River Area Research Articles

Detecting the Vertical Structure of Extreme Precipitation in the Headwater Area of Yellow River Using the Dual‐Frequency Precipitation Radar Onboard the Global Precipitation Measurement Mission

ABSTRACTIn the context of global warming, the rise in extreme precipitation events in high‐altitude headwater areas has introduced greater hydrological uncertainty. However, the limited understanding of the physical mechanisms driving extreme precipitation in these areas hinders efforts to mitigate the potential rise in future precipitation risks. This study analysed the extreme precipitation events in the headwater area of the Yellow River (HAYR) from May to September each year from 2015 to 2020 using satellite‐based data from Dual‐frequency Precipitation Radar (DPR) on the Global Precipitation Measurement (GPM) Core Observatory and Integrated Multi‐satellite Retrievals for GPM (IMERG). The results show that stratiform precipitation (SP) determines the spatial extent of extreme precipitation events, while convective precipitation (CP) largely affects the rainfall intensity. Statistical analysis from different extreme precipitation events indicates that the rain rate of CP is 2 to 3 times higher than that of SP, thus zones of intense precipitation in the study area are normally dominated by CP. Vertically, the topographic lifting in complex mountainous regions exerts opposite effects on the precipitation rates of SP and CP, weakening the precipitation intensity of SP while enhancing that of CP. The peak precipitation rate in the midstream and downstream regions is observed at approximately 5 km, whereas the upstream region displays a distinctive double‐peaked distribution, with one peak at 8.5 km and another near the surface. This study provides a better understanding of the interior structure evolution process of plateau precipitation, as well as the associated microphysical properties, and highlights some insights to improve microphysical parameterization in the future model developments.

Spatiotemporal distributions, sources, and health risks of heavy metals in an acid mine drainage (AMD)-contaminated karst river in southwest China

Acid mine drainage (AMD), characterized by its acidity and high content of heavy metals, is a significant global environmental problem that harms human health through its impact on rivers. Therefore, this study aims to identify heavy metals in both surface and underground AMD-polluted karst rivers, focusing on the Zhijin River area which is severely affected by AMD, and assess their health risks to residents. Through the collection of 30 surface water samples and 16 groundwater samples from both wet and dry seasons, the study examines the concentration, sources of pollution, and health implications of six heavy metals (Fe, Mn, Cr, Cd, As, and Hg). The results showed that Fe and Mn levels in surface water were highly polluted during both seasons, especially during the wet season, with Fe levels reaching 20.0 mg/L and Mn levels reaching 1.9 mg/L. Further correlation and principal component analyses revealed that mining activities are the primary contributors to the contamination in this region. Health risk assessments and Monte Carlo simulation, including both deterministic and probabilistic, showed that the noncarcinogenic health risk indices for surface water and groundwater were within acceptable limits for both seasons. However, groundwater poses a higher carcinogenic risk to children, with As levels during the wet season and Cr levels during the dry season warranting close monitoring. Factors such as body weight and intake rate played a crucial role in health risk evaluations. This study underscores the need for further attention to groundwater risk, temporal heterogeneity in the Zhijin River.

Potentially toxic elements (PTEs) in the invasive Asian clam (Corbicula fluminea) from polluted urban river areas of Bangladesh and evaluation of human health risk.

The invasive Asian clam species, Corbicula fluminea, has significant ecological and societal implications at both local and international levels due to its nutritional aspects. C. fluminea from four urban rivers in Bangladesh exhibited negative allometric growth and degree of contamination with potentially toxic elements (PTEs), which posed a concern to human health based on the AAS and USEPA risk models. The highest mean concentration of PTEs followed a decreasing order: Zn (155.08 ± 4.98mg/kg) > Cu (53.96 ± 7.61mg/kg) > Mn (14.29 ± 3.25mg/kg) > Cd (2.23 ± 0.10mg/kg) > Pb (1.64 ± 0.14mg/kg) > As (1.51 ± 0.45mg/kg) > Ni (1.25 ± 0.27mg/kg) > Cr (0.65 ± 0.02mg/kg) in C. fluminea and raising safety concerns. With the exception of Cr and Mn, all element levels were exceeded safety guideline value (SGV) (mg/kg. ww) and exhibited a strong positive correlation (p < 0.05) among the sites. The target hazard quotient of Mn is THQ > 1, and As showed a non-carcinogenic risk in children at OBR, BR, and MR site. The hazard index (HI > 1) value at the BR and MR sites indicated a public health risk associated with the clam. The target cancer risk (TCR) values for As, Cd, and Ni showed that consuming clams posed a carcinogenic risk to human health. These findings suggest that eating these clams may put consumers at significant risk for health issues related to As, Cd, Ni, and Mn exposure. The study emphasizes the need for strict monitoring and preventative measures to reduce the health risks posed by PTEs contamination in clams.

2023 Jishishan Earthquake-triggered river terrace landslide enabled by tectonic and human activities

The continued increase in demand for food is such that flood-irrigation-based agricultural techniques are not expected to change in the future. Consequently, in cultivated areas dominated by river terraces that experience neotectonic movements, catastrophes caused by earthquakes that trigger material liquefaction may continue to occur. Among such catastrophes, low-angle, ultra-long-distance landslides induced by synergistic effects of tectonic and human activities are events that are not fully understood but can potentially be mitigated. A landslide-mudflow that occurred on December 18, 2023, during an Ms 6.2 earthquake in Jishishan, China, on the tertiary terrace of the Yellow River. We reveal the causal mechanisms by which geomorphology, tectonics, and human activities controlled the landslide-mudflow, and outline a new, potentially widespread, dual liquefaction layer-dominated failure mode for earthquake-induced landslides on river terraces. Our findings serve as a warning that urgent landslide-potential assessments should be conducted across river terrace irrigation areas in tectonically active regions.

Factors influencing carbon and water use efficiency in changing environments

IntroductionVegetation plays a crucial role in terrestrial ecosystems, acting as a vital link connecting the lithosphere, hydrosphere, and atmosphere in terms of energy flow and material cycling. Changes in surface vegetation significantly regulate the water cycle, energy flow within terrestrial surfaces, and global carbon balance.MethodsThis study focuses on nine major river basins in China to quantitatively investigate the impacts of climate factors, vegetation dynamics, and land use changes on carbon use efficiency (CUE) and water use efficiency (WUE).ResultsThe primary controlling factors of WUE trends are NDVI (average contribution: 33.75% ± 6.90%) and VPD (average contribution: 28.04% ± 3.98%). NDVI predominates in the Haihe, Yellow River, Yangtze River, Pearl River, and Songliao River basins, while shortwave radiation (Srad) dominates in the southeastern rivers and inland river areas, and humidity (Shum) in the southwestern river basins. For CUE trends, the main controlling factors are Srad (average contribution: 36.46% ± 3.40%) and precipitation (Pre) (average contribution: 26.72% ± 5.20%). NDVI negatively influences the Huaihe River and southeastern river basins, while Pre negatively influences the Songliao River and Yellow River basins, and Srad negatively influences the Huaihe and southwestern river basins. Pre predominates in the Huaihe, Songliao, Haihe, southwestern river basins, and inland river areas, while Srad predominates in the Pearl River, Yangtze River, and Yellow River basins.DiscussionClimate factors and vegetation dynamics have significant regional impacts on WUE and CUE across different river basins, especially the roles of NDVI and VPD on WUE, and Srad and precipitation on CUE. These differences underscore the importance of developing region-specific management strategies to optimize ecosystem services in each basin.

Recommendations for Appropriate Design for Handling Landslides on the Slopes of the Balai River (Sei Balai), Batubara Regency

Sei Balai River, precisely in Nibung Hangus/Tanjung Tiram District, Batu Bara Regency, is one of the rivers in the Bah Bolon River Area (WS). Sei Balai River has experienced flooding several times and caused landslides on the riverbanks. One of the most critical locations is in Lima Beras Village, Nibung Hangus/Tanjung Tiram District, Batu Bara Regency, which has damaged the riverbanks which are feared that if not handled early, it may result in the breaking of community access roads in the mobilization and demobilization of agricultural and plantation products in the village. Based on the results of the geotechnical investigation, it was concluded that the Bearing Capacity Value of the Shallow Foundation Permit from the qc Data was obtained at No. Test. S - 1, with a depth of 5 meters, the permitted bearing capacity (Qi) was 3.8 (Ton / m2) with a square foundation width B = 1 m and No. Test. S – 2, with a depth of 5 meters, the permissible bearing capacity (Qi) is 4.53 (Ton/m2) B = 1 m

Detection and Transmission Dynamics of Intestinal Schistosomiasis among Primary School Pupils in Tharaka Nithi County in the Mt. Kenya Highlands

Emerging infections cause considerable public health problems to humanity worldwide. The presence of Biomphalaria spp vector snails, the compatibility of the snails with schistosomes, and the prevalence of intestinal schistosomiasis infection in school-going children were determined. The study sought to determine the presence and transmission dynamics of schistosomiasis in Tharaka Nithi, an emerging schistosomiasis transmission focus in the Mt. Kenya highlands. The Epidemiological Triangle Model (ETM), which sheds light on the transmission of infectious diseases, served as the foundation for this study. A cross-sectional study design was used. The study targeted 178 students in grades 1–8 from the two primary schools in Tharaka Nithi located along the catchment area of Mukothima and Thanantu rivers. The number of study participants was determined using the Cochran formula. Study participants were selected randomly from the class register while ensuring equal numbers of boys and girls to avoid bias in results. The stool samples collected from the participants were processed using Kato Katz's quantitative screening technique for helminths and formal ether concentration technique for intestinal protozoa. Biomphalaria snails were collected and identified based on morphology. Snails were also bred and experimentally infected with a laboratory strain of Schistosoma mansoni and passed to the F5 generation to check the compatibility with the Schistosoma mansoni parasite. The overall mean snail parasite infection rate was 23.51% with a positivity of 19.38% in Mukothima River compared to 27.64% in Thanantu River. Although none of the field sampled snails were found infected with S. mansoni, pupils tested were found to be infected with the parasite with a positivity rate of 15.5%. Other parasites detected included Ascaris lumbricoides with a prevalence rate of 9.23% and Entamoeba histolytica with a prevalence of 8.48%. Results from the snail susceptibility experiment showed that the snails supported the development of S. mansoni to full patency, indicating the potential to support the schistosomiasis transmission cycle. Despite not finding any field-sampled snails infected with S. mansoni, the demonstrated compatibility of the snails with the parasite and the finding of infection in school children suggests that transmission is a possibility. Schistosomiasis prevention strategies including deworming programs, school and community environment sanitation, and latrines provision are highly recommended to prevent further spread of the disease.

Preliminary detection of toxic organic pollutants in sediments of the confluence area of Hong river - Bach Hac, Phu Tho, Vietnam

Preliminary detection of toxic organic pollutants in sediments of the confluence area of Hong river - Bach Hac, Phu Tho, Vietnam

Identification of key areas for Territorial Ecological Restoration: focusing on ecological security and restoration potential

Implementing Territorial Ecological Restoration is a crucial approach to achieving ecological stability and regional sustainable development, and it also serves as an important measure for promoting the coordinated development of socioeconomic and ecological environments in the Yellow River Basin. However, effective identification of key areas for Territorial Ecological Restoration remains challenging in planning ecological restoration projects. This study focuses on ecological security and restoration potential, taking Linxia Prefecture in the ecologically fragile area of the upper Yellow River as an example. By evaluating six types of ecosystem services in this area, utilizing morphological spatial pattern analysis models and circuit theory, we identified the structural elements of ecological security patterns and assessed the potential for ecological restoration, identifying key areas for regional ecological restoration.The findings indicated that (1) 13 ecological patches were identified in total, predominantly distributed in the southwest and central regions of Linxia Prefecture. 25 ecological corridors were identified, demonstrating a high level of spatial coherence in terms of significance and connectivity, establishing a closely integrated ecological security network primarily in the southwest of Linxia Prefecture. (2) Thirteen ecological pinch points and seventeen ecological barrier points have been identified, concentrated in the central and southwestern regions of Linxia Prefecture. (3) Based on the characteristics and urgency of key areas for Territorial Ecological Restoration, they are classified and graded as “point-line-surface” and “primary-very important-important.” The primary restoration areas of the point type are mainly located in the central part of Linxia Prefecture, while the primary restoration areas of the line and plane types are mainly in the southwestern part of Linxia Prefecture. This paper emphasizing a holistic approach that prioritizes ecosystem integrity and social support to guide targeted restoration strategies across various ecological features, ultimately aiming for sustainable regional development and maximizing restoration benefits in ecologically fragile areas.

Using Advanced InSAR Techniques and Machine Learning in Google Earth Engine (GEE) to Monitor Regional Black Soil Erosion—A Case Study of Yanshou County, Heilongjiang Province, Northeastern China

The black soil region experiences complex erosion due to natural processes and intense human activities, leading to soil degradation and adverse ecological and agricultural impacts. However, the complexities involved in quantifying regional erosion poses remarkable challenges in accurately assessing the current status of regional soil erosion for effective soil conservation. To solve this issue, we proposed a new method for monitoring soil erosion using Interferometric synthetic aperture radar (InSAR) technology and machine learning algorithms within the Google Earth Engine platform. The new method not only enables regional-scale monitoring, but also ensures high accuracy in measurement (millimeter-level). The erosion susceptibility of the study area (Yanshou County, Heilongjiang Province, Northeastern China) was also classified using random forest algorithms to refine the monitored and predicted soil erosion. The results indicate that the five-year (2016–2021) deformation in Yanshou County was −11.08 mm, with a significant mean cumulative deformation of −8.08 mm yr−1 occurring in 2017. The driving factor analysis shows that the region was subject to the compound effect of water and freeze–thaw erosion, closely related to crop phenological stages. The susceptibility analysis indicates that 73.3% of the region was susceptible to erosion, with a higher probability in river areas, at high altitudes, and on steep slopes. However, good vegetation cover can reduce the risk of soil erosion to some extent. This study offers a new perspective on monitoring regional soil erosion in the black soil region of China. The proposed method holds potential for future expansion to monitor soil erosion in a larger areas, thereby guiding the strategies development for protection of the agriculturally important black soil.

New results of the U/Pb dating of cretaceous igneous rocks of the Komsomolsk ore district (Middle Amur River area)

The Komsomolsk tin ore district is located at the Miaochan Ridge in the Middle Amur River area (Khabarovsk territory) within the Badzhal accretionary terrane of the Sikhote-Alin orogenic belt. The paper presents new results of U-Pb zircon dating of tonalite of the Miaochan complex of the Silinka granitic pluton (99.7±1.1 Ma) and two rhyolites of the lower part of the Kholdami Formation (98.4±1.0 and 98.7±1.2 Ma) from the north-eastern part of the Komsomolsk district. The geochemical characteristics of rocks were also studied, which show that granitoids of the Miaochan complex are I-type granites, and coeval rhyolites of the Kholdami Formation are very peraluminous S-type rocks. New data on the geochemistry and early Cenomanian age of the igneous rocks allows us to consider the ore-magmatic system of the Komsomolsk ore district as part of the previously identified Albian-Cenomanian igneous province of Pacific Asia.

Bridging the Gap: Unveiling the Factors of Government Support Influencing the Success of Vietnamese Agricultural SMEs Post-COVID-19

This study investigates the essential role of government aid in enhancing the resilience and success of small and medium-sized agricultural firms in Vietnam during the COVID-19 pandemic. The research fills a gap in the existing literature by concentrating on strategies for long-term recovery rather than immediate reactions. Using a structured survey and multivariate linear regression analysis, the study engaged 200 proprietors and executives from the Red River and Mekong Delta areas. The results exhibit a favorable association between governmental support and the success of small and medium-sized enterprises, emphasizing the necessity of tailored governmental interventions to enhance sector competitiveness. While offering valuable insights for policymakers, the study’s geographical and sectoral scope is restricted, indicating the need for more extensive research and qualitative evaluations to deepen comprehension of the effects of governmental support in diverse settings. This research has the potential to significantly influence policy formulation and further scholarly investigation in the economic landscape post-pandemic.

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.

Wildlife Ecotourism in Protected Areas of the Lower Negro River, Brazilian Amazon: characterization, challenges, and potentials

In the last few decades, tourist interactions involving wildlife, one of the activities that distinguishes ecotourism, have attracted many fans in various regions of the world. This article maps, characterizes, and presents the challenges and potentials of wildlife ecotourism in protected areas of the Lower Negro River, in the Brazilian Amazon. Through data collection in the field, seven enterprises were visited and tourist interactions with twelve different species of wildlife were recorded. The activities that visitors engage in vary according to the species they are interacting with, but include watching the animals, offering food, physical contact (petting or holding the animals), and getting into the water with them. The recorded species include the Amazon River dolphin (Inia geoffrensis), the Woolly monkey (Lagothrix lagotricha), and the Bald uakari (Cacajao calvus), which are on the International Union for Conservation of Nature (IUCN) Red List of Threatened Species. Despite the negative impacts of these activities, they help create income for the host communities, increase the public use of protected areas, and raise awareness among visitors regarding the conservation of species and their habitats.

Spatiotemporal evolution and driving factors of ecosystem service value in the Upper Minjiang River of China.

The stability of ecosystems in high mountain canyon areas is poor, and the interaction between humans and the land is complex, making these ecosystems more vulnerable to destruction. Quantitatively assessing the ecosystem service value (ESV) in high mountain canyon areas and revealing its spatiotemporal evolution patterns and driving factors play a crucial role in the construction of regional ecological barriers and the assurance of ecological security. This study focuses on the Upper Minjiang River as the research area, using the InVEST model and the Equivalent Factor Method to estimate ESV. This combination aims to address the inadequacy of the Equivalent Factor Method in reflecting the variability of ESV across different regions, and the sensitivity of the InVEST model to data changes that results in insufficient accuracy of ESV assessments. By harnessing spatial au-tocorrelation and the geodetector method, we unravel the spatiotemporal evolution characteristics and driving factors of ESV. The results show that: (1) From 2000 to 2020, the ESVs estimated by the two estimations increased by 31.28% and 22.47%, respectively, both indicating that the eco-environment quality of the upper Minjiang River has been continuously improved. (2) When Moran's I was greater than 0.5 (p < 0.05), the spatial clustering of "High-High" and "Low-Low" ESV was obvious. It is clear that the ESV varies geographically. High values are primarily found in the study area's center and southern regions, as well as on both banks of the Minjiang River, whereas low values are more common in the region's northern region. (3) Slope and human activity intensity (HAI) are the principal contributors to the spatial differentiation of the ESV, more than 60% of the interaction types between the two factors were classified as dual-factor enhancement. The synergistic reinforcing effects of HAI, slope, elevation, and temperature collectively shape the shifts in ESV spatial distribution. This study offers a novel evaluative lens on the ESV of the Upper Minjiang River area, supplying a sturdy data support for crafting specific ecological preservation and rejuvenation strategies in the coming years.

Structural Characteristics of Phytoplankton Communities and Its Relationship with Environmental Factors in Different Habitats of Hedi Reservoir

To explore the characteristics of phytoplankton communities and their relationship with environmental factors in different habitats of Hedi Reservoir, the inflow rivers, estuaries, and reservoir area of Hedi Reservoir were investigated in February （recession period）, April （flood period）, July （flood period）, and December （recession period） of 2022. During the investigation, 231 species of phytoplankton that belong to seven phyla were identified, and the cell density of phytoplankton ranged from 2.94 × 106 - 8.04 × 108 cells·L-1. Phytoplankton cell density in flood periods were higher than that in recession periods, and that was higher in estuaries and the reservoir area than that in inflow rivers. Meanwhile, the cell density of phytoplankton in the estuarine and reservoir area was dominated by Cyanobacteria throughout the year, especially Raphidiopsis raciborskii, whereas the cell density of phytoplankton in inflow rivers was dominated by Cyanophyta, Chlorophyta, and Bacillariophyta. In the inflow river area, the dominant species of cyanobacteria were Microcystis aeruginosa, Limnothrix redekei, Pseudanabaena circinalis, and Merismopedia punctata； the dominant species of Chlorophyta were Chlorella vulgaris and Crucigenia tetrapedia； and the dominant species of Bacillariophyta were Chlorella vulgaris and Melosira granulate. The highest biodiversity （Shannon-Wiener Index, Pielou index, and Margalef index） were observed in the inflow river area of Hedi Reservoir. The correlation analysis （Pearson） indicated that the environmental factors that were significantly correlated to phytoplankton communities included water temperature, dissolved oxygen, pH, conductivity, nitrogen, and phosphorus concentration. The RDA analysis indicated that phytoplankton communities in the inflow river area were mainly affected by pH and total nitrogen concentration, which were majorly affected by water temperature and pH in the estuarine area and chiefly affected by turbidity and pH in the reservoir. The pH affected the changes in phytoplankton communities in all three different habitats, whereas the inflow river area was significantly affected by total nitrogen concentration, and the estuarine and reservoir were significantly affected by water temperature and turbidity, respectively.

Analysis of Plankton Diversity and Abundance in the Wiringtasi River, Barru Regency, South Sulawesi, Indonesia

The research aims to determine the level of plankton abundance and diversity in the Wiringtasi River, Barru Regency, South Sulawesi, Indonesia. The research was conducted from August to September 2024 at three research locations, namely location 1, namely the river location adjacent to rice fields; location 2, namely the river area adjacent to ponds and beaches; and location 3, namely the location around the mouth of the Wiringtasi River, Barru Regency. Water samples obtained at the research location were taken to the laboratory for analysis. The plankton samples obtained were calculated for abundance, species diversity, species uniformity, and dominance index. The data obtained was then processed and analyzed using descriptive analysis. The results showed that the highest abundance of plankton was in the Melosira sp. type plankton (location 1) and Navicula sp. type plankton (locations 2 and 3). The level of diversity and uniformity of plankton at the research location was highest at location 1, namely the location adjacent to the rice fields. The highest level of plankton dominance is found in the Melosira sp type plankton (location 1), while in locations 2 and 3, the plankton is dominated by the Navicula sp type.

The Anomalous Behavior of Stock Prices on the Canadian Securities Exchange

This paper examines the conformity of the distribution of stock prices on the Canadian Securities Exchange (CSE) to that theorized by Benford’s Law (BL). BL follows a logarithm law such that the leading digits have a higher probability of lower numbers such as 1, 2, or 3 versus higher numbers like 7, 8, or 9. This analysis can be used to detect fraudulent manipulation of stock prices. Previous research has applied BL to a broad range of data such as cost data, atomic weights, river areas, and populations, as well as stock prices. After collecting stock prices on the CSE, the number count for each digit was compared to the expected number given the frequencies posited by BL. A chi-square test was employed to determine statistical significance. The first digit was found to adhere to BL; however, the second digit was not congruent with that predicted by BL. There is an indication of possible manipulation on this stock exchange. These mixed results are consistent with the empirical evidence of other researchers. This evidence is relevant to auditors, shareholders, financial analysts, investment managers, government, and the CSE.

The Spatiotemporal Variation and Ecological Evaluation of Macroinvertebrate Functional Feeding Groups in the Upper Yellow River.

Against the backdrop of hydropower development in the upper Yellow River, comprehending the spatiotemporal variation and ecological evaluation of macroinvertebrate functional feeding groups (FFGs) is paramount for the conservation and restoration of aquatic biological resources in watersheds. Detailed surveys of macroinvertebrates were conducted in the gorge and plain areas of the upper Yellow River in July 2022 and March, May, and October 2023, culminating in the identification of 65 taxonomic units (genus or species) spanning 4 phyla, 14 orders, and 35 families. Of these, 41 taxonomic units were discovered in the gorge areas and 57 in the plain areas. Among the FFGs of macroinvertebrates in the upper Yellow River, collector-gatherers were overwhelmingly dominant, followed by scrapers, collector-filterers, predators, and shredders. Concerning river section types, dominant species in the gorge areas included Gammarus sp., Limnodrilus hoffmeisteri, and Polypedilum sp. among collector-gatherers, while in the plain areas, dominant species included Ecdyonurus sp. among scrapers, Hydropsyche sp. among collector-filterers, and Gammarus sp., Limnodrilus hoffmeisteri, and Chironomus sp. among collector-gatherers. A Mantel test revealed that dissolved oxygen, conductivity, and orthophosphate were the primary environmental factors affecting the FFGs of macroinvertebrates in the upper Yellow River, with variations observed in their effects across different months. The evaluation results of the Hilsenhoff Biological Index and Shannon-Wiener Index indicate that the water quality of the upper Yellow River is at a moderate level. An assessment of the upper Yellow River ecosystem using FFG parameters demonstrated that macroinvertebrate biomass progressively increased from upstream (gorge areas) to downstream (plain areas) spatially, accompanied by increasing habitat stability, with cascade hydropower development identified as a key factor impacting habitat stability. These findings provide pertinent data and a theoretical foundation for the protection of aquatic biological resources and watershed management in the upper Yellow River.

The impact of spatial resolution on inland water quality monitoring from space

Abstract Remote sensing of inland waters can provide timely and global water quality information to a wide variety of stakeholders. One of the parameters that determines the feasibility of using optical space-based instruments for monitoring inland waters is the ground sampling distance (GSD), defined as the width of a pixel projected on the Earth’s surface. We assume that to analyze a body of water with optical imagery, its characteristic width must be larger than 3 times the GSD to obtain an ‘unmixed’ pixel that doesn’t contain signal from the adjacent land. Here we obtain the size distribution of river lengths, river areas, and lake areas—as a function of width—for rivers and lakes in the Western United States (US) and in Australia. We base this analysis on the Surface Water and Ocean Topography River Database (SWORD) and HydroLAKES databases, extrapolated to 5 m-wide features. We show that the fraction of river length and river area larger than a certain width increases sharply as the width decreases, indicating that even small decreases in the GSD result in significant increases in the number of bodies that can be surveyed. On the other hand, the distribution of lake areas shows a ‘knee’ at around 400 m, indicating that gains from GSDs smaller than 130 m will be modest. We found that a satellite instrument with a GSD capability of 18 m can provide coverage of 4.4% of total river lengths, 38% of total river area, and 94% of total lake area within the study areas. We argue that decreasing the GSD incurs penalties associated with loss of signal-to-noise, larger instrument, smaller swath, and longer revisit times.