Large-scale River Research Articles

Complex geographic- and habitat-based niche partitioning of an East Asian habitat generalist mayflyIsonychia japonica(Ephemeroptera:Isonychiidae) with reference to differences in genetic structure

AbstractWe focused on the genetic structure and evolutionary divergence of a typical habitat generalist mayfly, Isonychia japonica, inhabiting rivers widely distributed across eastern Asia. In the Japanese Archipelago, they are distributed across a wide range of environments, including up- and downstream areas in 1 river basin. We analyzed DNA sequences of this mayfly from both the mitochondrial (cytochrome oxidase c subunit I [COI] and 16S ribosomal RNA) and nuclear genomes (Histone H3 and ITS2) of specimens from populations across the eastern Asian region, with emphasis on the Japanese Archipelago. Isonychia japonica is genetically differentiated into 2 major clades (C = continental clade, J = Japanese Archipelago clade). Furthermore, clade J is composed of 2 subclades (clades J-U and J-D). Clade J is separated by environment, with specimens constituting clade J-U occurring in small-scale rivers of the upstream regions and specimens constituting clade J-D occurring in large-scale rivers of downstream re...

Numerical evaluation of flow regime changes induced by the Three Gorges Dam in the Middle Yangtze

The full operation of the Three Gorges Dam (TGD) has altered the downstream natural flow regime. Flow regime changes have resulted in profound influences on the utility of water resources and hence a large area with a riparian ecosystem including China's two largest freshwater lakes in the Middle Yangtze. Because of complicated flow regimes in this large-scale river–lake system, the TGD's impacts on flow regimes are highly heterogeneous and require to be carefully addressed. To better understand them, we estimated water level and discharge changes solely induced by the TGD from 2006 to 2011 using a hydrodynamic model that facilitates the separation of the TGD's contribution to flow regimes. Results indicated that water regulation of the TGD caused profound impacts on the flow regimes of the Middle Yangtze. In the impoundment period from mid-September to October, rapid and significant decline of the water discharge downstream the TGD produced a prolonged dry season that occurred around 10 days earlier than before. Our analysis elucidated a pattern of recent changes in the flow regimes caused by the TGD. The findings are useful for addressing the TGD-induced environmental issues, optimizing the TGD's operation, and generating adaptive management strategy for the complex river–lake ecosystem.

EXPERIMENTAL STUDY OF BAR FORMATION IN SAND BED CHANNEL

A large number of studies both theoretical and experimental have been devoted to understand the physical mechanisms underlying the bar formation. This can be investigated by carrying out an experimental work in an erodible sand bed channel using a large-scale physical river model. The study included the various hydraulic characteristics with steady flow rates and sediment supply. An experimental work consists of four matrices of flow rate and channel width with other variables namely grains size and bed slope were kept constant. Details of bar profile development that generated using Surfer, a software used for 3D elevation plots are included.

Late Pleistocene river migrations in response to thrust belt advance and sediment-flux steering — The Kura River (southern Caucasus)

One reaction of rivers toward allogenic triggers is the large-scale river channel migration in the form of avulsions or progressive lateral migrations (combing) that are widespread phenomena around the world during the late Quaternary. Because they potentially cause significant human and economic losses and significantly change geomorphic processes in the affected regions, a deeper knowledge about causes and rates is essential and furthermore helps to identify the dominant drivers of regional landscape evolution during different periods. One possible cause for river channel migrations is sediment-flux steering, i.e. the shift of rivers in sedimentary basins against a tectonically driven trend caused by transverse sediment discharge. During the last 30years, sediment-flux steering has been investigated by field and experimental studies in extensional half-grabens with generally small-sized transverse catchments and/or volcaniclastic sedimentation.This study presents geomorphologic, geochronologic, and heavy mineral analyses together with complementary tectonomorphometric and earthquake data to investigate late Quaternary channel migrations of the Kura River in the southern foreland basin of the Greater Caucasus, a region where the late Quaternary landscape evolution is rather fragmentarily understood so far. Special emphasis of this study is given to the interplay between axial river flow and transverse sediment supply leading to sediment-flux steering. Large-scale migrations of the course of the Kura River during the late Quaternary reflect the interplay between tectonic processes leading to the southwestward advance of the Kura Fold-and-Thrust-Belt and climatically-triggered sediment-flux steering caused by aggradation phases of transverse rivers with comparatively large catchment areas in the Lesser Caucasus. During generally warmer periods such as the Holocene with fluvial incision and low sediment supply from the transverse rivers, the main Kura River could follow its tectonically driven trend toward the southwest. In contrast, during generally colder periods such as the upper late Pleistocene, sediment-flux steering caused by aggradation of the transverse rivers forced the main Kura River to migrate >10km against that tectonically induced trend toward the northeast. Apart from giving information about the main drivers of the late Quaternary landscape evolution in this part of the southern Caucasus region, this study also helps to understand the cause of a permanent threat of settlements and the loss of fertile agricultural land in the intensively labored Marneuli Depression of southern Georgia.

Will Mississippi River diversions designed for coastal restoration cause harmful algal blooms?

Large-scale river diversions have been proposed as a way to transport sediment to the deteriorating Mississippi River deltaic plain. These diversions would also transport immense nutrient loads to shallow receiving estuaries, including open water areas where there may be potential for blooms of toxin-producing cyanobacteria. We examined environmental variables and cyanobacteria dynamics in the Lake Pontchartrain Estuary during the spring-summer period of two years: (a) 2011 when the system received a massive inflow of diverted Mississippi River water from the Bonnet Carré Spillway, and (b) 2012 when no diversion occurred. Cluster analysis of 180 samples collected over the course of both years identified five distinct water types grouped according to salinity, temperature, clarity, bioavailable nutrients, and chlorophyll a. Three of these water types were unique to the 2011 diversion event. We found no evidence of immediate, direct cyanobacteria bloom stimulation by diverted nutrients in the “high phytoplankton biomass” cluster associated with the 2011 diversion. Substantial nitrate assimilation by non-harmful phytoplankton occurred as the plume of diverted freshwater traveled through the system that year. The “summer” cluster characterized by nitrogen-limited conditions and including data from both years was characterized by significantly greater cyanobacteria abundance than all other clusters. There was no difference in cyanobacteria abundance between years within the summer cluster. Microcystin levels detected suggested low probability of acute health risks for recreational waters and were not correlated to cyanobacteria abundance. Site-specific understanding of the following is needed to guide diversion management: (i) interannual phytoplankton community variability in non-diversion years, (ii) cyanobacteria inputs from local tributaries, (iii) interactions between plume physics, chemistry, and phytoplankton dynamics, (iv) internal phosphorus feedbacks that may indirectly link diversions to summer blooms, and (v) controls on cyanotoxin production.

Developments in Earth observation for the assessment and monitoring of inland, transitional, coastal and shelf-sea waters

The Earth's surface waters are a fundamental resource and encompass a broad range of ecosystems that are core to global biogeochemical cycling and food and energy production. Despite this, the Earth's surface waters are impacted by multiple natural and anthropogenic pressures and drivers of environmental change. The complex interaction between physical, chemical and biological processes in surface waters poses significant challenges for in situ monitoring and assessment and often limits our ability to adequately capture the dynamics of aquatic systems and our understanding of their status, functioning and response to pressures. Here we explore the opportunities that Earth observation (EO) has to offer to basin-scale monitoring of water quality over the surface water continuum comprising inland, transition and coastal water bodies, with a particular focus on the Danube and Black Sea region. This review summarises the technological advances in EO and the opportunities that the next generation satellites offer for water quality monitoring. We provide an overview of algorithms for the retrieval of water quality parameters and demonstrate how such models have been used for the assessment and monitoring of inland, transitional, coastal and shelf–sea systems. Further, we argue that very few studies have investigated the connectivity between these systems especially in large river–sea systems such as the Danube–Black Sea. Subsequently, we describe current capability in operational processing of archive and near real-time satellite data. We conclude that while the operational use of satellites for the assessment and monitoring of surface waters is still developing for inland and coastal waters and more work is required on the development and validation of remote sensing algorithms for these optically complex waters, the potential that these data streams offer for developing an improved, potentially paradigm-shifting understanding of physical and biogeochemical processes across large scale river–sea systems including the Danube–Black Sea is considerable.

Improving river health: insights into initiating collaboration in a transboundary river basin

ABSTRACTRiver health is a concern worldwide. Governance of river basins is particularly complicated when they are large scale and cross jurisdictional boundaries. Past approaches to making decisions in transboundary basins are limited and attention is increasingly being focused on the potential of collaboration. This research investigates the initiation phase of a collaborative conservation project (WWF-Canada Freshwater Program, St. John River project) in the St. John River Basin of Canada. A social-ecological inventory technique and social network analysis are used to identify the actors in the transboundary basin and their activities, perceptions and connections to river health, relationship with other stakeholders, and actual engagement with a milestone event in the project. Insights gained from exploring the relationships between/among these variables highlight the complicated nature of initiating collaboration. A common understanding of river health and a strong structure of connected actors were encouraging signs that collaboration may flourish, while the assertion of power and context surrounding the initiative were found to mediate its possibility. The collaborative potential of conservation projects in large-scale transboundary river basins may be enhanced through such research and by actively applying these insights.

River restoration by dam removal: Enhancing connectivity at watershed scales

Abstract The prolonged history of industrialization, flood control, and hydropower production has led to the construction of 80,000 dams across the U.S. generating significant hydrologic, ecological, and social adjustments. With the increased ecological attention on re-establishing riverine connectivity, dam removal is becoming an important part of large-scale river restoration nationally, especially in New England, due to its early European settlement and history of waterpower-based industry. To capture the broader dimensions of dam removal, we constructed a GIS database of all inventoried dams in New England irrespective of size and reservoir volume to document the magnitude of fragmentation. We compared the characteristics of these existing dams to the attributes of all removed dams over the last ∼25 years. Our results reveal that the National Inventory of Dams significantly underestimates the actual number of dams (4,000 compared to >14,000). To combat the effects of these ecological barriers, dam removal in New England has been robust with 127 dams having been removed between ca. 1990–2013. These removed dams range in size, with the largest number (30%) ranging between 2–4 m high, but 22% of the removed dams were between 4–6 m. They are not isolated to small drainage basins: most drained watersheds between 100–1,000 km2. Regionally, dam removal has re-connected ∼3% (3,770 river km) of the regional river network although primarily through a few select dams where abundant barrier-free river lengths occur, suggesting that a more strategic removal approach has the opportunity to enhance the magnitude and rate of river re-connection. Given the regional-scale restoration of forest cover and water quality over the past century, dam removal offers a significant opportunity to capitalize on these efforts, providing watershed scale restoration and enhancing watershed resilience in the face of significant regional and global anthropogenic changes.

Model Predictive Control of a Large-scale River Network

This study investigates the use of Model Predictive Control (MPC) for regulation of river flows. During the past decade, MPC has emerged for controlling open water systems, such as irrigation and drainage channels. Compared to a full river network, irrigation and drainage systems are of relatively small scale. The aim of the present work is to investigate MPC as a tool for control of releases from gates and dams in a large-scale river network using the Murrumbidgee River in New South Wales, Australia, as case study. The Murrumbidgee River has around 1300 kilometers of river reaches, and the travel time through the valley is of the order of one month. The research has focused on four points: 1) Configuring linear surrogate models to describe the characteristics of reaches and weir pools; 2) Formulating the control problem and its objectives; 3) Using MPC with a receding horizon to solve the control problem; and 4) Testing the accuracy of the calculated control action, by using it as forcing in a detailed hydraulic model. The tests show that a reliable computation of optimal releases from regulators throughout the river is obtained, despite the linear approximation of the dynamics. The tests also show that the computation time for setting up and solving the optimization problem is no more than a few minutes on today's laptops.

The response of hydrophyte growth forms and plant strategies to river restoration

Evaluating ecological responses to restoration is important for assessing the success of river restorations. We evaluated the response of species richness and diversity of aquatic macrophyte (hydrophyte, instream aquatic plant) growth forms and strategies (Grime’s CSR strategies; C competitive, S stress tolerant, R ruderal) in 10 small- and 10 large-scale river restoration projects in nine European countries. Restoration had no effect on total richness and diversity but significant effects if specific growth forms and plant strategies were considered. Results indicated that restoration caused an increase in the richness and diversity of submerged and a decrease in the proportion of competitive species. Responses were especially pronounced in relatively small widening projects in gravel-bed mountain rivers but not in relatively large restoration projects in sand-bed lowland rivers. Moreover, flow restoration increased the richness and diversity of floating-leaved species. In rivers with a high proportion of wetlands and waterbodies in the catchment, restoration increased the abundance of competitive plants. These results highlight that river and catchment properties need to be considered when evaluating river restoration projects. We suggest hydrophyte growth forms and plant strategies as suitable response variables to assess the effect of river restoration projects.

Nano-mineralogy of suspended sediment during the beginning of coal rejects spill.

Ultrafine and nanometric sediment inputs into river systems can be a major source of nutrients and hazardous elements and have a strong impact on water quality and ecosystem functions of rivers and lakes regions. However, little is known to date about the spatial distribution of sediment sources in most large scale river basins in South America. The objective of this work was to study the coal cleaning rejects (CCRs) spill that occurred from a CCRs impoundment pond into the Tubarão River, South Brazil, provided a unique occasion to study the importance and role of incidental nanoparticles associated with pollutant dispersal from a large-scale, acute aquatic pollution event. Multifaceted geochemical research by X-ray diffraction (XRD), High Resolution-Transmission Electron microscopy (HR-TEM)/(Energy Dispersive Spectroscopy) EDS/(selected-area diffraction pattern) SAED, Field Emission-Scanning Electron Microscopy (FE-SEM)/EDS, and Raman spectroscopy, provided an in-depth understanding of importance of a nano-mineralogy approach of Aqueous Pollution Scenarios. The electron beam studies showed the presence of a number of potentially hazardous elements (PHEs) in nanoparticles (amorphous and minerals). Some of the neoformed ultrafine/nanoparticles found in the contaminated sediments are the same as those commonly associated with oxidation/transformation of oxides, silicates, sulfides, and sulfates. These data of the secondary ultra/nanoparticles, puts in evidence their ability to control the mobility of PHEs, suggesting possible presentations in environmental technology, including recuperation of sensitive coal mine. The developed methodology facilitated the sediment transport of the catchment providing consistent results and suggesting its usefulness as a tool for temporary rivers management.

Heterolithic meandering-channel deposits from the Neoproterozoic of NW Scotland: Implications for palaeogeographic reconstructions of Precambrian sedimentary environments

Pre-Silurian fine-grained meandering river deposits are apparently rare in the rock record. Most modern-day river dynamics are influenced by vegetation through bank stabilization, fine-grained sediment production and retention, and runoff control, leading to the development of highly sinuous, single-channel systems. In contrast, pre-vegetation river dynamics are poorly understood, in part because there are no modern-day analogues for completely non-vegetated meandering river systems, particularly under humid climates. Some models attribute the paucity of fine-grained sediments described from studies of pre-vegetation fluvial deposits to lower rates of chemical weathering in the absence of land plants. The architecture of precambrian, fine-grained meandering stream deposits is here described for the first time.The Allt na Béiste Member at the base of the Applecross Formation of the Torridon Group (Neoproterozoic, NW Scotland) is characterized by heterolithic deposits, preserving a varied suite of fluvial forms including inclined heterolithic strata, lateral-accretion sets, up to 8m-thick muddy floodplain deposits with preserved crevasse-splays. Successions of laterally-accreting strata are interbedded with metre-scale channel-fill sandstones, in a succession up to 190m-thick related to the early stages of the Applecross Formation fluvial system, as large-scale rivers buried the Lewisian palaeovalleys over which fluvial and lacustrine sediments of the Diabaig Formation had been deposited. The lacustrine fine-grained sediments, coupled with relatively low gradients of the shallow lacustrine environments and denuded, highly weathered Lewisian basement, apparently provided considerable amounts of fine-grained sediment which added sufficient cohesion to this fluvial system to induce the adoption of laterally-migrating, meandering channel planforms at the expense of multi-thread braided channels.Our data suggest that, given appropriate conditions, pre-vegetation meandering channel planforms were indeed able to develop, without the buffering effects of land plants. The paucity of fine-grained sediments in the pre-vegetation rock record may be more a consequence of preservation-related issues than the actual paucity of such sediments. These results provide novel insights into the characteristics of Earth's landscape prior to the Silurian, and provide potential analogues for meandering channels interpreted from satellite imagery of Mars.

A novel approach for designing large-scale river temperature monitoring networks

Water temperature is an important control on processes in aquatic systems and particularly for freshwater fish, affecting growth, survival and demographic characteristics. In recognition of this importance, the Scottish Government has prioritised developing a robust national river temperature monitoring network. Advances in geographical information systems, spatial statistics and field data loggers make large-scale river temperature monitoring increasingly possible. However, duplication of environmental and thermal characteristics among monitoring sites means many networks have lower than expected statistical power. This paper describes a novel methodology for network design, illustrated by the development of the Scotland River Temperature Monitoring Network. A literature review identified processes controlling stream temperature and associated landscape controls. Metrics indicative of these landscape controls were calculated for points every 500 m along the river network. From these points, sites were chosen to cover the full range of observed environmental gradients and combinations of controlling variables. The resulting network contains sites with unique characteristics covering the range of relevant environmental characteristics observed in Scottish salmon rivers. The network will thus have minimal redundancy, often not seen in large networks, and high statistical power to separate the relative importance of predictor variables thereby allowing large-scale water temperature predictions.

Analysis of the Effect of Dredging and Weirs on Bed Change in the Nakdong River and its Tributary using HEC-6

It is necessary to evaluate the effect of dredging and weir operation on the flow and long-term bed change for river management. Especially, large scale river treatment project, with dredging or weir installation and operation, can increase the instability of riverbed in tributaries as well as mainstream. This study focuses on the effect of weir installation and dredging on the long-term bed change in Nakdong river (Gangjeong- Goryeong Weir~Dalseong Weir) and its tributary (Geumho river). HEC-6 model has been used to analyze the amount of long-term bed change and sediment transport resulted from the river treatment including dredging or weir installation. From the result, it was concluded that a large scale river treatment can accelerate and increase the long-term bed change both in mainstream and tributary.

WHU-Grace01s: A new temporal gravity field model recovered from GRACE KBRR data alone

A new temporal gravity field model called WHU-Grace01s solely recovered from Gravity Recovery and Climate Experiment (GRACE) K-Band Range Rate (KBRR) data based on dynamic integral approach is presented in this paper. After meticulously preprocessing of the GRACE KBRR data, the root mean square of its post residuals is about 0.2 micrometers per second, and seventy-two monthly temporal solutions truncated to degree and order 60 are computed for the period from January 2003 to December 2008. After applying the combination filter in WHU-Grace01s, the global temporal signals show obvious periodical change rules in the large-scale river basins. In terms of the degree variance, our solution is smaller at high degrees, and shows a good consistency at the rest of degrees with the Release 05 models from Center for Space Research (CSR), GeoForschungsZentrum Potsdam (GFZ) and Jet Propulsion Laboratory (JPL). Compared with other published models in terms of equivalent water height distribution, our solution is consistent with those published by CSR, GFZ, JPL, Delft institute of Earth Observation and Space system (DEOS), Tongji University (Tongji), Institute of Theoretical Geodesy (ITG), Astronomical Institute in University of Bern (AIUB) and Groupe de Recherche de Geodesie Spatiale (GRGS), which indicates that the accuracy of WHU-Grace01s has a good consistency with the previously published GRACE solutions.

The long-term response of rivers to engineering works and climate change

Rivers respond to changes in their geometry or their controls in various ways and at a wide range of space and time scales. The response consists of changes in properties such as cross-sectional shape and area, slope, planform pattern, bed roughness and bed sediment composition. Usually, attention for the morphological impact of engineering works focuses on short-term effects. The usually much slower, but also much more persistent large-scale response is often ignored, or countermeasures are ineffective. In many cases this has led to extra maintenance costs, in some even to hazardous situations or disaster. This paper refreshes and extends long-existing but seemingly forgotten knowledge on large-scale river behaviour. It gives examples of impacts of engineering works, climate change and sea level rise, discusses potential countermeasures and gives a number of general conclusions on the large-scale morphological behaviour of lowland rivers.

Verification of inflow into hydropower reservoirs using ensemble forecasts of the TIGGE database for large scale basins in Brazil

Abstract Study region This paper describes a major ensemble-forecasts verification effort for inflows of three large-scale river basins of Brazil: Upper Sao Francisco, Doce, and Tocantins Rivers. Study focus In experimental scenarios, inflow forecasts were generated forcing one hydrological model with quantitative precipitation forecasts (QPF) from three selected models of the TIGGE database. This study provides information on the regional ensemble performance and also evaluates how different QPF models respond for the different basins and what happens with the use of combined QPF in a greater ensemble. New hydrological insights for the region This work presents one of the first extensive efforts to evaluate ensemble forecasts for large-scale basins in South America using TIGGE archive data. Results from these scenarios provide validation criteria and confirm that ensemble forecasts depend on the particular EPS used to run the hydrological model and on the basin studied. Furthermore, the use of the Super Ensemble seems to be a good strategy in terms of performance and robustness. The importance of the TIGGE database is also highlighted.

Streamflow predictions in regulated river systems: hydrological non-stationarity versus anthropogenic water use

Abstract. Streamflow in a regulated river system is highly influenced by storage regulations and anthropogenic water use in addition to climate variability. Thus, changes in climate-streamflow relationships and dominant hydrological processes over time are difficult to quantify in a regulated system without partitioning influence of storage regulation and anthropogenic water uses. This requires a robust regulated river system model, which takes into consideration of both hydrological and man-made flow regulation processes, as well as anthropogenic water uses. In this study, a newly developed large-scale river system model (called "AWRA-R") was used to assess the influence of both anthropogenic and climate variability/change on streamflow non-stationarity in the Murray Darling Basin (MDB). MDB is one of the highly regulated basins in Australia with multiple large and small storages developed primarily for supplying water to irrigated agriculture. The modelling was undertaken for the period of 1950–2010, which includes rapid water resources development and both wet and dry climate. The AWRA-R model was calibrated for a reasonably long period and then, validated on an independent period. The calibrated parameters were used to simulate streamflow under current and pre-development conditions to analyse the streamflow variability and influence of climate variability and anthropogenic development on streamflow trend. This paper briefly introduces the model and the method used for assessing streamflow variability under natural and developed conditions and presents the results and findings.

Accretion and Vegetation Community Change in the Wax Lake Delta Following the Historic 2011 Mississippi River Flood

Carle, M.V.; Sasser, C.E., and Roberts, H.H., 2015. Accretion and vegetation community change in the Wax Lake Delta following the historic 2011 Mississippi River flood.During the 2011 Mississippi River flood, discharge to the lower river exceeded that of the 1927 and 1937 floods and the lower river remained above flood stage for nearly 2 months. A combination of WorldView-2 and Land Satellite 5 Thematic Mapper (Landsat 5 TM) imagery was used to assess the impact of this flood event on the Wax Lake Delta, one of few areas where the river is building new land. Vegetation community change was mapped from 2010 to 2011 and related to elevation change using plant species elevation distributions calculated from light detection and ranging (LIDAR) data. Changes in the land area in the delta were also assessed by regressing land area against water level for a series of pre- and postflood Landsat 5 TM images. The results indicate a net growth of 6.5 km2 at mean water level and 4.90 km2 at mean sea level. Areal gains were greatest at high water levels, indicating substantial vertical accretion across the subaerial delta. At least 8.7 km2, or 31.8%, of the area studied converted to a higher-elevation species. The most change occurred at low elevations with conversion from fully submerged aquatic vegetation to Potamogeton nodosus and Nelumbo lutea. Conversion to lower-elevation species occurred across 3.4 km2, or 12.8% of the study area, while 55.5% remained unchanged. The results highlight the importance of infrequent, large flood events in the maintenance of river deltas and provide a reference for estimating the impact of proposed large-scale river diversions on the Mississippi River Delta.

Source identification of fine-grained suspended sediment in the Kharaa River basin, northern Mongolia

Fine sediment inputs into river systems can be a major source of nutrients and heavy metals and have a strong impact on water quality and ecosystem functions of rivers and lakes, including those in semiarid regions. However, little is known to date about the spatial distribution of sediment sources in most large scale river basins in Central Asia. Accordingly, a sediment source fingerprinting technique was used to assess the spatial sources of fine-grained (<10μm) sediment in the 15 000km2 Kharaa River basin in northern Mongolia. Variation in geochemical composition (e.g. in Ti, Sn, Mo, Mn, As, Sr, B, U, Ca and Sb) was used for sediment source discrimination with geochemical composite fingerprints based on Genetic Algorithm (GA)-driven Discriminant Function Analysis, the Kruskal–Wallis H-test and Principal Component Analysis. All composite fingerprints yielded a satisfactory GOF (>0.97) and were subsequently used for numerical mass balance modelling with uncertainty analysis. The contributions of the individual sub-catchment spatial sediment sources varied from 6.4% (the headwater sub-catchment of Sugnugur Gol) to 36.2% (the Kharaa II sub-catchment in the middle reaches of the study basin), generally showing higher contributions from the sub-catchments in the middle, rather than the upstream, portions of the study area. The importance of river bank erosion is shown to increase from upstream to midstream tributaries. The source tracing procedure provides results in reasonable accordance with previous findings in the study region and demonstrates the applicability and associated uncertainties of the approach for fine-grained sediment source investigation in large scale semi-arid catchments.