Search

Wetlands cover a small portion of the world, but have disproportionate influence on global carbon (C) sequestration, carbon dioxide and methane emissions, and aquatic C fluxes. However, the underlying biogeochemical processes that affect wetland C pools and fluxes are complex and dynamic, making measurements of wetland C challenging. Over decades of research, many observational, experimental, and analytical approaches have been developed to understand and quantify pools and fluxes of wetland C. Sampling approaches range in their representation of wetland C from short to long timeframes and local to landscape spatial scales. This review summarizes common and cutting-edge methodological approaches for quantifying wetland C pools and fluxes. We first define each of the major C pools and fluxes and provide rationale for their importance to wetland C dynamics. For each approach, we clarify what component of wetland C is measured and its spatial and temporal representativeness and constraints. We describe practical considerations for each approach, such as where and when an approach is typically used, who can conduct the measurements (expertise, training requirements), and how approaches are conducted, including considerations on equipment complexity and costs. Finally, we review key covariates and ancillary measurements that enhance the interpretation of findings and facilitate model development. The protocols that we describe to measure soil, water, vegetation, and gases are also relevant for related disciplines such as ecology. Improved quality and consistency of data collection and reporting across studies will help reduce global uncertainties and develop management strategies to use wetlands as nature-based climate solutions., Funding Agencies|U.S. Geological Survey

This study was conducted to identify temporal changes in nutrient and sediment concentrations and loads (total phosphorus, particulate phosphorus, total dissolved phosphorus, total nitrogen, and total suspended solids) in Swan River and Woody River of the Swan Lake watershed, Manitoba. Temporal changes in physical hydrology (river discharge and precipitation) were also investigated to determine if these parameters influenced the changes in water quality concentrations and loads across the Swan Lake watershed. Annual and seasonal totals of water quality variables, river discharge, and average watershed total precipitation were examined for change over 30 years. The results showed a statistically significant increase in nutrients and total suspended solids (TSS), and river discharge, particularly in Swan River. Both rivers experienced statistically significant increases during the spring season with changes in median values as high as 450% in TSS between 1989 – 2000 and 2010 – 2018. Annual river discharge in Swan River and Woody River increased by 182% and 103%, respectively, with Swan River experiencing a statistically significant increase over the 30-year period. Seasonally, both rivers increased statistically significantly in the spring season with an 80% increase. Total precipitation across the watershed increased 3% annually, including a 6% increase in the spring, and summer and fall seasons, and 8% decrease in the winter season between 1995 – 2001 and 2009 – 2015. There were correlations between water quality variables and river discharge, and between river discharge and precipitation. Precipitation in this area influences river discharge and since nutrients and sediments are strongly correlated with river discharge, precipitation indirectly influences nutrient and sediment exports.

Water-eroded channels are focal points for water, wind, and tillage erosion processes as they can function as pathways for sediment transport, sources or traps of sediments and topography features that alter the nature of soil redistribution by tillage. The linkages and interactions of different erosion processes around the channel area are complex and dynamic, not only during the period when the channel is created but also after it is created. The effects of channels on subsequent water and tillage erosion and their contribution to total soil erosion have not been examined. To fill this knowledge gap, we carried out three studies, focusing on the role of channels in water and tillage erosion processes and the assessment of total soil erosion. In the first study, we examined the effects of a channel on tillage translocation. For downslope tillage, channels reduced total translocation, whereas, for upslope tillage, channels increased total translocation. For contour tillage, channels increased total translocation as well. The patterns of tillage translocation can be well explained by the balance of the trapping effect versus the energy-intensity-increase effect. Soil movement decreases when the trapping effect dominates and increases when other effect dominates. Additionally, a plot experiment examined the effects of an existing channel and tillage on water erosion. With an existing channel, runoff discharge and sediment export increased, whereas, with tillage, runoff discharge and sediment export decreased. When an existing channel was tilled, the effects of tillage dominated, while the existing channel only demonstrated some minor impacts. In the third study, a modeling procedure was developed to integrate the Raster-RUSLE2, Ephemeral Gully Erosion Estimator and Modified Directional Tillage Erosion Model for simulating water and tillage erosion. This integrated approach incorporated insights gained from previous studies on interaction effects. The individual models

Maintaining the future sustainability of agriculture and ensuring soil security is of primary concern across Canada. Understanding the state of soil erosion and determining the vulnerable areas are essential measures in combatting future soil erosion and avoiding soil degradation. Therefore, the general goal of this thesis was to quantify soil erosion rates and develop an improved understanding of erosion processes within the Canadian Prairies. To fulfill the aim of the research project, typical agricultural and native prairie landscapes of the region were studied within three watersheds including the Red River Valley and the Broughton’s Creek watershed in Manitoba, and the Bigstone Creek watershed in Alberta. Initially, passive uni-directional wind erosion sediment samplers were employed to assess wind-eroded soil movement in agricultural lands of the Red River Valley. Cesium-137 (137Cs) measurements were conducted to quantify total soil loss and deposition rates within the wetland landscapes in the Broughton’s Creek and Bigstone Creek watersheds. In addition, soil and sediment properties were characterized to understand tillage-, water- and wind-induced sediment transport dynamics and distinguish between eroded and depositional zones. Landform classification maps of the studied wetland catchments were also created to assist developing sediment budgets of soil loss and accumulation, and quantify sediment flux rates from agricultural fields to wetland environments. Furthermore, soil erosion models were used to characterize spatial patterns of soil loss by tillage, water, and wind erosion and assess relative contribution of these processes towards total soil erosion. This study found that: i) Measured soil loss and sedimentation caused by wind erosion are very small in the Red River Valley. Moreover, abrasion of crops by wind-transported sediment was not observed in this study; ii) Using the measurements of 137Cs, average annual soil losses in cultivated fields were

Soil erosion accelerated by agriculture reduces agricultural productivity and compromises the function of drainage infrastructure and downstream water quality. In Manitoba, the relationship between soil erosion and water quality is of particular concern, following measurable declines in Lake Winnipeg’s water quality since the 1990s. Understanding the state of soil erosion, transportation, and deposition in the Red River Valley is of interest, due to the extensive cultivation of the river’s watershed and its contribution to total flow (and by extension, sediment flux) into the lake. Sediment budgets were drafted for two sub-watersheds of the well-studied Boyne-Morris and La Salle River watersheds, located in the Red River Valley, and coded 05OF024 and 05OG008 by the Water Survey of Canada (WSC), respectively. To characterize soil erosion, the sediment budgets used published National Agri-Environmental Health Analysis and Reporting Program (NAHARP) soil erosion risk estimates calculated with the SoilERI model. Sediment transportation was quantified using flow and total suspended solids (TSS) measurements made by the WSC and other organizations. Deposition within the sub-watersheds was quantified through measurements made in road-side ditches (a common sediment sink in the Red River watershed) and inferred through imbalances in the sediment budgets. Rates of soil erosion, deposition within, and transportation out of the 05OF024 sub-watershed were an order of magnitude greater than in the 05OG008 sub-watershed due to differences in basin scale, but relative differences in their rates in each basin were the same. Rates of erosion were 1 order of magnitude greater than rates of deposition in road-side ditches and 3 orders of magnitude greater than transportation past the sub-watershed outlets. Differences between rates of soil erosion and deposition in road-side ditches were noted and attributed to unmeasured deposition in cultivated fields. Rates of deposition in such se

The goal of this thesis is to develop an improved understanding of sedimentary processes along the Nelson River system in the subarctic region of Canada. Sediment sources and transport dynamics in Lake Winnipeg, the Upper Nelson River (UNR) – between Lake Winnipeg and Split Lake – as well as the Burntwood River (BR) – the major tributary of the Nelson River in the subarctic region – were investigated. The properties of Lake Winnipeg’s bottom sediment and the lake’s total sediment budget were used to provide a better understanding of: a) the sedimentation dynamics in Lake Winnipeg; and b) its role in sediment transport in the Nelson River system. The sediment source fingerprinting technique and long-term record of sediment load data on the BR and the UNR were used for separating the importance of climate change from human-induced environmental changes on these two regulated rivers. Moreover, the influence of Split Lake on the downstream delivery of sediment to the Lower Nelson River and Hudson Bay was investigated by developing the sediment budget for this riverine lake. In addition, the collection of a representative sample of ambient suspended sediment using a well-established time-integrated sampler and two adapted discrete samplers was investigated. The performance of these samplers was examined in a controlled laboratory and under field conditions. Assessing these samplers was conducted to determine the most suitable device to collect representative bulk samples from the Nelson River system. The results show that the sediment load derived from the prairies area is sequestered in Lake Winnipeg, along with nutrients and contaminants bound to them. Another key finding was that sediment derived from bluff erosion on the northern shore of the lake is the major source for sediment being exported in the lake’s outflow. This thesis also found that the UNR is characterized by increases in sediment loading as a result of climate change. However, in the BR, cross-watershed

Hudson Bay is a large Arctic/sub-Arctic shelf sea that covers an area of approximately 841,000 km2, and is estuarine in character, with a large watershed and more than 40 rivers discharging into the bay. Sediment core data for 18 new cores in Hudson Bay was used to understand the processes effecting sedimentation in the bay. This data was interpreted together with sedimentation rates and inventories of 210Pb and 137Cs from previously published articles, archived cores, and geophysical data from the past four decades. Geophysical data shows that the bulk of sedimentation occurs offshore, between 100 and 150 m depth, on the east and northwest coasts of the bay, localized depressions along the southern coast between 50 and 100 m depth, and basins in the center of the bay. Inventories of 210Pb and 137Cs are variable but overall show a trend of lower inventories in the northwest to higher inventories in the southeast. Both geophysical and geochemical data show that sedimentation in the bay is largely transient with sediment deposits at the base of slopes, in localized depressions, and near the mouths of rivers.

Determining contributing areas, streamflow sources, flow pathways, and nutrient dynamics in typical agricultural Prairie watersheds in the presence of numerous anthropogenic disturbances is not straightforward. The three main objectives of this study were: (1) delineating contributing areas and the influence of temporal and spatial control factors, (2) identifying hydrological processes using direct and indirect methods, (3) assessing spatiotemporal patterns of water quality through the surface drainage network using hydrochemical connectivity principles. This study was conducted in the 589 km2 Elm Creek watershed (ECW) in Manitoba, Canada. Sixteen soil moisture maps and ten soil moisture thresholds were selected to produce indicator maps showing active and inactive areas. Contributing areas were then delineated as active areas physically connected to the watershed outlet, as opposed to isolated active areas. Also, streamflow sources and flow pathways were assessed for six successive rainfall events using hyetograph-hydrograph, isotopic hydrograph separation (IHS), concentration-discharge hysteresis, and spatiotemporal hydrometric analyses. Electrical conductivity (EC) and soluble reactive phosphorus (SRP) concentrations were measured for surface water samples collected from ten targeted drain channel locations on 15 occasions throughout spring and summer 2014. The spatiotemporal variability of EC and SRP was examined through the drainage channels. Additionally, hydrochemical connectivity was assessed among nine upstream-downstream pairs through the drainage network. Results show that climate, topography, and soil characteristics influence contributing areas for an effective range of soil moisture thresholds between 0.25 to 0.35 m3/m3. Different types of overland flow (infiltration-excess and saturation-excess overland flow) were observed in the ECW for six rainfall events. Isotope-based hydrograph separation results hinted at new water contributions, whereas hydrom

In recent decades, the Arctic marine environment has undergone a rapid change as represented by the dramatic reduction in sea ice extent and volume. Despite the recent decline in the Arctic multiyear ice cover, the Arctic and sub-Arctic regions continue to remain seasonally ice-covered. The annual cycle of growth and decay of the seasonal sea ice cover has far-reaching impacts on oceanographic conditions in the Arctic estuarine environments. Due to complicated and costly logistics associated with time-series observations in ice-infested waters, oceanographic moorings proved to be the most reliable and often the only possible method for studying temporal phenomena occurring over the annual cycle in Arctic marine environments. The broadscale goal for this study was to investigate how geophysical oceanographic processes characteristic of the Arctic and sub-Arctic estuarine environments (i.e. presence of seasonal snow and sea ice cover, estuarine and tidal water dynamics, atmospheric forcing and unique under-ice light regime) affect biological processes like zooplankton distribution and DVM throughout long-term mooring deployment. In this Ph.D. thesis, I present field observations relying on mooring observations conducted at three ice-covered locations, each presented in an individual chapter: (1) Young Sound (2014- 2014), which is a fjord in Southeast Greenland, (2) Belcher Islands (2013-2016) in the subarctic Southeastern Hudson Bay, and (3) Western Hudson Bay north of Churchill (2016-2017). From the acquired mooring records, we observed the influence of solar and lunar light and water dynamics on the vertical migration of zooplankton. At locations 1 and 3, we observed modifications or the complete disruption of DVM during highly energetic current and spring tide events. The mooring deployed at location 2 recorded oscillations of temperature and salinity throughout the whole water column, which we attributed to vertical displacement water parcels caused by internal ti

Numerous studies have ascertained detailed descriptions of hydrological processes for individual hillslopes and catchments. These studies have contributed to process understanding and have revealed considerable spatial and process heterogeneity. In hydrology, there is a scarcity of unifying theories to connect findings from individual studies. Thresholds in runoff response have been identified as a potential foundation for a unified theory, as thresholds are emergent properties that integrate spatial and process heterogeneity. However, our understanding of threshold behaviour has limitations. Most threshold research in hydrology focuses on storage thresholds for humid temperate environments and little is known about other types of thresholds or the ubiquity of thresholds for other environments. Additionally, the benefits of evaluating rainfall-runoff models using threshold information have not been determined. Our understanding of threshold behaviour has also been guided by conceptualizations featuring response as a function of a single meteorological factor, which is at odds with research showing a range of controls on hydrologic response. The goal of this thesis was to address these knowledge gaps and to contribute to a unified threshold-based hydrological theory. First, the spatial and temporal variability in rainfall-runoff event dynamics and the influence of fixed and dynamic controls on hydrologic response for 21 sites were assessed. Second, site-specific rainfall-runoff relationships were evaluated for thresholds. Threshold behaviour was observed at 20 out of 21 sites and in addition to rainfall depth, rainfall intensity and evapotranspiration proved to be important controls. Third, the benefits of constraining rainfall-runoff model outputs using threshold information were appraised. This work showed that threshold information can be powerful for identifying model simulations that adequately predict real-world processes. Lastly, the influence of multiple, pot

The Ininiw of Manitou (God's) Sakahigan (Lake), now known as God's Lake First Nation (GLFN), are an Indigenous people of Turtle Island, now called North America. As a GLFN Ininiw, I tell my autoethnography, drawing on a half-century of experience, both personal and professional, as well as a literature review, government data, and fieldwork. The medicine wheel framework required that I consider the spiritual, physical, emotional, and mental aspects of GLFN's water governance. I applied another Medicine wheel teaching regarding the Indigenous learning process to analyze this data, which provided an analytical framework to systematically process the data through heart, mind, body, and spirit. This thesis provides abundant evidence that the Ininiw of GLFN did not "cede or surrender" water governance in their traditional territory. Living in a lake environment, the GLFN Ininiw have survived, lived, thrived, and governed the aski (land and water) granted by Manitou (Creator) for thousands of years according to natural law. Through Ininiw governance, we kept God's Lake pristine. As GLFN Ininiw people's Aboriginal and treaty rights to govern over the waters of our ancestral lands were never surrendered, the GLFN Ininiw hold this governance still. I argue that natural law requires Canada and Manitoba to cede governance over aski to the GLFN Ininiw for their traditional territory. To sustain all Creation, the Ininiw assert our sovereignty over water in our traditional territory as was granted by Manitou (Creator). This sacred pact with Manitou requires a shift in water governance to fall under First Nation self-government. This perspective requires water to be considered sacred and a health issue, rather than a technical or infrastructure issue. This reconstitution of water under the health jurisdiction will ensure safe drinking water and restore women's central role in its governance.

Half of households on First Nations reserves in the Province of Manitoba do not have access to piped water, but rather rely on cisterns or wells, or have no running water (e.g., buckets). The purpose of this research was to assess whether First Nations perceptions of water is dependent on the type of water distribution system associated with the household. From July 2017 to October 2018, household surveys were developed in collaboration with each of three First Nations in Manitoba (Community A, B and C) and participants were recruited by going door-to-door in each community. Using a total of 273 responses, the study applied a factor analysis and found that four factors explained the majority of the underlying variance among survey answers: Safety, Sufficiency, Acceptability and Human Health. Households with cisterns reported significantly more safety and sufficiency concerns compared to households with piped water. Deductive and inductive analysis of open-ended survey reponses identified how households were describing their concerns. Households with safety concerns described finding contaminants in their water (e.g., dirt) and some households expressed concerns surrounding insufficient community resources to fix the water safety problems (e.g., additional water cleaning equipment and staff are needed). Households lacking sufficient water described not being able to keep up with their basic family needs (e.g., cleaning, laundry and bathing). Descriptions of negative health concerns caused by the household’s water largely included descriptions of gastrointestional illness symptoms or skin irritations. Importantly, the research also examined whether survey participants had full access to water, as defined by the United Nation’s General Assembly Resolution 64/292, The Human Right to Drinking Water and Sanitation, A/RES/64/292 (28 July 2010). The analysis indicated that 60.8% of households were not able to access water as described in this Human Right Resolution especial

Very few studies have attempted to identify priority criteria for wetland conservation and restoration in the Prairie Pothole Region (PPR), based on specific hydrology- and biogeochemistry-related watershed benefits. To guide the development of such criteria, the objectives of this Ph.D. thesis were to: 1) infer wetland-stream interaction dynamics; 2) study the influence of spatial characteristics on wetland hydrologic function; 3) investigate wetland hydrologic response to individual rainfall-runoff events; and 4) relate wetland soil and hydrological characteristics to wetland biogeochemical function. For the purpose of this thesis, sites (i.e., ten intact, three consolidated and ten fully drained wetlands and a nearby creek) within the Broughton’s Creek Watershed (Manitoba, Canada) were monitored over two years for water levels and water-soluble reactive phosphorus (SRP) concentrations. Soil cores were collected to measure soil physiochemical properties such as equilibrium phosphorus concentration. Hydrological behavioural metrics were computed to reflect year‐specific, season‐specific and event-specific wetland dynamics and were then correlated to wetland physical characteristics to identify landscape controls on wetland hydrologic function. Water column SRP concentrations and soil physiographic properties were also used to infer the time-variable source versus sink behaviour of each of wetland and the factors controlling this behavior. Results indicate a non-stationary behaviour of wetland hydrologic response across different antecedent moisture conditions. No hydrologic response metric showed positive or negative correlations with any of the spatial characteristics for more than 30% of the monitored events. Intact wetlands appeared more likely to provide specific watershed benefits (e.g., water and nutrient retention), compared to consolidated wetlands. Wetland equilibrium phosphorus concentrations ranged between 0 and 2 mg P L-1, but wetland phosphorus retenti

Pesticides are used to control pests in a variety of habitats including agricultural lands, forests, commercial lands, and domestic properties. Pesticide transport from such habitats to surface waters leads to environmental contamination. The objectives of this research were to compare the pesticide types present in the water-column and bottom-sediments of rivers flowing through intensively-managed and semi-natural habitats and to examine the extent of variations in MCPA and 2,4-D concentrations in the sediments that could be explained by measured laboratory parameters such as Kd, sediment organic carbon content and particle size distribution. This study screened water-column and sediment samples for 160 pesticide compounds which is substantially greater than what has been typically included in Prairie surface water research. River contamination primarily arises as a result of current-use pesticides applied in agricultural and urban habitats. For most compounds detected, there was no significant correlation between their concentrations detected in water and sediments, suggesting that pesticide concentration in the water-column is a poor indicator of the presence of pesticides in sediments. Pesticide mixtures were more common in water (72%) than sediments (51%) and dominated by broadleaf herbicides. The concentrations of pesticide mixtures detected in water never exceeded their calculated threshold value for the Pesticide Toxicity Index, indicating that the presence of pesticides in Prairie rivers continue to pose no significant risks to freshwater organisms. The batch-equilibrium study found that regardless of the lower sorption to sediments, more frequent presence of MCPA in the water-column allowed for greater opportunities for MCPA to partition to sediments compared to 2,4-D. Thus, the water-column loadings of those compounds, and not sediment characteristics, are the driving force for determining their frequencies and concentrations in sediments. Since this stud

Humanity depends on the existence of healthy soils, both for the production of food and for ensuring a healthy, biodiverse environment, among other functions. COVID-19 is threatening food availability in many places of the world due to the disruption of food chains, lack of workforce, closed borders and national lockdowns. As a consequence, more emphasis is being placed on local food production, which may lead to more intensive cultivation of vulnerable areas and to soil degradation. In order to increase the resilience of populations facing this pandemic and future global crises, transitioning to a paradigm that relies more heavily on local food production on soils that are carefully tended and protected through sustainable management is necessary. To reach this goal, the Intergovernmental Technical Panel on Soils (ITPS) of the Food and Agriculture Organization of the United Nations (FAO) recommends five active strategies: improved access to land, sound land use planning, sustainable soil management, enhanced research, and investments in education and extension. The soil is the great connector of lives, the source and destination of all. It is the healer and restorer and resurrector, by which disease passes into health, age into youth, death into life. Without proper care for it we can have no community, because without proper care for it we can have no life.

The Nelson River, a subarctic river in north-central Manitoba, is the largest river discharging to Hudson Bay and its watershed has seen extensive land-modification in the upper reaches, permafrost thaw in the lower reaches, and hydroelectric development throughout. To characterize sources of sediment and particulate organic matter (OM) in the Nelson River system, and to identify processes influencing its transport to Hudson Bay, water quality parameters, Compound-Specific Stable Isotope (CSSI) fingerprinting, and Bayesian unmixing models were employed on terrestrial and instream samples. Distinct regional, longitudinal, and temporal differences in water quality parameters and particulate OM sources were observed among all three regions of the Nelson River system (upper Nelson River, Rat-Burntwood River, lower Nelson River). The application of CSSI fingerprinting and unmixing models showed that the dominant sources of OM to suspended sediment in the lower reaches of the Nelson River are proximally derived and comprise soils, upstream suspended sediment, river bed sediment, and tributary suspended sediment.

A vegetated buffer strip (VBS) is a common measure implemented in agricultural landscapes to improve water quality. However, much of the evidence to support their effectiveness comes from warm regions dominated by rainfall driven runoff. This study assessed the performance of VBS plots and compared them to annual crop strips to reduce phosphorus (P) levels in runoff in the cold climate of the Canadian prairies. Analysis of water samples from 22 events during the study indicated no significant difference in the inflow and outflow concentrations of total dissolved phosphorus (TDP) or total phosphorus (TP) for either the VBS or the annual crop strips. While the VBS plots had little effect on TDP or TP during the spring, they performed better during the growing season reducing mean TP concentrations in five out of seven, or 71%, of these events. The VBS plots did not perform as well during the fall events, with the overall mean TP concentration in runoff increasing after flowing through the buffers during this time period. Although mean soil P levels in the VBS plots increased over the course of the study, the difference was not statistically significant. Vegetation within the VBS represents a substantial pool of P, with the harvestable portion containing 3.33 kg/ha of TP and the post-harvest plant residues containing 1.71 kg/ha of TP.

Soil erosion can cause sedimentation and eutrophication of waterbodies, which can decrease the quality of water. This study took place in southern Alberta within the Lower Little Bow River (LLBR) watershed, which has been a source of water quality studies as a part of the Oldman River Basin Water Quality Initiative. The objectives of this study were, firstly, to identify and apportion sources of suspended sediment using a sediment fingerprinting technique and the mixing model, MixSIAR, within a small 6-km reach of the LLBR, secondly, to build a better understanding of colour properties as tracers, and thirdly, to explore the effect of reach sampling within using the MixSIAR model. The first objective was accomplished through the sampling of multiple watershed sources including Agricultural Land, Coulee Walls, Stream Banks, an Irrigation Return-Flow channel and Upstream sediment. Suspended sediment was collected within the reach itself and un-mixed to determine source proportions contributed by each of the five potential sediment sources. The second objective was accomplished by taking three approaches in order to determine the appropriate environmental tracer combination to apportion sources accurately and how these affect choosing appropriate environmental tracers for sediment fingerprinting. The third objective of this thesis was accomplished by determining the composition and incorporation of upstream inflowing sediment into a watershed reach when conducting a sediment fingerprinting study. The mixing model, MixSIAR, was used as a tool to manipulate the watershed in order to determine how to improve the efficiency of the sediment fingerprinting process regarding tracer selection and sampling approaches. The MixSIAR model is used as a tool to determine how to design an approach to a reach within a watershed and the significance of upstream inflowing sediment inclusion as a sediment source.

Increasing complexity in human-environment interactions at multiple watershed scales presents major challenges to sediment source apportionment data acquisition and analysis. Herein, we present a step-change in the application of Bayesian mixing models: Deconvolutional-MixSIAR (D-MIXSIAR) to underpin sustainable management of soil and sediment. This new mixing model approach allows users to directly account for the ‘structural hierarchy’ of a river basin in terms of sub-watershed distribution. It works by deconvoluting apportionment data derived for multiple nodes along the stream-river network where sources are stratified by sub-watershed. Source and mixture samples were collected from two watersheds that represented (i) a longitudinal mixed agricultural watershed in the south west of England which had a distinct upper and lower zone related to topography and (ii) a distributed mixed agricultural and forested watershed in the mid-hills of Nepal with two distinct sub-watersheds. In the former, geochemical fingerprints were based upon weathering profiles and anthropogenic soil amendments. In the latter compound-specific stable isotope markers based on soil vegetation cover were applied. Mixing model posterior distributions of proportional sediment source contributions differed when sources were pooled across the watersheds (pooled-MixSIAR) compared to those where source terms were stratified by sub-watershed and the outputs deconvoluted (D-MixSIAR). In the first example, the stratified source data and the deconvolutional approach provided greater distinction between pasture and cultivated topsoil source signatures resulting in a different posterior distribution to non-deconvolutional model (conventional approaches over-estimated the contribution of cultivated land to downstream sediment by 2 to 5 times). In the second example, the deconvolutional model elucidated a large input of sediment delivered from a small tributary resulting in differences in the reported contr