West River Research Articles

First record of Labeo capensis (Smith, 1841) in the Crocodile River (West) system: another successful non-native freshwater fish introduction in South Africa

South Africa is one of six global fish invasion hotspots and as a result, non-native fishes are common components of the fish assemblages in all of the major river systems. The rate of establishment for introduced fish into South African rivers is high (79%) and the vector responsible for the highest establishment rate is interbasin transfer schemes with 80%. Introductions of non-native fish into river systems can negatively affect native fish species through hybridisation, competition for food sources and predation, and the introduction of associated parasites and diseases. The aims of the current study were to provide evidence of the introduction of Labeo capensis into the Crocodile River (West) system, using morphological and molecular techniques, and to record the fish health and gonadosomatic index to determine the invasive status of L. capensis. From the fish health assessment index and gonadosomatic index of L. capensis collected from Olifantsnek Dam, it can be concluded that L. capensis is a healthy reproducing population. Because this fish species can survive and reproduce in newly colonised river systems, it has the potential to compete with the native fish species for food and habitat, but can also hybridise with native Labeo species.

An American Terrestrial Leech

Our common land leech was first obtained by me in April, 1876, at Normal, McLean County, Illinois, where it was dug up in a house garden, about a dozen rods from the nearest rivulet. An example sent the following year to Prof. A. E. Verrill, with some remarks on its superficial characters, was by him identified provisionally and with some hesitation as his Semiscolex grandis, originally described* from three aquatic individuals obtained from Lake Huron, Lake Superior, and West River, Connecticut. I have now, however, fifty-six specimens of this leech, all from the earth in Central Illinois, some of them half a mile or more from water, and representing collections made at different times from April, 1876, to June, 1890 ; while, on the other hand, it has not once occurred in the course of a large amount of aquatic work done in the same regions during these fifteen years. It has, moreover, constant characters which clearly distinguish it from Semiscolex qrandis as far as one may judge by a comparison with Verrill's description, and I do not doubt that it is distinct.

Noteworthy Collections: Virginia

Trillium nivale Riddell (TRILLIACEAE)— Rockingham County: Approximately 4.0 km N of Keezletown, off of Mountain Valley Road, at the end of Walnut Hill Drive on forested hillside; 38u26.6509N, 078u46.3179W; elevation ca. 526 m; 30 March 2008. Conley K. McMullen 891 (photo) (JMUH). Significance. This is the first collection of T. nivale (snow trillium) from Rockingham County, and the second report for Virginia. An earlier collection was made near Forks of Waters in Highland County by Charles E. Stevens on 17 April 1983 [Charles E. Stevens 18455 (VPI)]. The specific location listed by Stevens is ‘‘wooded, limestone bluff of South Branch Potomac River ca. 0.15 mi S of where West Virginia line crosses river.’’ Stevens lists the elevation as 2330 ft. Trillium nivale is also found in Pendleton County, West Virginia, which borders both Rockingham and Highland Counties. Although considered rare in West Virginia, it is also listed for the counties of Cabell, Grant, Preston, Randolph, and Tucker (Harmon et al. 2006). The Cabell County record was likely planted and has not been observed since the mid-1970s (Paul J. Harmon pers. comm.). Other states reporting T. nivale include Illinois, Indiana, Iowa, Kentucky, Maryland, Michigan, Minnesota, Missouri, Nebraska, Ohio, Pennsylvania, South Dakota, and Wisconsin (Case 2002). This species is found primarily at the southern edge of Pleistocene glaciation, and tends to prefer areas devoid of humus, leaf litter, and other plants (Case 2002). *email address: mcmullck@jmu.edu Received May 8, 2008; Accepted July 18, 2008.

Effects of recent morphodynamic evolution on flood regimes in the Pearl River Delta

Both the river network and the regions outside the estuary mouths in the Pearl River Delta (PRD) of China experienced significant changes from 1999 to 2014. A validated hydrodynamic model across the entire PRD and adjacent regions outside the estuary mouths is employed to simulate both present (circa 2014) and past conditions (circa 1999). The total net water flux of the PRD decreased. The flow division of the West River is increasing, with values of 3.63% and 4.66% for the Makou and Denglongshan sections, respectively. The flood flow division of the North River is correspondingly decreasing. The value of the flood levels significantly decreased (more than 2 m) in the upper portion of the PRD, moderately decreased in the middle of the PRD (more than 1.1 m) and slightly decreased in the bottom part of the PRD (less than 0.22 m). In addition, the effects of morphodynamic evolution in different regions (i.e., the river network, coastline and bathymetry changes outside the estuary mouth) on floods are quantified. The results indicate that the decreased net water flux was caused by the increased channel’s capacity and the gentler water-level profile from the downcutting riverbed of the river network. The uneven morphodynamic evolution of the riverbed of the river network was primarily responsible for changes in the flood flow division in the PRD, and morphological evolution outside the estuary mouth was primarily responsible for reallocation within the outlets. The downcutting riverbed in the river network was primarily responsible for the lower flood levels in the upper and middle portion of the PRD. Reclamation seemed to have barely affected the flood level. The deepening bathymetry outside the estuary mouth was mainly responsible for the decrease in the flood level in the bottom portion of the PRD. The downcutting riverbed may decrease the stability of the riverbank, increasing the flood risk. The morphodynamic evolution of both the river network and the regions outside the estuary mouth should be considered to avoid unwanted side effects when designing local projects and flood mitigation strategies for the PRD.

Study on the Non-point Source Pollution in the Mountainous Area of West Sichuan — A Case Study of Livestock and Poultry breeding in Baoxing County

In this paper, the impact of non-point source pollution of livestock and poultry farming in mountainous areas on the water environment in mountainous areas is studied, which is in order to provide a scientific basis for the migration control of non-point source pollution and managing the water environment. Concluded as follows: (1) The main pollutants are TN and COD. What’s more, TN, COD, TP and NH4+-N in the East River are insensitive. TN and COD sensitivity of the West River and Baoxing Rriver are mildly sensitive and TP and NH4+-N is insensitive. (2) The risk sources of East River, West River and Baoxing River are explored. According to 4R control technology of non-point source pollution, source reduction, process interruption, recycling and ecological restoration should be strengthened. Therefore, this study diagnoses the main pollutants and identifies the sources of risk and provides a scientific basis for effective control measures.

Flow Analysis through Collector Well Laterals: A Case Study from Sonoma County Water Agency, California

The Sonoma County Water Agency (SWCA) uses six radial collector wells along the Russian River west of Santa Rosa, to provide water for several municipalities and water districts in north-western California. Three collector wells (1, 2, and 6) are located in the Wohler area, and three collector wells (3, 4, and 5) are located in the Mirabel area. The objective of this paper is to highlight the performance of the three collector wells located in the Mirabel area since their construction. The 2015 investigation showed a lower performance of Collectors 3 and 4 compared to their original performances after construction in 1975, while the performance of Collector 5 was relatively stable since 1982. The potential change in capacity could be due to the increase in encrustation observed during the visual inspection of laterals in all three collector wells. Overall, the three collectors are still within the optimal design parameters (screen entrance velocity < 0.305 m min−1 and axial flow velocity of lateral screens < 1.524 m s−1).

Multiyear variations in High Arctic river temperatures in response to climate variability

Water temperature measurements (2004–2016) from two small rivers in the High Arctic were analyzed to determine the effects of climate variability on thermal regime and the sensitivity to climate change. The East and West rivers (unofficial names) drain similar watersheds (11.6 and 8.0 km2, respectively) and are located at the Cape Bounty Arctic Watershed Observatory (CBAWO), Melville Island, Canada (74°55′N, 109°35′W). Differences in seasonal timing of river temperatures were evident when comparing the coldest and warmest years of the study period, and across different discharge conditions. Snowmelt runoff is characterized by uniformly cold water (∼0–1 °C) over a wide range of discharge conditions, followed by warming water temperatures during flow recession. The rivers showed varying sensitivity to mid-summer air temperature conditions in a given year, with warmer years indicating high correlation (r2 = 0.794–0.929), whereas colder years showed reduced correlation (r2 = 0.368–0.778). River temperatures reached levels which are reported to negatively affect fish and other cold-water aquatic species (>18 °C) with greater frequency and duration during the warmest years. These results provide a basis to further enhance prediction of river thermal conditions to assess ecosystem health in a river system and to refine insights into the effects of climate change on High Arctic aquatic ecosystems.

Quantifying the impacts of small dam construction on hydrological alterations in the Jiulong River basin of Southeast China

The hydrological alterations induced by dam construction modify natural flora and fauna habitats and impair ecosystem stability. Although many studies have documented the impacts of large dams on streamflow, few have described the effects of small dam construction on hydrological conditions. The cumulative effects of intensive small dams may also cause severe ecological problems. To evaluate the impacts of dam construction on the indicators of hydrological alterations, a framework that combined a hydrological model and the post bias correction method was proposed. The hydrological alterations of two individual rivers in the Jiulong River basin that experienced impacts from intensifying small hydropower reservoirs, the North River and the West River, were analyzed using the proposed framework. The results show that the framework can successfully avoid misleading the impacts of dam construction on monthly runoff and multi-minimum values detected by the previously common method that did not separate the impacts of climate change and dam construction on flow regime. The small hydropower-dominated North River and the flood-control-dominated West River exhibited generally consistent change patterns of unchanging monthly river discharge, reduced high pulse count, reduced rise and fall rates, and increased number of reversals. Conversely, the changes to several Indicators of Hydrologic Alterations (IHA) differed between the two rivers. The flood-control-dominated West River exhibited 1) increased indicators, such as the base flow index, multi-day minimum flow and high pulse duration and 2) decreased multi-day maximum flow and low pulse count. Unlike the West River, the hydropower-dominated North River experienced 1) increased low pulse count and 2) decreased indicators such as multi-day minimum flow and low pulse duration. Our results implied that the ecological impacts of the small hydropower-dominated North River may exceed those of the flood-control-dominated West River. Therefore, the minimum ecological water demand should be considered not only in the large reservoirs operation, but also in the operation of small hydropower reservoirs.

Post-accretionary exhumation of the Meguma terrane relative to the Avalon terrane in the Canadian Appalachians

The accretion of the Avalon and Meguma terranes to the Laurentian margin was a major event in the development of the Appalachian orogen. The Minas Fault Zone delineates the boundary between these terranes. A strongly lineated and foliated granite intrusion (Kelly Brook pluton) exposed along the West River St. Mary's Fault intruded into Meguma Supergroup metasedimentary rocks. Well-developed C-S fabrics characterize the pluton with muscovite aligned in the S fabric, and a shallow (~10°) westerly plunging quartz stretching lineation. New U-Pb (zircon, LA-ICP-MS) geochronological data yield a crystallization age of 375.0 ± 4.6 Ma for the Kelly Brook pluton that is indistinguishable from other Late-Devonian intrusive rocks in the Meguma terrane. Petrographic data for muscovite indicate that it grew prior to deformation. A 100% plateau 40Ar/39Ar age of 369.0 ± 1.2 Ma on a single muscovite grain constrains the time of cooling of the granite to approximately 450 to 420 °C. Apatite grains also demonstrate pre- to syn-deformational fabrics and yield a U-Pb (LA-ICP-MS) age of 361.2 ± 5.6 Ma indicating the temperature of the granite was still above 350 °C at this time. Earliest Tournaisian fossils in the unconformably overlying Horton Group strata indicate that the granite was exposed by ca. 359 Ma. Exhumation rates of the Kelly Brook pluton and the Meguma terrane from approximately 9.5–13.3 km depth from ca. 375 Ma to surface exposure at ca. 359 Ma are 0.06 to 0.08 cm yr−1. Estimates for the Upper Devonian regional geothermal gradient in the northern Meguma terrane are high between 39.5 °C km−1 and 67.8 °C km−1, gradients that are common in extensional tectonic environments such as the Basin and Range province. An apatite fission-track age of 215 ± 14 Ma indicates Mesozoic reburial and reheating of the granite prior to opening of the Atlantic Ocean.

Possibilities of Flood Forecasting in the West Caucasian Rivers Based on FCM Model

The West Caucasus is the only Russian region where disastrous floods cause a great number of victims regularly. Developing the automated monitoring networks in the Kuban River Basin and Krasnodar Krai has improved the quality of hydrological information over the last years; however, its use for flood forecasting has to be more effective. The paper presents methods of short-term flood forecasting for West Caucasian rivers with rain floods prevalence during the warm season. They are based on applying the Flood Cycle Model (FCM), which has been tested for the first time in the region (the case study of the Tuapse, Psekups, and Pshish rivers). The presented forecasting methods, whose quality completely conforms to the criteria of the Russian Hydrometeorological Service, can enhance the existing hydrological forecasting systems. To further develop the flood forecasting methods for the West Caucasian rivers using physically based models, it is critically important to increase the precipitation measuring network density within the mountain parts of watersheds.

Book Review: The Remarkable Hybrid Maritime World of Hong Kong and the West River Region in the Late Qing Period

Book Review: The Remarkable Hybrid Maritime World of Hong Kong and the West River Region in the Late Qing Period

VARIATION IN SEDIMENT CONCENTRATION AND WATER DISCHARGE DURING STORM EVENTS IN TWO CATCHMENTS, NORTHEAST OF ALGERIA

The relation between concentration and discharge is not normally homogenous during the storm event, often producing hysteretic loops. In this study relations between sediment concentration and water discharge for hydrologic events are studied by analyzing temporal graphs (discharge and concentration versus time) in terms of spread and skewness. The hysteresis types of the discharge and concentration of 170 storm events have been analyzed to identify the relations between hysteretic loops and the associated controlling factors in the Saf Saf and Kebir West basins. Surveys of suspended sediment concentration and water discharge are being carried out at gauging stations. The selected storm events are based on samples having many sediment concentrations at water discharges. Comparing C/Q ratios at a given discharge on the rising and falling limbs of hydrographs is providing a consistent, reliable method for analyzing C-Q relations. Four common classes of such relations are determined such as single-valued line, clockwise loop, counterclockwise loop and figure eight. The plot of points has exhibited a hysteresis loop which is explained by the variability of sediment concentrations during storm events and seasonal effects. The most frequent floods at Saf Saf and Kebir West rivers are clockwise and single-valued line (62% and 59% of floods respectively) that have brought 73% and 81% of the total sediment flux. Intra-annual variability is very high. Over 31-years, the three biggest floods at each Saf Saf and Kebir West rivers have cumulated 97% and 68% of the total sediment flux and are of two classes.

Spatial and temporal shifts in fluvial sedimentary organic matter composition from a High Arctic watershed impacted by localized slope disturbances

Arctic warming may induce slope failure in upland permafrost soils. These landslide-like events, referred to as active layer detachments (ALDs), redistribute soil material into hydrological networks during spring melt and heavy rainfall. In 2011, 2013 and 2014, fluvial sediments from the West River at the Cape Bounty Arctic Watershed Observatory were sampled where ALDs occurred in 2007–2008. Two ALD-impacted subcatchments were examined exhibiting either continuing disturbance or short-term stabilization. Solid-state 13C nuclear magnetic resonance (NMR) spectroscopy and targeted biomarker analysis via gas chromatography–mass spectrometry were used to investigate shifts in organic matter (OM) composition. Additionally, radiocarbon ages were determined using accelerator mass spectrometry. Biomarker concentrations and O-alkyl carbon assessed via NMR were both lower in sediments nearest the active disturbance and increased in sediments downstream where other aquatic inputs became more dominant. This suggests immobilization of recalcitrant OM near the ALD and the sustained transport of labile ALD-derived OM further downstream. Shifts toward older radiocarbon dates along the river between 2011 and 2014 suggest the continued transport of permafrost-derived OM downstream. The stabilizing subcatchment revealed high O-alkyl carbon via NMR and increased concentrations of unaltered terrestrial-derived biomarkers indicative of enhanced OM accumulation following ALD activity. The relatively young radiocarbon ages from these sediments suggest accumulation from contemporary sources and potential burial of the previously dispersed ALD inputs. Within the broader context of Arctic climate change, these results portray a complex environmental trajectory for thaw-released permafrost-derived OM and highlight uncertainty in the relationship between lability and persistence upon release by permafrost disturbance.

Recent changes in the sediment regime of the Pearl River (South China): Causes and implications for the Pearl River Delta

AbstractRiverine sediments have played an important role in the morphological evolution of river channels and river deltas. However, the sediment regime in the many world's rivers has been altered in the context of global changes. In this study, temporal changes in the sediment regime of the Pearl River were examined at different time scales, that is, annual, seasonal, and monthly time scales, using the Mann–Kendall test. The results revealed that precipitation variability was responsible for monthly and seasonal distribution patterns of the sediment regime and the long‐term changes in the water discharge; however, dam operation has smoothed the seasonal distribution of water discharge and resulted in decreasing trends in the annual, wet‐season, and dry‐season sediment load series since the 1950s. Due to the different regulation magnitudes of dam operation, differences were observed in sediment regime changes among the three tributaries. In addition, human activities have altered the hysteresis of seasonal rating curves and affected hysteresis differences between increasing and decreasing water discharge stages. Sediment supply is an important factor controlling river channel dynamics, affecting channel morphology. From the 1950s to the 1980s, siltation was dominant in river channels across the West River and North River deltas in response to the sediment increases; however, scouring occurred in the East River deltas due to sediment reduction. Significant erosion occurred in river channels in the 1990s, which was mostly due to downcutting of the river bed caused by sand excavations and partly because of the reduced sediment load from upstream. Although sand excavations have been banned and controlled by authority agencies since 2000, the erosion of cross sections was still observed in the 2000s because of reduced sediment caused by dam construction. Our study examines the different effects of human activities on the sediment regime and downstream channel morphology, which is of substantial scientific importance for river management.

'On Psilorhynchus sucatio and P. nudithoracicus', the sequel: Unnecessary and unscientific names lead to rapid synonymization and taxonomic time wasting-A response to Arunachalam et al. (2018).

The Torrent minnows Psilorhynchus sucatio (Hamilton, 1822) and P. nudithoracicus Tilak Husain, 1980 are widespread throughout the Ganges-Brahmaputra drainage of India, Bangladesh and Nepal (Conway et al., 2013). Like many widespread species, P. sucatio and P. nudithoracicus exhibit high levels of variation in morphological traits (particularly colour pattern) across their respective ranges and both have been described on more than one occasion by different authors examining material obtained from different parts of their range and/or unaware of earlier works. The distinctive, long-snouted torrent minnow Psilorhynchus sucatio was described by Hamilton (1822: 347) based on material from "Northern Bengal" (no types known). David (1953) introduced the name P. sucatio damodarai for a "variety" (=subspecies; ICZN, 1999; art. 45.6.4) of P. sucatio from the Damodar River (Jharkhand and West Bengal) and Tilak Husain (1980) described the subspecies P. sucatio nudithoracicus based on material from Uttar Pradesh. In 1983, Rainboth described Psilorhynchus gracilis based on a smaller, more slender series of Psilorhynchus with a shorter snout than P. sucatio, collected in the tributaries of the Ganges and Brahmaptura rivers in northern Bangladesh. In 2013, Conway et al. argued that the names P. s. nudithoracicus and P. gracilis referred to the same species, placed the latter in the synonymy of the former, and elevated P. nudithoracicus to species status. As part of their redescription of P. sucatio and P. nudithoracicus, Conway et al. (2013) examined large series of specimens representing a range of body sizes (462 specimens of P. sucatio [13-67 mm SL] and 97 of P. nudithoracicus = [10-68 mm SL]), and encompassing almost the entire range of both species, provided multiple figures illustrating the important anatomical features of both species and, most importantly, provided clear diagnoses.

More frequent flooding? Changes in flood frequency in the Pearl River basin, China, since 1951 and over the past 1000 years

Abstract. Flood risks across the Pearl River basin, China, were evaluated using a peak flood flow dataset covering a period of 1951–2014 from 78 stations and historical flood records of the past 1000 years. The generalized extreme value (GEV) model and the kernel estimation method were used to evaluate frequencies and risks of hazardous flood events. Results indicated that (1) no abrupt changes or significant trends could be detected in peak flood flow series at most of the stations, and only 16 out of 78 stations exhibited significant peak flood flow changes with change points around 1990. Peak flood flow in the West River basin increased and significant increasing trends were identified during 1981–2010; decreasing peak flood flow was found in coastal regions and significant trends were observed during 1951–2014 and 1966–2014. (2) The largest three flood events were found to cluster in both space and time. Generally, basin-scale flood hazards can be expected in the West and North River basins. (3) The occurrence rate of floods increased in the middle Pearl River basin but decreased in the lower Pearl River basin. However, hazardous flood events were observed in the middle and lower Pearl River basin, and this is particularly true for the past 100 years. However, precipitation extremes were subject to moderate variations and human activities, such as building of levees, channelization of river systems, and rapid urbanization; these were the factors behind the amplification of floods in the middle and lower Pearl River basin, posing serious challenges for developing measures of mitigation of flood hazards in the lower Pearl River basin, particularly the Pearl River Delta (PRD) region.

Assessment of Reproductive Performance and Flock Composition of Small-houlders Sheep and Goat Production Systems Under Assiut Governorate

This study was aimed to recognize the reproductive performance and herd composition of sheep and goat in six studied area located in east and west river Nile at Assiut governorate. A set of semi-structured questionnaire was used to collect information from 300 sheep owners based on single-visit-interviews. The study revealed that farmers keep mixed livestock species. Sheep and goat production are the major livestock activity in located study area. The average farm size of households surveyed in Assiut Governoratewas 8.2 feddan. The farmers cultivated 50.74% and 50.86 % of their lands for green fodder and field crops in winter and summer, respectively. About 50.89 % of the total farm size area cultivated with animal fodder around the year. In summer 25.37%. Of the area was cultivated with field crops. The reproductive and productive performance of sheep and goats were discussed and data showed that, no significant differences were observed in lambing interval and age at first lambing between sheep and goats, while goats were significantly higher in litter size (P<0.01), lambing mortality (p<0.05) weaning weight (p<0.01) and age at marketing (p<0.05) than sheep. Generally, Sheep and goat production in the studied areas was constrained by different problems; where the major ones are availability and cost of feeds, limitation of land for the expansion of production and poor extension services. Sheep and goats are very important smallholder producers due to their biological factors such as short generation interval, twinning, short growth periods, do not require much space and low food requirements. In this domain, reasons of high lamb mortality rates should be identified and reduced in order to make sheep and goat production profitable and sustainable.

The Meeting of the Waters

The Meeting of the Waters

Multi-timescale sediment responses across a human impacted river-estuary system

Hydrological processes regulating sediment transport from land to sea have been widely studied. However, anthropogenic factors controlling the river flow-sediment regime and subsequent response of the estuary are still poorly understood. Here we conducted a multi-timescale analysis on flow and sediment discharges during the period 1967–2014 for the two tributaries of the Jiulong River in Southeast China. The long-term flow-sediment relationship remained linear in the North River throughout the period, while the linearity showed a remarkable change after 1995 in the West River, largely due to construction of dams and reservoirs in the upland watershed. Over short timescales, rainstorm events caused the changes of suspended sediment concentration (SSC) in the rivers. Regression analysis using synchronous SSC data in a wet season (2009) revealed a delayed response (average 5 days) of the estuary to river input, and a box-model analysis established a quantitative relationship to further describe the response of the estuary to the river sediment input over multiple timescales. The short-term response is determined by both the vertical SSC-salinity changes and the sediment trapping rate in the estuary. However, over the long term, the reduction of riverine sediment yield increased marine sediments trapped into the estuary. The results of this study indicate that human activities (e.g., dams) have substantially altered sediment delivery patterns and river-estuary interactions at multiple timescales.

Thermal and isotopic evidence for surface and subsurface water contributions to baseflow in a high Arctic river

AbstractSeven longitudinal water temperature tow surveys were conducted to attempt to identify the location of surface and subsurface river water exchanges along the length of the West River at the Cape Bounty Arctic Watershed Observatory, Melville Island, Nunavut, Canada (74°55′ N, 109°35′ W). Water temperature data were collected using a calibrated thermistor with an accuracy of ±0.002 °C (resolution &lt;0.00005 °C) along the river during July 2014 in conjunction with stable water isotope sampling to support the thermal data and to determine the extent of surface water mixing from different sources such as precipitation, snowmelt, and surface/subsurface water contributions to the river. Atmospheric conditions were found to be the main contributor to seasonal temperature variance in the river, whereas tributary inflows and residual channel snow also had important thermal effects to river temperatures. Residual channel snow was a sustained source of cold water during much of the 2014 summer season (June–August) and substantially offset downstream warming. The longitudinal temperature profiles indicate notable changes to the thermal state of the river, which are interpreted to be indicative of subsurface and surface water exchange through inputs of relatively cold or warm water. Broadly, surface inflows were found to provide warmer water relative to the West River, and contributed to downstream warming of the river, along with downstream enrichment of δD and δ18O. Subsurface inflows provided cooler water relative to the river, and contributed to downstream depletion of δD and δ18O and downstream cooling of river temperatures. These results demonstrate that localized changes in river temperature, in conjunction with isotopic tracers, can be used to track channel–slope water interactions in Arctic hydrological systems, work previously limited to alpine and temperate settings.