Silt Fence Research Articles

Post-fire soil erosion: Two years of monitoring − First time detected implications between extremely intense consecutive rainfall events and erosion rates

The research was carried out in one of the most important suburban forests of Greece, after a wildfire (2021). The objectives include the estimation of the annual soil erosion, the effect of extremely intense and consecutive rainfalls on erosion process, the correlation among erosion, rainfall intensity and other factors. To monitor soil erosion in burned and unburned areas, erosion measurements were obtained installing silt fences. The results showed that the main factor affecting annual erosion is the presence or not of vegetation. Rainfall intensity is a major determinant of erosion, especially when it exceeds 6–7 mm/30 min. However, it was revealed that erosion does not increase significantly in burned areas, despite the increase of rainfall intensity. In unburned area the erosion was significantly increased, above a rainfall intensity threshold (>10 mm/30 min). For the first time, it was shown that in cases of two consecutive and very heavy rainfalls, the second and more intense rain caused significantly lower erosion than the first one. A 690 % average increase in R factor during the 2nd storm, showed an average decrease in soil erosion of 20 % (burned and unburned areas). The present study also revealed that the high increase of R factor in the 2nd post-fire year did not trigger a significant increase of soil erosion, since the extreme erosive events occurred very close to each other in time. These findings highlight that the use of R factor in RUSLE, to calculate the annual erosion in burned or unburned areas, detached from the respective field data establishment to validate the model, involves high uncertainties, which could possibly result in wrong erosion rates calculations. Researches and stakeholders, who use the R factor in erosion modeling, should previously examine in detail the exact dates of erosive events, before the implementation of the erosion model.

Holistic evaluation of inlet protection devices for sediment control on construction sites

To address the deleterious impacts of excess soil erosion from the construction sites, the United States Clean Water Act requires that erosion and sediment control measures (ESCs) be implemented on construction projects disturbing more than 0.4 ha. Inlet protection devices (IPDs) are a common ESC utilized on construction projects to reduce the amount of sediment entering storm sewers. In Ohio, regulatory agencies use approved, non-proprietary IPDs made from commonly available materials (e.g., silt fence, geotextile, lumber, and aggregate) to mitigate sediment on construction projects; however, these IPDs often rely on extended ponding to remove sediment and require frequent maintenance making these unsuitable for road construction projects. Commercially manufactured (i.e., proprietary) IPDs which rely on filtration to quickly dewater following rainfall may prove more practical for road construction projects. However, little research which quantitatively compares the holistic performance of these two types of IPDs in field settings has been performed to date. To address this knowledge gap, the performance of 24 proprietary IPDs was evaluated at field-scale using simulated construction site runoff and compared to three non-proprietary IPDs currently approved for use in Ohio. Bypass flows, which typically occurred due to poor IPD fit to standard drainage inlets used in Ohio transportation settings, significantly increased effluent total suspended solids (TSS) and turbidity compared to tests of IPDs where bypass did not occur. Overflow, or intentional bypass around primary IPD flow pathways during high flows, did not significantly impact effluent water quality. Despite differences in treatment mechanisms (i.e., sedimentation versus filtration), the water quality performance of non-proprietary and proprietary IPDs were not statistically different, indicating comparable sediment removal was provided by both categories. Findings from this research can provide design engineers and state regulatory agencies the necessary tools to evaluate IPD performance in road construction settings and, ultimately, alleviate the impact of excess sediment discharged from construction sites.

Large-Scale Performance Evaluation of Various Woven Silt Fence Installations under Nebraska Highway Conditions

Sediment barriers are used on construction sites to protect downstream waterbodies from the impacts of sediment-laden stormwater runoff. Although ubiquitous on construction sites, many sediment barrier practices lack performance-based testing to determine effectiveness and treatment mechanisms, with previous evaluations being limited to conditions local to the Southeastern U.S., with conditions in other regions remaining untested. Testing was conducted to determine the effectiveness of woven silt fence barriers and provide structural improvements to common installation methods. Testing was conducted using a large-scale sediment barrier testing apparatus at the Auburn University—Stormwater Research Facility. The results from testing indicate that Nebraska DOT standard silt fence installations can be improved to reduce the risk of structural failures such as undermining, complete installation failure, slow dewatering, and overtopping. To improve structural performance, four modifications (a 15.2 cm [6 in.] offset trench, wooden posts, a dewatering board with an overflow weir, and a dewatering board with an overflow weir with adjusted post spacing) were tested. On average, 83% of introduced sediment was retained behind the tested barriers. The water quality results across the testing of standard and modified installations indicated that stormwater treatment was due to sedimentation within the impoundment formed by silt fence installations and not filtration through geotextile fabric.

Effectiveness of Structural Sediment Perimeter Barriers: Literature Review and Suggestions for Future Research

Highlights Need a unified test standard to evaluate the effectiveness of a sediment perimeter barrier (SPB). Water sampling location affects the evaluation of a SPB in terms of water quality. Explore more approaches with computational models to simulate the effectiveness of SPBs. Over 80% of studies were done in the southeast region of the U.S., emphasizing more research with diverse geographical climate conditions. Abstract. A sediment perimeter barrier is a common practice along the perimeter of construction sites to prevent sediment from being washed over all the way to the nearby storm drains or directly into water bodies. It is important to apply barriers during construction since the grading and demolition do not allow the application of other ground surface protection, such as erosion control blankets. To better understand the mechanism, this paper conducted a comprehensive review of the effectiveness of structural sediment perimeter barriers (SPBs) in preventing sediment pollution. The study systematically analyzed the experimental design and results of previous research studies, including their strengths and limitations. The findings suggest that while SPBs have shown promise in reducing sediment pollution, their effectiveness varies depending on factors such as experimental design, installation, and sampling approach. Worse still, the criteria to evaluate the SPBs also differed across different studies. From the reviewed studies, we identified that there is a need to develop a unified test standard, especially on evaluation criteria and water sampling protocol. Additionally, there is a need for more studies to be conducted in various geographical and climatic conditions to assess the performance of SPBs. Although some models (WEPP and VFSMOD) have been proven to be effective in predicting the effectiveness of non-structural SPBs (vegetative filter strips), exploring the feasibility of these existing models in simulating structural SPBs to be subjected to sediment-laden water is recommended. Other software or methods used in the area of computational fluid dynamics, such as HYDRUS-3D, ANASYS, EDEM, and finite volume methods (FVM), could also be introduced in this field. Keywords: Compost log, Filter sock, Perimeter control, Sediment control, Silt fence.

Sediment Barriers’ Performance in the Laboratory: Evaluation of Clogging and Filtration Characteristics in Geotextiles Subjected to Discharge Cycles

This research aims to assess the clogging process of geotextiles within silt fences. For that purpose, the filtering efficiency, flow rate, and clogging of three geotextiles (GTX-1, GTX-2, and GTX-3) employing two distinct soils and under three sediment discharge cycles were investigated. The analysis adhered to the American standard D5141-11 and, as further analyses, qualitative and quantitative inspections were conducted through microscopic images of the materials. The results showed greater clogging of the nonwoven geotextile, GTX-1, with higher retention efficiency (approximately 100%) and better turbidity removal for both soils, equal to a reduction of around 94%. For GTX-2, a woven geotextile with a larger pore opening, less intense clogging and lower retention efficiency were observed after the third discharge; the average was 96% for both soils. GTX-3, a woven geotextile with a smaller apparent opening, exhibited a behavior similar to GTX-1: as the number of cycles increased, the material experienced more clogging and higher retention efficiency for soil 1 (approximately 98.5%). Based on these findings, it can be inferred that the discharge cycles impact the tested geotextiles in diverse ways and, therefore, the selection of the material should be contingent on project requirements.

Effects of forest residue mulching on organic matter and nutrient exports after wildfire in North-Central Portugal

The quick implementation of emergency stabilization measures is vital for minimizing post-fire soil erosion and the associated fertility loss. Mulching has proven to be highly effective in minimizing post-fire soil erosion, however few studies have investigated its impacts on organic matter (OM) and nutrient mobilization from burned forest areas. This study evaluates the effectiveness of forest residue mulching at reducing OM, N and P losses within the sediments after a moderate-severity wildfire over a period of 5 years (Ermida, North-central Portugal). Untreated and mulched plots of ca. 100 m2 were bounded with geotextile fabric and sediments were collected from silt fences after a total of 29 periods.During the first five years after the fire, the accumulated OM, N and P exportations in the untreated plots were, respectively, 199, 5.2 and 0.38 g m−2; and mulch significantly reduced these figures in, respectively, 91 %, 94 % and 95 % (p < 0.05). The overall OM content in the sediments of the untreated plots (45 %) was not different from the OM content of the mulched plots (34 %, p = 0.16). However, the N (8.9 g kg−1) and Pav contents (0.62 g kg−1) in the untreated plots were significantly higher than the N (5.6 g kg−1; p < 0.05) and Pav contents (0.36 g kg−1; p < 0.05) in the mulched plots. This effect was especially noticeable in the first year after fire. OM and TN contents in the sediments were highly variable throughout the study period, whereas Pav contents declined sharply in the first post-fire rainfall events, maintaining low values afterwards. The main factors driving nutrient exports were ash and litter cover, whereas no significant relationship was observed for OM exports. The present work has shown that forest residues application can be a sustainable strategy for the conservation of soil carbon and nutrients in fire-affected areas.

Isolation and characterization of biological soil crust forming algae from Malaysia

Soil erosion permanently reduces the quality of physicochemical and biological properties, soil fertility, and land productivity, all of which have a significant impact on cultivated areas. Communities that live on the top few centimetres of soil surfaces, are known as “biological soil crust” (BSC). This microorganism is essential for soil stabilisation, water retention, and soil fertility. A case study of a Japanese company that uses these organisms to combat soil erosion has inspired this study. Ground covers, slope drains, silt fences, blankets, and plastic covers are currently used to reduce soil erosion which are expensive and less environmentally friendly. An artificially induced BSC can be created on the specific targeted area. The first step in implementing this strategy in Malaysia is to collect, isolate, and identify the BSC-forming algae species. Our findings show that the isolated algae (C3 strain), based on its morphology, has been identified as the Tribonema species and has a yellow-green filament under a microscope. The C3 strain therefore, has been chosen as the potential native BSC forming algae. This research aims to provide information on isolated strains of Malaysian algae for application as BSC in tropical settings.

Improving the Design and Performance of Double-Row Sediment Barriers Used During Highway Construction

Sediment barriers (SBs) are stormwater management devices often installed along the perimeter of a construction site to intercept and treat overland sediment-laden flow before discharge into the surrounding environment. Effective SB practices remove stormwater pollutants by creating a temporary impoundment upstream of the practice which facilitates sediment capture via sedimentation. Controlling agencies and design practitioners often specify the installation of two SB practices (i.e., primary and secondary SB) in areas where enhanced stormwater treatment is critical because of downstream environmental concerns (e.g., impaired waters). This study sought to identify the overall performance of a commonly specified double-row SB (i.e., double-row silt fence), as well as six alternative designs that utilized various secondary SB practices that could be easily paired with a primary silt fence SB. Small-scale experiments were conducted on each of these double-row design configurations to develop a comprehensive understanding of their performance capabilities. A statistical analysis conducted on 700 water quality data points suggests that all six alternative double-row designs significantly outperformed the double-row silt fence installation. Water quality improvements achieved using alternative secondary SBs ranged from 11% to 71% during the 30 min test period and 14% to 60% during the 90 min dewatering period. In comparison, the double-row silt fence installation only achieved 5% and 1%, respectively. Additionally, post-test observations of secondary SB cross sections indicate that, at best, only half of the matrix filter media within the secondary SB contacts sediment-laden flow. This observation suggests that alternative cross-sectional designs could improve media utilization.

Check-Dams and Silt Fences: Cost-Effective Methods to Monitor Soil Erosion under Various Disturbances in Forest Ecosystems

The present study was conducted in the suburban forest “Seich Sou”, which is located at the north-east of Thessaloniki city (north Greece). “Seich Sou” is one of the most significant suburban forests of North Greece. However, many disastrous events have taken place in the suburban forest during the last 25 years, caused by either human interference or other biotic/abiotic factors, such as insect outbreaks. In the present study, erosion measurements and field data were collected using a combination of silt fences (USLE plots) and depositions retained behind the constructed check-dams, aiming to monitor the impact of the significant biotic and abiotic disturbances (forest fires, insect outbreaks, logging) in Seich Sou forest. Specifically, the aim of this study is to present a cost-effective and time saving methodology towards the achievement of accurate and reliable soil erosion measurements and field data acquisition. Additionally, the installation details, data recording and collection, field work, supplementary materials and the advantages of silt fences and check-dams are presented in detail, as well as the limitations of the methods and the difficulties during the installation, maintenance and data collection period. The proposed methodology could be effectively applied in many environments and in the context of varied purposes, to quantify the erosion and runoff processes with high accuracy, as well as to increase the accuracy of soil erosion modeling performance, through implementation of calibration and/or validation processes, which is a major issue for the scientific community.

Assessment of Soil Erosion Potential From the Disturbed Surface of Skid Trails in Small Shovel Harvesting System

Forest roads, haul roads, and especially skid trails have been associated with sedimentation and soil erosion risk. Despite the widespread small shovel harvesting system on steep terrains in South Korea, the subsequent risks of deep (rut depth &amp;gt;5 cm) and compact disturbances, and erosion rates in skid trails are largely unknown. Therefore, the main objectives of this study were to compare the soil erosion rate in each skid trail and predict the total soil erosion rate in a small shovel harvesting area. The soil erosion rate was measured at the plot scale (5 × 3 m) in different skid trail parts (bladed skid trail by small-shovel loader passage, BT; and compacted skid trail CT by carrier passage with construction by a small-shovel loader) using a silt fence experiment. In addition, we investigated the applicability of the Water Erosion Prediction Project (WEPP) model to each disturbance. Among all disturbances, the highest erosion rate (average value of 9.13 ± 0.96 kg m−2 4 months−1) was because of CT. The model predictions were over- and under-estimated and showed particularly poor performance where uncovered soil was exposed (less than 1%) to high machine traffic frequency and excavation. Further, the annual soil erosion rates ranged from 11.59 to 28.94 ton ha−1 year−1. The results suggested that the WEPP model could partially validate the soil erosion results, and further research is still required to improve the accuracy of the model.

Impacts of forest biomass operations on forest hydrologic and soil erosion processes

The use of biomass from forests by humans has been practiced since the dawn of time. Such practices have resulted in severe watershed degradation historically and in today's world. As modern society seeks alternative energy sources, they are once again turning to forests, but now use mechanized harvesting systems to remove the biomass and transport it to processing or utilization sites. This study investigated the impacts of different mechanized biomass operations on sediment displacement, soil hydraulic conductivity, and canopy interception to determine if severe watershed impacts associated with biomass utilization in the northwest U.S.A. may occur as seen elsewhere. Three field sites were selected that used different biomass operation methods: the Payette National Forest (NF) in Idaho using a forwarder system, the Colville NF in Washington State using a tractor-skidder system, and the Flathead NF in Montana using a skyline system. A total of 47 silt fences (5 m × 10 m) were installed to monitor soil movement from biomass operations: 28 silt fences on disturbed plots and 19 on control plots. No soil loss was observed except on the forwarder trails in the Payette NF where animal disturbances were responsible for some soil movement into the silt fences. Infiltration rates measured using a constant head permeameter showed that the saturated hydraulic conductivity on the disturbed plots for the ground-based operations was lower than the control plots, but unlikely to cause significant changes in runoff on any of the plots except the Payette forwarder trails, where the saturated hydraulic conductivity values averaged only 5.3 mm h−1, compared to greater than 20 mm h−1 on all other observations. Ground cover increased on the disturbed plots to levels observed on undisturbed plots within two years. The only significant increase in bulk density was observed on the forwarder trails at the Payette NF site where the density averaged 1.41 on the trails, compared to the densities of 1.0 elsewhere. The loss of canopy observed on the three biomass studies led to a complementary study on the effects of canopy loss on snow accumulation and melt on the Priest River Experimental Forest in Northern Idaho. The study found that the canopy only intercepted an average of 7 mm of snow water equivalent during three winter months, but average annual interception of precipitation was 114 mm, indicating that interception of rainfall is greater than snow. Overall, these results suggest that there were no direct detrimental hydrologic impacts due to biomass operations except on the compacted, and sometimes pulverized forwarder trail conditions observed in the Payette NF. The impact of the canopy on rainfall interception is less than the water yield differences due to clear cutting on nearby forested watersheds that were attributed to differences in evapotranspiration.

Implementation of Forestry Best Management Practices and Sediment Delivery in Three Regions of North Carolina and Virginia

Abstract Forestry best management practices (BMPs) were created in response to the Clean Water Act of 1972 to protect water quality from nonpoint source pollutants such as sediment. The objectives of this study were to quantify the relationship between BMP implementation and sediment delivery on 58 recently harvested sites across three physiographic regions and five forest operational features. BMP implementation rates, erosion rates, sediment delivery ratios, and sediment masses were calculated at 183 silt fences functioning as sediment traps adjacent to streams in Virginia and North Carolina. Major access system features, including stream crossings, skid trails, and haul roads, typically delivered the greatest sediment mass to streams and had the highest sediment delivery ratios on a per feature basis. When accounting for sediment mass delivered and area in each feature, harvest area accounted for approximately 70% of sediment delivered to streams for all regions. Most features had proportionally higher erosion rates than sediment masses collected at silt fences, indicating that most erosion generated by forest operations is being trapped by either harvest areas or streamside management zones. For most features and regions, as BMP implementation increased, erosion rates and the sediment masses delivered to streams decreased.

SILTspread: Performance-Based Approach for the Design and Installation of Silt Fence Sediment Barriers

AbstractConstruction 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...

Consequences of Piñon-Juniper Woodland Fuel Reduction: Prescribed Fire Increases Soil Erosion While Mastication Does Not

Fire suppression has increased fuel load and the risk of catastrophic wildfire in forest and woodland ecosystems across the Western United States. In an effort to reduce fuel load and restore historical structure and function, land managers have implemented fuel reduction treatments on millions of acres. Reducing fuel loads protects people, structures, and in some cases, improves ecosystem health. However, the ecological risks of soil surface disturbance related to fuel reduction strategies, and subsequent soil erosion, may be significant in some cases. Here, we examined the effects of common fuel reduction strategies (mechanical mastication and two techniques for prescribed burning) on wind and water erosion in two upland pinon-juniper woodlands in SE Utah over 2 years. We also tested the impact of broadcast seeding coupled with fuel reduction as a way to mitigate erosional soil loss. Finally, we analyzed biotic and abiotic predictor variables to evaluate important drivers of soil erosion following fuel treatments. We found that both techniques for prescribed burning—pile burning and broadcast burning—increased wind-related sediment fluxes by an average of 11-fold and 58-fold, respectively. Mastication did not increase wind-related losses over untreated controls. Erosional fluxes measured at silt fences, that captured both wind- and water-driven sediments, followed similar trends with moderate increases from pile burning (fivefold) but larger increases from broadcast burning (17-fold). Seeding did not affect erosion rates. Our results suggest that prescribed fire significantly increases soil erosion in fuel-treated pinon-juniper woodlands and may be a degradation pathway when implementing treatments.

Evaluating Exclusion Barriers for Treefrogs in Agricultural Landscapes

ABSTRACTAgricultural co‐management aims to promote environmental sustainability while maintaining food‐safety standards. Amphibians, especially treefrogs, are known to enter fields of fresh produce intended for human consumption, which raises concerns for food safety and quality. We evaluated the effects of modifications to reduce the scalability of exclusion barriers on the fence‐crossing behavior of Pacific treefrogs (Hyliola regilla) from lettuce fields in the Salinas Valley of California during January to May 2019. From small‐scale field experiments, we found that fences modified with a horizontal lip at the top prevented all treefrogs from successfully crossing over. Fences incorporating sandpaper were also effective at deterring treefrog crossings compared to fences made of fiberglass square mesh (window screen) and polypropylene fabric (silt fence). The fence design that inhibited the most treefrog crossings—aluminum flashing with a horizontal lip—was a modification to commercially available material that is feasible to install at large scales, is durable over long periods of time, and can help to exclude additional nuisance wildlife, such as small mammals and lizards. Our findings provide quantitative evidence on the efficacy of an exclusion barrier constructed with off‐the‐shelf material that can be easily modified to improve the co‐management of amphibians and agriculture. © 2021 The Authors. Wildlife Society Bulletin published by Wiley Periodicals LLC on behalf of The Wildlife Society.

Field Evaluation of Wattle and Silt Fence Ditch Checks

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.

Practical Silt Fence Design Enhancements for Effective Dewatering and Stability

AbstractMany 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...

Evaluating post‐wildfire logging‐slash cover treatment to reduce hillslope erosion after salvage logging using ground measurements and remote sensing

AbstractContinuing long and extensive wildfire seasons in the Western US emphasize the need for better understanding of wildfire impacts including post‐fire management scenarios. Advancements in our understanding of post‐fire hillslope erosion and watershed response such as flooding, sediment yield, and debris flows have recently received considerable attention. The potential impacts of removing dead trees, called salvage logging, has been studied, however the use of remotely sensed imagery after salvage logging to evaluate spatial patterns and recovery is novel. The 2015 North Star Fire provided an opportunity to evaluate hillslope erosion reduction using two field experiments and coincidental remotely sensed imagery over 3 years. Simulated rill experiments with four flow rates were used to quantify hillslope erosion on skidder trails with and without added logging slash compared with a burned‐only control. Seven replicated hillslope silt fence plots with the same treatments were also evaluated for natural rainfall events. WorldView‐2 satellite imagery was used to relate ground cover and erodible bare soil between the two experiments using multi‐temporal Normalized Differenced Vegetation Index (NDVI) values. Results indicate that the skid trails produced significantly more sediment (0.70 g s−1) than either the slash treated skid trail (0.34 g s−1) or controls (0.04 g s−1) with the simulated rill experiment. Similarly, under natural rainfall conditions sediment yield from hillslope silt fence plots was significantly greater for the skid trail (3.42 Mg ha−1) than either the slash treated skid trail (0.18 Mg ha−1) or controls (0 Mg ha−1). An NDVI value of 0.32 on all plots over all years corresponded to a ground cover of about 60% which is an established threshold for erosion reduction. Significant relationships between NDVI, ground cover, and sediment values suggest that NDVI may help managers evaluate ground cover and erosion potential remotely after disturbances such as a wildfire or salvage logging.

Evaluation of adaptation options for reducing soil erosion due to climate change in the Swat River Basin of Pakistan

Changes in climate have a direct impact on basin hydrology, soil erosion, and sediment yield and this could adversely affect the water availability and efficiency of hydraulic structures. Hence, there is a need to assess the relationship between climate, hydrology, and related processes. In this study, future climate data on three regional climate models: REMO, CNRM, and MPI under RCP 4.5 and 8.5 scenarios are downscaled using linear scaling techniques to create climate change scenarios in the Swat River Basin of Pakistan. In this study, the relationships between climate, discharge, and sediment yield are analysed using the Soil and Water Assessment Tool (SWAT), while also evaluating the effectiveness of two adaptation options: sediment management, i.e., check dams, silt fences, terraces, and sediment basins; and two erosion reduction options, i.e., filter strips and grassed waterways. Based on the results, an overall increase in temperature of 0.6 to 2.3 °C in the 2020s, 1.1 to 3.3 °C in the 2050s, and 2 to 5.6 °C in the 2080s is projected relative to the baseline period (1979–2005). The precipitation change varies from −24 to 34%. The model R2 values are 0.67 and 0.75, while NSE values are 0.63 and 0.74 during calibration (1984–1993) and validation periods (1994–2001), respectively. The overall change in future streamflow is predicted to vary from −28 to 28%. The projected annual average sediment yield at the outlet of the basin follows a pattern similar to that exhibited by precipitation and discharge. The results indicate that the provision of terraces, silt fences, a sediment basin, check dam, filter strips, and grassed waterway reduce the sediment yield in the basin by 73, 66, 65, 58, 54, and 48%, respectively. We conclude that a sediment basin is the most economical option for the management of soil erosion under climate change in the case of the Swat River.

Interaction of wind and cold‐season hydrologic processes on erosion from complex topography following wildfire in sagebrush steppe

AbstractWildfire is a natural component of sagebrush (Artemisia spp.) steppe rangelands that induces temporal shifts in plant community physiognomy, ground surface conditions, and erosion rates. Fire alteration of the vegetation structure and ground cover in these ecosystems commonly amplifies soil losses by wind‐ and water‐driven erosion. Much of the fire‐related erosion research for sagebrush steppe has focused on either erosion by wind over gentle terrain or water‐driven erosion under high‐intensity rainfall on complex topography. However, many sagebrush rangelands are geographically positioned in snow‐dominated uplands with complex terrain in which runoff and sediment delivery occur primarily in winter months associated with cold‐season hydrology. Current understanding is limited regarding fire effects on the interaction of wind‐ and cold‐season hydrologic‐driven erosion processes for these ecosystems. In this study, we evaluated fire impacts on vegetation, ground cover, soils, and erosion across spatial scales at a snow‐dominated mountainous sagebrush site over a 2‐year period post‐fire. Vegetation, ground cover, and soil conditions were assessed at various plot scales (8 m2 to 3.42 ha) through standard field measures. Erosion was quantified through a network of silt fences (n = 24) spanning hillslope and side channel or swale areas, ranging from 0.003 to 3.42 ha in size. Sediment delivery at the watershed scale (129 ha) was assessed by suspended sediment samples of streamflow through a drop‐box v‐notch weir. Wildfire consumed nearly all above‐ground live vegetation at the site and resulted in more than 60% bare ground (bare soil, ash, and rock) in the immediate post‐fire period. Widespread wind‐driven sediment loading of swales was observed over the first month post‐fire and extensive snow drifts were formed in these swales each winter season during the study. In the first year, sediment yields from north‐ and south‐facing aspects averaged 0.99–8.62 t ha−1 at the short‐hillslope scale (~0.004 ha), 0.02–1.65 t ha−1 at the long‐hillslope scale (0.02–0.46 ha), and 0.24–0.71 t ha−1 at the swale scale (0.65–3.42 ha), and watershed scale sediment yield was 2.47 t ha−1. By the second year post fire, foliar cover exceeded 120% across the site, but bare ground remained more than 60%. Sediment yield in the second year was greatly reduced across short‐ to long‐hillslope scales (0.02–0.04 t ha−1), but was similar to first‐year measures for swale plots (0.24–0.61 t ha−1) and at the watershed scale (3.05 t ha−1). Nearly all the sediment collected across all spatial scales was delivered during runoff events associated with cold‐season hydrologic processes, including rain‐on‐snow, rain‐on‐frozen soils, and snowmelt runoff. Approximately 85–99% of annual sediment collected across all silt fence plots each year was from swales. The high levels of sediment delivered across hillslope to watershed scales in this study are attributed to observed preferential loading of fine sediments into swale channels by aeolian processes in the immediate post‐fire period and subsequent flushing of these sediments by runoff from cold‐season hydrologic processes. Our results suggest that the interaction of aeolian and cold‐season hydrologic‐driven erosion processes is an important component for consideration in post‐fire erosion assessment and prediction and can have profound implications for soil loss from these ecosystems. © 2019 John Wiley &amp; Sons, Ltd.