DOCSLIB.ORG

Sedimentation

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Sedimentation United States Department of National Agriculture Soil Engineering Conservation Service Handbook Section 3 Sedimentation Chapter 6 Sediment Sources, Yields, and Delivery Ratios Contents Page Introduction .............................................................................. 6-1 L' General ................................................................................6-1 Interrelationship of processes .............................................................. 6-1 Sedimentsources ..........................................................................6-2 General ................................................................................6-2 Determining the relative importance of various sources ......................................... 6-2 Mapsandaerialphotographs ............................................................. 6-2 Distinctiveminerals .................................................................... 6-2 Colluviation ...........................................................................6-2 Procedure ............................................................................. 6-2 Sediment yield ............................................................................ 6-3 General ................................................................................6-3 Climaticfactors .........................................................................6-3 Watershedfactors ........................................................................ 6-3 Size .................................................................................. 6-3 Topography ...........................................................................6-4 Channeldensity ....................................................................... 6-4 Soilandcoverconditions ................................................................. 6-4 Landuse .............................................................................. 6-4 Methods of determination ................................................................. 6-5 Gross erosion and the sediment delivery ratio ................................................ 6-5 Measuredsedimentaccumulation ......................................................... 6-5 Suspended load records .................................................................. 6-6 Predictiveequations .................................................................... 6-6 Informationsources ...................................................................... 6-6 Sediment delivery ratio ..................................................................... 6-8 L1Influencing factors ...................................................................... 6-8 Sediment source ....................................................................... 6-8 Proximity of sediment sources ............................................................ 6-8 Transportsystem .............................................................i. ........ 6-8 Texture of eroded material ............................................................... 6-9 Depositionalarea ...................................................................... 6-9 Watershed characteristics ............................................................... 6-9 Procedures for estimating the sediment delivery ratio ........................................... 6-9 Size of drainage area .................................................................... 6-10 Relief-lengthratio ......................................................................6-10 Source-texture analysis .................................................................. 6-10 Source deposition ....................................................................... 6-11 Summary ................................................................................ 6-12 References ...............................................................................6-13 Figures Page 6-1. Asedimentratingcurve ............................................. ................ 6-7 6-2. Relationship between drainage area and sediment delivery ratio ............ ................ 6-11 Tables Page 6-1. Sediment yield from various sources ..................................................... 6-3 6-2. Sediment source and the delivery ratio ................................................... 6-11 Chapter 6 Sediment Sources, Yields, and Delivery Ratios Introduction General watershed and on the transport of eroded material out of the watershed. Only part of the material C Sediment yield depends on the erosion processes eroded from uplant areas in a watershed is carried at the sediment source and on the efficiency of the out of the watershed. Variation in the proportion of system, that transports the sediment to the point of the eroded material deposited as colluvium at the measurement. The sediment yield usually differs at base of slopes and in swales, as alluvium on flood different locations in a stream system. plains and in channels, and as lacustrine deposits Many interrelated factors affect sediment yield. in natural or artificial lakes usually results in Knowledge of each of these factors is important in: variation in the yield rate for different parts of a 1. Evaluating downstream sediment damages. watershed. 2. Determining the location and extent of sedi- Field determination of sediment yield may require ment sources so that effective controls can be plan- long-term sampling and measuring procedures. A ned and installed. short-term procedure is to extrapolate (and adjust as 3. Recognizing the relative contribu Eon of the appropriate) known sediment yield from measured various sources to present and future sedi lent similar watershed in the same physiographic yield. section. 4. Determining the sediment storage require- ment for designing proposed structural works of improvement. This chapter presents several procedures for deter- mining sediment sources, sediment yields, and delivery ratios. Interrelationship of Processes L Sediment yield depends on gross erosion in the Sediment Sources General sediment deposits helps in identifying and evaluating sediment sources. Because a watershed Sources of sediment must be delineated to plan an may contain contrasting rock formations, the adequate program for reducing downstream sedi- distinctive erosion products of these rock formations ment yield. Sediment sources include agricultural may clearly indicate the location of the sediment land, range and forest land, road banks and ditches, sources. These distinctive minerals are quartz, stream channels and banks, flood plains, spoil micas, iron oxide, feldspar, chert, and calcite; some banks, and gullies. In planning a program to reduce can be easily identified and traced to their original sediment yield, the relative importance of the source. Other watersheds may lack geologic variety various sources and the methods for treating them and hence may not provide such specific clues to must be determined before the physical and the location of significant erosion. economic feasibility of the program can be deter- mined. Sediment derived from sheet erosion can Colluviation usually be reduced by land treatment measures, Another aid in evaluating the sediment sources is whereas that derived from channel-type erosion the extent and location of colluvial deposition. If a usually requires structural works. coarse-grained material such as sand or gravel is A sediment source study is made to determine: (1) being actively eroded, it may produce large volumes the origin of the sediment; (2) the rate of erosion of sediment, little of which moves very far from the from each source; (3) the proportion of the sediment site of erosion. Substantial deposits may form at the derived from each source; (4) for program planning foot of the first slope. Fans and valley deposits may or structure design, the kinds of treatment that form in small tributary valleys or in the next lower should be recommended for reducing sediment valleys downstream. yield; and (5) the relative effect that reducing ero- sion from the various sources will have on reducing Procedure sediment yield and damage. Any procedure requires study of the various types The relative importance of the sediment source of erosion apparently producing sediment. Sorting may differ at different locations in a watershed. the types of erosion according to the treatments J Therefore, the treatment measures may also vary, that could be recommended to reduce erosion and depending on the location in the watershed where a thus sediment yield will make the effectiveness of reduction in sediment yield is desired. the various treatments much easier to evaluate. Several procedures can be used to determine the relative importance of the various sediment sources. Determining the Relative Importance of A recommended procedure is to gather information Various Sources on that part of the sediment yield which can be at- tributed to each of the various sources. Erosion and The following items must be considered in the the sediment delivery ratio should be estimated early stages of any study made to determine the above each reach or other point of interest for the location, extent, and relative importance of the sedi- drainage area. ment sources. The sediment yield at the point of interest must be allocated to the recognized sources. Analyzing Maps and Aerial Photographs the available data, studying the watershed, and Careful review of aerial photographs often reveals considering the sediment delivery ratios
Load more

Recommended publications
  • (P 117-140) Flood Pulse.Qxp
    117 THE FLOOD PULSE CONCEPT: NEW ASPECTS, APPROACHES AND APPLICATIONS - AN UPDATE Junk W.J. Wantzen K.M. Max-Planck-Institute for Limnology, Working Group Tropical Ecology, P.O. Box 165, 24302 Plön, Germany E-mail: [email protected] ABSTRACT The flood pulse concept (FPC), published in 1989, was based on the scientific experience of the authors and published data worldwide. Since then, knowledge on floodplains has increased considerably, creating a large database for testing the predictions of the concept. The FPC has proved to be an integrative approach for studying highly diverse and complex ecological processes in river-floodplain systems; however, the concept has been modified, extended and restricted by several authors. Major advances have been achieved through detailed studies on the effects of hydrology and hydrochemistry, climate, paleoclimate, biogeography, biodi- versity and landscape ecology and also through wetland restoration and sustainable management of flood- plains in different latitudes and continents. Discussions on floodplain ecology and management are greatly influenced by data obtained on flow pulses and connectivity, the Riverine Productivity Model and the Multiple Use Concept. This paper summarizes the predictions of the FPC, evaluates their value in the light of recent data and new concepts and discusses further developments in floodplain theory. 118 The flood pulse concept: New aspects, INTRODUCTION plain, where production and degradation of organic matter also takes place. Rivers and floodplain wetlands are among the most threatened ecosystems. For example, 77 percent These characteristics are reflected for lakes in of the water discharge of the 139 largest river systems the “Seentypenlehre” (Lake typology), elaborated by in North America and Europe is affected by fragmen- Thienemann and Naumann between 1915 and 1935 tation of the river channels by dams and river regula- (e.g.
    [Show full text]
  • Deposition Patterns and Rates of Mining-Contaminated Sediment Within a Sedimentation Basin System, S.E
    BearWorks Institutional Repository MSU Graduate Theses Spring 2017 Deposition Patterns and Rates of Mining- Contaminated Sediment within a Sedimentation Basin System, S.E. Missouri Joshua Carl Voss Missouri State University - Springfield, [email protected] Follow this and additional works at: http://bearworks.missouristate.edu/theses Part of the Environmental Indicators and Impact Assessment Commons, Environmental Monitoring Commons, and the Hydrology Commons Recommended Citation Voss, Joshua Carl, "Deposition Patterns and Rates of Mining-Contaminated Sediment within a Sedimentation Basin System, S.E. Missouri" (2017). MSU Graduate Theses. 3074. http://bearworks.missouristate.edu/theses/3074 This article or document was made available through BearWorks, the institutional repository of Missouri State University. The orkw contained in it may be protected by copyright and require permission of the copyright holder for reuse or redistribution. For more information, please contact [email protected]. DEPOSITION PATTERNS AND RATES OF MINING-CONTAMINATED SEDIMENT WITHIN A SEDIMENTATION BASIN SYSTEM, BIG RIVER, S.E. MISSOURI A Masters Thesis Presented to The Graduate College of Missouri State University ATE In Partial Fulfillment Of the Requirements for the Degree Master of Science, Geospatial Sciences in Geography, Geology, and Planning By Josh C. Voss May 2017 Copyright 2017 by Joshua Carl Voss ii DEPOSITION PATTERNS AND RATES OF MINING-CONTAMINATED SEDIMENT WITHIN A SEDIMENTATION BASIN SYSTEM, BIG RIVER, S.E. MISSOURI Geography, Geology, and Planning Missouri State University, May 2017 Master of Science Josh C. Voss ABSTRACT Flooding events exert a dominant control over the deposition and formation of floodplains. The rate at which floodplains form depends on flood magnitude, frequency, and duration, and associated sediment transport capacity and supply.
    [Show full text]
  • Lesson 4: Sediment Deposition and River Structures
    LESSON 4: SEDIMENT DEPOSITION AND RIVER STRUCTURES ESSENTIAL QUESTION: What combination of factors both natural and manmade is necessary for healthy river restoration and how does this enhance the sustainability of natural and human communities? GUIDING QUESTION: As rivers age and slow they deposit sediment and form sediment structures, how are sediments and sediment structures important to the river ecosystem? OVERVIEW: The focus of this lesson is the deposition and erosional effects of slow-moving water in low gradient areas. These “mature rivers” with decreasing gradient result in the settling and deposition of sediments and the formation sediment structures. The river’s fast-flowing zone, the thalweg, causes erosion of the river banks forming cliffs called cut-banks. On slower inside turns, sediment is deposited as point-bars. Where the gradient is particularly level, the river will branch into many separate channels that weave in and out, leaving gravel bar islands. Where two meanders meet, the river will straighten, leaving oxbow lakes in the former meander bends. TIME: One class period MATERIALS: . Lesson 4- Sediment Deposition and River Structures.pptx . Lesson 4a- Sediment Deposition and River Structures.pdf . StreamTable.pptx . StreamTable.pdf . Mass Wasting and Flash Floods.pptx . Mass Wasting and Flash Floods.pdf . Stream Table . Sand . Reflection Journal Pages (printable handout) . Vocabulary Notes (printable handout) PROCEDURE: 1. Review Essential Question and introduce Guiding Question. 2. Hand out first Reflection Journal page and have students take a minute to consider and respond to the questions then discuss responses and questions generated. 3. Handout and go over the Vocabulary Notes. Students will define the vocabulary words as they watch the PowerPoint Lesson.
    [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]
  • 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]
  • Biogeochemical and Metabolic Responses to the Flood Pulse in a Semi-Arid Floodplain
    View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by DigitalCommons@USU 1 Running Head: Semi-arid floodplain response to flood pulse 2 3 4 5 6 Biogeochemical and Metabolic Responses 7 to the Flood Pulse in a Semi-Arid Floodplain 8 9 10 11 with 7 Figures and 3 Tables 12 13 14 15 H. M. Valett1, M.A. Baker2, J.A. Morrice3, C.S. Crawford, 16 M.C. Molles, Jr., C.N. Dahm, D.L. Moyer4, J.R. Thibault, and Lisa M. Ellis 17 18 19 20 21 22 Department of Biology 23 University of New Mexico 24 Albuquerque, New Mexico 87131 USA 25 26 27 28 29 30 31 present addresses: 32 33 1Department of Biology 2Department of Biology 3U.S. EPA 34 Virginia Tech Utah State University Mid-Continent Ecology Division 35 Blacksburg, Virginia 24061 USA Logan, Utah 84322 USA Duluth, Minnesota 55804 USA 36 540-231-2065, 540-231-9307 fax 37 [email protected] 38 4Water Resources Division 39 United States Geological Survey 40 Richmond, Virginia 23228 USA 41 1 1 Abstract: Flood pulse inundation of riparian forests alters rates of nutrient retention and 2 organic matter processing in the aquatic ecosystems formed in the forest interior. Along the 3 Middle Rio Grande (New Mexico, USA), impoundment and levee construction have created 4 riparian forests that differ in their inter-flood intervals (IFIs) because some floodplains are 5 still regularly inundated by the flood pulse (i.e., connected), while other floodplains remain 6 isolated from flooding (i.e., disconnected).
    [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]
  • Classifying Rivers - Three Stages of River Development
    Classifying Rivers - Three Stages of River Development River Characteristics - Sediment Transport - River Velocity - Terminology The illustrations below represent the 3 general classifications into which rivers are placed according to specific characteristics. These categories are: Youthful, Mature and Old Age. A Rejuvenated River, one with a gradient that is raised by the earth's movement, can be an old age river that returns to a Youthful State, and which repeats the cycle of stages once again. A brief overview of each stage of river development begins after the images. A list of pertinent vocabulary appears at the bottom of this document. You may wish to consult it so that you will be aware of terminology used in the descriptive text that follows. Characteristics found in the 3 Stages of River Development: L. Immoor 2006 Geoteach.com 1 Youthful River: Perhaps the most dynamic of all rivers is a Youthful River. Rafters seeking an exciting ride will surely gravitate towards a young river for their recreational thrills. Characteristically youthful rivers are found at higher elevations, in mountainous areas, where the slope of the land is steeper. Water that flows over such a landscape will flow very fast. Youthful rivers can be a tributary of a larger and older river, hundreds of miles away and, in fact, they may be close to the headwaters (the beginning) of that larger river. Upon observation of a Youthful River, here is what one might see: 1. The river flowing down a steep gradient (slope). 2. The channel is deeper than it is wide and V-shaped due to downcutting rather than lateral (side-to-side) erosion.
    [Show full text]
  • River Processes- Erosion, Transportation and Deposition Task 1: for Each of the Processes of Erosion and Transportation Draw a Diagram Show the Process at Work
    River Processes- Erosion, Transportation and Deposition Task 1: For each of the processes of erosion and transportation draw a diagram show the process at work In the upper course of the main process is Erosion. This is where the bed and banks of the river are worn away. A river can erode in one of four ways: Process Definition Diagram Hydraulic the sheer force of water hitting the action banks of the river: Abrasion fine material rubs against the riverbank The bank is worn away by a sand- papering action called abrasion, and collapses. This occurs on the outside of meanders. Attrition material is moved along the bed of a river, collides with other material, and breaks up into smaller pieces. Corrosion rocks forming the banks and bed of a river are dissolved by acids in the water. Once the material is eroded it can then be transported by one of four ways, which will depend upon the energy of the river: Process Definition Diagram Traction large rocks and boulders are rolled along the bed of the river. Saltation smaller stones are bounced along the bed of the river Suspension fine material which is carried by the water and which gives the river its 'muddy' colour. Solution dissolved material transported by the river. In the middle and lower course, the land is much flatter, this means that the river is flowing more slowly and has much less energy. The river starts to deposit (drop) the material that it has been carry Deposition Challenge: Add labels onto the diagram to show where all of the processes could be happening in the river channel.
    [Show full text]
  • Sediment and Sedimentary Rocks
    Sediment and sedimentary rocks • Sediment • From sediments to sedimentary rocks (transportation, deposition, preservation and lithification) • Types of sedimentary rocks (clastic, chemical and organic) • Sedimentary structures (bedding, cross-bedding, graded bedding, mud cracks, ripple marks) • Interpretation of sedimentary rocks Sediment • Sediment - loose, solid particles originating from: – Weathering and erosion of pre- existing rocks – Chemical precipitation from solution, including secretion by organisms in water Relationship to Earth’s Systems • Atmosphere – Most sediments produced by weathering in air – Sand and dust transported by wind • Hydrosphere – Water is a primary agent in sediment production, transportation, deposition, cementation, and formation of sedimentary rocks • Biosphere – Oil , the product of partial decay of organic materials , is found in sedimentary rocks Sediment • Classified by particle size – Boulder - >256 mm – Cobble - 64 to 256 mm – Pebble - 2 to 64 mm – Sand - 1/16 to 2 mm – Silt - 1/256 to 1/16 mm – Clay - <1/256 mm From Sediment to Sedimentary Rock • Transportation – Movement of sediment away from its source, typically by water, wind, or ice – Rounding of particles occurs due to abrasion during transport – Sorting occurs as sediment is separated according to grain size by transport agents, especially running water – Sediment size decreases with increased transport distance From Sediment to Sedimentary Rock • Deposition – Settling and coming to rest of transported material – Accumulation of chemical
    [Show full text]
  • Impacts of a Flood Pulsing Hydrology on Plants and Invertebrates in Riparian Wetlands
    IMPACTS OF A FLOOD PULSING HYDROLOGY ON PLANTS AND INVERTEBRATES IN RIPARIAN WETLANDS A dissertation submitted to Kent State University in partial fulfillment of the requirements for the degree of Doctor of Philosophy by Maureen K. Drinkard August 2012 Dissertation written by Maureen K. Drinkard B.S., Kent State University, 2003 Ph.D., Kent State University, 2012 Approved by ___Ferenc de Szalay_, Chair, Doctoral Dissertation Committee ___Mark Kershner_______, Members, Doctoral Dissertation Committee _____Oscar Rocha________, ____Mandy Munro-Stasiuk_, Accepted by _____James Blank______, Chair, Department of Biological Sciences ______Raymond Craig___, Dean, College of Arts and Sciences ii TABLE OF CONTENTS LIST OF FIGURES ............................................................................................................... vi LIST OF TABLES ................................................................................................................. vii ACKNOWLEDGEMENTS .................................................................................................... x CHAPTER I. INTRODUCTION ................................................................................................ 1 Dissertation Goals ............................................................................................. 1 Definition of the Flood Pulse Concept .............................................................. 2 Ecological and economic importance ............................................................... 3 Impacts of environmental
    [Show full text]