River Management Research Articles

Hematological and plasma biochemical profile of two species of freshwater stingrays from the Amazon.

The evaluation of hematological and plasma biochemical parameters and the subsequent establishment of reference intervals facilitate the diagnosis of the health status of animals. This work aimed to determine the blood parameters of wild specimens of the stingrays Potamotrygon motoro and Potamotrygon orbignyi from the lower Solimões River region, Amazonas, Brazil. One hundred forty-one stingrays were captured, 92 specimens of P. motoro and 49 of P. orbignyi, of both sexes and at different stages of development. No effect of sex was observed on the blood parameters of juvenile animals for both species. P. motoro neonates presented a distinct hematological and biochemical profile, with significantly lower hematocrit values, hemoglobina, number of erythrocytes, mean corpuscular hemoglobin concentration, monocytes, plasma glucose, total proteins, albumin, and globulin. On the other hand, total cholesterol and urea levels were significantly higher in this same group compared to juveniles of the same species. Comparison between species revealed lower values of triglycerides and total cholesterol in P. orbignyi of both sexes. The results obtained are pioneering for these Amazonian species in white water environments and will serve as a basis for evaluating the health status of wild stingrays. Thus, from the analysis of the blood of the P. motoro and P. orbignyi stingrays, it was possible to observe good health conditions.

Predicting the scouring depth around a rectangular pier with a round nose by artificial intelligence methods

Local scour around bridge piers constitutes a significant phenomenon in river engineering. The development of artificial intelligence models and their capabilities has resulted in the widespread adoption of these models. In the experiments, various factors were considered, encompassing three different pier angles (0, 5, and 10°), six submerged vanes with two angles (20 and 30°) aligned with the flow direction, three vane heights (0, 1.25, and 2.5 cm) on the bed, and a collar. The study evaluated the performance of distinct machine learning models, namely, the multi-linear regression (MLR) model, radial basis function neural network (RBF), multilayer perceptron neural network (MLP), support vector machine (SVM), and adaptive neuro-fuzzy inference system (ANFIS) in predicting the scouring depth. Application of these models (RBF, MLP, ANFIS, SVM, and MLR) yielded positive outcomes, with corresponding R2 values of 0.99, 0.98, 0.97, 0.96, and 0.90 for scour depth assessment. The results demonstrated that the RBF artificial neural network model exhibited excellent generalizability in comparison to the other models. It consistently provided accurate predictions with minimal errors across varying training set sizes. Conversely, the ANFIS model exhibited limited generalizability compared to the other models, as reducing the training set size resulted in a significant increase in prediction errors during testing. Furthermore, although the MLR model demonstrated good generalizability, its prediction error was relatively high compared to the alternative models.

Household-level effects of seasonal malaria chemoprevention in the Gambia.

In 2022 the WHO recommended the discretionary expansion of the eligible age range for seasonal malaria chemoprevention (SMC) to children older than 4 years. Older children are at lower risk of clinical disease and severe malaria so there has been uncertainty about the cost-benefit for national control programmes. However, emerging evidence from laboratory studies suggests protecting school-age children reduces the infectious reservoir for malaria and may significantly impact on transmission. This study aimed to assess whether these effects were detectable in the context of a routinely delivered SMC programme. In 2021 the Gambia extended the maximum eligible age for SMC from 4 to 9 years. We conducted a prospective population cohort study over the 2021 malaria transmission season covering 2210 inhabitants of 10 communities in the Upper River Region, and used a household-level mixed modelling approach to quantify impacts of SMC on malaria transmission. We demonstrate that the hazard of clinical malaria in older participants aged 10+ years ineligible for SMC decreases by 20% for each additional SMC round per child 0-9 years in the same household. Older inhabitants also benefit from reduced risk of asymptomatic infections in high SMC coverage households. Spatial autoregression tests show impacts are highly localised, with no detectable spillover from nearby households. Evidence for the transmission-reducing effects of extended-age SMC from routine programmes implemented at scale has been previously limited. Here we demonstrate benefits to the entire household, indicating such programmes may be more cost-effective than previously estimated.

Environmental surveillance of the rice massif in the Kuban-Protoka river region ​

Environmental surveillance of the rice massif in the Kuban-Protoka river region ​

Cyclical ‘Wetting’ Phenomenon in the Source Region of Yellow River under Long-term Trends from 1956 to 2022

Study regionthe source region of the Yellow River (SRYB) Study focusDue to environmental changes, the drying and wetting processes have become increasingly intricate, and it is uncertain whether the wetting phenomenon in the SRYB indicates a long-term trend or a temporary cyclic event. This study utilized monthly streamflow and precipitation records from 1956 to 2022 to calculate hydrological and meteorological-dryness/wetness, represented by the standardized streamflow and precipitation indices, respectively. This study used detrended, wavelet, and cross-wavelet methods to investigate dry-wet variability and identified the atmospheric circulation phenomena driving the dryness/wetness and cyclical changes in the region. New hydro-meteorological insights for the SRYB(i) The SRYB showed an overall fluctuating wetting trend, which intensified after 2000. (ii) There were notable oscillatory cycles at 3–5 years, 10–12 years, and approximately 20–25 years in both hydrological and meteorological dry-wet variability. (iii) Transitions from dry to wet conditions had no significant link to short-term cycles (e.g., 3–5 years), but were linked to decadal cycles (e.g., 20–25 years). (iv) Spring and winter precipitation and streamflow dominated the interannual dry-wet variability. (v) The ENSO, AMO, and PDO influenced short-term cyclic fluctuations, while the AO and PDO influenced decadal cyclic fluctuations. This indicates that the wetting trend follows a cyclic pattern, and the intensification since 2000 is consistent with a decadal cyclic signal.

Orbital global change drove fluvial aggradation and incision in Tibetan upper Mekong river: Chronological perspectives

The Tibetan Plateau (TP), often known as the “Asia Water Tower”, is the source region of several continental-scale rivers. However, due to the extremely difficult access and harsh living conditions in the interior plateau, fluvial processes in the headwaters of these large rivers and their connections to global climate changes remain unknown. In this study, the luminescence (using both quartz and K-feldspar) and AMS 14C dating techniques were employed to date the four terraces of the Zado Basin in order to elucidate the aggradation and incision history of the initial intermontane basin in the headwater of the Mekong River. One sample from the upper part of T4 terrace (which features a 12 m thick gravel layer, the base of which is unexposed) provides a K-feldspar pIR50IR225 age of 125 ± 10 ka, indicating that the initial deposition of this terrace could predate marine isotope stage (MIS) 5. Considering the margin of error, this age also suggests that the onset of incision on T4 terrace during the climate transition from MIS 6 (glacial) to early MIS 5 (interglacial). This incision likely occurred due to increased meltwater and precipitation, causing the Mekong carving into the bedrock for more than 50 m. Eight luminescence samples are collected from T3 terrace (26.5 m in thickness) with ages ranging from 83 ± 7.6 ka to 22.3 ± 1 0.2 ka, indicating T3 formation/aggradation from late MIS 5 to the Last Glacial Maximum (LGM), possibly owing to reduced precipitation and enhanced sediment supply from intensive glacial activities. At around 22 ka, the Mekong once again shifted towards incision, crafting the T3 terrace, situated roughly 28 m above the current floodplain. This incision event was recorded by two luminescence samples from a sandy lens located at the top of gravel layer of T3, with OSL ages of about 22 ka. Floodplain samples from T2 and T1, dated at 16 ka and 2.8 ka respectively, demonstrate that from the last deglaciation to the Holocene, the Mekong continued its downward incision. This erosion developed two cut and fill terraces at elevations of 22 m and 11 m above the present floodplain, likely due to increased precipitation and enhanced vegetation at that time. Overall, the glacial–interglacial climate changes were the most likely driving force behind fluvial processes in the upper Mekong basin since the Late Pleistocene, with aggradation occurring during the glacial period while incision in deglacial and interglacial periods, suggesting a close link between the fluvial geomorphic evolution and orbital-scale climate changes.

Effectiveness assessment of protected areas based on the states, trends, and relative changes in forest ecosystem: a case study in the Three Parallel Rivers Region, China

Establishing protected areas (PAs) is a major measure of biodiversity conservation, and various methods have been explored to assess PAs’ effectiveness. However, those methods mainly compared the relative changes in land cover between treated samples inside the PAs and their matched samples outside the PAs, which would produce misjudgments, especially in some climax communities with a relatively steady state. Thus, in this study, we constructed an integrated framework through a series of assessments according to the state, trend, and relative change of each PA to explore the conservation effectiveness of PAs in the Three Parallel Rivers Region in China from 2000 to 2020. Here, “state” refers to the difference among samples from within and outside the PA, assessed through yearly sample mean comparison. “Trend” means linear regression of mean forest area of each PA throughout the assessment period. “Relative change” means the difference in the mean value of the slope of forest changes between the treated samples inside each PA and their matched control samples outside of PAs. The entire forest area within all PAs in the Three Parallel Rivers Region showed a significant increasing trend from 2000 to 2020 (R2 = 0.919, P<0.05). Among all the PAs, twelve (86%) had a positive effect on protecting the forest ecosystem, and two had a nonsignificant effect. Among the factors affecting the state and relative change in PAs’ forests, the annual total precipitation was the most important, followed by distance to the nearest road. Moreover, the management-level variable was an essential factor in the state of PAs’ forest ecosystems, which indicated that national PAs (nature reserves and natural parks) were in a better state than local (provincial- and county-level) nature reserves. Overall, the conservation effectiveness of forests in PAs was assessed at a regional scale in the Three Parallel Rivers Region, implying that our framework would be additional useful in regions with high biodiversity and steady ecosystems. This framework better avoids underestimating conservation effectiveness assessment tasks than traditional methods do. Thus, we posit that this framework is suitable for future global or country-level assessments.

KNN Local Linear Regression for Demarcating River Cross-Sections with Point Cloud Data from UAV Photogrammetry URiver-X

Aerial surveying with unmanned aerial vehicles (UAVs) has been popularly employed in river management and flood monitoring. One of the major processes in UAV aerial surveying for river applications is to demarcate the cross-section of a river. From the photo images of aerial surveying, a point cloud dataset can be abstracted with the structure from the motion technique. To accurately demarcate the cross-section from the cloud points, an appropriate delineation technique is required to reproduce the characteristics of natural and manmade channels, including abrupt changes, bumps and lined shapes. Therefore, a nonparametric estimation technique, called the K-nearest neighbor local linear regression (KLR) model, was tested in the current study to demarcate the cross-section of a river with a point cloud dataset from aerial surveying. The proposed technique was tested with synthetically simulated trapezoidal, U-shape and V-shape channels. In addition, the proposed KLR model was compared with the traditional polynomial regression model and another nonparametric technique, locally weighted scatterplot smoothing (LOWESS). The experimental study was performed with the river experiment center in Andong, South Korea. Furthermore, the KLR model was applied to two real case studies in the Migok-cheon stream on Hapcheon-gun and Pori-cheon stream on Yecheon-gun and compared to the other models. With the extensive applications to the feasible river channels, the results indicated that the proposed KLR model can be a suitable alternative for demarcating the cross-section of a river with point cloud data from UAV aerial surveying by reproducing the critical characteristics of natural and manmade channels, including abrupt changes and small bumps as well as different shapes. Finally, the limitation of the UAV-driven demarcation approach was also discussed due to the penetrability of RGB sensors to water.

Channel changes over the last 200 years: A meta data analysis on European rivers

AbstractThe combined analysis of past evolutionary trajectories of channel morphology and temporal patterns of driving factors is fundamental to understanding present river conditions, supporting river management and evaluating future changes. Rivers in Europe underwent important channel changes during the Anthropocene in response to changing natural drivers and anthropogenic pressures. A considerable number of papers have been published on this topic, in the last decades. In this study, a comprehensive meta‐analysis on channel changes during the last 200 years in Europe was performed, aiming to provide quantitative information on the intensity of changes, to highlight regional scale similarities and dissimilarities in evolutionary morphological trajectories and to discuss the main causes of such changes. Based on a review, 102 papers were selected, addressing 145 channel reaches flowing through five main mountain ranges (Iberians, Alps, Apennines, Balkans and Carpathians) in the southern and eastern parts of Europe. The results show that active channel narrowing (between 26% and 36% on average) and incision (between 1 and 2 m) prevailed in most rivers between the 1800s and the 1950s, although widening was documented in some rivers of the Alps and the Apennines. Most multi‐thread reaches maintained their pattern until the mid‐20th century. Active channel changes accelerated during the 1950s–1990s (or 2000s) period, with channel narrowing up to 60% and channel incision up to 14 m. Multi‐thread patterns strongly decreased in frequency, with anabranching channels disappearing and single‐thread patterns becoming predominant. The cumulative effect of multiple and concomitant human pressures (gravel mining, channelisation and damming) was identified as the main driving factor for these accelerated changes. These findings must feed the public debate about preventing alterations of river ecosystems—exerted by anthropic disturbances—in a context of rapid economic development, especially in river systems still poorly altered and thus preserving wide, active and heterogeneous fluvial corridors.

Sediment control and flow redistribution with submerged vanes: a review

ABSTRACT The most challenging issues in rivers include sediment management, outer bank erosion, intake choking, channel bed shoaling, and river meandering. This paper provides a concise review of the newly developed sediment and flow control technique known as the Iowa vane or submerged vane. Submerged vanes are small flow training structures designed to redistribute flow and sediment within the channel cross-section. The structural stability and economic feasibility of submerged vanes, which distinguish them from conventional methods such as dikes and groins, have inspired many researchers to study their use and efficiency in river management over many decades. Various hydrodynamic characteristics, such as flow structure, sediment motion, vortex generation, and scouring around submerged vanes and arrays of vanes, have been reviewed. Additionally, various vane parameters that influence these characteristics are also explained. This paper also underscores current limitations in understanding the flow and sediment behavior around submerged vanes, while also providing recommendations for future research in the field.

Transcriptome analysis of antioxidant system response in Styrax tonkinensis seedlings under flood-drought abrupt alternation

BackgroundStyrax tonkinensis (Pierre) Craib ex Hartwich faces challenges in expanding in the south provinces of Yangtze River region due to climate extremes like flood-drought abrupt alternation (FDAA) caused by global warming. Low tolerance to waterlogging and drought restricts its growth in this area. To study its antioxidant system and molecular response related to the peroxisome pathway under FDAA, we conducted experiments on two-year-old seedlings, measuring growth indexes, reactive oxygen species content, antioxidant enzyme activity, and analyzing transcriptomes under FDAA and drought (DT) conditions.ResultsThe physiological results indicated a reduction in water content in roots, stems, and leaves under FDAA conditions. The most significant water loss, amounting to 15.53% was observed in the leaves. Also, ROS accumulation was predominantly observed in leaves rather than roots. Through transcriptome analysis, we assembled a total of 1,111,088 unigenes (with a total length of 1,111,628,179 bp). Generally, SOD1 and CAT genes in S. tonkinensis seedlings were up-regulated to scavenge ROS. Conversely, the MPV17 gene exhibited contrasting reaction with up-regulation in leaves and down-regulation in roots, leading to increased ROS accumulation in leaves. CHS and F3H were down-regulated, which did not play an essential role in scavenging ROS. Moreover, the down-regulation of PYL, CPK and CALM genes in leaves may not contribute to stomatal closure, thereby causing continuous water loss through transpiration. Whereas, the decreased root vigor during the waterlogging phase and up-regulated CPK and CALM in roots posed obstacles to water absorption by roots. Additionally, the DEGs related to energy metabolism, including LHCA and LHCB, were negatively regulated.ConclusionsThe ROS generation triggered by MPV17 genes was not the main reason for the eventual mortality of the plant. Instead, plant mortality may be attributed to water loss during the waterlogging phase, decreased root water uptake capacity, and continued water loss during the subsequent drought period. This study establishes a scientific foundation for comprehending the morphological, physiological, and molecular facts of S. tonkinensis under FDAA conditions.

Spatiotemporal Variation, Meteorological Driving Factors, and Statistical Models Study of Lake Surface Area in the Yellow River Basin

The surface area changes of 151 natural lakes over 37 months in the Yellow River Basin, based on remote sensing data and 21 meteorological indicators, employing spatial distribution feature analysis, principal component analysis (PCA), correlation analysis, and multiple regression analysis, identify key meteorological factors influencing these variations and their interrelationships. During the study period, lake area averages were from 0.009 km2 to 506.497 km2, with standard deviations ranging from 0.003 km2 to 184.372 km2. The coefficient of variation spans from 3.043 to 217.436, indicating considerable variability in lake area stability. Six primary meteorological factors were determined to have a significant impact on lake surface area fluctuations: 24 h precipitation, maximum daily precipitation, hours of sunshine, maximum wind speed, minimum relative humidity, and lakes in the source region of the Yellow River generally showed a significant positive correlation. For maximum wind speed (m/s), 28 lakes showed significant correlations, with five positive and twenty-three negative correlations, correlation coefficients ranging from −0.34 to −0.63, average −0.47, indicating an overall negative correlation between lake surface area and maximum wind speed. For maximum daily precipitation (mm), 36 lakes had 21 showing a positive correlation, indicating a positive correlation between lake surface area and daily precipitation in larger lakes. Furthermore, of the 117 lakes with sufficient data to model, the predictive capabilities of various models for lake surface area changes showcased distinct advantages, with the random forest model outperforming others in a dataset of 65 lakes, Ridge regression is best for 28 lakes, Lasso regression performs best for 20 lakes, Linear model is only best for 4 cases. The random forest model provides the best fit due to its ability to handle a large number of feature variables and consider their interactions, thereby offering the best fitting effect. These insights are crucial for understanding the influence of meteorological factors on lake surface area changes within the Yellow River Basin and are instrumental in developing predictive models based on meteorological data.

Establishing morpho-dynamic baseline for flow-sediment management of a tidal river in the Ganges–Brahmaputra–Meghna Delta system through field measurement

Establishing morpho-dynamic baseline for flow-sediment management of a tidal river in the Ganges–Brahmaputra–Meghna Delta system through field measurement

How does the daily regulation hydropower station reduce the hydrological regime impact? A case study in upper Yellow River

ABSTRACT The regulation of hydropower stations has profoundly altered river flow patterns. While studies have extensively assessed the impact of large or multiyear regulated hydropower stations on hydrological regimes using indicators of hydrological alteration (IHA) and range of variability approach (RVA), the impact of daily regulation hydropower stations has received comparatively less attention. This study aims to evaluate the influence of daily regulation hydropower stations on hydrological regime changes. The analysis focuses on the upper Yellow River region in China, which houses cascade hydropower stations, utilizing daily runoff data from the Guide hydrological station spanning from 1954 to 2020. The Mann–Kendall test revealed 27 of 32 IHAs with a significant trend when considering the operation of the multiyear regulated hydropower station (Longyangxia). However, this number decreased to 18 IHAs when daily regulation hydropower stations (Laxiwa and Nina) were included. Evaluation using the RVA method indicated that only 46.87% of IHAs showed high alterations from the natural regime when considering the operation of daily regulation hydropower stations, a decrease from 75.00% when solely considering Longyangxia. Findings suggest that daily regulation hydropower stations can effectively mitigate the adverse effects of multiyear regulated hydropower stations, bringing the hydrological regime closer to a natural state.

How big is a boulder? The importance of boulder definition choice in earth science research and river management

AbstractBoulders are globally widespread and influence processes across many landscapes including hillslopes, coasts, rivers and extra‐terrestrial settings. Boulders are described as particles, sufficiently large, that they have a disproportionate effect on the surrounding landscape. Moving beyond this conceptual definition, however, requires a somewhat arbitrary decision of how to define a minimum boulder size. The implications of boulder definition on study findings are rarely considered. We investigate the suitability of five boulder definitions, two based on fixed sizes: (1) 0.26 m and (2) 1 m, and three definitions which vary based on system characteristics: (3) grain mobility, (4) grain protrusion and (5) surface grain size distribution (> 84th percentile, D84). We consider the impact of definition on calculated boulder metrics, and, for the >1m and >D84 definitions, their association with channel and catchment characteristics across 20 boulder‐bed streams in northern Sweden. We also surveyed river managers responsible for restoring these rivers, to gain a practitioner insight on boulder size definition. We found that boulder definition matters; for metrics relating to the number or density of boulders, the >D84 and >1m size definitions were negatively correlated. Surveys indicated the importance of communicating boulder definition. We conclude that, whilst the best choice of boulder size definition will vary based on the questions of interest and techniques employed, evaluating the implications of the chosen boulder size definition and communicating the reasoning behind boulder definition choice is crucial.

Geophysical characterization of Saraswati River palaeochannel in parts of Yamuna Nagar and Kurukshetra districts of Haryana, India.

Palaeochannels are remnants of rivers or stream channels filled with younger sediments over the period of time. In ancient times, these rivers/channels were thriving in phenomenal conditions, but due to frequent tectonic activities, they lost the direction of their original path and were gradually either lost or buried under thick beds of younger alluvium. Palaeochannels act as reservoirs for fresh groundwater since they are made up of coarser sediments and were formerly flowing rivers. Depending on the groundwater regime and local topography, these could either be saturated or dry. The palaeochannels have high groundwater potential if saturated. These are ideal sites for artificial groundwater recharge, if dry. The identification of palaeochannels becomes quite challenging if they are buried under thick deposits of finer younger sediments. In the present study, an attempt has been made to characterize the Saraswati River Palaeochannel in parts of Yamuna Nagar and Kurukshetra districts of Haryana by using surface and subsurface geophysical methods. Till date, the palaeochannels in this area were mainly discerned on the basis of remote sensing only; therefore, geophysical characterization of these palaeochannels has been attempted in this study. In surface geophysical methods, electrical resistivity surveys, especially gradient resistivity profiling (GRP) and vertical electrical sounding (VES), were conducted in the study area, while electrical and natural gamma logging was used as subsurface geophysical approaches to identify the coarser sands of buried palaeochannels. The main objective of the study was to characterize the Saraswati River palaeochannel and analyze the quality of the groundwater stored in the palaeochannel in the study area. The findings were compared with the well-log data and were found in good agreement.

Assessing regional employment effects of the national emission trading scheme in China: Does Okun's law work?

Employment creation and climate change mitigation are core tasks for achieving sustainable development goals. Whether or not carbon mitigation policy facilitate employment deserves deep exploration. Through the construction of multi-regional dynamic computable general equilibrium model (CGE) with more scientific energy & environment block, this paper first evaluates regional employment effects of the national emission trading scheme (ETS) in China. Furthermore, we explore the Okun's law of the national ETS based on the mediating effect model. The results show that whether in carbon-intensive industries (CIIs) or non-carbon-intensive industries (NCIIs), employment effects of the national ETS are differentiated across regions. Specifically, the national ETS generally promotes CIIs' employment in Southern, Eastern, Middle Yangtze River and Southwest regions, and has negative effects on CIIs' employment in other regions. Meanwhile, the national ETS brings employment creation to NCIIs of Southern region, while there are opposite results in NCIIs of Northeast region and mixed results in NCIIs of other regions. Moreover, the Okun's law of the national ETS holds in CIIs of each region, but it not fits the data for NCIIs. Therefore, it is important for the Chinese government to consider the differentiated employment effects in different regions carefully rather than adopt one-size-fit-all solution when constructing the national carbon market.

Restoration thinning accelerates small tree growth but may slow large tree growth in a multi‐age flood‐dependent forest

Abstract Large tree decline is occurring globally with critical implications for biodiversity and carbon sequestration. Restoration thinning is a potential management action to accelerate tree growth and promote large tree development in forests, yet trials have been limited and results have been mixed. We conducted a large‐scale trial to determine whether restoration thinning could accelerate the development of large trees in river red gum forests in Australia that had experienced widespread woody thickening and a decline of large trees due to long‐term commercial timber harvesting and river regulation. Thinning was conducted on 44 9‐ha plots by removing trees <40 cm diameter from around retained trees at a range of spacings. Initial tree densities ranged from ~260 to ~1860 trees per ha and 8%–86% of trees were removed by thinning. We monitored 1980 trees prior to thinning, and annually for 5 years post‐thinning. We tested the effects of thinning intensity on diameter growth of different sized trees and explored whether long‐ and short‐term water availability affected outcomes. Thinning promoted the growth of small trees <56 cm diameter, especially in drier sites during wet years. Higher thinning intensities reduced the growth rates of large trees (no smaller than 79.5 cm diameter) in wetter sites. For medium‐ and large‐sized trees, long‐ and short‐term water availability were stronger drivers of tree growth than competition due to tree density. Synthesis and applications. Restoration thinning may accelerate tree growth in young river red gum forests where all trees are small. But restoration thinning may be ineffective or detrimental in multi‐aged forests where the goal is to promote the growth rates of trees that are already medium to large in size.

Seasonal changes of Chlorophyll-A concentration in Jiujiang city based on remote sensing

Abstract. The Chlorophyll-a (Chla) concentration is an important parameter characterizing the water quality of rivers and lakes. Satellite remote sensing provides new opportunities for the quantitative monitoring of Chla concentration in large-scale water bodies. In this study, Sentinel-2 satellite remote sensing data integrated on the Google Earth Engine (GEE) remote sensing big data platform are employed, along with hourly measured water quality site data, to establish a quantitative inversion model for Chla concentration water quality parameters in Jiujiang City within Jiangxi Province, China. The Chla concentration is estimated for each quarter from 2020 to 2022, and the spatial distribution is analyzed, revealing the changing trend of Chla concentration over the past three years. The key findings are as follows: (1) The quantitative inversion model for Chla concentration has been validated with measured data, achieving a model accuracy of 0.53; (2) The spatial inversion results of Chla concentration exhibit an increasing trend that is consistent with actual measurement site results; (3) Owing to the influence of human activities and the peak-low water level of rivers and lakes, Chla concentration shows a discernible seasonal variation pattern. This methodology offers a new perspective for analyzing the seasonal variation characteristics of Chla concentration in rivers and lakes, providing valuable insights for the sustainable management of river and lake water quality.

Response of Streamflow to Future Land Use and Cover Change and Climate Change in the Source Region of the Yellow River

This study utilizes meteorological and leaf area index (LAI) data for three shared socioeconomic pathways (SSP1–2.6, SSP2–4.5, and SSP5–8.5) from four general circulation models (GCMs) of the sixth climate model intercomparison project (CMIP6) spanning from 2015 to 2099. Employing calibrated data and incorporating future land use data under three SSPs, the distributed hydrology soil vegetation model (DHSVM) is employed to simulate streamflow in the source region of the Yellow River (SRYR). The research aims to elucidate variations in streamflow across different future scenarios and to estimate extreme streamflow events and temporal distribution changes under future land use and cover change (LUCC) and climate change scenarios. The main conclusions are as follows: The grassland status in the SRYR will significantly improve from 2020 to 2099, with noticeable increases in temperature, precipitation, and longwave radiation, alongside a pronounced decrease in wind speed. The probability of flooding events increases in the future, although the magnitude of the increase diminishes over time. Both LUCC and climate change contribute to an increase in the multi-year average streamflow in the region, with respective increments of 48.8%, 24.5%, and 18.9% under SSP1–2.6, SSP2–4.5, and SSP5–8.5. Notably, the fluctuation in streamflow is most pronounced under SSP5–8.5. In SSP1–2.6, the increase in streamflow during the near future (2020–2059) exceeds that of the distant future (2059–2099). Seasonal variations in streamflow intensify across most scenarios, leading to a more uneven distribution of streamflow throughout the year and an extension of the flood season.