DOCSLIB.ORG

Urban Soil Erosion and Sediment Control

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Urban Soil Erosion and Sediment Control United States Department of Agriculture Association of Illinois Natural Resources Soil and Water Conservation Service Conservation Districts Urban Soil Erosion and Sediment Control Conservation Practices for Protecting and Enhancing Soil and Water Resources in Growing and Changing Communities March 2008 Urban Soil Erosion and Sediment Control Conservation Practices for Protecting and Enhancing Soil and Water Resources Introduction What’s inside Land use change is a fact of life for many communities in Illinois. From cities to suburbs to rural villages, farmland Page Topic is being developed to accommodate a population that wants larger homes, larger lots and more shopping, 2 Water Quality Regulations for Illinois recreation, schools and roads. 3 What is Soil Erosion and What is Sediment? 4 How to Control Erosion? These land use changes are intensifying pressure on the 5 Grading Strategies and Dust Control 6 Temporary/Permanent Vegetation and Mulching natural environment. When land is under construction, 7 Rolled Erosion Control Products (RECPs) and soil erosion can be significant – often many times greater Compost Blanket than on land used for agriculture. The resulting sediment 8 PAM* Application for Erosion Control and Outlet damages surface water resources (including community Protection water supplies), obstructs roads and degrades wildlife 9 How to Control Sediment? habitat. 10 Silt Barriers/Filters and Stabilized Construction Entrance Once developed, the land has more roofs, roads, parking 11 Inlet Protection and Sediment Basin/Trap lots, and compacted turf. Impervious surfaces like these 12 PAM* Application for Sediment Control and Filter send more runoff across landscapes, and consequently, Strips the risk of flooding is increased. Urban runoff impairs 13 Where to go for help and Additional Information water quality in streams, lakes and wetlands by delivering *PAM = polyacrylamide (water-soluble anionic) sediment, nutrients, hydrocarbons and other pollutants. Ground water recharge is also reduced by impervious surfaces. This brochure provides information about specific strategies for addressing soil erosion and sediment control on construction sites and on land that is already developed. It will help local decision-makers meet the changing land use needs of communities without compromising the need for clean and abundant water, protection from flooding, recreation amenities, and preserving wildlife habitat. Developers, planners, engineers, local units of government, and interested citizens will find this brochure helpful for understanding: • Soil erosion and sedimentation processes and issues, • Illinois water quality laws and regulations related to erosion and sedimentation, Aerial photo with contour lines showing lakes and wetlands • Specific practices that protect local natural that will need protection if adjacent upland areas are resources by controlling soil erosion and disturbed for future development. sedimentation. For each practice, this guide will: • Provide a description, For more information on practice selection, design, • List design techniques for implementation, implementation and maintenance, refer to the most current • Indicate challenges or limitations that may limit edition of the Illinois Environmental Protection Agency’s effectiveness, “Illinois Urban Manual: A Technical Manual Designed for • Illustrate with photos. Urban Ecosystem Protection and Enhancement.” (This list of practices is not all inclusive and may not work for every situation. Evaluation of each situation must be made before deciding on a specific practice.) 1 Why be concerned? Urban runoff and construction Nonpoint Pollutants site erosion have been identified as Most common pollutants from Urban Land after Construction is significant sources of pollution for surface completed: water quality. • Nutrients Sediment deposits destroy fish • Hydrocarbons spawning areas, resulting in the loss • Pathogens of sensitive or threatened fish species; • Sediment & Road Grit adversely impact aquatic insects which • Organic Matter (e.g. lawn clippings, leaves) are at the base of the food chain; reduce • Litter channel capacity; and decrease the • Thermal Pollution (heated runoff from impervious surfaces) overall quality of lakes, streams and wetlands. Sedimentation can cause flooding; piers, pipelines, dredging, discharging or In addition, in designated require additional water treatment; pose other work in navigational waters of the urbanized areas, there are regulations safety and nuisance issues on roadways; U.S. requiring permit applications for storm and increase cost of construction and water discharges for industrial sources maintenance. Chemicals (such as Clean Water Act of 1977 (CWA) and municipal separate storm sewer some pesticides, phosphorus, as well Formerly known as the Federal Water systems (MS4’s). Communities with as toxicants and trace metals) can be Pollution Control Act, this statute was greater than 10,000 population (ILR40 transported with sediment to receiving enacted to address the problem of water permit) are required to implement six waters where they cause additional quality by reducing the discharge of minimum control measures to improve damage to aquatic ecosystems. pollutants into lakes, rivers, streams and the quality of storm water runoff. The And lastly, it is a Federal, state and wetlands. The CWA established a system control measures include the following: sometimes local law to place good soil of water quality standards, discharge • Storm water runoff control from erosion and sediment control practices limitations and permits. construction sites. on construction sites. In Illinois, US-EPA has delegated • Post-construction storm water responsibility for Section 401 and 402 to management for developments. the Illinois EPA. Prior to the issuance of • Detection and elimination of illicit Nonpoint Pollutants either a Section 402 or 404 permit, you discharges to storm sewer systems. Most common pollutants from must obtain a Section 401 certification. • Public education and outreach construction sites: This states that any discharge complies regarding storm water runoff • Sediment with all applicable effluent limitations impacts. • Oil & Greases and water quality standards in Illinois. • Public involvement in storm water • Concrete Truck Washout See the following for each Section runoff related issues. • Construction Debris explanation. • Good housekeeping procedures and • Construction Chemicals practices. Section 401-Water Quality Water Quality Regulations Certification Section 404-Dredge or Fill (What the Law Requires) You must receive the Section Permitting You should be aware that the US Army 401 certification before applying for a Establishes a permit program to Corps of Engineers (Corps) and the US federal permit for any work, which may regulate the discharge of dredged or Environmental Protection Agency (US- result in a discharge to waters of the fill material into waters of the U.S., EPA) are the two federal agencies that U.S., to ensure that actions would not including some wetlands. This section regulate water quality. Both agencies violate Illinois’ water quality standards. of the CWA is administered by the have authority under Section 404 of the Corps. Clean Water Act (CWA), but only the Section 402 – National Pollutant Corps has the authority under Section 10 Discharge Elimination System Ordinances in Illinois of the Rivers and Harbors Act. A review (NPDES) Check to see if your county or by other federal and state agencies, as NPDES requires that a Storm municipality has implemented ordinances well as public notification, is provided Water Pollution Prevention Plan or other enforcement mechanisms prior to the issuance or denial of permit. (SWPPP), including a soil erosion and that require water quality and quantity sediment control plan, be developed issues be addressed during the land Section 10 – Rivers and Harbors Act for all construction activity projects that development process. Ordinances often of 1899 (RHA) require a permit. require the implementation of both Under the RHA, the Corps regulates Current regulations require a temporary and permanent “Practices”. “all work or structures” placed in or permit for ALL construction activities in The development of a soil erosion affecting the navigational waters of the Illinois (ILR10 permit) that disturb one and sediment control plan prior to the U.S. You are required to get a permit (1) acre or more, or smaller projects onset of construction is also often a from the Corps for marinas, bulkheads, that are part of a larger common plan requirement of these ordinances. bank stabilization, shoreline protection, of development or sale. 2 What is Soil Erosion? Erosion is a three-step process involving the detachment, transport and deposition of soil particles. There are many kinds of erosion. Sheet and rill erosion, gully erosion, streambank/bed erosion and wind erosion are the primary concerns. Each of these types of erosion involves the detachment and transport of soil and downstream/downwind deposition of sediment. What is Sediment? Sediment is the result of erosion. Once soil particles have detached from the surface, are transported from their site of origin and have come to rest on other ground surfaces or in lakes, ponds, watercourses, or wetlands, they are referred to as sediment. The process of soil particles being transported and deposited is known as sedimentation. Types of Erosion Mechanism for Sheet & Rill Erosion: Gully Erosion: Rill Streambank and Wind
Load more

Recommended publications
  • The Role of Geosynthetics in Erosion and Sediment Control: an Overview
    Geotextiles and Geomembranes I I (1992) 535-550 The Role of Geosynthetics in Erosion and Sediment Control: An Overview M. S. Theisen Erosion Control Materials, Synthetic Industries, Construction Products Division, 4019 Industry Drive, Chattanooga, Tennessee 37416, USA ABSTRACT The use ofgeosynthetic erosion and sediment materials continues to expand at a rapid pace. From their early beginnings in the late 1950s, geosynthetic materials today are the backbone of the erosion and sediment control industry. Geosynthetic components are an integral part of erosion and sediment materials ranging from temporary products such as hydraulic mulch geofibers, plastic erosion control meshes and nettings, erosion control blankets and silt fences to high performance turf reinforcement mats, geocellular confinement systems, erosion control geotextiles andfabric formed revetments. This paper provides a brief overview of these materials and concepts. INTRODUCTION Hopefully we are entering a new environmental era where concern for the protection of our planet's natural resources will reach global proportions. Continued technological advances have led to improved monitoring of Earth's vital signs. As such, prior theoretical modeling of environmental concerns such as the greenhouse effect, ozone depletion, rising sea levels, deforestation, drought, accelerated erosion, sediment loading of waterways, species extinction and the eventual downfall of mankind appear chillingly realistic. 535 536 M. S. Theisen Slogans such as 'Think globally, act locally', 'Love your mother' and 'Someone always lives downstream' are spearheading the efforts of numerous preservation groups. With the continued demise of oppressive governments, optimism for world peace and an unprecedented feeling of global unity, a spirit of environmental cooperation is beginning to prevail.
    [Show full text]
  • Protection Against Wave-Based Erosion
    Protection against Wave­based Erosion The guidelines below address the elements of shore structure design common to nearly all erosion control structures subject to direct wave action and run-up. 1. Minimize the extent waterward. Erosion control structures should be designed with the smallest waterward footprint possible. This minimizes the occupation of the lake bottom, limits habitat loss and usually results in a lower cost to construct the project. In the case of stone revetments, the crest width should be only as wide as necessary for a stable structure. In general, the revetment should follow the cross-section of the bluff or dune and be located as close to the bluff or dune as possible. For seawalls, the distance that the structure extends waterward of the upland must be minimized. If the seawall height is appropriately designed to prevent the majority of overtopping, there is no engineering rationale based only on erosion control which justifies extending a seawall out into the water. 2. Minimize the impacts to adjacent properties. The design of the structure must consider the potential for damaging adjacent property. Projects designed to extend waterward of the shore will affect the movement of littoral material, reducing the overall beach forming process which in turn may cause accelerated erosion on adjacent or down-drift properties with less protective beaches. Seawalls, (and to a lesser extent, stone revetments) change the direction (wave reflection) and intensity of wave energy along the shore. Wave reflection can cause an increase in the total energy at the seawall or revetment interface with the water, allowing sand and gravel to remain suspended in the water, which will usually prevent formation of a beach directly fronting the structure.
    [Show full text]
  • Effects of Erosion Control Practices on Nutrient Loss
    Effects of Erosion Control Practices on Nutrient Loss George F. Czapar, University of Illinois John M. Laflen, Iowa State University Gregory F. McIsaac, University of Illinois Dennis P. McKenna, Illinois Department of Agriculture Elements of Soil Erosion Soil erosion by water is the detachment of soil particles by the direct action of raindrops and runoff water, and the transport of these particles by splash and very shallow flowing water to small channels or rills. Detachment of soil particles also occurs in these rills due to the force exerted by the flowing water. When rills join together and form larger channels, they may become gullies. These gullies can be either temporary (ephemeral) or permanent (classical). Non-erodible channels might be grassed waterways, or designed channels that limit flow conditions so that channel erosion does not occur. Gross erosion includes sheet, rill, gully and channel erosion, and is the first step in the process of sediment delivery. Because much eroded sediment is deposited in or near the field of origin, only a fraction of the total eroded soil from an area contributes to sediment yield from a watershed. Sediment delivery is affected by a number of factors including soil properties, proximity to the stream, man made structures-including sediment basins, fences, and culverts, channel density, basin characteristics, land use/land cover, and rainfall-runoff factors. Coarse- textured sediment and sediment from sheet and rill erosion are less likely to reach a stream than fine-grained sediment or sediment from channel erosion. In general, the larger the area, the lower the ratio of sediment yield at the watershed outlet or point of interest to gross erosion in the entire watershed, defined as the sediment delivery ratio (SDR).
    [Show full text]
  • Sediment Transport in the San Francisco Bay Coastal System: an Overview
    Marine Geology 345 (2013) 3–17 Contents lists available at ScienceDirect Marine Geology journal homepage: www.elsevier.com/locate/margeo Sediment transport in the San Francisco Bay Coastal System: An overview Patrick L. Barnard a,⁎, David H. Schoellhamer b,c, Bruce E. Jaffe a, Lester J. McKee d a U.S. Geological Survey, Pacific Coastal and Marine Science Center, Santa Cruz, CA, USA b U.S. Geological Survey, California Water Science Center, Sacramento, CA, USA c University of California, Davis, USA d San Francisco Estuary Institute, Richmond, CA, USA article info abstract Article history: The papers in this special issue feature state-of-the-art approaches to understanding the physical processes Received 29 March 2012 related to sediment transport and geomorphology of complex coastal–estuarine systems. Here we focus on Received in revised form 9 April 2013 the San Francisco Bay Coastal System, extending from the lower San Joaquin–Sacramento Delta, through the Accepted 13 April 2013 Bay, and along the adjacent outer Pacific Coast. San Francisco Bay is an urbanized estuary that is impacted by Available online 20 April 2013 numerous anthropogenic activities common to many large estuaries, including a mining legacy, channel dredging, aggregate mining, reservoirs, freshwater diversion, watershed modifications, urban run-off, ship traffic, exotic Keywords: sediment transport species introductions, land reclamation, and wetland restoration. The Golden Gate strait is the sole inlet 9 3 estuaries connecting the Bay to the Pacific Ocean, and serves as the conduit for a tidal flow of ~8 × 10 m /day, in addition circulation to the transport of mud, sand, biogenic material, nutrients, and pollutants.
    [Show full text]
  • Sedimentation and Clarification Sedimentation Is the Next Step in Conventional Filtration Plants
    Sedimentation and Clarification Sedimentation is the next step in conventional filtration plants. (Direct filtration plants omit this step.) The purpose of sedimentation is to enhance the filtration process by removing particulates. Sedimentation is the process by which suspended particles are removed from the water by means of gravity or separation. In the sedimentation process, the water passes through a relatively quiet and still basin. In these conditions, the floc particles settle to the bottom of the basin, while “clear” water passes out of the basin over an effluent baffle or weir. Figure 7-5 illustrates a typical rectangular sedimentation basin. The solids collect on the basin bottom and are removed by a mechanical “sludge collection” device. As shown in Figure 7-6, the sludge collection device scrapes the solids (sludge) to a collection point within the basin from which it is pumped to disposal or to a sludge treatment process. Sedimentation involves one or more basins, called “clarifiers.” Clarifiers are relatively large open tanks that are either circular or rectangular in shape. In properly designed clarifiers, the velocity of the water is reduced so that gravity is the predominant force acting on the water/solids suspension. The key factor in this process is speed. The rate at which a floc particle drops out of the water has to be faster than the rate at which the water flows from the tank’s inlet or slow mix end to its outlet or filtration end. The difference in specific gravity between the water and the particles causes the particles to settle to the bottom of the basin.
    [Show full text]
  • Shoreline Management in Chesapeake Bay C
    Shoreline Management In Chesapeake Bay C. S. Hardaway, Jr. and R. J. Byrne Virginia Institute of Marine Science College of William and Mary 1 Cover Photo: Drummond Field, Installed 1985, James River, James City County, Virginia. This publication is available for $10.00 from: Sea Grant Communications Virginia Institute of Marine Science P. O. Box 1346 Gloucester Point, VA 23062 Special Report in Applied Marine Science and Ocean Engineering Number 356 Virginia Sea Grant Publication VSG-99-11 October 1999 Funding and support for this report were provided by... Virginia Institute of Marine Science Virginia Sea Grant College Program Sea Grant Contract # NA56RG0141 Virginia Coastal Resource Management Program NA470Z0287 WILLIAM& MARY Shoreline Management In Chesapeake Bay By C. Scott Hardaway, Jr. and Robert J. Byrne Virginia Institute of Marine Science College of William and Mary Gloucester Point, Virginia 23062 1999 4 Table of Contents Preface......................................................................................7 Shoreline Evolution ................................................................8 Shoreline Processes ..............................................................16 Wave Climate .......................................................................16 Shoreline Erosion .................................................................20 Reach Assessment ................................................................23 Shoreline Management Strategies ......................................24 Bulkheads and Seawalls
    [Show full text]
  • Audubon Bend Gravel Road Repair Gavins Point Dam, SD
    SPECIFICATIONS & DRAWINGS (Purchase Order - For Construction Contract) Solicitation Number W9128F21Q0018 ____________________________________________________________ Audubon Bend Gravel Road Repair Gavins Point Dam, SD March 2021 US Army Corps of Engineers Omaha District This page was intentionally left blank for duplex printing. AUDUBON BEND GRAVEL ROAD REPAIR GAVINS POINT DAM, SD PROJECT TABLE OF CONTENTS DIVISION 00 - PROCUREMENT AND CONTRACTING REQUIREMENTS 00 10 00-3 PRICING SCHEDULE STATEMENT OF WORK 00 73 00 SUPPLEMENTARY CONDITIONS (SPECIAL CONTRACT REQUIREMENTS)FOR PURCHASE ORDERS DIVISION 01 - GENERAL REQUIREMENTS 01 22 00 MEASUREMENT AND PAYMENT 01 33 00 SUBMITTAL PROCEDURES 01 41 26.02 24 (NEBRASKA) NPDES PERMIT REQUIREMENTS FOR STORM WATER DISCHARGES FROM CONSTRUCTION SITES 01 57 20.00 10 ENVIRONMENTAL PROTECTION 01 57 23 TEMPORARY STORM WATER POLLUTION CONTROL DRAWINGS -- End of Project Table of Contents -- Page 1 This page was intentionally left blank for duplex printing. Audubon Bend Gravel Road Repairs, Gavins Point Dam, NE GP82 SECTION 00 10 00 PRICING SCHEDULE CLIN DESCRIPTION QTY UNIT UNIT PRICE AMOUNT BASE ITEMS 0001 Mobilization and Demobilization 1 JOB XXX $_______________ Blade entire length of road surface prior to placing gravel to smooth out 0002 1 JOB XXX $_______________ scour holes, rebuild crown. Includes areas over culverts. – 4,750 FEET Reset existing 24’’ CMP with flared 0003 ends to properly drain to North East – 1 JOB XXX $_______________ 1 EACH. Install new USACE provided 48’’ 0004 culvert with flared end (includes trees’ 1 JOB XXX $_______________ removal as necessary) – 1 EACH. Reconstruct approximately 270’ of 0005 eroded road at the existing culvert 720 CY $_______________ $_______________ (includes sodding and seeding).
    [Show full text]
  • Agricultural Soil Compaction: Causes and Management
    October 2010 Agdex 510-1 Agricultural Soil Compaction: Causes and Management oil compaction can be a serious and unnecessary soil aggregates, which has a negative affect on soil S form of soil degradation that can result in increased aggregate structure. soil erosion and decreased crop production. Soil compaction can have a number of negative effects on Compaction of soil is the compression of soil particles into soil quality and crop production including the following: a smaller volume, which reduces the size of pore space available for air and water. Most soils are composed of • causes soil pore spaces to become smaller about 50 per cent solids (sand, silt, clay and organic • reduces water infiltration rate into soil matter) and about 50 per cent pore spaces. • decreases the rate that water will penetrate into the soil root zone and subsoil • increases the potential for surface Compaction concerns water ponding, water runoff, surface soil waterlogging and soil erosion Soil compaction can impair water Soil compaction infiltration into soil, crop emergence, • reduces the ability of a soil to hold root penetration and crop nutrient and can be a serious water and air, which are necessary for water uptake, all of which result in form of soil plant root growth and function depressed crop yield. • reduces crop emergence as a result of soil crusting Human-induced compaction of degradation. • impedes root growth and limits the agricultural soil can be the result of using volume of soil explored by roots tillage equipment during soil cultivation or result from the heavy weight of field equipment. • limits soil exploration by roots and Compacted soils can also be the result of natural soil- decreases the ability of crops to take up nutrients and forming processes.
    [Show full text]
  • Erosion-1.Pdf
    R E S O U R C E L I B R A R Y E N C Y C L O P E D I C E N T RY Erosion Erosion is the geological process in which earthen materials are worn away and transported by natural forces such as wind or water. G R A D E S 6 - 12+ S U B J E C T S Earth Science, Geology, Geography, Physical Geography C O N T E N T S 9 Images For the complete encyclopedic entry with media resources, visit: http://www.nationalgeographic.org/encyclopedia/erosion/ Erosion is the geological process in which earthen materials are worn away and transported by natural forces such as wind or water. A similar process, weathering, breaks down or dissolves rock, but does not involve movement. Erosion is the opposite of deposition, the geological process in which earthen materials are deposited, or built up, on a landform. Most erosion is performed by liquid water, wind, or ice (usually in the form of a glacier). If the wind is dusty, or water or glacial ice is muddy, erosion is taking place. The brown color indicates that bits of rock and soil are suspended in the fluid (air or water) and being transported from one place to another. This transported material is called sediment. Physical Erosion Physical erosion describes the process of rocks changing their physical properties without changing their basic chemical composition. Physical erosion often causes rocks to get smaller or smoother. Rocks eroded through physical erosion often form clastic sediments.
    [Show full text]
  • Estuarine and Coastal Sedimentation Problems1
    ESTUARINE AND COASTAL SEDIMENTATION PROBLEMS1 Leo C. van Rijn Delft Hydraulics and University of Utrecht, The Netherlands. E•mail: [email protected] Abstract: This Keynote Lecture addresses engineering sedimentation problems in estuarine and coastal environments and practical solutions of these problems based on the results of field measurements, laboratory scale models and numerical models. The three most basic design rules are: (1) try to understand the physical system based on available field data; perform new field measurements if the existing field data set is not sufficient (do not reduce on the budget for field measurements); (2) try to estimate the morphological effects of engineering works based on simple methods (rules of thumb, simplified models, analogy models, i.e. comparison with similar cases elsewhere); and (3) use detailed models for fine•tuning and determination of uncertainties (sensitivity study trying to find the most influencial parameters). Engineering works should be designed in a such way that side effects (sand trapping, sand starvation, downdrift erosion) are minimum. Furthermore, engineering works should be designed and constructed or built in harmony rather than in conflict with nature. This ‘building with nature’ approach requires a profound understanding of the sediment transport processes in morphological systems. Keywords: Sedimentation, sediment transport, morphological modelling 1. INTRODUCTION This lecture addresses sedimentation and erosion engineering problems in estuaries and coastal seas and practical solutions of these problems based on the results of field measurements, laboratory scale models and numerical models. Often, the sedimentation problem is a critical element in the economic feasibility of a project, particularly when each year relatively large quantities of sediment material have to be dredged and disposed at far•field locations.
    [Show full text]
  • The Evolution of Geosynthetics in Erosion and Sediment Control
    Presented at GRI-25, Geosynthetics Research Institute, Long Beach, CA, 2013 THE EVOLUTION OF GEOSYNTHETICS IN EROSION AND SEDIMENT CONTROL C. Joel Sprague TRI/Environmental, Inc., Greenville, SC ABSTRACT Much of the development of geosynthetics technology in environmental applications has been in response to government regulations. This is certainly true for geosynthetics used in erosion and sediment control. Geosynthetics continue to replace traditional materials such as soil and stone in performing important engineering functions in erosion and sediment control applications while simultaneously introducing greater versatility and cost-effectiveness. Geosynthetics are widely used as a “carrier” for degradable materials to the enhancement of vegetative establishment; as nondegradable materials to extend the erosion control limits of vegetation or soil; as primary slope or channel linings; as components in silt fences and turbidity curtains; and as a component in an ever growing array of sediment retention devices. Along with the introduction of geosynthetics into this wide range of applications has come the need for industry-wide initiatives to promote their correct use and new test methods to characterize them. All of which, are a “work in progress”. THE NEED FOR EROSION AND SEDIMENT CONTROLS Much of the development of geosynthetics technology related to erosion and sediment control applications has been in response to government regulations. A progression of regulatory actions has brought a national focus on erosion and sediment control, including: Amendments to the Federal Water Pollution Control Act (1985) - eliminating discharge of any pollutant to navigable waters. The Clean Water Act (1987) - requiring National Pollution Discharge Elimination System (NPDES) Permits for large construction sites.
    [Show full text]
  • Progressive and Regressive Soil Evolution Phases in the Anthropocene
    Progressive and regressive soil evolution phases in the Anthropocene Manon Bajard, Jérôme Poulenard, Pierre Sabatier, Anne-Lise Develle, Charline Giguet- Covex, Jeremy Jacob, Christian Crouzet, Fernand David, Cécile Pignol, Fabien Arnaud Highlights • Lake sediment archives are used to reconstruct past soil evolution. • Erosion is quantified and the sediment geochemistry is compared to current soils. • We observed phases of greater erosion rates than soil formation rates. • These negative soil balance phases are defined as regressive pedogenesis phases. • During the Middle Ages, the erosion of increasingly deep horizons rejuvenated pedogenesis. Abstract Soils have a substantial role in the environment because they provide several ecosystem services such as food supply or carbon storage. Agricultural practices can modify soil properties and soil evolution processes, hence threatening these services. These modifications are poorly studied, and the resilience/adaptation times of soils to disruptions are unknown. Here, we study the evolution of pedogenetic processes and soil evolution phases (progressive or regressive) in response to human-induced erosion from a 4000-year lake sediment sequence (Lake La Thuile, French Alps). Erosion in this small lake catchment in the montane area is quantified from the terrigenous sediments that were trapped in the lake and compared to the soil formation rate. To access this quantification, soil processes evolution are deciphered from soil and sediment geochemistry comparison. Over the last 4000 years, first impacts on soils are recorded at approximately 1600 yr cal. BP, with the erosion of surface horizons exceeding 10 t·km− 2·yr− 1. Increasingly deep horizons were eroded with erosion accentuation during the Higher Middle Ages (1400–850 yr cal.
    [Show full text]