Transport In Streams Research Articles

Watershed Vulnerability To Herbicide Transport in Northern Missouri and Southern Iowa Streams

Herbicide contamination of streams has been well documented, but little is currently known about the specific factors affecting watershed vulnerability to herbicide transport. The primary objectives of this study were (1) to document herbicide occurrence and transport from watersheds in the northern Missouri/southern Iowa region; (2) to quantify watershed vulnerability to herbicide transport and relate vulnerability to soil properties; and (3) to compute the contribution of this region to the herbicide load of the Missouri and Mississippi Rivers. Grab samples were collected under baseflow and runoff conditions at 21 hydrologic monitoring stations between April 15 and July 15 from 1996 to 1999. Samples were analyzed for commonly used soil-applied herbicides (atrazine, cyanazine, acetochlor, alachlor, metolachlor, and metribuzin) and four triazine metabolites (deisopropylatrazine, deethylatrazine, hydroxyatrazine, and cyanazine amide). Estimates of herbicide load and relative losses were computed for each watershed. Median parent herbicide losses, as a percentage of applied, ranged from 0.33 to 3.9%; loss rates that were considerably higher than other areas of the United States. Watershed vulnerability to herbicide transport, measured as herbicide load per treated area, showed that the runoff potential of soils was a critical factor affecting herbicide transport. Herbicide transport from these watersheds contributed a disproportionately high amount of the herbicide load to both the Missouri and Mississippi Rivers. Based on these results, this region of the Corn Belt is highly vulnerable to transport of herbicides from fields to streams, and it should be targeted for implementation of management practices designed to reduce herbicide losses in surface runoff.

Contribution of benthic fish to the patch dynamics of gravel and sand transport in streams

Barbel and gudgeon differ in their biology and ecology so that their bioturbation of streambed sediments may have specific effects on the patch dynamics of the sediment transport. Using experimental streams, we tested this idea by measuring the impact of a naturally occurring biomass gradient of each fish on the (1) transport of gravel and sand at base flow; (2) sediment surface characteristics; and (3) critical shear stress (τC) causing incipient gravel and sand motion during simulated floods. Corresponding to their biology and ecology, the fish specifically modified base flow transport and surface of the sediments. The greatest τC reduction for gravel/sand caused through these base flow fish activities was ∼50%/∼60% in the barbel and ∼35%/∼60% in the gudgeon experiment. We integrate these results into a conceptual framework that outlines the contribution of benthic animals to the patch dynamics of the gravel and sand transport in real streams.

Bedload Transport in Gravel-Bed Streams with Unimodal Sediment

Bedload transport in many gravel-bed streams becomes highly complicated because of the nonuniformity of the grain size and the vertical stratification of channel bed material. A new relation for computing bedload transport rates in gravel-bed streams is proposed here. In an effort to account for the variation of the makeup of the surface material within a wide range of Shields stresses, the relation employs a two-parameter approach, one related to the material in the pavement and the other to that in the subpavement layers. The mode is used to represent the grain sizes of each layer. Available bedload transport data from gravel-bed streams with unimodal sediment are used to test the accuracy of the relation. A comparison with other bedload transport relations is also considered.

Incorporating transient storage in conjunctive stream–aquifer modeling

There has been growing interest in incorporating the transient storage effect into modeling solute transport in streams. In particular, for a smaller mountain stream where flow is fast and the flow field is irregular (a favorable environment to induce dead zones along the stream), long tails are normally observed in the stream tracer data, and adding transient storage terms in the advection–dispersion transport equation can result in more accurate simulation. While previous studies on transient storage modeling account for temporary, localized exchange between the stream and the shallow groundwater in the hyporheic zone, larger-scale exchange with the groundwater in the underlying aquifer has rarely been included or properly coupled to surface water modeling. In this paper, we complement previous modeling efforts by incorporating the transient storage concept in a conjunctive stream–aquifer model. Three well-documented and widely used USGS models have been coupled to form the core of this conjunctive model: MODFLOW handles the groundwater flow in the aquifer; DAFLOW accurately computes unsteady streamflow by means of the diffusive wave routing technique, as well as stream–aquifer exchange simulated as streambed leakage; and MOC3D computes solute transport in the groundwater zone. In addition, an explicit finite difference package was developed to incorporate the one-dimensional transient storage equations for solute transport in streams. The quadratic upstream interpolation (QUICK) algorithm is employed to improve the accuracy of spatial differencing. An adaptive stepsize control algorithm for the Runge–Kutta method is incorporated to increase overall model efficiency. Results show that the conjunctive stream–aquifer model with transient storage can handle well the bank storage effect under a flooding event. When it is applied over a stream network, the results also show that the stream–aquifer interaction acts as a strong source or sink along the stream and is too significant to be ignored. The adaptive stepsize control for stream solute transport improves overall model performance.

Modeling of flow and contaminant transport in coupled stream–aquifer systems

This paper describes an integrated approach for modeling flow and contaminant transport in hydraulically connected stream–aquifer systems. The code, FTSTREAM, extended the capabilities of the ground-water model, FTWORK, to incorporate chemical fate and transport in streams. Flow in the stream network is modeled as an unsteady, spatially varying flow, while transport modeling is based on a one-dimensional advection–dispersion equation. In addition to sorption and decay during transport in ground water, the model incorporates volatilization, settling and decay during transport in surface water. The interaction between surface water and ground water is accommodated by a leakage term and is implemented in the model using an iterative Picard-type procedure to ensure mass conservation across the interface between the two systems. The modeling approach is used to simulate contaminant transport in the Mad River, Ohio, which is hydraulically connected to a buried valley aquifer of sand and gravel outwash. The river is a receiving stream in the upstream part of the modeled area. Downstream, heavy pumping from a municipal well field causes the river to become a loosing stream. Induced infiltration from the river is responsible for a considerable portion of the well yield. The flow and transport model, developed for this study, simulates coupling between flow in the aquifer and the river. Hypothetical sources of contamination are introduced at selected locations in the upstream portion of the aquifer. The model is then used to simulate the expected transport in both the aquifer and the stream. A series of simulations elucidates the role of the river in facilitating the transport of the hypothetical contaminants in ground water and surface water. Effect of sorption, retardation and volatilization on contaminant transport is also examined for the case of the volatile organic compounds.

Parameter estimation of the transient storage model by a routing method for river mixing processes

This paper reports on a routing method to estimate values of four parameters of a transient storage (TS) model that represent solute transport in natural streams with transient storage zones. In this approach a functional relationship between the TS model parameters and an analytical solution of the TS model equation is constructed. Results from a robust constrained nonlinear equation solver are used to obtain an explicit relationship between the mixing data and the terms in the functional relationship. The new method and several existing methods are compared with independently observed values of the TS model parameters. Laboratory flume experiments show that the parameters estimated by the new method are in better agreement with observations than are earlier methods. TS model parameters of 58 mixing data sets obtained from 33 natural streams are estimated. Dispersion data show that the concentration curves from analytical solutions using parameters estimated by the new method provide a good match to the observed concentration curves.

Comparison of Corn Pollen and Natural Fine Particulate Matter Transport in Streams: Can Pollen Be Used as a Seston Surrogate?

The transport of fine particulate organic matter (FPOM) in streams is an important process that links stream reaches, but until recently little was known about the distances traveled by fine particles in streams or the mechanisms governing their transport, deposition, and resuspension. Within the past decade, a number of studies have measured FPOM transport distances using either natural stream particles or a variety of artificial particles as FPOM surrogates. The purpose of our study was to compare estimates of FPOM transport distances in streams using: 1) radioactively labeled natural FPOM, and 2) corn pollen as an FPOM surrogate. We compared the particle types with simultaneous releases at 3 locations in Bloomington Creek, Idaho, and in a streamside flume in Pennsylvania. Mean transport distances in the stream and in the flume ranged from 49 to 637 m for corn pollen, compared with 23 to 1164 m for natural FPOM. Particle deposition velocities, which adjust for the effects of water depth and velocity on ...

Automated calibration of a stream solute transport model: implications for interpretation of biogeochemical parameters

AbstractThe hydrologic processes of advection, dispersion, and transient storage are the primary physical mechanisms affecting solute transport in streams. The estimation of parameters for a conservative solute transport model is an essential step to characterize transient storage and other physical features that cannot be directly measured, and often is a preliminary step in the study of reactive solutes. Our study used inverse modeling to estimate parameters of the transient storage model OTIS (One dimensional Transport with Inflow and Storage). Observations from a tracer injection experiment performed on Uvas Creek, California, USA, are used to illustrate the application of automated solute transport model calibration to conservative and nonconservative stream solute transport. A computer code for universal inverse modeling (UCODE) is used for the calibrations. Results of this procedure are compared with a previous study that used a trial-and-error parameter estimation approach. The results demonstrate...

Transport and retention of coarse woody debris in mountain streams: An in situ field experiment of log transport and a field survey of coarse woody debris distribution

Although coarse woody debris (CWD) is an important component of stream ecosystems in forested areas, the processes of CWD distribution, transport, and retention have not been clarified. In this study the distribution process of CWD pieces shorter than the bankfull width (S‐CWD) is discussed using an in situ field experiment of log transport and a field survey of CWD distribution in mountain streams. The transport experiment showed that transport distance has a close relation to flow depth and also implied that the magnitude and sequence of a series of flows were important factors for S‐CWD transport and retention in streams. The survey of CWD distribution indicated that in‐stream obstructions played an important role in the S‐CWD retention in deeper channels where S‐CWD pieces were potentially transported distances more than spacing between trapping sites of CWD. Overall, the in situ field experiment and the segment‐ to reach‐scaled analysis using h* (=depth/diameter) helped us understand the actual movement and distribution of CWD.

Particle transport and transient storage along a stream-size gradient in the Hubbard Brook Experimental Forest

AbstractThe transport and deposition of fine particulate organic matter (FPOM) is an important flux linking upstream and downstream reaches of stream ecosystems. However, few studies have attempted to identify physical controls on particle transport. One reason has been the lack of relatively simple, inexpensive methods. We describe a new technique for measuring fine particle transport in streams using fluoresently labeled yeast as FPOM analogs. We used steady state injections of yeast and a conservative tracer (Cl) in 6 reaches along a stream continuum at the Hubbard Brook Experimental Forest to explore the relationship between hydrologic properties of stream reaches and particle transport. The yeast technique is relatively easy and inexpensive, and measures of fine particle transport derived from this approach were comparable to those obtained for natural seston and other seston analogs in similarly sized streams. The transport distance of yeast particles (Sp) increased along the stream continuum. Sp wa...

Seasonal patterns in macroinvertebrate drift and seston transport in streams of an alpine glacial flood plain

1. We measured drift of macroinvertebrates and organic matter in five different channel types (upper and lower main channel, intermittent side‐channel, side‐slope tributary, and a groundwater channel) draining a glacial flood plain in the Swiss Alps. Samples were collected seasonally over 3 years (May 1997 to November 1999) to encompass major periods of floodplain expansion and contraction.2. Total wetted channel length ranged from ≤ 5 km during maximum floodplain contraction to ≥ 24 km under system expansion. Principal components analysis (PCA) of key physical and chemical measures collected over an annual cycle showed that the main and side channel sites differed spatially and seasonally from the tributary and groundwater sites, reflecting the glacial influence on the former.3. Two‐way ANOVA indicated a significant Site × Date interaction for all measured variables. Transported organic matter, caused by blooms of Hydrurus foetidus, was typically five to 10 times higher in the lower main channel and side‐channel than the other channel types, and was least variable among dates in the groundwater and tributary channels.4. The number of drifting macroinvertebrates was usually highest in the groundwater channel, although highly variable among years. Other channel types had highest drift rates in November and lowest rates in May, reflecting seasonal changes in the life cycles of particular taxa, such as Baetis alpinus and the Simuliidae. The lower main channel exhibited the greatest, and the groundwater the lowest, seasonality in drift compared with the other channels.5. The Chironomidae displayed the highest drift rates in most seasons, especially in summer when other taxa were relatively low in the drift. The number of taxa in the drift also varied among channel types and season, ranging from less than two in early spring to four to six in other seasons.6. The observed differences in drift rate and transported organic matter among channel types and seasons have important implications for ecosystem dynamics, through its effect, for instance, on dispersal among channel types or on organic matter exchange.

Effect of flow‐induced exchange in hyporheic zones on longitudinal transport of solutes in streams and rivers

Temporary storage of solutes in streams is often controlled by flow‐induced uptake in hyporheic zones. This phenomenon accounts for the tails that are generally observed following the passage of a solute pulse, and such exchange is particularly important for the transport of reactive substances that can be subject to various biogeochemical processes in the subsurface. Advective pumping, induced by streamflow over an irregular permeable bed, leads to a distribution of pore water flow paths in the streambed and a corresponding distribution of subsurface solute residence times. This paper describes a modeling framework that couples longitudinal solute transport in streams with solute advection along a continuous distribution of hyporheic flow paths. Moment methods are used to calculate the shape of solute breakthrough curves in the stream based on various representations of hyporheic exchange, including both advective pumping and several idealized formulations. Basic hydrodynamic principles are used to derive the distribution of solute residence times due to pumping. The model provides an accurate representation of the breakthrough curves of tritium along a 30 km reach of Säva Brook in Uppland County in Sweden. Both hydrodynamic theory for pumping exchange and pore water samples obtained from the bed during the tracer experiment suggest that the residence time for solutes in the hyporheic zone is characterized by a log normal probability density function. Closed‐form solutions of the central temporal moments of solute breakthrough curves in the stream reveal a significant similarity between this new model and existing models of hyporheic exchange, including the Transient Storage Model. The new model is advantageous because its fundamentally derived exchange parameters can be expressed as functions of basic hydrodynamic quantities, which allows the model results to be generalized to conditions beyond those directly observed during tracer experiments. The utility of this approach is demonstrated by using the pumping theory to relate the spatial variation of hyporheic exchange rate along Säva Brook with the local Froude number, hydraulic conductivity and water depth.

A simple device for estimating rates of fine sediment transport along the bed of shallow streams

This paper describes a simple trap suitable for estimating rates of fine sediment transport in small streams, which improves upon the design of traps previously described in the literature. In a field evaluation of the efficiency of the traps at two sites, they were found, on average, to collect (± S.E.) 71.9 ± 3.8% and 47.0 ± 3.5% of the inorganic and organic material, respectively, that was transported over the patch of bed where the traps were buried. The traps have great potential in environmental monitoring because they allow the collection of information on fine sediment transport at temporal and spatial scales appropriate for detecting many sorts of impacts on the biotic component of aquatic ecosystems.

The effects of partly irreversible solute exchange: comparison between conservative and sorptive transport in streams

Contaminant transport in streams and rivers is often affected by the solute exchange between the main stream and various adjacent storage zones as well as chemical and biological processes. This paper focuses on the difference between the effects of conservative and reactive solute exchange, respectively, in terms of an analytical transport model that takes into account main stream advection, solute exchange with storage zones, instantaneous equilibrium sorption and first order reactions. The effects of longitudinal variation of water flow and hydraulic radius as well as transversal variation of streambed porosity were included in the analysis, which was conducted on a reach by reach basis. To be able to use a temporally variable upstream concentration as boundary concentration, the measured breakthroughs were divided into 30–150 segments of constant concentration and the solutions were obtained as the sum of solutions for all segments. An experiment in Uppland County in Sweden, constitutes the basis for this study. Results from a simultaneous injection of the tracers tritium, 3H 2O, and chromium, 51Cr(III), made it possible to distinguish between conservative and reactive transport along a 30 km reach of the Säva Stream. The peak concentration of the reactive chromium decreased faster with distance, than that of tritium. The main hypothesis is that the chromium exchange is affected by both rapid sorption processes and slower reactions in the subsurface storage zones. In this framework, the slow processes appear as irreversible, which is true at least on the time scale represented by the data. The irreversibility is probably caused by the net effect of various slow chemical processes, e.g. solute precipitation/co-precipitation and irreversible sorption, which decreases the washout rate after the main bulk of the solute has passed by in the stream. A fully reversible exchange description, with instantaneous equilibrium partitioning, gives a clearly overestimated tail for chromium, which is not the case with the present concept. Results obtained by independently evaluating seven subreaches of the stream give mean Reaction Damköhler numbers for the storage zone equalling 2.63 for the transport of 51Cr and 0 for 3H 2O.

Comparison of bed load transport in torrents and gravel bed streams

Data are compiled on bed load transport and discharge in gravel bed rivers and torrents with bed slopes up to 0.17. The transport characteristics of 19 streams are compared with simple bed load transport equations and with measurements from flume experiments. In simple form the bed load transport is a function of an “effective” discharge times a bed slope factor. The efficiency of the streams in transporting bed load is defined as the deviation from the transport function. It varies over several orders of magnitude, particularly for smaller and steeper streams, whereas flume experiments and larger streams are in better agreement with the simple bed load transport relation. The large variation and the strong decrease in efficiency in smaller streams appears to be associated with substantial form losses for relative flow depths (defined by h/d90) smaller than ∼4–6.

Cross-shore distribution of longshore sediment transport: comparison between predictive formulas and field measurements

The skill of six well-known formulas developed for calculating the longshore sediment transport rate was evaluated in the present study. Formulas proposed by Bijker [Bijker, E.W., 1967. Some considerations about scales for coastal models with movable bed. Delft Hydraulics Laboratory, Publication 50, Delft, The Netherlands; Journal of the Waterways, Harbors and Coastal Engineering Division, 97 (4) (1971) 687.], Engelund–Hansen [Engelund, F., Hansen, E., 1967. A Monograph On Sediment Transport in Alluvial Streams. Teknisk Forlag, Copenhagen, Denmark], Ackers–White [Journal of Hydraulics Division, 99 (1) (1973) 2041], Bailard–Inman [Journal of Geophysical Research, 86 (C3) (1981) 2035], Van Rijn [Journal of Hydraulic Division, 110 (10) (1984) 1431; 110(11) (1984) 1613; 110(12) (1984) 1733], and Watanabe [Watanabe, A., 1992. Total rate and distribution of longshore sand transport. Proceedings of the 23rd Coastal Engineering Conference, ASCE, 2528–2541] were investigated because they are commonly employed in engineering studies to calculate the time-averaged net sediment transport rate in the surf zone. The predictive capability of these six formulas was examined by comparison to detailed, high-quality data on hydrodynamics and sediment transport from Duck, NC, collected during the DUCK85, SUPERDUCK, and SANDYDUCK field data collection projects. Measured hydrodynamics were employed as much as possible to reduce uncertainties in the calculations, and all formulas were applied with standard coefficient values without calibration to the data sets. Overall, the Van Rijn formula was found to yield the most reliable predictions over the range of swell and storm conditions covered by the field data set. The Engelund–Hansen formula worked reasonably well, although with large scatter for the storm cases, whereas the Bailard–Inman formula systematically overestimated the swell cases and underestimated the storm cases. The formulas by Watanabe and Ackers–White produced satisfactory results for most cases, although the former overestimated the transport rates for swell cases and the latter yielded considerable scatter for storm cases. Finally, the Bijker formula systematically overestimated the transport rates for all cases. It should be pointed out that the coefficient values in most of the employed formulas were based primarily on data from the laboratory or from the river environment. Thus, re-calibration of the coefficient values by reference to field data from the surf zone is expected to improve their predictive capability, although the limited amount of high-quality field data available at present makes it difficult to obtain values that would be applicable to a wide range of wave and beach conditions.

Patterns of nitrogen transport in streams of the Lake Tahoe Basin, California‐Nevada

In an effort to characterize the spatial and temporal patterns of nitrogen concentration and load in streams of the Lake Tahoe basin, we analyzed 10 years of data from 10 streams, developing discharge‐concentration relationships and total load estimates for nitrate‐N, ammonium‐N, and organic N. The results indicate that (1) most of the nitrate transport occurs early in the snowmelt season or during large winter rainstorms; (2) dissolved organic nitrogen concentrations peak early in the runoff season, decline during snowmelt, and in some streams peak again during the summer low‐flow period; (3) organic nitrogen accounts for over 90% of the total nitrogen load in basin streams; (4) averaged over 10 years and the area of 10 watersheds, the nitrogen flux rates in kg ha−1 yr−1 are 0.081 for nitrate‐N, 0.017 for ammonium‐N, 0.58 for dissolved organic N, and 0.47 for particulate organic N; (5) the variation in annual runoff explains most of the interannual and interwatershed variability in total nitrogen load; and (6) the dominance of organic nitrogen relative to nitrate‐nitrogen in Tahoe basin streams contrasts with sites in eastern North America.

Physical factors influencing fine organic particle transport and deposition in streams

The influence of physical factors on the transport and deposition of fine particulate organic matter (FPOM, 53–106 μm) in streams was investigated using 14C-labeled natural detritus. Field estimates of mean FPOM transport distance (SP) were calculated as the inverse of the longitudinal loss rate (kP) of particles. Deposition was determined by standardizing kP for depth and velocity and expressed as the mass transfer coefficient, vdep. SP varied by orders of magnitude (7–1000 m) within and among streams. As expected, vdep behaved more conservatively than SP but still varied by a factor of 18 (0.06–1.10 mm/s).Field-estimated deposition velocities were always less than the quiescent water fall velocity (vfall) but no consistent relationship existed between the 2 (r = 0.26, p = 0.53). Variability in SP was strongly associated with the cross-sectional area of the transient storage zone (AS; r = 0.93, p < 0.01) and the uptake length of water (SW; r = 0.84, p = 0.01). The transfer coefficient was highest in the 2 smallest streams (Q < 15 L/s) but was similar, and unrelated to stream size, among 6 experiments conducted in stream segments where Q exceeded 100 L/s. Variability in FPOM vdep was less related to physical characteristics than SP, although a significant, positive correlation was detected between vdep and AS/A.Evidence from this study suggests that the mechanisms assumed to govern particle transport in gravitational/hydrodynamic models may not be solely responsible for FPOM deposition in streams and that alternative processes, such as hyporheic filtration and biotic retention, may be important.

Characterizing multiple timescales of stream and storage zone interaction that affect solute fate and transport in streams

The fate of contaminants in streams and rivers is affected by exchange and biogeochemical transformation in slowly moving or stagnant flow zones that interact with rapid flow in the main channel. In a typical stream, there are multiple types of slowly moving flow zones in which exchange and transformation occur, such as stagnant or recirculating surface water as well as subsurface hyporheic zones. However, most investigators use transport models with just a single storage zone in their modeling studies, which assumes that the effects of multiple storage zones can be lumped together. Our study addressed the following question: Can a single‐storage zone model reliably characterize the effects of physical retention and biogeochemical reactions in multiple storage zones? We extended an existing stream transport model with a single storage zone to include a second storage zone. With the extended model we generated 500 data sets representing transport of nonreactive and reactive solutes in stream systems that have two different types of storage zones with variable hydrologic conditions. The one storage zone model was tested by optimizing the lumped storage parameters to achieve a best fit for each of the generated data sets. Multiple storage processes were categorized as possessing I, additive; II, competitive; or III, dominant storage zone characteristics. The classification was based on the goodness of fit of generated data sets, the degree of similarity in mean retention time of the two storage zones, and the relative distributions of exchange flux and storage capacity between the two storage zones. For most cases (&gt;90%) the one storage zone model described either the effect of the sum of multiple storage processes (category I) or the dominant storage process (category III). Failure of the one storage zone model occurred mainly for category II, that is, when one of the storage zones had a much longer mean retention time (ts ratio &gt; 5.0) and when the dominance of storage capacity and exchange flux occurred in different storage zones. We also used the one storage zone model to estimate a “single” lumped rate constant representing the net removal of a solute by biogeochemical reactions in multiple storage zones. For most cases the lumped rate constant that was optimized by one storage zone modeling estimated the flux‐weighted rate constant for multiple storage zones. Our results explain how the relative hydrologic properties of multiple storage zones (retention time, storage capacity, exchange flux, and biogeochemical reaction rate constant) affect the reliability of lumped parameters determined by a one storage zone transport model. We conclude that stream transport models with a single storage compartment will in most cases reliably characterize the dominant physical processes of solute retention and biogeochemical reactions in streams with multiple storage zones.

Predicting stream transient storage zone characteristics from tracer data

A method for predicting solute transport in streams with transient storage is presented. The method uses the principle of superposition to generate general solutions for an arbitrary inflow boundary condition based on a fundamental solution for a constant finite duration loading. The principle of superposition is shown to give excellent results for the cases studied here. The method can be used to compute stream and transient storage characteristics from measured concentration versus time data from stream tracer studies.