Creek Catchment Research Articles

Historical water-plant occurrence and environmental change in two contrasting catchments

Historical conditions in riparian systems can be derived from the recorded distribution of water plants and their ecological requirements. Herbarium and literature records were used to assess historical species occurrence, and a field survey and a seed-bank study were used to assess present-day occurrence in two adjacent, southern Australian catchments: the Angas River and the Tookayerta Creek. There was an increase in the proportion of salinity- and drought-tolerant species detected in the Angas River catchment since European settlement. Field-survey data and the seed-bank study data were similar for that catchment, indicating that the submerged flora of the Angas River catchment is resilient to drought. In contrast, the dissimilarity of the seed-bank study data and the survey data from the Tookayerta Creek catchment indicated that the submerged flora in that catchment is not tolerant of drought. Although submerged species in the Tookayerta Creek catchment are dependent on the presence of permanent fresh water, there were more salinity-tolerant species in the lower Tookayerta catchment in the present study than were detected in the past. Comparison of the historical plant distribution and present-day distribution in catchments can provide interpretation of environmental conditions and ecological filters now, and since European settlement.

Identifying flood recharge and inter-aquifer connectivity using multiple isotopes in subtropical Australia

Abstract. An understanding of hydrological processes is vital for the sustainable management of groundwater resources, especially in areas where an aquifer interacts with surface water systems or where aquifer interconnectivity occurs. This is particularly important in areas that are subjected to frequent drought/flood cycles, such as the Cressbrook Creek catchment in Southeast Queensland, Australia. In order to understand the hydrological response to flooding and to identify inter-aquifer connectivity, multiple isotopes (δ2H, δ18O, 87Sr/86Sr, 3H and 14C) were used in this study in conjunction with a comprehensive hydrochemical assessment, based on data collected 6 months after severe flooding in 2011. The relatively depleted stable isotope signatures of the flood-generating rainfall (δ2H: −30.2 to −27.8‰, δ18O: −5.34 to −5.13‰ VSMOW) were evident in surface water samples (δ2H: −25.2 to −23.2‰, δ18O: −3.9 to −3.6‰ VSMOW), indicating that these extreme events were a major source of recharge to the dam in the catchment headwaters. Furthermore, stable isotopes confirmed that the flood generated significant recharge to the alluvium in the lower part of the catchment, particularly in areas where interactions between surface waters and groundwater were identified and where diffuse aquifer recharge is normally limited by a thick (approximately 10 m) and relatively impermeable unsaturated zone. However, in the upper parts of the catchment where recharge generally occurs more rapidly due to the dominance of coarse-grained sediments in the unsaturated zone, the stable isotope signature of groundwater resembles the longer-term average rainfall values (δ2H: −12.6, δ18O: −3.4‰ VSMOW), highlighting that recharge was sourced from smaller rainfall events that occurred subsequent to the flooding. Interactions between the bedrock aquifers and the alluvium were identified at several sites in the lower part of the catchment based on 87Sr/86Sr ratios; this was also supported by the hydrochemical assessment, which included the modelling of evaporation trends and saturation indices. The integrated approach used in this study facilitated the identification of hydrological processes over different spatial and temporal scales, and the method can be applied to other complex geological settings with variable climatic conditions.

English

Trace metals (Zn, Cu and Pb) fluxes were studied in five intertidal flats at Bodo Creek, Eastern Niger Delta, Nigeria in 2006, and re-evaluated in 2010 following two major oil spills that occurred in the creek. This study is the first to look at trace metal loads in the interstitial sediments of Bodo creek. Standard methods were employed in the sampling campaign and analysis. The concentration of all metals under study were higher than stipulated limit by WHO (2006) during post spill analysis. Concentration of Zn did not vary between stations and months pre-spill but did in post-spill, having values slightly higher than WHO (2006) stipulated limit. During the pre-spill sediment analysis, Pb concentrations ranged from no detection to 0.0012 mg/kg in 2006, increasing to 0.169 mg/kg post spill in 2010. Cu content ranged from 0.1312 - 0.1858 and 0.3374 - 0.4504 mg/kg pre- and post-spill, respectively. In addition to oil-induced metal loadings, the metals concentration dynamics show strong correlation with season. Metals had higher concentrations during the dry season due to reduced water volume in the creek and consequently less dilution. Implication for uptake, bioaccumulation and biotransformation by food species in the creek catchment above biosafety limits for user population is stressed and measures to avert public health consequences are advocated. Key words: Trace metals, inter-tidal sediment, Niger Delta, oil pollution.

Bedload yields for sand‐bed streams in the Ngarradj Creek catchment, Northern Territory, Australia

AbstractBedload yields were calculated by 39 methods at the East Tributary gauge, nine methods at Upper Swift Creek gauge and 11 methods at Swift Creek gauge in the Ngarradj Creek catchment in northern Australia. These methods involved combining various significant bedload rating curves determined for a measured bedload data set for a 4‐year period with either the hourly or daily hydrographs or flow duration curves for the same period, 1 September 1998 to 31 August 2002. Bedload ratings were both statistically significant (ρ ≤ 0.05) and explained at least 60% of the variance in bedload flux. Bias corrections were used with all methods based on log10‐transformed ratings. Estimated mean annual bedload yields varied by three orders of magnitude at the East Tributary gauge and by two orders of magnitude at Upper Swift Creek and Swift Creek gauges. Hourly discharges usually produced higher estimated yields than daily discharges. The bedload rating‐flow duration curve technique overestimates yields and bias correction methods always produce even higher yields. Ratings using both immersed bedload weight and adjusted immersed bedload weight always under‐predicted yields because they contain an implicit threshold of motion condition that is at least four times greater than that predicted by Bagnold's threshold equation. Such a result questions the applicability of Bagnold's threshold equation to the Ngarradj Creek catchment. The best estimates of mean annual bedload yield at East Tributary, Upper Swift Creek and Swift Creek gauges are 600 ± 170 (SE), 1065 ± 150 and 1795 ± 270 t/year, respectively. © 2015 Commonwealth of Australia. Hydrological Processes © 2015 John Wiley & Sons Ltd.

A space–time observation system for soil organic carbon

In this paper, we present a framework for a space–time observation system for soil organic carbon (STOS-SOC). We propose that the RothC model be embedded within the STOS-SOC, which is driven by satellite-derived inputs and readily available geospatial inputs, such as digital soil maps. In particular, advances in remote sensing have enabled the development of satellite products that represent key inputs into soil carbon models, examples being evapotranspiration and biomass inputs to soil, which characterise space–time variations in management and land use. Starting from an initial calibrated base for prediction, as new observations are acquired, data assimilation techniques could be used to optimise calibration algorithms and predicted model outputs. We present initial results obtained from the implementation of the proposed STOS-SOC approach to the 1445-km2 Cox’s Creek catchment in northern New South Wales, Australia. Our results showed that use of satellite-derived biomass inputs with a MODIS satellite product (MOD17A3) improved the accuracy of simulations by 16% compared with carbon inputs derived through other methods normally adopted in the spatialisation of the RothC model. We further discuss the possibility of improving the capabilities of the STOS-SOC for future applications.

Groundwater oligochaetes show complex genetic patterns of distribution in the Pilbara region of Western Australia

Patterns of genetic diversity in the groundwater fauna of Australia have largely focused on obligate stygobites of relatively large size, namely, crustaceans. Oligochaete worms, with their smaller size and broader ecological niches, provide a contrasting model in which to examine such patterns. Genetic diversity in subterranean oligochaetes in the Pilbara region of Western Australia were examined using one nuclear (18S) and two mitochondrial (COI, 12S) regions. The observed variation was assessed at three levels of hydrology – river basin, creek catchment, and individual bore or site – to document geographic patterns. Most species appeared to be restricted to an individual catchment; however, five species, representing three families, were widespread, with some haplotypes being shared between bores, catchments and even basins. General patterns suggest that while hydrology plays a role in the distribution of oligochaete species, it does not always confine them to catchments, in contrast to patterns observed in groundwater isopods and amphipods in the region. We suggest that intrinsic characteristics of oligochaetes, such as body size, shape, reproductive strategy and ecological requirements, may have allowed them greater dispersal within the subterranean biome of the Pilbara. In particular, oligochaetes may occupy subterranean and surface waters, increasing their opportunities for dispersal.

Can we model the implementation of water sensitive urban design in evolving cities?

This study showcases the dynamic simulation capabilities of the Urban Biophysical Environments And Technologies Simulator (UrbanBEATS) on a Melbourne catchment. UrbanBEATS simulates the planning, design and implementation of water sensitive urban design (WSUD) infrastructure in urban environments. It considers explicitly the interaction between urban and water infrastructure planning through time. The model generates a large number of realizations of different WSUD interventions and their evolution through time based on a user-defined scenario. UrbanBEATS' dynamics was tested for the first time on a historical case study of Scotchman's Creek catchment and was trained using historical data (e.g. planning documents, narratives, urban development and societal information) to adequately reproduce patterns of uptake of specific WSUD technologies. The trained model was also used to explore the implications of more stringent future water management objectives. Results highlighted the challenges of meeting this legislation and the opportunities that can be created through the mix of multiple spatial scales.

Confirmation of the presence of the spotted-tailed Quoll, Dasyurus maculatus (Dasyuridae, Marsupialia) from the Late Pleistocene King Creek Catchment, Darling Downs, Southeastern Queensland, Australia

Confirmation of the presence of the spotted-tailed Quoll, Dasyurus maculatus (Dasyuridae, Marsupialia) from the Late Pleistocene King Creek Catchment, Darling Downs, Southeastern Queensland, Australia

Confirmation of the presence of the spotted-tailed Quoll, Dasyurus maculatus (Dasyuridae, Marsupialia) from the Late Pleistocene King Creek Catchment, Darling Downs, Southeastern Queensland, Australia

Confirmation of the presence of the spotted-tailed Quoll, Dasyurus maculatus (Dasyuridae, Marsupialia) from the Late Pleistocene King Creek Catchment, Darling Downs, Southeastern Queensland, Australia

Parameterization of training images for aquifer 3‐D facies modeling integrating geological interpretations and statistical inference

AbstractWe develop a stochastic approach to construct channelized 3‐D geological models constrained to borehole measurements as well as geological interpretation. The methodology is based on simple 2‐D geologist‐provided sketches of fluvial depositional elements, which are extruded in the 3rd dimension. Multiple‐point geostatistics (MPS) is used to impair horizontal variability to the structures by introducing geometrical transformation parameters. The sketches provided by the geologist are used as elementary training images, whose statistical information is expanded through randomized transformations. We demonstrate the applicability of the approach by applying it to modeling a fluvial valley filling sequence in the Maules Creek catchment, Australia. The facies models are constrained to borehole logs, spatial information borrowed from an analogue and local orientations derived from the present‐day stream networks. The connectivity in the 3‐D facies models is evaluated using statistical measures and transport simulations. Comparison with a statistically equivalent variogram‐based model shows that our approach is more suited for building 3‐D facies models that contain structures specific to the channelized environment and which have a significant influence on the transport processes.

Isotopic evidence for determining the sources of dissolved organic sulfur in a forested catchment.

Understanding sulfur (S) biogeochemistry, especially in those watersheds subject to elevated levels of atmospheric S inputs, is needed for determining the factors that contribute to acidification, nutrient losses and the mobilization of toxic solutes (e.g., monomeric aluminum and methylmercury). S is found in a variety of both organic and inorganic forms undergoing a range of biotic and abiotic transformations. In watersheds with decreasing atmospheric S inputs, internal cycling is becoming dominant in affecting whether there is net loss or retention of S. Little attention has been given to the role of dissolved organic S (DOS) in affecting S biogeochemistry. DOS originates from assimilatory and bacterial dissimilatory S reduction (BDSR), the latter of which produces (34)S-depleted S. Within groundwater of the Archer Creek Catchment in the Adirondack Mountains (New York) there was reoxidation of reduced S, which was an important source of SO4(2-). DOS in surface waters had a higher variation of δ(34)S-DOS values (-6.0 to +8.4‰) than inorganic S with δ(34)S-SO4(2-) values ranging from +1.0 to +5.8‰. Inverse correlations between δ(34)S values of SO4(2-) and DOS suggested that BDSR played an important role in producing DOS.

Modeling the effect of uncertainties in rainfall characteristics on flash flood warning based on rainfall thresholds

This study proposes a risk assessment framework for quantifying the reliability of the rainfall threshold used in flash flood warning, which should be influenced by the uncertainties in the rainfall characteristics, including rainfall duration, depth, and storm pattern. This risk assessment framework incorporates the correlated multivariate Monte Carlo simulation method, the Sobek 1D–2D hydrodynamic model, and a logistic regression equation to establish a quantile relationship of the rainfall threshold for quantifying reliability of the rainfall threshold. The Shuhu Creek catchment locates in East Taiwan, and its historical hourly rainfall records on eight typhoon events are used as the study area and data. The results from the proposed framework indicate that the variation in the rainfall threshold declines with the duration; 12-h duration associated with a stable coefficient of variance of the rainfall threshold appears to be appropriate for the flash flood warning in the Shuhu Creek catchment. Moreover, the issued rainfall thresholds in the Shuhu Creek catchment by Water Resources Agency in Taiwan have a low exceedance probability. This infers that inundation might occur as the observed rainfall depth approaches the threshold, so that it is necessary to lower the rainfall threshold in accordance with higher exceedance probability in order to achieve the goal of early flood warning.

Spatial patterns of lacustrine fish assemblages in a catchment of the Mississippi Alluvial Valley

ABSTRACTIn the alluvial valley of the lower Mississippi River, floodplain lakes form isolated aquatic fragments that retain differing degrees of connectivity to neighbouring rivers. Within these floodplain lakes it was hypothesized that fish species composition, relative abundance, and biodiversity metrics would be shaped largely by aquatic connectivity within a catchment.Fish assemblages in 13 floodplain lakes (five on‐channel; eight off‐channel) were assessed with electrofishing in 2006–2012 in the Bear Creek catchment, Mississippi, USA. Bear Creek spans approximately 80 km before draining into the Yazoo River, a tributary of the Mississippi River.Fish assemblages in on‐channel and off‐channel lakes were different, and fish assemblages in on‐channel lakes were as a group more homogeneous than off‐channel lakes. Moreover, a longitudinal gradient in fish assemblages occurred in on‐channel lakes. The observed patterns in fish assemblages are linked largely to differing intensities in connectivity among lakes within the catchment. Lakes with irregular connections have greater individuality, whereas lakes with continuous or chronic connection are more similar. The wide variation in connectivity could be a key to the distinctive biodiversity of catchments and the focus of fish conservation programmes.Off‐channel floodplain lakes are among the first landscape elements to vanish as a consequence of agricultural development. These habitats tend to accumulate sediments at fast rates and are converted to agricultural land as soon as suitable drainage can be attained. Considering that off‐channel lakes with limited connectivity contribute greatly to the heterogeneity of fish assemblages, such losses pose great concerns to conservation of biodiversity. Published 2014. This article is a U.S. Government work and is in the public domain in the USA.

Impact of modellers' decisions on hydrological a priori predictions

Abstract. In practice, the catchment hydrologist is often confronted with the task of predicting discharge without having the needed records for calibration. Here, we report the discharge predictions of 10 modellers – using the model of their choice – for the man-made Chicken Creek catchment (6 ha, northeast Germany, Gerwin et al., 2009b) and we analyse how well they improved their prediction in three steps based on adding information prior to each following step. The modellers predicted the catchment's hydrological response in its initial phase without having access to the observed records. They used conceptually different physically based models and their modelling experience differed largely. Hence, they encountered two problems: (i) to simulate discharge for an ungauged catchment and (ii) using models that were developed for catchments, which are not in a state of landscape transformation. The prediction exercise was organized in three steps: (1) for the first prediction the modellers received a basic data set describing the catchment to a degree somewhat more complete than usually available for a priori predictions of ungauged catchments; they did not obtain information on stream flow, soil moisture, nor groundwater response and had therefore to guess the initial conditions; (2) before the second prediction they inspected the catchment on-site and discussed their first prediction attempt; (3) for their third prediction they were offered additional data by charging them pro forma with the costs for obtaining this additional information. Holländer et al. (2009) discussed the range of predictions obtained in step (1). Here, we detail the modeller's assumptions and decisions in accounting for the various processes. We document the prediction progress as well as the learning process resulting from the availability of added information. For the second and third steps, the progress in prediction quality is evaluated in relation to individual modelling experience and costs of added information. In this qualitative analysis of a statistically small number of predictions we learned (i) that soft information such as the modeller's system understanding is as important as the model itself (hard information), (ii) that the sequence of modelling steps matters (field visit, interactions between differently experienced experts, choice of model, selection of available data, and methods for parameter guessing), and (iii) that added process understanding can be as efficient as adding data for improving parameters needed to satisfy model requirements.

Comparison of Methods for Estimating Evapotranspiration in a Small Rangeland Catchment

Evapotranspiration (ET) was quantified for two rangeland vegetation types, aspen and sagebrush‐grassland, over an 8‐yr study period by comparing the following approaches for estimating ET: eddy covariance systems (EC, available for only 6 yr); soil water storage loss measured by time domain reflectometry (TDR) and neutron probe; and model simulation. The research site, the Upper Sheep Creek catchment in the Reynolds Creek Experimental Watershed, is part of a study on the effects of prescribed fire and vegetation removal. Estimates of seasonal ET for the aspen using EC with the turbulent fluxes adjusted to force energy balance closure, a 180‐cm TDR soil profile, two 225‐cm neutron access tubes, and the Simultaneous Heat and Water (SHAW) model agreed well with each other. If the two neutron probes were averaged, the RMSD of all approaches over the 6 yr was within 8% of the average. For the sagebrush‐grassland, a 120‐cm TDR profile underestimated seasonal ET for all years except the year immediately following the prescribed fire, when rooting depth likely had not recovered. A 195‐cm neutron probe access tube located within 30 m of the stream underestimated ET for every year except when there was no streamflow, suggesting that lateral flow may have biased the results for this tube. A comparison of the other methods (EC flux adjusted to force energy balance closure, soil water loss measured from a 225‐cm neutron access tube, and SHAW model simulation) agreed within 3% during the 6 yr with EC measurements at that site.

Probabilistic nature of storage delay parameter of the hydrologic model RORB: a case study for the Cooper's Creek catchment in Australia

In rainfall–runoff modeling, Design Event Approach is widely adopted in practice, which assumes that the rainfall depth of a given annual exceedance probability (AEP), can be converted to a flood peak of the same AEP by assuming a representative fixed value for the other model inputs/parameters such as temporal pattern, losses and storage-delay parameter of the runoff routing model. This paper presents a case study which applies Monte Carlo simulation technique (MCST) to assess the probabilistic nature of the storage delay parameter (kc) of the RORB model for the Cooper's Creek catchment in New South Wales, Australia. It has been found that the values of kc exhibit a high degree of variability, and different sets of plausible values of kc result in quite different flood peak estimates. It has been shown that a stochastic kc in the MCST provides more accurate design flood estimates than a fixed representative value of kc. The method presented in this study can be adapted to other catchments/countries to derive more accurate design flood estimates, in particular for important flood study projects, which require a sensitivity analysis to investigate the impacts of parameter uncertainty on design flood estimates.

Ecological evidence links adverse biological effects to pesticide and metal contamination in an urban Australian watershed

Summary Aquatic ecosystems near urban areas are often ecologically impaired, but causative factors are rarely identified. Effects may be revealed by considering multiple lines of evidence at different levels of biological organization. Biological impairment is evident in the urban section of the Upper Dandenong Creek Catchment (Victoria, Australia). We assessed whether episodic sewage spills or other pollutants were the cause of poor ecological condition in the stream. The evidence evaluated included chemical and invertebrate assessments, caging studies of mudsnails Potamopyrgus antipodarum, antioxidant biomarkers and endocrine disruption‐related endpoints in fish (Carassius auratus and Gambusia holbrooki) and toxicological studies with chironomids (Chironomus tepperi). A combination of metals and pesticides is likely to be affecting the aquatic fauna across all biological levels, with macroinvertebrate communities, P. antipodarum and C. tepperi populations and C. auratus individuals all ecologically impaired. Adverse alterations to aquatic fauna were consistently seen in Bungalook Creek and persisted downstream of this confluence into Dandenong Creek. In addition, chemical assessments and toxicity identification evaluation (TIEs) resulted in several point sources of both metals and pesticides being identified as origins of impairment. This contrasted with an expectation that adverse effects were likely to be associated with sewer‐related pollution. As a consequence, target areas and specific pollutants were identified for remediation instead of an expensive sewer upgrade. Synthesis and applications. The results demonstrate that it is important to investigate biological effects in different taxa, in both the laboratory and field, to understand which stressors are causing adverse effects on faunal assemblages. When adverse effects are seen across multiple levels of biological organization and caused by the same pollutant from an identifiable source, there is a clear remedial path for managers.

Spatio-temporal variability of piezometric response on two steep alpine hillslopes

Information on the main drivers of subsurface flow generation on hillslopes of alpine headwater catchments is still missing. Therefore, the dominant factors controlling the water table response to precipitation at the hillslope scale in the alpine Bridge Creek Catchment, Northern Italy, were investigated. Two steep hillslopes of similar size, soil properties and vegetation cover but contrasting topography were instrumented with 24 piezometric wells. Sixty-three (63) rainfall-runoff events were selected over three years in the snow-free months to analyse the influence of rainfall depth, antecedent moisture conditions, hillslope topographic characteristics and soil depth on shallow water table dynamics. Piezometric response, expressed as percentage of well activation and water peak magnitude, was strongly correlated with soil moisture status, as described by an index combining antecedent soil moisture and rainfall depth. Hillslope topography was found to be a dominant control only for the convex-divergent hillslope and during wet conditions. Timing of water table response depended primarily on soil depth and topographic position, with piezometric peak response occurring later and showing a greater temporal variability at the hillslope bottom, characterized by thicker soil. The relationship between mean hillslope water table level and standard deviation for all wells reflected the timing of the water table response at the different locations along the hillslopes. The outcomes of this research contribute to a better understanding of the controls on piezometric response at the hillslope scale in steep terrain and its role on the hydrological functioning of the study catchment and of other sites with similar physiographic characteristics. Copyright © 2014 John Wiley & Sons, Ltd.

How much is enough? Minimal responses of water quality and stream biota to partial retrofit stormwater management in a suburban neighborhood.

Decentralized stormwater management approaches (e.g., biofiltration swales, pervious pavement, green roofs, rain gardens) that capture, detain, infiltrate, and filter runoff are now commonly used to minimize the impacts of stormwater runoff from impervious surfaces on aquatic ecosystems. However, there is little research on the effectiveness of retrofit, parcel-scale stormwater management practices for improving downstream aquatic ecosystem health. A reverse auction was used to encourage homeowners to mitigate stormwater on their property within the suburban, 1.8 km2 Shepherd Creek catchment in Cincinnati, Ohio (USA). In 2007–2008, 165 rain barrels and 81 rain gardens were installed on 30% of the properties in four experimental (treatment) subcatchments, and two additional subcatchments were maintained as controls. At the base of the subcatchments, we sampled monthly baseflow water quality, and seasonal (5×/year) physical habitat, periphyton assemblages, and macroinvertebrate assemblages in the streams for the three years before and after treatment implementation. Given the minor reductions in directly connected impervious area from the rain barrel installations (11.6% to 10.4% in the most impaired subcatchment) and high total impervious levels (13.1% to 19.9% in experimental subcatchments), we expected minor or no responses of water quality and biota to stormwater management. There were trends of increased conductivity, iron, and sulfate for control sites, but no such contemporaneous trends for experimental sites. The minor effects of treatment on streamflow volume and water quality did not translate into changes in biotic health, and the few periphyton and macroinvertebrate responses could be explained by factors not associated with the treatment (e.g., vegetation clearing, drought conditions). Improvement of overall stream health is unlikely without additional treatment of major impervious surfaces (including roads, apartment buildings, and parking lots). Further research is needed to define the minimum effect threshold and restoration trajectories for retrofitting catchments to improve the health of stream ecosystems.

Catchment scale mapping of measureable soil organic carbon fractions

This study aims to map the measurable fractions of soil organic carbon related to the RothC carbon model at the catchment scale and to assess the model and prediction quality. It also discusses how the outputs can be used to provide initial pool estimates for process modelling of soil carbon in a spatial context. The study was carried out in Cox's Creek catchment in northern New South Wales, Australia. Samples were collected in 2010 using a design-based sampling scheme. The measurable fractions of the RothC soil carbon model considered in this study were resistant organic carbon, humus organic carbon and particulate organic carbon. It has been reported that these measurable fractions of soil organic carbon can successfully substitute for the conceptual pools of carbon in the RothC soil carbon model. All the samples were scanned to create MIR spectra and recently developed spectroscopic models by Commonwealth Scientific and Industrial Research Organisation (CSIRO) under the national soil carbon research programme (2009–2012) were used to carry out the prediction of respective fractions. We used linear mixed models to create a model for mapping the measurable fractions of soil organic carbon across the catchment. The cross validation results revealed that the highest Lin's concordance correlation between measured and predicted values was recorded for resistant organic carbon (0.78), followed by humus organic carbon (0.74) and particulate organic carbon (0.58). Finally, to assess the uncertainty of the predictions we carried out conditional sequential Gaussian simulations. We demonstrated that measurable fractions of carbon related to the RothC model can be mapped at catchment scale with reasonable accuracy. The derived maps could be used in future studies to initialize the RothC model at any location across the landscape with quantified uncertainties.