![\"Sediment](\"https:\/\/www.fondriest.com\/environmental-measurements\/wp-content\/uploads\/2014\/06\/turbidity_suspended-solids.jpg\")
Sediment particles come in different sizes and can be inorganic or organic in origin.<\/p>\n
These particulates are typically small, with clay defined as particles less than 0.00195 mm in diameter, and coarse sand reaching up only to 1.5 mm in diameter 5<\/sup>. However, during a flood or other high flow event, even large rocks can be classified as sediment as they are carried downstream 6<\/sup>. Sediment is a naturally occurring element in many bodies of water, though it can be influenced by anthropogenic factors 8<\/sup>.<\/p>\n <\/p>\n In an aquatic environment, sediment can either be suspended (floating in the water column) or bedded (settled on the bottom of a body of water). When both floating and settled particles are monitored, they are referred to as SABS: Suspended And Bedded Sediments 4<\/sup>.<\/p>\n <\/p>\n Fine sediment can be found in nearly any body of water, carried along by the water flow. When the sediment is floating within the water column it is considered suspended. In this application, the terms \u201csuspended sediment\u201d and \u201csuspended solids\u201d are nearly interchangeable. The main difference between the two is in the method of measurement 2<\/sup>.<\/p>\n Despite the similarity in meaning, the data provided by the different measurement methods are neither interchangeable nor comparable 2<\/sup>. The suspended sediment concentration (SSC) is in mg\/L by filtering and drying an entire water sample. Total suspended solids (TSS), while also measured in mg\/L, are obtained by subsampling. While acceptable for homogenized or well mixed samples with very fine sediment, the TSS measurement often excludes larger suspended particles, like sand 2<\/sup>. This means that the SSC measurement tends to be higher and more representative of a water body as a whole, often measuring within 5% of the true particle concentration 7<\/sup>. Due to the incomparability between suspended sediment measurements and total suspended solids measurements, the U.S. Geological Survey recommends SSC analysis over TSS when sampling in surface water 2<\/sup>.<\/p>\n <\/p>\n Sediment transport is the movement of organic and inorganic particles by water 10<\/sup>. In general, the greater the flow, the more sediment that will be conveyed. Water flow can be strong enough to suspend particles in the water column as they move downstream, or simply push them along the bottom of a waterway 11<\/sup>. Transported sediment may include mineral matter, chemicals and pollutants, and organic material.<\/p>\n Another name for sediment transport is sediment load. The total load includes all particles moving as bedload, suspended load, and wash load 11<\/sup>.<\/p>\n <\/p>\n Bedload is the portion of sediment transport that rolls, slides or bounces along the bottom of a waterway 12<\/sup>. This sediment is not truly suspended, as it sustains intermittent contact with the streambed, and the movement is neither uniform nor continuous 11<\/sup>. Bedload occurs when the force of the water flow is strong enough to overcome the weight and cohesion of the sediment 12<\/sup>. While the particles are pushed along, they typically do not move as fast as the water around them, as the flow rate is not great enough to fully suspend them 11<\/sup>. Bedload transport can occur during low flows (smaller particles) or at high flows (for larger particles). Approximately 5-20% of total sediment transport is bedload 10<\/sup>. In situations where the flow rate is strong enough, some of the smaller bedload particles can be pushed up into the water column and become suspended.<\/p>\n <\/p>\n While there is often overlap, the suspended load and suspended sediment are not the same thing. Suspended sediment are any particles found in the water column, whether the water is flowing or not. The suspended load, on the other hand, is the amount of sediment carried downstream within the water column by the water flow 11<\/sup>. Suspended loads require moving water, as the water flow creates small upward currents (turbulence) that keep the particles above the bed 13<\/sup>. The size of the particles that can be carried as suspended load is dependent on the flow rate 11<\/sup>. Larger particles are more likely to fall through the upward currents to the bottom, unless the flow rate increases, increasing the turbulence at the streambed. In addition, suspended sediment will not necessarily remain suspended if the flow rate slows.<\/p>\n <\/p>\n The wash load is a subset of the suspended load 13<\/sup>. This load is comprised of the finest suspended sediment (typically less than 0.00195 mm in diameter). The wash load is differentiated from the suspended load because it will not settle to the bottom of a waterway during a low or no flow period 11<\/sup>. Instead, these particles remain in permanent suspension as they are small enough to bounce off water molecules and stay afloat 11<\/sup>. However, during flow periods, the wash load and suspended load are indistinguishable.<\/p>\n Turbidity in lakes and slow moving rivers is typically due the wash load 8<\/sup>. When the flow rate increases (increasing the suspended load and overall sediment transport), turbidity also increases. While turbidity cannot be used to estimate sediment transport, it can approximate suspended sediment concentrations at a specific location 14<\/sup>.<\/p>\n <\/p>\n Sediment is necessary to the development of aquatic ecosystems through nutrient replenishment and the creation of benthic habitat and spawning areas 10<\/sup>. These benefits occur due to sediment deposition – when suspended particles settle down to the bottom of a body of water. This settling often occurs when water flow slows down or stops, and heavy particles can no longer be supported by the bed turbulence. Sediment deposition can be found anywhere in a water system, from high mountain streams, to rivers, lakes, deltas and floodplains. However, it should be noted that while sediment is important for aquatic habitat growth, it can cause environmental issues if the deposition rates are too high, or too low.<\/p>\n <\/p>\n The suspended particles that fall to the bottom of a water body are called settleable solids 10<\/sup>. As they are found in riverbeds and streambeds, these settled solids are also known as bedded sediment 8<\/sup>. The size of settleable solids will vary by water system – in high flow areas, larger, gravel-sized sediment will settle out first. Finer particles, including silt and clay, can be carried all the way out to an estuary or delta 17<\/sup>.<\/p>\n In marine environments, nearly all suspended sediment will settle. This is due to the presence of salt ions in the water. Salt ions bond to the suspended particles, encouraging them to combine with other particles in the water 15<\/sup>. As the collective weight increases, the sediment begins to sink to the seafloor. This is why oceans and other marine ecosystems tend to have lower turbidity levels (greater water clarity) than freshwater environments 15<\/sup>.<\/p>\n While estuaries and other tidal areas may be considered marine, they are not necessarily clearer than freshwater. Estuaries are the collection point for suspended sediment coming down river. Furthermore, in a tidal zone, the constant water movement causes the bottom sediment to continually resuspend, preventing high water clarity during tidal periods 16<\/sup>. The clarity of an estuary will depend on its salinity level, as this will assist with particle deposition 17<\/sup>.<\/p>\n <\/p>\n Many ecosystems benefit from sediment transport and deposition, whether directly or indirectly. Sediment builds aquatic habitats for spawning and benthic organisms 10<\/sup>. It is also responsible for providing nutrients to aquatic plants, as well vegetation in nearshore ecosystems such as floodplains and marshes 10<\/sup>. Without sediment deposition, coastal zones can become eroded or nonexistent.<\/p>\n <\/p>\n Sediment deposition creates habitats for aquatic life. While too much sediment can be detrimental, too little sediment can also diminish ecosystem quality 10<\/sup>. Some aquatic habitats are even grain-size specific. Many spawning habitats require a specific sediment size (e.g. gravel) and too fine of sediment can end up smothering the eggs and other benthic creatures 8<\/sup>.<\/p>\n Too much sediment deposition can also bury habitats and even physically alter a waterway. Excessive levels of suspended load tend to have negative impacts on aquatic life. Suspended sediment can prevent light from reaching submerged vegetation and clog fish gills 8<\/sup>. If a body of water is continually exposed to high levels of sediment transport, it may encourage more sensitive species to leave the area, while silt-tolerant organisms move in 8<\/sup>.<\/p>\n On the other hand, too little sediment transport can lead to nutrient depletion in floodplains and marshes, diminishing the habitat and vegetative growth 10<\/sup>. While water clarity is often heralded as a benchmark of water quality, low amounts of turbidity can protect aquatic species from predation 18<\/sup>. In addition, too little sediment deposition can lead to the erosion of riverbanks and coastal areas, causing land loss and destroying the nearshore habitats 10, 18<\/sup>.<\/p>\n <\/p>\n Sediment comes from geologic, geomorphic, and organic factors 10<\/sup>. The amount, material and size of the transported sediment is a sum of these influences in any particular waterway. Sediment transported in rivers with headwaters from a mountain range often include glacial silt, while a body of water surrounded by swampland will be inundated with decomposing organic material 23<\/sup>.<\/p>\n <\/p>\n Many sediment particles are mineral-based. The exact nature of the sediment is dependent on location, and the geology of that location 10<\/sup>. Glacial-type sediment is common in mountain ranges, while low-lying rivers are more apt to collect soil-based sediment. In high-flow waterways, sediment transport will include local gravel, pebbles and small rocks. Harder rocks are less likely to become sediment, while soft rocks erode quicker and are easily carried away by flowing water 13<\/sup>. The physical make-up of transported sediment is strongly influenced by the geology of the surrounding environment.<\/p>\n Specific geologic elements are typically localized, such as basalt near volcanic plate boundaries, or limestone in historically shallow marine regions 21<\/sup>. Sediment transport is often responsible for intermixing these geologic features by carrying mineral particle far away from their origin. Mountains streams full of glacial silt can transport that sediment all the way into a tidal bay 10<\/sup>. Likewise, rivers that run through agricultural regions can carry fertilized soil into the ocean 24<\/sup>.<\/p>\n Millions of years ago, sediment deposition helped to form many of these geologic features20<\/sup>. Sedimentary rocks such as sandstone and limestone, are created by sediment deposits, which eventually become pressurized into stone 20<\/sup>. Once these rocks become re-exposed to water and air, the sediment transport process can begin again.<\/p>\n <\/p>\n Geomorphology refers to both the surface of the Earth (terrain), and the processes acting on it (e.g. wind and rain) 22<\/sup>. As defined earlier – sediment is the collection of particles that can be carried away by wind, water and ice. These particles can come from the weathering of rocks and the erosion of surface materials 19<\/sup>. When wind, rain, glaciers and other elements scour away a rock face, the particles are carried away as sediment 10<\/sup>. Runoff can carry away top soils, pushing the sediment into nearby streams and rivers.<\/p>\n In addition to the influence of wind and rain, sediment transport is also affected by the local topography 19<\/sup>. The amount of sediment that enters the water and the distance that it travels is due to the terrain that a waterway runs through 13<\/sup>. Bedrock streams are less likely to contribute to the sediment load, as the channel is resistant to quick erosion 13<\/sup>. These rivers, as well as man-made channels with no sediment, are considered non-alluvial channels.<\/p>\n The majority of rivers however, are alluvial, or self-formed 13<\/sup>. Alluvial rivers and streams create their own path by carrying sediment away. In an alluvial stream, the depth and breadth of the waterway will depend on the strength of the water flow and the material that makes-up the channel boundaries 13<\/sup>. Rivers that run through soft soil typically have a higher sediment transport load than rivers exposed to bedrock, as much of the sediment load is taken from the sides and bottom of the channel. In addition to non-erodible bedrock terrains, highly vegetated areas are less subject to runoff erosion during flood events, as the roots of the plants hold the soil in place 19<\/sup>.<\/p>\n In addition to the effects that geomorphology has on sediment transport rates, the process itself plays a part in creating the terrain. As sediment is transported down stream, the water flow helps to shape the planet\u2019s surface by carrying away the eroded material away from some regions and depositing it in others 19<\/sup>.<\/p>\n <\/p>\n In addition to the mineral-based aspect, sediment can be organic in source. Organic sediment comes from decaying algae, plants, and other organic material that falls in the water (such as leaves) 4<\/sup>. Bacteria attached to this detritus or other inorganic matter are also categorized as organic 18<\/sup>. Organic sediment transport is will vary by location and season. In one estuarine study, the organic portion of the suspended load fell from 85% to 18% from February to November due to seasonal effects on sediment transport 18<\/sup>.<\/p>\n Some phytoplankton can play a unique role in their contribution to sediment loads. In addition to the organic factor they provide, specific phytoplankton (such as diatoms) can contribute an inorganic component as well 1<\/sup>. This inorganic material comes from diatom frustules and calcium carbonate detritus. While this material is not specifically organic, it is organic in origin 1<\/sup>.<\/p>\n <\/p>\n Sediment transport is not constant. In fact, it is constantly subject to change. In addition to the changes in sediment load due to geology, geomorphology and organic elements, sediment transport can be altered by other external factors. The alteration to sediment transport can come from changes in water flow, water level, weather events and human influence.<\/p>\n <\/p>\n Water flow, also called water discharge, is the single most important element of sediment transport. The flow of water is responsible for picking up, moving and depositing sediment in a waterway 26<\/sup>. Without flow, sediment might remain suspended or settle out – but it will not move downstream. Flow is required to initiate the transport 18<\/sup>. There are two basic ways to calculate flow. Water discharge can be simplified as area (a cross-section of the waterway) multiplied by velocity, or as a volume of water moved over time 25<\/sup>.<\/p>\n Flow (ft3<\/sup>\/s) =Area (ft2<\/sup>) * Velocity (ft\/s) The equations describing the relationship of water flow and sediment transport are a bit more complex. The complexity of sediment transport rates are due to a large number of unknowns (e.g. bed geometry, particle size, shape and concentration), as well as multiple forces acting upon the sediment (e.g. relative inertia, turbulent eddies, velocity fluctuations in speed and direction) 11<\/sup>. The sediment transport rate in particular is difficult to measure, as any measurement method will disturb the flow and thus alter the reading. Most flow rate and sediment transport rate equations attempt to simplify the scenario by ignoring the effects of channel width, shape and curvature of a channel, sediment cohesion and non-uniform flows 11<\/sup>.<\/p>\n The two main flow factors in sediment transport are the settling rate and the boundary layer shear stress 27<\/sup>. The settling rate (also called Stokes settling) is the rate at which sediment falls through a liquid and it is controlled by the drag force (keeping a particle suspended) and the gravitational force (a function of the particle size) 27<\/sup>. Understanding this relationship helps to define some of the forces that sediment transport has to overcome relative to particle size.<\/p>\n Shear stresses in the boundary layer of a sediment bed explain how much force is required for water flow to overcome relative inertia and begin sediment transport (through bedload or suspended load) 27<\/sup>.<\/p>\n In a basic freshwater river system, u\u2217 can be calculated as:<\/p>\n In the ocean and in other more complex water systems, this equation is inadequate. Instead, the Von Karman-Prandlt equation should be used. The shear stress is influenced not only by the viscosity of the liquid, but the roughness of the sediment 27<\/sup>. The turbulent eddies created at the bottom by water flow must also be accounted for. This is also known as the Law of the Wall 30<\/sup>.<\/p>\n The above equations help to give a basic understanding of some of the forces acting on sediment in the water. To further understand the conditions required for sediment transport, the Shields stress equation can be used. Shields stress, along with the particle Reynolds number, can be used to predict how much flow is required for substantial sediment transport 27<\/sup>. The Reynolds number is an expression of a particle\u2019s resistance to viscous force 28<\/sup>. In other words, the Reynolds number demonstrates whether or not a flow is viscous enough to overcome the relative inertia of sediment. For sediment transport, the Reynolds number for flow through a sediment bed can be calculated from the boundary layer shear stress equation:<\/p>\n The point at which water flow begins to transport sediment is called the critical Shields stress 27<\/sup>. This creates an empirical curve to approximate at what flow rate a sediment particle will move (based on particle size) 27<\/sup>.<\/p>\n While these equations help define minimum flow rates for sediment transportation, they do not determine sediment load and sediment transport rates themselves. One sediment transport rate equation was developed by van Rijn, for the bedload transport of particles between 0.2-2mm.<\/p>\n The suspended load transport rate (still assuming cohesionless sediment and a sediment size of 0.2-2mm) is even more complicated:<\/p>\n Other sediment rating curves have been developed, but they cannot be equally applied to all water bodies 13<\/sup>. This is because in any application, there are seven main variables that have an effect on sediment transport rates 11,31<\/sup>.<\/p>\n The sediment transport rate is a function of these seven variables, as well as the size-shape-density distribution (often assumed as a standard deviation of the particle diameter) of the suspended particles 31<\/sup>. In addition, the largest river discharge does not automatically mean that a river will have the largest sediment load. The quantity and material of the sediment particles, as well as the geography of the local terrain will still play a contributing role in the sediment load 10<\/sup>.<\/p>\n The sediment load itself is calculated as a depth-integrated sediment mass above a unit area 11<\/sup>. It is variable for multiple reasons, but can be estimated with a time-average collected sediment concentration 11<\/sup>. While it is dependent on flow to initiate and continue transport, it is not calculated from flow rates, as the main variables in sediment load come from environment factors.<\/p>\n <\/p>\n Sediment transport relies on water flow to move a load downstream. Water flow is variable, affected not only by the local terrain (e.g. slope), but by water level which, in turn, is influenced by precipitation (or lack thereof).<\/p>\n Most changes in water level are due to weather events such as rainfall 26<\/sup>. Precipitation causes water levels to initially rise, and then return to previous levels (base flow) over the course of hours or days. Rainfall, whether slight or heavy can affect water flow and sediment transport. The extent to which a weather event will influence sediment transport is dependent on the amount of sediment available. Snowmelt in a glaciated area will result in a high sediment load due to glacial silt 10<\/sup>. Heavy rainfall over an area of loose soil and minimal vegetation will create runoff, carrying loose particles into the waterway. Likewise, flooding will also pick up sediment from the local area. In fact, most of an waterway\u2019s sediment load occurs during flood events 10<\/sup>.<\/p>\n Increased water level creates additional volume in a channel, and increases the hydraulic radius (cross-sectional area of a waterway). The increased hydraulic radius increases the discharge rate, regardless of whether or not flow is uniform or non-uniform 31<\/sup>. Increased flow will increase the stress on the bed, making it more likely for water flow to initiate sediment transport. The higher velocity also increases erosion rates as flow overcomes the shear stress of sediment 13<\/sup>.<\/p>\n Seasonal effects are also responsible for changes in water level and flow 26<\/sup>. Most seasonal changes are due to precipitation levels and events such as snowmelt. During low precipitation and low flow periods, sediment transport falls. During the peak of snowmelt, the sediment load can increase by a factor of 15 or more 13<\/sup>. Climate change can also play a role in sediment transport, as it affects both the timing and magnitude of floods and other weather events 10<\/sup>.<\/p>\n <\/p>\n Anthropogenic factors, such as dams and altered land use will affect both the sediment load and sediment transport rate 10<\/sup>. Dams affect the water flow through complete detention or restricted channels 26<\/sup>. The restricted flow can cause the channel downstream of the dam to become \u201csediment-starved\u201d, while the sediment load behind the dam builds up. A sediment-starved river will not be able to provide habitats for benthic organisms or spawning fish 35<\/sup>. The highly silted reservoir behind the dam may face issues of too much sediment, including changes in aquatic life and the potential for algal blooms. On the other side of the spectrum, when a dam release occurs, the flow rate downstream can dramatically increase. If the release is controlled, it can refresh the bed material, building bars and other habitat areas. An uncontrolled release or dam removal can result in flooding, carrying the released sediment further downstream than is needed 10<\/sup>.<\/p>\nSuspended or Bedded?<\/h3>\n
Suspended Sediment vs Suspended Solids<\/h3>\n
![\"sediment_bed_suspend\"](\"https:\/\/www.fondriest.com\/environmental-measurements\/wp-content\/uploads\/2017\/07\/sediment_bed_suspend.jpg\")
<\/p>\nWhat is Sediment Transport?<\/h2>\n
![\"Sediment](\"https:\/\/www.fondriest.com\/environmental-measurements\/wp-content\/uploads\/2014\/11\/turbidity_runoff_ocean-e1417470675644.jpg\")
Bedload<\/h3>\n
![\"Bedload](\"https:\/\/www.fondriest.com\/environmental-measurements\/wp-content\/uploads\/2014\/12\/sediment_bedload_movement.jpg\")
Suspended Load<\/h3>\n
![\"If](\"https:\/\/www.fondriest.com\/environmental-measurements\/wp-content\/uploads\/2014\/12\/sediment_suspendedload_movement.jpg\")
Wash Load<\/h3>\n
![\"The](\"https:\/\/www.fondriest.com\/environmental-measurements\/wp-content\/uploads\/2014\/12\/sediment_washload_movement.jpg\")
What is Sediment Deposition?<\/h2>\n
![\"When](\"https:\/\/www.fondriest.com\/environmental-measurements\/wp-content\/uploads\/2014\/12\/sediment_deposition_landscape.jpg\")
Settleable Solids<\/h3>\n
![\"Salt](\"https:\/\/www.fondriest.com\/environmental-measurements\/wp-content\/uploads\/2014\/06\/turbidity_salinity.jpg\")
Salt ions can cause suspended sediment to aggregate and sink to the seafloor.<\/p>\nWhy are Sediment Transport and Deposition Important?<\/h2>\n
Sediment and Aquatic Life<\/h3>\n
![\"Sockeye](\"https:\/\/www.fondriest.com\/environmental-measurements\/wp-content\/uploads\/2014\/11\/092812_spawning_sockeye_lrg.jpg\")
Where Does Sediment Come From?<\/h2>\n
Sediment and Geology<\/h3>\n
![\"Glacial](\"https:\/\/www.fondriest.com\/environmental-measurements\/wp-content\/uploads\/2014\/11\/Ruth_Glacier_Muller-300x225.jpg\")
Sediment and Geomorphology<\/h3>\n
![\"Alluvial](\"https:\/\/www.fondriest.com\/environmental-measurements\/wp-content\/uploads\/2014\/11\/geograph-3364895-by-Richard-West-300x225.jpg\")
Sediment and Organic Factors<\/h3>\n
![\"Organic](\"https:\/\/www.fondriest.com\/environmental-measurements\/wp-content\/uploads\/2014\/11\/bluejaybarrens-300x225.jpg\")
Factors that Influence Sediment Transport<\/h2>\n
Water Flow<\/h3>\n
![\"Whether](\"https:\/\/www.fondriest.com\/environmental-measurements\/wp-content\/uploads\/2014\/12\/sediment_erosion_transport_deposition.jpg\")
\nOR<\/strong> Flow (ft3<\/sup>\/s) =Volume (ft3<\/sup>)\/ Time (s)<\/p>\n![\"sediment_equation_settling_velocity\"](\"https:\/\/www.fondriest.com\/environmental-measurements\/wp-content\/uploads\/2014\/12\/sediment_equation_settling_velocity.jpg\")
\nvs<\/sub> = (g * (\u03c1p<\/sub> – \u03c1f<\/sub>) * Dp<\/sub>2<\/sup>) \/ 18\u03bc<\/strong>
\nvs<\/sub> = settling velocity
\ng = gravitational constant
\n\u03c1p<\/sub> = particle density
\n\u03c1f<\/sub> = fluid density
\nDp<\/sub> = particle diameter
\n\u03bc= fluid viscosity 29<\/sup><\/p>\n![\"sediment_equation_shear_stress\"](\"https:\/\/www.fondriest.com\/environmental-measurements\/wp-content\/uploads\/2014\/12\/sediment_equation_shear_stress.jpg\")
\n\u03c4 = \u03c1f<\/sub> * u\u22172<\/sup><\/strong>
\n\u03c4 = shear stress
\n\u03c1f<\/sub> = fluid density
\nu\u2217 = characteristic velocity of turbulent flow (shear velocity) (see following equations) 27<\/sup><\/p>\n![\"sediment_equation_shear_velocity\"](\"https:\/\/www.fondriest.com\/environmental-measurements\/wp-content\/uploads\/2014\/12\/sediment_equation_shear_velocity.jpg\")
\nu\u2217 = Sqrt(g * h * S)<\/strong>
\nu\u2217 = shear velocity
\ng = gravitational constant
\nh = river depth
\nS = river slope 27<\/sup><\/p>\n![\"sediment_equation_average_flow_velocity\"](\"https:\/\/www.fondriest.com\/environmental-measurements\/wp-content\/uploads\/2014\/12\/sediment_equation_average_flow_velocity.jpg\")
\nu\/u\u2217 = (1\/\u03ba) * ln(z\/z0<\/sub>)<\/strong>
\nu = averaged flow velocity
\nu\u2217 =shear velocity
\n\u03ba = Von Karman\u2019s constant (0.4)
\nz = roughness height above the bed
\nz0<\/sub> = roughness height as flow velocity approaches zero 30<\/sup><\/p>\n![\"sediment_equation_reynolds_number\"](\"https:\/\/www.fondriest.com\/environmental-measurements\/wp-content\/uploads\/2014\/12\/sediment_equation_reynolds_number.jpg\")
\nRep<\/sub> = (u\u2217 * Dp<\/sub>) \/ \u03bd<\/strong>
\nRep<\/sub> = Reynolds number of the particle
\nu\u2217 = characteristic velocity of turbulent flow (shear velocity)
\nDp<\/sub> = particle diameter
\n\u03bd = kinematic viscosity (viscosity\/ fluid density, (\u03bc\/\u03c1f<\/sub>))27<\/sup><\/p>\n![\"sediment_equation_shields_stress\"](\"https:\/\/www.fondriest.com\/environmental-measurements\/wp-content\/uploads\/2014\/12\/sediment_equation_shields_stress.jpg\")
\n\u03c4\u2217 = \u03c4 \/(g * (\u03c1p<\/sub> – \u03c1f<\/sub>) * Dp<\/sub>)<\/strong>
\n\u03c4\u2217 = Shields stress
\n\u03c4 = shear stress
\ng = gravitational constant
\n\u03c1p<\/sub> = particle density
\n\u03c1f<\/sub> = density of fluid
\nDp<\/sub> = particle diameter 13<\/sup><\/p>\n![\"The](\"https:\/\/www.fondriest.com\/environmental-measurements\/wp-content\/uploads\/2014\/12\/sediment_stress_diameter.jpg\")
![\"sediment_equation_bedload_transport\"](\"https:\/\/www.fondriest.com\/environmental-measurements\/wp-content\/uploads\/2014\/12\/sediment_equation_bedload_transport-300x155.jpg\")
\nqb<\/sub> = 0.053 * [(s-1)*g]0.5<\/sup> * d50<\/sub>1.5<\/sup> * [T\u22172.1<\/sup> \/ D\u22170.3<\/sup>]<\/strong>
\nqb<\/sub> = bedload transport rate
\ns= specific density of sediment
\ng = gravitational constant
\nd50<\/sub> = median particle diameter
\nT\u2217 = transport stage parameter
\nD\u2217 = dimensionless grain size 18<\/sup><\/p>\n![\"sediment_equation_suspended_transport\"](\"https:\/\/www.fondriest.com\/environmental-measurements\/wp-content\/uploads\/2014\/12\/sediment_equation_suspended_transport-300x140.jpg\")
\nqs<\/sub> = u * h * ca<\/sub> * [ ((a\/h)Z’<\/sup> – (a\/h)1.2<\/sup>) \/ ((1-a\/h)Z’<\/sup> * (1.2-Z’)) ]<\/strong>
\nqs<\/sub>= suspended load transport rate
\nu = average flow velocity
\nh = average flow depth
\nca<\/sub>= reference concentration
\na = height above the bed, relative to particle size
\nZ\u2019 = suspension number 18<\/sup><\/p>\n![\"sediment_equation_sediment_transport\"](\"https:\/\/www.fondriest.com\/environmental-measurements\/wp-content\/uploads\/2014\/12\/sediment_equation_sediment_transport.jpg\")
\nqs<\/sub> = f (\u03c4, h, D, \u03c1p<\/sub>, \u03c1f<\/sub>, \u03bc, g)<\/strong>
\nqs<\/sub> = sediment transport rate per unit width
\n\u03c4 = shear stress
\nh = depth
\nD = particle diameter
\n\u03c1p<\/sub> = particle density
\n\u03c1f<\/sub> = fluid density
\n\u03bc = water viscosity
\ng = gravitational constant<\/p>\nWeather Events and Water Level<\/h3>\n
![\"rain_river_water_level\"](\"https:\/\/www.fondriest.com\/environmental-measurements\/wp-content\/uploads\/2014\/11\/3River-Rain-Jason-Hollinger.jpg\")
Human Influence<\/h3>\n