and in-situ measurements were 0.52, 0.057 m3·m-3, 0.067 m3·m-3, and 0.054 m3·m-3, respectively, compared to 0.45, 0.070 m3·m-3, 0.083 m3·m-3, and 0.060 m3·m-3 for the original SMAP SSM. Thus, the research significantly enhances both the accuracy and spatial resolution of SMAP SSM estimations, underscoring its vital role in advancing hydrological studies within the SRYR.

The Holocene evolution of the fluvial system of the southern Hessische Ried (Upper Rhine Graben, Germany) and its role for the use of the river Landgraben as a waterway during Roman times

Abstract. Intensive human intervention in the natural drainage system of the Hessische Ried (Upper Rhine Graben, Germany) resulted in the transformation of a large wetland into an intensively used cultural landscape. At least since the first century CE, when Romans conducted early river regulation and water management, the natural water network has experienced extensive anthropogenic re-organisation. The LandGraben project focuses on the reconstruction of the natural and anthropogenic watercourse systems along the river Landgraben, a tributary to the river Rhine in the northern Hessische Ried. Several rivers from the southern Hessische Ried could have fed the river Landgraben during Roman times via the meandering Palaeo-Neckar depression, thus increasing both length and discharge of the Roman waterway. In this study, we present results of our investigations within the southern Hessische Ried to reconstruct the former channel network that was used by Romans for the transportation of troops, wares and border security. Our approach integrates the use of high-resolution digital elevation models (DEMs) as a base for geophysical measurements (electrical resistivity tomography, ERT), direct push sensing and sediment coring in combination with sedimentological and geochemical analyses of the encountered sedimentary units. Local chronostratigraphies were established based on radiocarbon dating. Based on our results, we are able to differentiate a palimpsest of several abandoned fluvial channels throughout the southern Hessische Ried and to reconstruct the spatio-temporal development of the corresponding fluvial systems. Chronostratigraphic data show that the Palaeo-Neckar stopped flowing through the Hessische Ried around 10 000 cal BCE. Moreover, we found that the river Weschnitz, the largest of the possible Landgraben tributaries, stopped flowing through the Palaeo-Neckar depression at ca. 3000 cal BCE. Instead, it took a right-angled shortcut westwards to the river Rhine, north of the city of Lorsch. For the first time, we present geomorphological evidence that the river Weschnitz was not diverted by the Romans as speculated so far. This is corroborated by numerous wooden posts of human-made construction crossing an E–W running water course at the modern Weschnitz knee, with the oldest posts being dendrochronologically dated to the fourth and third millennia BCE. We further argue that the river Winkelbach/Lauter formed its knee towards the river Rhine and thus left the Palaeo-Neckar depression not later than the second century CE but most probably even contemporaneously with the formation of the Weschnitz diversion. In the case of the Winkelbach/Lauter, a high-energy flood event presumably related to strong rainfall and/or meltwater processes in the Odenwald Mountains is assumed to be responsible for the initiation of the new, diverted water course. With regard to the Landgraben and its use as a waterway within the Roman fluvioscape of the Hessische Ried, we therefore conclude that the Romans successfully collected water from several smaller rivers, such as from the rivers Modau and Darmbach and from even smaller tributaries, to make the river Landgraben a navigable waterway. The rivers Weschnitz and Winkelbach/Lauter, however, did not contribute any water to the Landgraben system during Roman times.

The Effects of Acid-Modified Biochar and Biomass Power Plant Ash on the Physiochemical Properties and Bacterial Community Structure of Sandy Alkaline Soils in the Ancient Region of the Yellow River

The application of biochar can effectively enhance soil organic matter (SOM) and improve soil structure. Biomass power plant ash (BPPA) is also rich in essential nutrients for plants, with similar carbon content. Considering production cost and agricultural waste recycling, it is beneficial to apply BPPA to improve soil fertility and quality. However, it remains unclear whether its ameliorative effects surpass those of biochar in alkaline soils. In the study, we set up seven pot experiments of faba beans in sandy alkaline soils from the ancient region of the Yellow River, including the controls (CK), different amounts of acid-modified BPPA (A1, A2, A3), and the same amounts of acid-modified biochar (B1, B2, B3), to compare their effects on soil physiochemical properties and bacterial community structure. The results indicate that the application of both biochar and BPPA can improve soil physiochemical properties. At the same dosage, the biochar application outperformed BPPA treatment in terms of soil physical properties such as bulk density (BD), maximum water-holding capacity (FC), and soil capillary porosity (SP2). Conversely, BPPA treatment displayed advantages in chemical properties such as readily oxidizable organic carbon (ROOC), total nitrogen (TN), alkaline nitrogen (AN), available phosphorus (AP), available potassium (AK), and electrical conductivity (EC). All the treatments enhanced the richness and diversity of bacterial communities, increasing the relative abundance of eutrophic groups such as Bacteroidota and Firmicutes while decreasing that of oligotrophic groups like Actinobacteriota. BPPA also increased the relative abundance of Proteobacteria, while the opposite was observed for biochar. Correlation analysis showed that the environmental factors such as soil pH, EC, TN, AK, SOM, and SP2 emerged as primary factors influencing the bacterial community structure of alkaline soils, significantly affecting their diversity and abundance. Among them, SP2 and SOM were the dominant physical and chemical factors, respectively. Overall, the application of both acid-modified BPPA and biochar can enhance the physiochemical properties of sandy alkaline soils, while the application of BPPA is superior for improving soil nutrient content and enhancing bacterial community structure. The study explores the potential mechanisms through which the application of acid-modified BPPA affects soil characteristics and microbial features, providing new insight into developing optimizing fertilization strategies for enhancing soil quality in the ancient region of the Yellow River.

ʻĀina as resilience: mapping community networks and collaborative care in Hawaiʻi

This article examines the growth of Indigenous grassroots community groups across Hawaiʻi, whose efforts are pivotal to place-based climate change resilience and community well-being. Instead of focusing on specific ecosystem resilience actions, it highlights the people and places that make this movement of community organizations resilient, leveraging both social and cultural strengths to adapt to climate impacts. For many Indigenous peoples, climate change is not new; adaptation has already been integral to relationships between environment and culture. These changes require culturally responsive approaches, not short-term engineering solutions such as coastal hardening or stream channelization. A collaboration between a grassroots artist mapping initiative (‘ĀINAVIS) and a university’s community-based research project (‘ĀINA KUPU), this study utilizes a novel data index compiled using publicly available information to inform a series of in-depth student interviews with community groups across Hawai‘i whose mission, vision, and work are dedicated to caring for ‘āina. We find that these “ʻĀina Organizations” articulate climate resilience in multi-faceted and culturally grounded ways, maintaining reciprocal and mutual relationships with ʻāina, the Hawaiian term for land meaning “that which feeds.” Facing various challenges and needing different systems of support, our work maps the dynamic adaptability of ‘āina expressed through community networks of collaborative care with emphasis on the importance of intergenerational knowledge and genealogical connection to place shared and passed onto future generations. The article concludes by emphasizing the importance of working on ‘āina as an exercise of Indigenous sovereignty, expanding climate resilience with cultural practice and social justice as both outcome and process of climate change adaptation.

A high-precision radiocarbon chronology of Inka rule in the Upper Loa River Region of northern Chile

Abstract The chronology of the Inka Empire is poorly resolved, with most scholars utilizing a post hoc ethnohistoric reconstruction of imperial expansion as a common reference point. Radiocarbon-based analyses can now accomplish sufficient resolution for meaningful independent estimates of Inka chronology, however, and it is incumbent upon archaeologists to develop such appraisals. Here we produce a Bayesian analysis of radiocarbon data from the Upper Loa River area of northern Chile to estimate the timing of Inka incorporation of this region. In order to accurately associate samples with Inka rule, only radiocarbon dates from Inka sites without prior occupations are used (n = 34), producing a model for the onset of Inka rule of AD 1401–1437 (95% hpd) with a median date of AD 1420. This estimate is further used as a point of comparison for understanding diachronic imperial processes in the region. Site-level models of a variety of site types indicate that the Inka rapidly founded several administrative/mining bases at the onset, followed by the addition of smaller infrastructure components during a second pulse of activity near the middle of the 15th century. Date assemblages at the agricultural sites of Topaín and Paniri also indicate a decline in activity at the former and an increase in activity at the latter from early on in Inka rule. These results provide a high-resolution data point for reconstructing Inka imperial chronology, and expanding such studies will be essential to understanding processes of Inka imperialism at larger scales.

Research on the Path to High-Quality Development of Grassroots Libraries in the Era of Artificial Intelligence in Henan

Since the age of digital intelligence, the government has introduced policies to actively promote the intelligent transformation of grassroots public cultural services. Based on the investigation and analysis of the development status quo of grassroots libraries in Henan Province, we put forward the path of high-quality development of grassroots libraries in Henan, namely, improving the mechanism and system, leading with digital intelligence technology, empowering by Yellow River culture (the heritage and values rooted in the history and traditions of the Yellow River region), and driven by users’ demand.

Quantitative analysis of the contribution of moisture recycling to precipitation in the cold region

This study quantitatively analyzed the contribution rate of recycled moisture to precipitation in the basin based on the Craig-Gordon model and the three-end-member mixing model through selecting 456 precipitation sample data collected from six sampling points in the source region of the Yellow River from September 2019 to August 2021. The results showed that: the contribution rate of moisture recycling to precipitation during the growing season is 40 %, and the total contribution to local moisture recycling is equivalent to 41 mm of precipitation. The contribution rate of evaporation and transpiration has obvious seasonal variation characteristics, showing a trend of decreasing first and then increasing in the source region of the Yellow River. Spatially, the contribution rate of evaporation and transpiration showed an increasing trend from south to north. It is assumed that all the precipitation generated by moisture recycling produces runoff, and the water yield is about 51 × 108 m3, which is 25 % of the total annual average runoff. In addition, the proportion of local moisture recirculation is mainly related to altitude, topography, vegetation coverage, and meteorological factors. Moisture recirculation is one of the important sources of precipitation in the source region of the Yellow River.

Has river regulation damaged the Peace-Athabasca Delta?

ABSTRACT The Peace-Athabasca Delta (PAD) is a complex, dynamic, and misunderstood ecosystem. This study uses landscape, ecological, climatic, hydrologic, historical, stratigraphic, and wildlife data that document how and why the PAD has changed and varied from ~1900 to 2023. The ecological, climatic, and hydrologic components of the ecosystem vary in concert. Flood-drawdown cycles influenced by physical and biological factors have driven a host of landscape changes over the past 120 years. Prior to regulation, net drying of the PAD took place over the period ~1900 to the mid-1940s. Since mid-20th century, there has been no multidecadal drying trend but rather decadal-scale wet and dry episodes. Levels of the confluent Lakes Athabasca, Claire, and Mamawi, and their adjacent restricted basins, are strongly correlated with the combined flows of the Peace, Athabasca, Fond du Lac, and Birch Rivers. River regulation has changed the seasonal distribution of flows and suppressed summer flows. There is, however, no evidence that ‘dramatic landscape change is underway, devastating local fauna’ or that river regulation has caused delta desiccation, declines in spring flooding, declines in lake levels, or declines in wildlife, waterfowl, or their habitat. The great areal extent of the PAD watershed imparts hydrologic and ecological resilience.

The Spatial and Temporal Dynamics of Soil Conservation and Its Influencing Factors in the Ten Tributaries of the Upper Yellow River, China

Soil erosion is a global environmental problem, and soil conservation is the prevention of soil loss from erosion. The Ten Kongduis (kongdui is the translation of “short-term flood gullies” in Mongolian) are ten tributaries in the upper Inner Mongolia section of the Yellow River Basin. The study of the spatial and temporal variability in soil conservation in the Ten Kongduis is of extraordinary scientific significance both in terms of the discipline and for the ecological and environmental management of the region. With the InVEST model, the characteristics of the spatial and temporal variations in soil conservation service in the Ten Kongduis since 2000 and how rainfall and land use have influenced soil conservation were analyzed. The results show that both avoided erosion and avoided export varied considerably between years. The minimum values of avoided erosion and avoided export were both in 2015, with values of 17.59 × 106 t and 0.92 × 106 t, respectively. The maximum value of avoided erosion was 57.03 × 106 t in 2020 and that of avoided export was 4.08 × 106 t in 2000. Spatially, avoided export was primarily found in the upper reaches of the east–central portion of the study area, and avoided erosion, with values of >40 t·(ha·yr)−1, was in the upper east–central portion of the study area, followed by the upper west–central portion. The difference between upstream and downstream was larger in the western part of the study area. The effect of rainfall was dominant and positive in both avoided erosion and avoided export. The relationships between the rain erosivity factor and the values of avoided erosion and avoided export were significantly positive. Where more erosion occurs, more erosion is retained. Soil that has been eroded away from slopes under vegetation or other water conservation measures may not necessarily be transported to the stream channel in the current year. These conclusions will help us to have a clearer understanding of where sediments are generated and transported and provide a scientific basis for soil and water conservation and ecosystem safety management of watersheds.