Turbidity Events Research Articles

Multispectral Insights into Turbidity Variations Over Time in The Derawan Island

Abstract This investigation delves into the temporal and spatial dynamics of turbidity in the Derawan Islands, Indonesia, utilizing a comprehensive approach that combines multispectral satellite imagery from Sentinel-2, in-situ measurements via AAQ Licor sensors across 165 observation stations, and continuous data collection from a Turbidity Logger. Situated within the Coral Triangle, understanding the turbidity variations in the Derawan Islands is crucial for the conservation and sustainable management of its marine ecosystems. Our research developed and validated empirically derived algorithms to accurately estimate turbidity, utilizing a strategic partition of in-situ data—70% for model development and 30% for validation. This approach resulted in robust models, demonstrating their efficacy with Root Mean Square Error (RMSE) values as low as 0.85 and R-Squared (R2) values up to 0.56, indicating a high degree of accuracy in satellite-derived turbidity measurements. The study unveiled significant spatial and temporal turbidity heterogeneity, linking these variations to both natural and anthropogenic factors. The high-resolution data from the Turbidity Logger revealed critical diurnal fluctuations and short-term turbidity events, providing insights into the dynamic marine environment of the Derawan Islands.

Impacts of High-Concentration Turbid Water on the Groundwater Environment of the Tedori River Alluvial Fan in Japan

The occurrence of high-concentration turbid water due to a large landslide in the upper reaches of the Tedori River Basin in Japan in May 2015 led to a rapid decline in the groundwater levels within the alluvial fan. However, factors other than turbid water, such as changes in precipitation patterns, can have a significant impact on groundwater levels but have not been thoroughly investigated. By analyzing the relationship between river water and groundwater levels, we found that by 2018, conditions had returned to those observed prior to the turbidity events. Regarding seepage, we found that approximately 24% of the Tedori River’s discharge contributed to seepage before the turbidity event. In contrast, during the post-turbidity years, seepage decreased between 2015 and 2017 and returned to the pre-turbidity levels by 2018. Furthermore, by constructing a hydrological model and examining the contributions of turbidity and precipitation, we found that in 2015, turbidity contributed to 76% of the groundwater level changes, whereas precipitation accounted for 24%. In contrast, in 2016, turbidity contributed to 67%, while precipitation contributed to 33%. In essence, the first year was characterized by a significant contribution from turbidity, while precipitation also played a significant role in groundwater level fluctuations in the second year.

ARIMA and TFARIMA Analysis of the Main Water Quality Parameters in the Initial Components of a Megacity’s Drinking Water Supply System

The objective of this paper is to use autoregressive, integrated, and moving average (ARIMA) and transfer function ARIMA (TFARIMA) models to analyze the behavior of the main water quality parameters in the initial components of a drinking water supply system (DWSS) of a megacity (Bogota, Colombia). The DWSS considered in this study consisted of the following components: a river, a reservoir, and a drinking water treatment plant (WTP). Water quality information was collected daily and over a period of 8 years. A comparative analysis was made between the components of the DWSS based on the structure of the ARIMA and TFARIMA models developed. The results show that the best water quality indicators are the following: turbidity > color > total iron. Increasing the time window of the ARIMA analysis (daily/weekly/monthly) suggests an increase in the magnitude of the AR term for each DWSS component (WTP > river > reservoir). This trend suggests that the turbidity behavior in the WTP is more influenced by past observations compared to the turbidity behavior in the river and reservoir, respectively. Smoothing of the data series (moving average) as the time window of the ARIMA analysis increases leads to a greater sensitivity of the model for outlier detection. TFARIMA models suggest that there is no significant influence of past river turbidity events on turbidity in the reservoir, and of reservoir turbidity on turbidity at the WTP outlet. Turbidity outlier events between the river and reservoir occur mainly in a single observation (additive outliers), and between the reservoir and WTP also have a permanent effect over time (level shift outliers). The AR term of the models is useful for studying the transfer of effects between DWSS components, and the MA term is useful for studying the influence of external factors on water quality in each DWSS component.

Tracking flowpaths in a complex karst system through tracer test and hydrogeochemical monitoring: Implications for groundwater protection (Gran Sasso, Italy)

Groundwater in karst aquifers is frequently tapped for drinking purposes, due to frequent huge volumes of resources. Unfortunately, vulnerability of these aquifers can be high, due to possible fast transfer of recharge water on springs by the karst network. On Gran Sasso Mountain regional aquifer, several springs are subjected to drinking withdrawal and an updated evaluation of their potential is now a fundamental issue to be considered, facing climate change effects, which reflect on variation of discharge regimen and values. To distinguish between different contribution of spring recharge, a tracer test has been carried out on the Vitella d’Oro spring, fed both by the regional aquifer and by a local system exposed to karst features developed in the Rigopiano Conglomerates formation. Thanks to hydrogeological, hydrogeochemical and isotopic data, a conceptual model of spring recharge has been proposed and subsequently validated by the tracer test results. All information confirms the superimposition on the regional base flow, by a relevant contribution of the karst network, influencing the spring discharge in recharge periods. In detail, a fast flow component is responsible for discharge peaks and frequently of turbidity events, having a mean velocity ranging from 30 to 70 m/h in the aquifer. Besides of this fast flow, an additional aliquot of the recharge is due to the same local aquifer, but slower flow clearly identifiable by hydrochemistry and isotopic data. Thanks to these findings, a renewed management of the spring has been suggested, considering the different degrees of aquifer vulnerability (turbidity occurrence) directly related to the discharge regimen.

Algorithms to mimic human interpretation of turbidity events from drinking water distribution systems

Abstract Deriving insight from the increasing volume of water quality time series data from drinking water distribution systems is complex and is usually situation- and individual-specific. This research used crowd-sourcing exercises involving groups of domain experts to identify features of interest within turbidity time series data from operational systems. The resulting labels provide insight and a novel benchmark against which algorithmic approaches to mimic the human interpretation could be evaluated. Reflection of the results of the labelling exercises resulted in the proposal of a turbidity event scale consisting of advisory <2 NTU, alert 2 < NTU < 4, and alarm >4 NTU levels to inform utility response. Automation, for scale up, was designed to enable event detection within these categories, with the <2NTU category being the most challenging. A time-based averaging approach, based on data at the same time of day, was found to be most effective for identifying these advisory events. The automation of event detection and categorisation presented here provides the opportunity to gain actionable insight to safeguard drinking water quality from ageing infrastructure.

The hyperturbid mesotidal Guadalquivir estuary during an extreme turbidity event: Identifying potential management strategies

The Guadalquivir estuary (SW Iberian Peninsula) is a mesotidal system within a Mediterranean climatic region. It experiences severe and persistent hyperturbid conditions during the wet and cold season, significantly impacting both the ecosystem and various economic activities.During an investigation of an extreme turbidity event, suspended particulate matter (SPM) concentrations exceeding 30 g/L were found near the salt intrusion limit, with a 45 km stretch showing a depth-averaged SPM concentration greater than 10 g/L. Throughout this event, the estuary can accumulate more than 900,000 tonnes of SPM, leading to severe surface light blockage, with the euphotic layer remaining shallower than 10 cm in most areas. Additionally, hypoxia develops in the zone of maximum turbidity, near the bottom.These extreme turbidity events are linked to short-duration freshets that discharge a large amount of sediment from a highly erodible catchment area, followed by a significant reduction in river flow, primarily due to strong water regulation. However, hyperturbid conditions never extend into the summer in this estuary, indicating a non-negligible capacity to clear the SPM.Considering these findings, several recommendations are proposed. First, establishing a monitoring programme for extreme turbidity processes can aid in implementing necessary management actions. Second, it is crucial to develop an optimal protocol for water discharges from the network of dams to maximise sediment export to the sea, minimise plankton washout, and prevent excessive freshwater loss.

From cave to spring: Understanding transport of suspended sediment particles in a fully phreatic karst conduit using particle analysis and geochemical methods

AbstractKarst aquifers are vulnerable to contamination, especially in the context of heavy rainfall events. Contamination is often associated with turbidity that can originate from the soil zone, infiltrating surface waters or resuspension of previously deposited sediments within the aquifer. While turbidity events can be well monitored at karst springs, related information about the sediment origin and the spatiotemporal input function usually remain unknown. Thus, the mobility and attenuation of the particulate matter and associated pollutants can hardly be determined quantitatively. A tracer test with suspended cave sediments and solute tracers for comparison has hence been performed in a karst aquifer at the Blue Spring (Blautopf) in Southern Germany. The tracers were injected in the cave system, at the beginning of a fully phreatic karst conduit, and monitored at the spring after a travel distance of 1250 m. The particle‐size distribution was monitored using a particle counter and sediment samples were filtered with 0.45‐μm cellulose acetate filters. Particles on the filter were analysed for major and trace elements as well as rare earth elements (REE) by ICP‐MS after acid digestion. Results show that (1) sediment particles were transported faster than solutes, which was interpreted as a transport in the main flow path of the conduit, whereas conservative tracers tend to diffuse into smaller fissures as well. (2) All measured particles sizes were transported at similar flow velocities. (3) A transport associated to sediment particles could be shown for all measured elements. This study presents a methodological improvement of comparative sediment tracer tests as well as deeper insights into particle and element transport processes in karst aquifers, originating from previously deposited cave sediment. Results provide deeper knowledge into transport processes of sediment‐associated contaminants, such as heavy metals which may strongly be affected by the particle size. This knowledge contributes to a better management of karst water resources in the context of turbidity events.

Comparison of high turbidity events: Sand nourishments and storm events on sandy beaches at the Baltic Sea, Germany

Coastal zones are permanently under stress by storms, cliff breaks, waves and currents. These events can cause the retreat of the coastline and are currently compensated by beach nourishments. The commonality of these sediment eroding and accumulating processes are turbidity plumes created in coastal waters, increasing the resuspension of particles and possibly nutrient concentrations. To compare sand nourishments and storm events, total suspended solids (TSS) and nutrient measurements were performed during winter season at the German Baltic Sea Coast. A pre-experiment showed that the TSS was homogenous through the water column. There were significant differences between both events, with sand nourishments exceeding the TSS of storms with the factor two. Due to the nourishment mechanism, the relative organic content was lower than during storm events. The nutrient uptake was unsteady. Therefore, sand nourishment can be considered to have more influence on the ecology of sand shores than storm events.

Integrating remote sensing and machine learning to detect turbidity anomalies in hydroelectric reservoirs

Monitoring water quality in reservoirs is essential for the maintenance of aquatic ecosystems and socioeconomic services. In this scenario, the observation of abrupt elevations of physicochemical parameters, such as turbidity and other indicators, can signal anomalies associated with the occurrence of critical events, requiring operational actions and planning to mitigate negative environmental impacts on water resources. This work aims to integrate Machine Learning methods specialized in anomaly detection with data obtained from remote sensing images to identify with high turbidity events in the surface water of the Três Marias Hydroelectric Reservoir. Four distinct threshold-based scenarios were evaluated, in which the overall performance, based on F1-score, showed decreasing trends as the thresholds became more restrictive. In general, the anomaly identification maps generated through the models ratified the applicability of the methods in the diagnosis of surface water in reservoirs in distinct hydrological contexts (dry and wet), effectively identifying locations with anomalous turbidity values.

Three-Dimensional Numerical Modeling of Ground Ice Ablation in a Retrogressive Thaw Slump and Its Hydrological Ecosystem Response on the Qinghai-Tibet Plateau, China

Retrogressive thaw slumps (RTSs), which frequently occur in permafrost regions of the Qinghai-Tibet Plateau (QTP), China, can cause significant damage to the local surface, resulting in material losses and posing a threat to infrastructure and ecosystems in the region. However, quantitative assessment of ground ice ablation and hydrological ecosystem response was limited due to a lack of understanding of the complex hydro-thermal process during RTS development. In this study, we developed a three-dimensional hydro-thermal coupled numerical model of a RTS in the permafrost terrain at the Beilu River Basin of the QTP, including ice–water phase transitions, heat exchange, mass transport, and the parameterized exchange of heat between the active layer and air. Based on the calibrated hydro-thermal model and combined with the electrical resistivity tomography survey and sample analysis results, a method for estimating the melting of ground ice was proposed. Simulation results indicate that the model effectively reflects the factual hydro-thermal regime of the RTS and can evaluate the ground ice ablation and total suspended sediment variation, represented by turbidity. Between 2011 and 2021, the maximum simulated ground ice ablation was in 2016 within the slump region, amounting to a total of 492 m3, and it induced the reciprocal evolution, especially in the headwall of the RTS. High ponding depression water turbidity values of 28 and 49 occurred in the thawing season in 2021. The simulated ground ice ablation and turbidity events were highly correlated with climatic warming and wetting. The results offer a valuable approach to assessing the effects of RTS on infrastructure and the environment, especially in the context of a changing climate.

Impacts of a tailings dam failure on water quality in the Doce river: The largest environmental disaster in Brazil

BackgroundOn November 5, 2015, the Fundão Dam, owned by Samarco Mineração SA, experienced a catastrophic failure, releasing approximately 55 to 62 million m3 of mining ore waste into the Doce River. This event had severe consequences as the Doce River serves as a vital source of water and food for numerous communities. ObjectiveEvaluate the spatiotemporal distribution of water parameters before, during, and after the failure of the Samarco tailings dam, with the goal of support the management and restoration of water quality. The study utilizes a long historical series of data from 1997 to 2018. MethodologyIn this study, data from 13,916 measurements of variables including HCO3−, Mg2+, Ca2+, SO42−, pH, EC, and metal(oids) such as Fe, Mn, As, Cu, Ba, Pb, Zn, Cd, Cr, and Ni were compiled. These measurements were collected from 1997 to 2018 to investigate the impact of the dam rupture. ResultsThe dam failure resulted in an increase in high turbidity events and total suspended solids (TSS), leading to a decline in water quality. The Kruskal-Wallis test revealed a homogenization effect along the river watershed caused by the accident, particularly for Pb, Ni, Cd, Cr, and coliforms. Additionally, there was a change in the seasonal distribution of PO43−, NH4+, Na+, SO42−, and Zn. The factor analysis identified four main factors: i) HCO3−, Mg2+, Ca2+, SO42−, pH, and electrical conductivity (37.55%) were indicative of weathering processes from lithotypes; ii) Fe+Mn and the metal(oids) (As, Cu, Ba, Pb, Zn, Cd, Cr, and Ni) (15.89%) were associated with ore waste and regional geology; iii) total coliforms, NO3−, NH4+, and PO43− (9.39%) were linked to anthropogenic influences in the river; and iv) K+, Na+, and Cl− (8.22%) represented the impact of domestic and industrial sewage discharge as well as the marine environment in the lower sector of the Doce River. ConclusionThe dam rupture significantly altered water quality in the Doce River, particularly in relation to metal(oids), three years after the disaster. The presence of ore waste in the bottom sediments creates an environmental liability as it can be remobilized by human activities or extreme weather events, further impacting water quality.

Using deep learning to assess temporal changes of suspended particles in the deep sea

While suspended particles play many important roles in the marine environment, their concentrations are very small in the deep sea, making observation difficult with existing methods: water sampling, optical sensors, and special imaging systems. Methods are needed to fill the lack of environmental baseline data in the deep sea, ones that are inexpensive, quick, and intuitive. In this study we applied object detection using deep learning to evaluate the variability of suspended particle abundance from images taken by a common stationary camera, “Edokko Mark 1”. Images were taken in a deep-sea seamount in the Northwest Pacific Ocean for approximately one month. Using the particles in images as training data, an object detection algorithm YOLOv5 was used to construct a suspended particle detection model. The resulting model successfully detected particles in the image with high accuracy (AP50 > 85% and F1 Score > 82%). Similarly high accuracy for a site not used for model training suggests that model detection accuracy was not dependent on one specific shooting condition. During the observation period, the world’s first cobalt-rich ferromanganese crusts excavation test was conducted, providing an ideal situation to test this model’s ability to measure changes in suspended particle concentrations in the deep sea. The time series showed relatively little variability in particle counts under natural conditions, but there were two turbidity events during/after the excavation, and there was a significant difference in numbers of suspended particles before and after the excavation. These results indicate that this method can be used to examine temporal variations both in small amounts of naturally occurring suspended particles and large abrupt changes such as mining impacts. A notable advantage of this method is that it allows for the possible use of existing imaging data and may be a new option for understanding temporal changes of the deep-sea environment without requiring the time and expense of acquiring new data from the deep sea.

Press, pulse, and perceptions: How does media attention signal perceptions about environmental crises?

AbstractAt what point do environmental phenomena become crises, and how do these impact the quantity and quality of media attention? As climate patterns change, societies face crises that are slow‐moving in nature (such as sea level rise and drought) or fast‐changing (such as hurricanes or flash floods). A third type of event is those that are slow‐occurring while at the same time being punctuated by extreme, fast‐changing occurrences. The practical and theoretical consequences of these complex events are often difficult to pinpoint. We argue that it is necessary to evaluate how the features of such events affect stakeholder perceptions. We do so by analyzing water‐quality crises in Northeastern Patagonia, Argentina. Combining turbidity data collected over a decade with 10 years of newspaper articles published in response to high turbidity events, we assess the extent and sentiment of media attention to better understand the linkage between extreme natural events and how these relate to the media agenda. We find that as events increase in duration and intensity, their media coverage increases. These effects are more accentuated when the duration and intensity of an event surpass limits imposed by local infrastructure and practices.

Sharp Increase of Extreme Turbidity Events Due To Deglaciation in the Subtropical Andes

AbstractClimate change may affect sediment fluvial export from high mountain regions, leading to downstream environmental disruptions and direct impacts on human activities. In this paper, three decades (1990–2020) of turbidity measurements, along with climate and hydro‐glaciological variables, were used to investigate the interannual and interdecadal variability in the number of extreme turbidity events (ETE) in the glacierized Maipo River basin, located in the western subtropical Andes. ETE are defined as a sequence of days (most often 1 or 2) during which the daily maximum turbidity was in the 99% quantile of the entire study period. Some of these events compromised the drinking water provision for the city of Santiago, with more than 6 million inhabitants. ETE are more frequent during summer and are mostly associated with melt‐favourable conditions. The number of ETE tends to increase in summers with large glacier ice melt and low snowmelt (outside or over glaciers). Most notable, the mean annual number of ETE exhibits a 6‐fold increase in the last decade compared with the 1990–2010 period. After 2010, ETE also shifted their seasonal maximum from late spring to mid‐summer and their occurrence became strongly coupled with large ice melt rates. We hypothesize that such regime change was caused by an enhanced hydrological connectivity of subglacial sediment pools that increased the sensitivity of the sediment system to glacier melt. The latter is in line with recent research and is consistent with the ongoing glacier retreat due to strong regional warming and drying.

Improved Process Monitoring Isolates Root Cause of Turbidity Events

A Colorado drinking water facility equipped with ceramic membranes for microfiltration was experiencing daily occurrences of turbidity events, often resulting in shutdowns. A new turbidity measurement system was used to improve operations and water quality.

On Using Si to Unravel Potential Sources of Dissolved Al to the Deep Arctic

AbstractAn examination of the vertical profiles of aluminum, silicic acid, and the Si:Al ratio indicates that the enrichment of dissolved Al in the bottom waters of the Arctic basins cannot be explained by the water column remineralization of vertically transported biological material. Instead, it is suggested that the bottom water enrichments are a result of the dissolution of amorphous aluminosilicates that are produced within the sedimentary pore waters by a reverse weathering process. We suggest that these materials are released into the low Si, low Al overlying water column by turbidity currents descending from the broad Arctic shelves which deliver sediments, water, and the products of reverse weathering into the bottom waters of the Arctic basins. It is suggested that from its delivery point at the basin edges, this dissolved Al signal then spreads out, enriching the signals in the bottom of the basins and mixes upward into the overlying water column to produce the observed vertical gradients. Thus, the deepwater Al enrichment is driven by a concentration gradient from below, that is, it is a bottom up (sedimentary driven), rather than the top down (particle export) process that has been previously suggested. It is also suggested that this dissolved Al signal might potentially be used as a tracer of these sporadic turbidity events, which in addition to transporting sediments, also are a mechanism for subducting water into abyssal regions. The observation of elevated dissolved Al signals at other ocean boundaries adjacent to Al‐rich lithogenic materials further suggests that the formation of the products of reverse weathering within sediments is probably widespread along continental margins.

Prediction Model suitable for Long-term High Turbidity Events in a Reservoir

The turbidity events caused by Typhoon “Kong-rey” in 2018 were selected as the measured turbidity data required to build the CE-QUAL-W2 model. The turbidity, water temperature, climate data, and discharge measured in the main dam were used as input data for numerical simulations. To ensure the reliability of the parameters, the turbidity events caused by Typhoon “Mitak” in 2019 were additionally selected, and optimal parameters for water temperature and other parameters were selected using case by case simulation. The analysis showed that the error rate and reliability were relatively good as the turnover phase approached through the turbidity rise and fall periods. The results of the verification of the maximum and average turbidity were better than those of the verification of the period-specific simulation. Thus, the models constructed in this study were determined to be suitable for the flood season.

Deep-sea water displacement from a turbidity current induced by the Super Typhoon Hagibis.

Turbidity currents are the main drivers behind the transportation of terrestrial sediments to the deep sea, and turbidite deposits from such currents have been widely used in geological studies. Nevertheless, the contribution of turbidity currents to vertical displacement of seawater has rarely been discussed. This is partly because until recently, deep-sea turbidity currents have rarely been observed due to their unpredictable nature, being usually triggered by meteorological or geological events such as typhoons and earthquakes. Here, we report a direct observation of a deep-sea turbidity current using the recently developed Edokko Mark 1 monitoring system deployed in 2019 at a depth of 1,370 m in Suruga Bay, central Japan. A turbidity current occurred two days after its probable cause, the Super Typhoon Hagibis (2019), passed through Suruga Bay causing devastating damage. Over aperiod of 40 hours, we observed increased turbidity with turbulent conditions confirmed by a video camera. The turbidity exhibited two sharp peaks around 3:00 and 11:00 on October 14 (Japan Standard Time). The temperature and salinity characteristics during these high turbidity events agreed with independent measurements for shallow water layers in Suruga Bay at the same time, strongly suggesting that the turbidity current caused vertical displacement in the bay’s water column by transporting warmer and shallower waters downslope of the canyon. Our results add to the previous few examples that show meteorological and geological events may have significant contributions in the transportation of shallower seawater to the deep sea. Recent technological developments pertaining to the Edokko Mark 1 and similar devices enable straightforward, long-term monitoring of the deep-seafloor and will contribute to the understanding of similar spontaneous events in the deep ocean.

Water-level fluctuation enhances sediment and trace metal mobility in lake littoral

Water-level fluctuation (WLF) is a widespread management action in lakes and reservoirs whose impacts on contaminant fate have seldom been investigated. We used near shore hourly measurements (n = 2122) of turbidity (contaminant proxy) and water velocity (sediment resuspension proxy) to track high-frequency contaminant dynamics during a 0.6 m change in water level observed in autumn 2017 in a large French lake. Simultaneously, discrete trace metal measurements highlighted that trapped sediment was more contaminated and finer than surficial sediment supporting that suspended particles (measured by turbidity) were a preferential medium for contaminant mobility. General additive models involving tensor products revealed the enhancement of wind-speed and river discharge effects on turbidity with water draw down. The decrease of the explained deviances by the models over time-lags indicated short time-scale response of turbidity to external forcing. Three of the four major turbid events occurred at the lowest water-level and were concomitant of sediment resuspension as well as precipitation events and/or river flood suggesting a complex interplay among in-lake and watershed processes at controlling sediment mobility during the WLF. These results shed in light that WLF can affect lake littoral hydrodynamic cascading up to the enhancement of contaminant mobility. Sediment resuspension may be an overlooked feature of WLF increasing contamination risk and exposure for littoral organisms with widespread ecological consequences due to the large number of water-level regulated ecosystems.

Multiple‐indicator study of the response of groundwater recharge sources to highly turbid river water after a landslide in the Tedori River alluvial fan, Japan

AbstractThe large volume of groundwater stored in the Tedori River alluvial fan, Ishikawa Prefecture, Japan, is an important source of local drinking and industrial water. The Tedori River was observed to be highly turbid from the beginning of May 2015 to at least November 2017 due to a landslide in the upper reach of the river. After the landslide, the groundwater level was drawn down by several to 10 m near the middle river section during paddy irrigation periods in 2015 and 2016. This study addresses the impacts of the highly turbid water on groundwater recharge from the river and paddy fields. In 2016, we sampled groundwater, river water, paddy irrigation water, paddy ponding water, and precipitation five times at 2‐month intervals. We analysed the H, O, and Sr stable isotopic compositions and major dissolved ion (and Sr) concentrations and compared our data to previous data obtained in June 2011. Ca, Sr, Cl, SO4, and TN concentrations and δ18O values were higher in June 2016 than in June 2011; these increases were more extreme along the left bank of the Tedori River than along the right bank. We explored the mixing of Tedori River water with groundwater using a two‐endmember mixing model based on their Sr concentrations and isotopic compositions. Compared to June 2011, mixing ratios were decreased near the Tedori River in 2016, and larger decreases were observed along the left bank and in the middle stream area. These results confirm that the contribution to groundwater recharge from the river decreased during the turbidity event, particularly along the left bank.