Search

Erosion and sediment control practices are implemented during construction activities to mitigate downstream effects, but limited field-performance data exists. Field assessments were conducted to evaluate ditch check installations during highway construction in Tama County, Iowa. Data collection included daily rainfall, topographical surveys of sediment deposition, pre- and post-rain event images, and visual observations. Variations to the standard Iowa Department of Transportation silt fence ditch check installation evaluated as part of this study include: (a) upgrading non-reinforced geotextile to a multi-belted, reinforced geotextile (i.e., SF-M1); (b) installing V-shape, as opposed to linear, while incorporating wire reinforcement to support hydrostatic loads placed on the geotextile, inclusion of a weir to facilitate controlled flow discharge, and offsetting the geotextile entrenchment location to improve ground securement (i.e., SF-M2); and (c) installing the dich check as described for SF-M2 substituting slicing for trenching (i.e., SF-M3). The modified wattle installation (i.e., W-M) incorporated a teepee staking configuration to facilitate ground contact, and an excelsior underlay, secured by sod staples, to minimize wattle undercutting. Results from field experiments indicated that sediment retention rates significantly improved for installations of SF-M2 and SF-M3 when compared with the standard installation and SF-M1 at the 85% confidence level, and served as viable control measures in concentrated flow applications. The W-M installation exhibited a statistically significant improvement in sediment retention over the W-S installation at the 95% confidence level. These findings suggest that ditch check performance is a function of specified practice and of installation methods described within regulatory agency specifications and design guidelines.

Construction operations are susceptible to high rates of rainfall-induced soil erosion due to the earth-disturbing nature of land-grading activities. Silt fence sediment barriers are a temp...

Silt fence have been used as a means for intercepting and treating construction site stormwater runoff prior to offsite discharge for well over 30 years. Standard small-scale testing methodologies for evaluating the filtering component of silt fence installations have failed to mimic realistic flows and sediment loadings commonly seen in field applications. To address these issues, this study evaluated the performance capabilities of two nonwoven and three woven silt fence geotextiles using an innovative testing methodology and a newly developed small-scale testing apparatus. The overall intent for conducting the evaluations was to develop a deeper understanding of effluent flow rates, sediment retention capabilities, and water quality impacts associated with geotextile fabrics. Results suggest that effluent flow rates of nonwoven geotextiles are on average 43% lower than woven materials, which results in extensive upstream retention times of impounded stormwater for nonwoven materials. Sediment retention results indicate that nonwoven geotextiles have an average sediment retention rate of 97% while woven geotextiles average 91%. Finally, water quality analyses suggest that the primary means for turbidity reductions rely on the process of sedimentation during the 30-min test period (i.e., 46% reduction) and filtration during the 90-min dewatering period (i.e., 19% reduction).

Post-fire flooding and elevated sediment loads in channels can pose hazards to people and structures within the wildland-urban interface. Mitigation of these hazards is essential to protect downstream resources. Straw bale check dams are one treatment designed to reduce sediment yields in small ephemeral catchments ( 60 Mg ha−1). 1- and 2-yr I30 return period rain events early in the study quickly filled the straw bale check dams indicating the treatment did not statistically reduce annual sediment yields. First year annual sediment yields across all catchments were 19.6 to 25.7 Mg ha−1. Once the check dams were full, they had limited storage capacity during the second post-fire year, allowing 3.8 to 13.1 Mg ha−1 of sediment to pass over the check dams. The mean mass of sediment trapped by individual straw bale check dams was 1.3 Mg, which allowed them to trap a mean of 5.9 Mg ha−1 of sediment at the given treatment rate. Straw bale check dams trapped

Soil erosion is a significant environmental impact of surface mining affecting the initial establishment of vegetation, especially on steep slopes, during reclamation. Consequently, we investigated the potentials of biological geotextiles constructed from two local plants, Pennisetum purpureum and Broussonetia papyrifera, in reducing erosion and sedimentation during reclamation at Newmont Ghana Gold Limited. Six experimental plots were constructed on a 33% slope waste rock, covered with a 70-cm layer of stockpiled subsoil. Concrete gutters, lined with silt fence, were installed at the lower end of each plot to collect eroded sediment. The two kinds of biological geotextiles, “York” mat and elephant grass mat, were used with bare ground as control in a randomized block design with two replicates each. Data on sediment yield was collected after each substantial rainfall. The performance of each geotextile in reducing soil loss was expressed as a percentage from the mean total sediment yield. With total precipitation of 306 mm in the period April 18, to July 4, 2016, both elephant grass mat and York mat significantly (p

Many of today’s construction sites rely on perimeter control practices to capture and treat sediment-laden stormwater emanating from disturbed lands. Silt fence systems are a common sedimen...

Erosion and sediment controls on construction sites minimize environmental impacts from sediment-laden stormwater runoff. Sediment is contained on project sites by installing sediment barriers. However, there is little performance-based testing data for the various designs, configurations, and materials for sediment barriers. To better understand sediment barrier performance, researchers at the Auburn University-Erosion and Sediment Control Testing Facility (AU-ESCTF) developed a full-scale testing apparatus to conduct performance testing on sediment barriers. Using this apparatus, researchers have evaluated five sediment barrier options to compare performance and identify possible shortcomings using standardized full-scale testing methods. This performance testing subjected sediment barrier practices to simulated field conditions typically experienced on-site without the variability of testing in nonstandard field locations or the limitations imposed by small-scale testing. Through testing, the researchers measured sediment barrier performance in the following areas: improvement in water quality by measuring turbidity, sediment retention, and structural integrity. The sediment barriers were installed using the same tools and techniques used for construction site installation. The full-scale testing apparatus exposed the evaluated sediment barriers to water and sediment loads expected to be encountered as the result of a 2-year, 24-h storm for central Alabama. Two nonwoven, wire-backed silt fence installations were evaluated with which the standard trenched method proved to capture a greater amount of sediment compared to the sliced-method of installation, which experienced significant undermining. The best performing practice was the ALDOT Sediment Retention Barrier that captured over 90% of sediment introduced without undermining. The worst performing practice was a wheat straw wattle that undermined so significantly, it was deemed to be a failing practice, resulting in the premature stoppage of each test.

Silt fences have long been a key component for controlling construction stormwater runoff; nonetheless, many silt fence installations fail to perform in the field as intended. Silt fences are temporary sediment control measures used to retain sediment by impounding runoff and allowing for sedimentation on-site, while simultaneously discharging stormwater runoff at a controlled rate. This study evaluated the performance of eight alternative configurations of the Alabama Department of Transportation (ALDOT) standard wire-backed, nonwoven silt fence. Standard installation parameters associated with the ALDOT silt fence include (1) 32-in. (81.3-cm) high fence, (2) 0.95 lb/ft (1.4 kg/m) support T-post, and (3) 10 ft (3.0 m) T-post spacing. Throughout the series of configurations tested, these standard parameters were varied individually and jointly in efforts to improve overall performance. Variations to the standard parameters include (1) 24-in. (61.0-cm) high fence, (2) 1.25 lb/ft (1.9 kg/m) support T-post, (3) 5 ft (1.5 m) T-post spacing, and (4) trench offsetting. Performance analyses were conducted on each configuration and results were evaluated to determine the best overall configuration to enhance the in-field performance of the ALDOT silt fence. Ultimately, the offset 24 in. (61.0 cm) fence with 1.25 lb/ft (1.9 kg/m) T-post spaced 5 ft (1.5 m) on-center resulted in the best overall improvement, retaining an average of 93% of sediment and deflection of only 0.18 ft (0.004 m) over the course of three simulated storm events.

Post–dam removal geomorphologic adjustment of a stream channel has been documented in the scientific literature at watershed, hillslope, and laboratory scales. Hillslope-scale studies in channel cross sections are most common and add significant value in the dam-removal literature. This study examines geomorphic stream channel adjustment following dam removal at the hillslope scale under natural climatic conditions. A sediment-filled silt fence dam (1 m tall, 12.65 m wide) was removed in three stages, and the width and depth of the upstream developing channel was monitored at six transects for 15 months. Headcut retreat and changes in channel sinuosity were also recorded. After the silt fence dam was removed, channel development was initiated by headcut formation, which migrated upstream at a rate of 4 cm/d for about 10 months and then gradually reached attenuation. The channel progressed through four distinct stages: Stage 1 (Initial conditions); Stage 2 (Downcutting)—wide, shallow, meandering channel incised to a maximum depth of 0.52 m, and sinuosity decreased; Stage 3 (Floodplain development)—upon reaching base level, surface runoff began to meander within the channel, widening it through bank slumps and erosion; and Stage 4 (Quasi-equilibrium)—channel development reached dynamic (quasi-) equilibrium with only minor widening at downstream transects (maximum width of the incised channel reached 0.46 m), accompanied by sediment aggradation. The stages of upstream channel development and headcut retreat pattern in this study are consistent with the findings of other studies at the laboratory and watershed scales, indicating that channel development after dam removal is scale independent.

Poorly designed and maintained forest road stream crossings can directly link erosion sources to streams. Forestry best management practices (BMPs) provide techniques that are useful for preventing sedimentation associated with ditch erosion. However, few studies have quantified ditch BMP sediment reductions. Thus, our primary objective was to evaluate erosion control effectiveness due to ditch BMPs and secondarily to quantify ditch BMP implementation costs. Sixty ditch segments near stream crossings were reconstructed, and five ditch BMP treatments were applied using a completely randomized design resulting in 11 to 13 replications per treatment. Ditch BMP treatments were (1) bare ditch (Bare), (2) grass seed with lime fertilizer (Seed), (3) grass seed with lime fertilizer and erosion control mat (Mat), (4) rock check dams (Dam), and (5) completely rocked (Rock). Silt fence sediment traps and sediment pins were measured over one year to determine treatment effectiveness. Trapped sediment deposits indicated that median erosion rates were greatest for Dam (6.14 Mg ha−1 y−1 [2.74 tn ac−1 yr−1]), followed by Bare (4.92 Mg ha−1 y−1 [2.19 tn ac−1 yr−1]), Rock (1.73 Mg ha−1 y−1 [0.77 tn ac−1 yr−1]), Seed (1.04 Mg ha−1 y−1 [0.46 tn ac−1 y−1]), and Mat (0.82 Mg ha−1 y−1 [0.37 tn ac−1 yr−1]). Results suggested that Mat treatments had significantly lower erosion rates than Bare and Dam, while Rock and Seed provided intermediate levels. Costs of BMP treatments were least expensive for Seed (US$6.10 approach−1), followed by Mat (US$21.33 approach−1), Dam (US$71.43 approach−1), and Rock (US$141.08 approach−1). Results suggest that erosion began to accelerate disproportionately when bare soil levels were between 30% and 50%; therefore, minimum soil cover of 50% is recommended for ditches.

The world is composed of various river basins. Within a specific river basin, water and sediment dynamics, and the relationship between them, can be assessed to reflect the basin's functions and services. Due to its changing nature, understanding and balancing the relationship between water and sediment is a global concern and is crucial for the sustainable management of river basins, especially for the Yellow River (YR), which is one of the most sediment-laden rivers in the world. Here, we used the past 60 years of runoff and sediment load observations to investigate the middle reach of the YR, i.e., the Loess Plateau (LP), the source of nearly 90% of the sediment load of the river. We found that a sharp (58%) reduction of sediment after 1979 was mainly (59%) caused by a water yield decrease. Engineering and vegetation measures have induced land surface modifications, which are responsible for 76% of the water reduction. These measures have been implemented as part of a coordinated set of soil and water conservation, and sediment control polices. We propose the cessation of such construction and the maintenance of a sustainable (i.e., minimal water consumption) vegetated ecosystem on the LP for soil conservation, and the establishment of an integrated basin-wide ecosystem and land use management regime for sustainable water use and sediment regulation.

The objective of this study was to assess the non-point source pollution reductions by a silt fence and berm through field monitoring. Experimental plots were established in two sizes on three slopes (110 m2 on 3 and 9% slopes, and 225 m2 on 6% slope). Flumes were used to monitor plot runoff. Runoff samples were collected during heavy rainfall (12 events from 2011 to 2014) for subsequent analysis. Cultivated crops were radish, Chinese cabbage and soybean. Runoff from the silt fence and berm treatment plots was 23.1 and 25.8% lower, respectively, than that from the control plot. On average the silt fence reduced BOD losses by −10.0% (i.e. 10% increase), COD by 28.7%, T-N by 42.5%, T–P by 22.7%, and SS by 48.0% compared to losses from the control plot. The berm reduced BOD losses by 34.1%, COD by 30.0%, T-N by 30.8%, T–P by 68.9%, and SS by 59.9% compared to losses from the control plot. The SS load reductions were statistically significant (5% level). Thus, the silt fence and berm were both effective in reducing pollutant losses in surface runoff. However, long-term monitoring is required to obtain a more quantitative and reliable description of the reduction effect for diverse crops. Copyright © 2016 John Wiley & Sons, Ltd.

Excessive sedimentation derived from anthropogenic activities is a main factor in habitat and biodiversity loss in freshwater ecosystems. To prevent offsite movement of soil particles, many environmental regulatory agencies mandate the use of perimeter silt fences. However, research regarding the efficiency of these devices in applied settings is lacking, and fences are often ineffective due to poor installation and maintenance. Here, we provide an overview of the current state of research regarding silt fences, address the current culture surrounding silt fence installation and maintenance, and provide several recommendations for improving the knowledge base related to silt fence effectiveness. It is clear that there is a need for integrated long-term (i.e., extending from prior to fence installation to well after fence removal) multi-disciplinary research with appropriate controls that evaluates the effectiveness of silt control fences. Through laboratory experiments, in silico modelling and field studies there are many factors that can be experimentally manipulated such as soil types (and sediment feed rate), precipitation regimes (and flow rate), season, slope, level of site disturbance, fence installation method, type of fence material, depth of toe, type and spacing of support structures, time since installation, level of inspection and maintenance, among others, that all require systematic evaluation. Doing so will inform the practice, as well as identify specific technical research needs, related to silt fence design and use. Moreover, what constitutes "proper" installation and maintenance is unclear, especially given regional- and site-level variation in precipitation, slope, and soil characteristics. Educating and empowering construction crews to be proactive in maintenance of silt fencing is needed given an apparent lack of compliance monitoring by regulatory agencies and the realities that the damage is almost instantaneous when silt fences fail. Our goal is not to dismiss silt fences as a potentially useful tool. Instead, we question the way they are currently being used and call for better science to determine what factors (in terms of fence design, installation and site-characteristics) influence effectiveness as well as better training for those that install, maintain and inspect such devices. We also encourage efforts to "look beyond the fence" to consider how silt fences can be combined with other sediment control strategies as part of an integrated sediment control program.

Besides direct damage, wildfires can produce striking direct and indirect impacts, including extreme runoff–erosion responses with serious negative consequences for land-use sustainability and downstream values at risk. The best way to reduce post-fire runoff is the rapid application of mulch: a protective cover of straw, needles, wood-based material, or other ground cover. In this study, we assessed the efficacy of forest residue mulching for reducing post-fire runoff across spatial scales on a logged and burnt eucalypt hillslope. Additionally, we assessed the underlying processes involved in the hydrologic responses of burnt areas in central Portugal during the first 2 years after a wildfire, with special focus on soil moisture, soil water repellency, and rainfall. Forest residue mulch reduced post-fire runoff by 50% in both micro-plots (0·25 m2) and hillslope scale silt fence plots (100 m2) during the first year after the wildfire. Runoff in the micro-plots was tenfold higher than the larger plots, regardless of mulching. The main controlling factors for the volume of runoff were rainfall amount (direct correlation) and soil moisture (inverse correlation). Soil water repellency and soil moisture were not affected by the mulch but played a role in the hydrologic response. In contrast, there was no decrease in runoff rate within the first two post-fire years. Forest residue mulching can be an effective post-fire treatment for reducing runoff rates, and the consistent decrease in runoff rates between the two spatial scales suggests that the scaling of runoff was not affected by the mulch. Copyright © 2015 John Wiley & Sons, Ltd.

Fine sediment (here defined as fine sand, silt and clay) is a serious management problem in lowland rivers because of alterations to river channels, floodplains and the wider landscape. The multi-scale, complex and stochastic nature of sediment production, delivery and transport processes complicates the diagnosis of fine sediment sources, pathways and impacts. The hydromorphological assessment framework developed by the REFORM project offers a flexible approach to investigate fine sediment pressures. In this study, the framework was applied to a lowland river impacted by excess fine sediment (River Frome, Dorset, UK) to investigate likely sources and timing of sediment production, the segment-scale capacity of the river to transport sediment, and the reach-scale geomorphological response of the river. Land use mapping and agricultural census records suggest that intensive cultivation of cereals and high livestock numbers during the second half of the twentieth century are the probable causes of fine sediment production and that a lack of any significant riparian buffer zone facilitates delivery of fine sediment to the river network. Sediment budget modelling indicates that transport capacities for gravel and sand are low along the river, which is supported by field observations of compacted gravel/sand beds covered with algae. Analysis of historical maps reveals that the river has responded to the increase in fine sediment over the last 40–50 years with channel narrowing and an increase in sinuosity, as fine sediment is trapped and stabilised by aquatic vegetation in the channel margins. Interactions between hydrodynamic forces, sediment supply and vegetation are driving progressive adjustment of the River Frome, and are the key to its holistic future management.

A field-scale data collection plan to monitor and evaluate the performance of a sediment basin design was developed and implemented using portable automatic stormwater samplers, flow modules, a rain gauge, and inflow weirs. The design configuration consisted of a skimmer as the primary dewatering device, three coir baffles installed inside the basin, polyacrylamide flocculant blocks and ditch checks in the inflow channel. A sediment basin built on a highway construction site in Franklin County, Alabama, U.S. using the aforementioned design configuration was monitored over 16 rainfall events from 15 November 2011 to 6 February 2012. The basin effectively removed sediments during the early stages of construction when the correct type of polyacrylamide flocculant blocks was used, e.g., 97.9% of sediment removal after a rainfall event on 16 November 2011. It is difficult and challenging to dose sediment-laden stormwater inflow with an exact amount of flocculating agent across all runoff producing events since rainfall is a stochastic variable. Based upon results from this study, it is recommended that a minimum volume of 251.9 m3/ha of contributing drainage area be used to sufficiently size a basin, which is still significantly under-designed for a 2-year, 24-h storm event in the southeast. This paper presents challenges and lessons learned regarding sediment basin design, monitoring, and performance that are beneficial to future studies.

Perimeter controls [i.e., sediment barriers (SBs) or sediment retention devices] are typically used on construction sites to retain sediment and prevent polluted stormwater runoff from adve...

Erosion and sediment controls on construction sites minimize environmental impacts from sediment-laden stormwater runoff. Silt fence, a widely specified perimeter control practice on construction projects used to retain sediment on-site, has limited performance-based testing data. Silt fence failures and resultant sediment losses are often the result of structural failure. To better understand silt fence performance, researchers at the Auburn University-Erosion and Sediment Control Testing Facility (AU-ESCTF) have evaluated three silt fence options to determine possible shortcomings using standardized full-scale testing methods. These methods subject silt fence practices to simulated, in-field conditions typically experienced on-site without the variability of field testing or the limited application of small-scale testing. Three different silt fence practices were tested to evaluate performance, which included: (1) Alabama Department of Transportation (ALDOT) Trenched Silt Fence, (2) ALDOT Sliced Silt Fence, and (3) Alabama Soil and Water Conservation Committee (AL-SWCC) Trenched Silt Fence. This study indicates that the structural performance of a silt fence perimeter control is the most important performance factor in retaining sediment. The sediment retention performance of these silt fence practices was 82.7%, 66.9% and 90.5%, respectively. When exposed to large impoundment conditions, both ALDOT Trench and Sliced Silt Fence practices failed structurally, while the AL-SWCC Trenched Silt Fence did not experience structural failure.

Summary The rapid expansion of agriculture in Brazil has increased erosion rates and sediment yields, causing many negative environmental and economic impacts, both on- and off-site. However, to date, very few catchment-scale sediment budget investigations have been carried out in Brazil. Given the need to reduce the negative off-site impacts of increasing agricultural activity, there is an important need for such investigations in order to inform the development of effective sediment management strategies. Against this background, 137Cs measurements have been combined with measurements of sediment yield and fingerprinting the source of the fine sediment output, to establish a provisional sediment budget for a small (1.19 km2) agricultural catchment in southern Brazil. The catchment is located in an area of steep highly erodible basaltic terrain, which has been intensively cultivated with tobacco. An ongoing monitoring programme provided information on the sediment yield from the catchment and existing suspended sediment source fingerprinting investigations provided information on the main sediment sources contributing to the sediment load at the catchment outlet. 137Cs measurements have been used to estimate medium-term erosion and deposition rates along 17 transects across the cultivated slopes and to quantify sedimentation rates within valley floor sediment sinks. These data have been used to estimate sediment redistribution rates within the cultivated areas of the study catchment and sediment accumulation in the valley floor sinks. The information provided by the three primary data sources has been integrated to establish the sediment budget for the catchment over the past 57 years. The individual terms of the budget necessarily involve much uncertainty, but its closure adds confidence to the final result. The budget calculations indicate that the study catchment has a sediment delivery ratio of ∼15%. The implications of the key features of the budget for developing effective sediment management strategies are discussed.

This paper reports a study of the origin of fine-grained river sediments and their potential impact to a reservoir that supplies drinking water. Excess sediment may affect water quality and decrease the storage capacity of the reservoir. Three sediment cores were taken in 2011 from the Rockaway River in New Jersey that leads into the reservoir to determine the sources of the sediment and propose remediation actions. The coring sites spanned an area upstream in the watershed to just above the reservoir, and the sites varied in land use. Sediment was analyzed in one to two centimeter intervals to determine the radionuclide activity of excess 210 Pb and 137 Cs. The sediment activity level at two of the sites (the ones farthest up- and downstream) show predominantly low levels of excess 210 Pb and 137 Cs, suggesting that the sediment is coming from deeper sources such as river channel widening/lateral migration and hillslope failures and/or legacy sediment sources. The sediment from site 2 exhibited higher activity of excess 210 Pb, suggesting more surficial sources of sediment or relatively recent sediments and likely tied to widespread urbanization. The different radionuclide profiles between the cores suggest spatial variation in the sediments’ sources, with the sources varying between surficial and deeper ones. Establishing the origin of this sediment would help to derive management solutions to lessen sediment delivery, stabilize and/or remove legacy sediment supplies to minimize downstream impacts.

This paper presents the results of the investigation of the performance efficiencies of silt fence fabrics in turbidity and sediment concentration removal, and the determination of flow-through-rate on simulated construction sites in real time. Two silt fence fabrics, (1) a woven type and (2) a nonwoven type, were subjected to material index property tests and a series of field-scale tests. The fabrics were tested for removal efficiency by varying the rainfall intensities and events for different embankment slopes on a tilting test-bed. Collected influent and effluent samples were analyzed for sediment concentration and turbidity, and the flow-through-rate for each fabric was evaluated. Test results revealed that the woven and nonwoven silt fence achieved 14 and 52 percent average turbidity reduction efficiency, and 23 and 56 percent average sediment concentration removal efficiency, respectively. Evaluation of sediment concentration reduction based on percent removal does not correctly account for the sediment concentration transported and deposited downstream. Fabric flowrates were functions of the rainfall intensity, embankment slope and field conditions, and fluctuates with every rainfall event.

Temporary skid trail stream crossings have repeatedly been identified as having considerable potential to introduce sediment to streams. Forestry Best Management Practices (BMPs) have proven to be effective for controlling erosion and subsequent sedimentation, yet few studies have quantified sedimentation associated with various levels of BMPs for skidder stream crossings. Three skid trail stream crossing BMP treatments were installed and replicated three times to quantify BMP efficacy for reducing sedimentation. BMP treatments were: (1) slash, (2) mulch and grass seed, and (3) mulch, grass seed, and silt fence. Water samples were collected daily both upstream and downstream from operational skidder stream crossings for one year following timber harvesting and BMP treatment installation. Samples were evaluated for total suspended solids (TSSs). Results indicate that both slash and mulch treatments effectively reduced TSS following harvesting. Slash could be the preferred method of stream crossing closure, due to lower cost, especially if application is incorporated into logging operations. However, if slash was being utilized for biomass and was not available, seed and mulch is a viable option for stream crossing closure. The mulch, seed, and silt fence treatment was the most expensive treatment and led to increased TSS, probably due to silt fence installation disturbances near the streams. Thus, silt fences should not be installed directly adjacent to streambanks, if other alternatives exist.

The conventional best management practice of sediment basins may create a reservoir for pathogenic bacteria. The fine particles that enter these basins have been shown to provide protection for bacteria; the small pores of clays and silts minimize predators and block sunlight. Therefore, while these basins decrease sediment loadings to water bodies downstream, they may introduce harmful levels of pathogenic bacteria into surface waters. In addition to causing human health risks, high bacteria levels alter natural biological makeup of downstream ecosystems. This paper describes the attachment of Escherichia coli to various particle sizes in construction site sediment basins. Five sediment basins, located in Anderson, South Carolina were sampled after rain events to explore trends that exist between various particle sizes and E. coli densities. Results provide evidence to suggest that sediment basins are a reservoir for pathogenic bacteria. Data showed that most E. coli attached to smaller particles with diameters less than 0.004 mm. These particles do not settle out of the water column quickly and are often passed through the basin during intense storms. Consequently, high levels of bacteria are passed to downstream waters. This research provides considerable evidence that the clays and silts within man-made construction basins can cause detrimental effects to South Carolina surface waters. With this knowledge, better stormwater management practices may be developed with the goal of remediating impaired surface waters of South Carolina.

In the northwestern U.S., the greatest amounts of forest erosion usually follow infrequent wildfires. Sediment from these fires is gradually routed through the stream system. The forest road network is usually the second greatest source of sediment, generating sediment annually. Erosion rates associated with timber harvest, biomass removal, and prescribed fire are generally minimal with current management practices. Landslides and debris flows can contribute significant amounts of sediment during infrequent wet years or following wildfire. A relatively new source of sediment in forested watersheds is recreation, particularly all-terrain vehicle trails. Stream channels store and route sediment; in the absence of channel disturbance, they tend to reach an equilibrium condition in which sediment entering a given reach is balanced by sediment carried downstream. At times, sediment from roads, wildfire, or landslides may accumulate in channels until higher flow rates, often associated with rainfall on melting snow, flush it downstream. Prediction tools are needed to aid forest managers in estimating the impacts of soil erosion on upland productivity and the risks of sediment delivery to downstream habitats and water users. Tools have been developed to aid in estimating long-term, low-level erosion in undisturbed forests and delivery of sediment from roads, and tools for estimating short-term, event-driven sediment from disturbed forests have also been developed. Online and GIS interfaces were developed using the Water Erosion Prediction Project (WEPP) model, including soil, vegetation, and climate databases. The online interfaces were developed to allow users to more easily predict soil erosion and sediment delivery for a wide range of climatic and forest conditions, including roads, fires, and timber harvest. There have been ongoing efforts to improve the online watershed interface to better model channel processes, road networks, and spatial variability associated with wildfire and weather.

Stormwater regulations require construction-generated pollution to be controlled on-site prior to discharge to avoid impairment of receiving waterbodies. Sediment basins are stormwater detention practices commonly used to capture and treat sediment-laden runoff prior to discharging from a construction site. Federal and state highway and environmental protection agencies have developed standardized guidance on the design of sediment basins, however further research is necessary to understand basin performance under various design conditions using large-scale testing techniques. This study details the design and construction of a 79.0 m3 (2,790 ft3), large-scale sediment basin at the Auburn University Erosion and Sediment Control Testing Facility (AU-ESCTF). A testing methodology and phased experimental regime were developed to allow for future testing of various sediment basin design configurations and high-rate lamella plate settler technology within the basin. Data collection efforts including w...

Construction activities require contractors to install, continuously monitor, and maintain controls to minimize erosion and sediment transport. Construction sites discharge up to 100 times ...

The erosion, transport and redeposition of sediments shape the Earth's surface, and affect the structure and function of ecosystems and society(1,2). The Yellow River was once the world's largest carrier of fluvial sediment, but its sediment load has decreased by approximately 90% over the past 60 years(3). The decline in sediment load is due to changes in water discharge and sediment concentration, which are both influenced by regional climate change and human activities. Here we use an attribution approach to analyse 60 years of runoff and sediment load observations from the traverse of the Yellow River over China's Loess Plateau - the source of nearly 90% of its sediment load. We find that landscape engineering, terracing and the construction of check dams and reservoirs were the primary factors driving reduction in sediment load from the 1970s to 1990s, but large-scale vegetation restoration projects have also reduced soil erosion from the 1990s onwards. We suggest that, as the ability of existing dams and reservoirs to trap sediments declines in the future, erosion rates on the Loess Plateau will increasingly control the Yellow River's sediment load.