EESB20 Take Home Midterm

Hunain Sindhu 1004444942 EESB20 March 12, 2023 Take Home Midterm Part 1: Streams and Sediments Imagine we are investigating sediment erosion, transport, and deposition along a stream (1000 km long) which originates in the Northern Alps and travels all the way to the North Sea (Germany). a. Name and describe at least two equations, including river characteristics and flow parameters, that let us make predictions where sediment erosion versus transport versus deposition would most likely occur along this stream? Explain how the individual numerical parameters influence the mechanical processes along the river by giving example numbers and draw a sketch/-es or diagrams to strengthen your reasoning. (4 P.) When investigating sediment erosion, transport and deposition, there are several different factors to consider and a few relationships that help us study and make predictions about the given environment. A few equations/relationships that help us make predictions about sediment erosion, transport and deposition are: • Reynolds Number (related to fluid dynamics) o Re = (V* L)/v o V is the flow velocity; L is the diameter of the stream/channel and v is the dynamic viscosity. o This parameter is associated with fluid dynamics that help characterize the flow type in a river. It relates the driving forces with the resisting forces. Knowing what type of flow is situated in a river helps determine the type of sediment transport that is dominant as well as the critical shear stress that is required to begin sediment motion. There are three types of flow that are important: Laminar, Transitional and Turbulent. Laminar flow is where the water travels smoothly and in an ordered manner. Turbulent flow is very chaotic and unsteady. Transitional flow is where the moving water is laminar in some areas and turbulent in other. o A measure of the Reynolds number that is less than 500 would indicate laminar flow, a value between 500 and 2000 would indicate transitional flow and, anything above 2000 would be turbulent flow.

Hunain Sindhu 1004444942 EESB20 March 12, 2023 • The Shields Equation o τ * = τ / (ρs - ρ)gD o τ is the shear stress, ρs is the density of the sediment, ρ is the density of the fluid, g is the standard constant for gravity and D is the characteristic particle diameter of the sediment. o This equation, also known as the Shields criterion is used to determine the initiation of motion required for deposited sediments to move in a river or flowing fluid. o For example, if the flow velocity is high and the riverbed is composed of loose sediment with a low critical shear stress for transport, sediment erosion is more likely to occur. The greater the density ( ρs - ρ) difference between the sediment and water, the higher the critical shear stress required for erosion to occur. • Meyer-Peter and Muller equation (MPM) o Qs = α(Rh^β)(S^γ) o Qs is the rate of sediment transport, Rh is the river ’ s hydraulic radius (cross-sectional area divided by wetted perimeter), S is the slope of the riverbed , and α, β, and γ are empirical coefficients o This equation helps determines that the sediment transport rate increases with increasing hydraulic radius as well as slope. External references used: https://digitalcommons.unl.edu/cgi/viewcontent.cgi?article=1019&context=envengdiss https://eprints.hrwallingford.com/1134/1/Roulund_ICSE2016.pdf https://ascelibrary.org/doi/10.1061/%28ASCE%290733-9429%282006%29132%3A11%281159%29 b. Considering the length, potential morphology/profile of this river and your data collection process, name 3 things you should consider that may lower the accuracy of your data analysis and final prediction. Briefly describe what you would need to do to avoid each of these issues to create the most accurate predictions on sediment erosion, transport, deposition processes/conditions for this or any other river? (total 5 P.) When analyzing and making predictions about the sediment erosion, transport, and deposition processes/conditions in a 1000 km long stream originating in the Northern Alps and flowing into the North Sea, there are several factors that may lower the accuracy of the data analysis and final predictions. Three of these factors are: • Spatial and temporal variability: Streams are very dynamic and are constantly changing in response to changes in type of flow, sediment size, velocity, and other factors. Sediment transport processes can vary significantly over the course of a 1000 km stream. This variability can make it difficult to accurately measure sediment transport rates at every point along the stream. • Uncertainty in input data:

Hunain Sindhu 1004444942 EESB20 March 12, 2023 beds are flat, that suggests that it was a low energy deposition with a relatively calm and deep water environment. On the other hand, if there are crossbeds present, that suggests high energy currents. The angle and the shape of the crossbeds can indicate the direction and flow rate of the water. Steeper and larger crossbeds would indicate a much higher energy flow. • Other paleocurrent indicators: o Studying different paleocurrent indicators such as imbrications, or ripple marks can also help determine the type and direction of flow. If there are ripple marks, it would suggest that this river had a multidirectional flow with much weaker and intermittent currents rather than a unidirectional flow. Part 2: Climate, Weather and Sediments/Sedimentary Rocks/Processes: a. How can climate and weather influence sediment / rock formation and destruction processes and/or how can sediment / rock formation and destruction processes influence climate/weather? Provide a total of 5 examples and explain each (2 P. for each, total 10 P.) The formation and destruction of sediments and rocks are dependant on climate and weather in some ways and vice versa. The processes behind rock formation and destruction include a combination of physical, chemical and biological components. Influence of climate/weather on the formation and destruction of rocks/sediments: • Precipitation: o Depending on the climate and the weather, precipitation varies and can play a big role in the formation of sediments and rocks. Precipitation mostly falls in the form of rain or snow and these cause erosion and transport of different materials. Over a long period of time, these materials or sediments can be compressed together and form sedimentary rocks. Certain climates and weathers bring more precipitation (equatorial zone) whereas others have much less (arid areas). • Temperature: o The rate of weathering of parent material heavily depends on the temperature. Warmer climates tend to have a higher rate of chemical weather whereas physical weather tends to occur more in colder climates (such as freeze-thaw cycles). • Sea level: o Sea level depends on the overall climate and slightly on the weather as warmer climates can cause seawater to expand which raises the sea level. When sea level rises, it can erode coastlines and these eroded materials can be deposited in areas which were previously underwater. This forms new sedimentary rocks. • Wind

Hunain Sindhu 1004444942 EESB20 March 12, 2023 o One of the biggest factors besides water, for the transport of materials is wind and it can cause erosion as well (in drier climates). Sand dune formation primarily occurs with the help of wind. Influence of rocks/sediments formation and destruction on climate/weather: • Carbon cycle and albedo effect: o The carbon cycle largely depends on the amount of carbon present in the atmosphere. Accumulation of calcium carbonate leads to the formation of some sedimentary rocks, such as limestone and these store large amounts of carbon. When these rocks are broken down, that carbon escapes into the atmosphere and affect the balance of carbon dioxide which in return influences the climate. The Albedo effect on the other hand is the amount of sunlight that is reflected into space. Light colored sedimentary rocks such as sandstone or limestone reflect back more sunlight and lead to a slight cooling of the earth's surface. External references used: https://opentextbc.ca/geology/chapter/5-6-weathering-and-climate-change/ https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2019RG000692 b. In your opinion, which of the examples you provided in 2.a. is the most important climate/weather – process relationship compared to the others? Explain your reasons. (1 points) In my opinion, precipitation is the most important climate/weather process in comparison to the other points. As temperatures increase due to climate change, it can lead to more frequent and intense precipitation events which in return causes higher rates of chemical and physical weathering of rocks. c. Convert the information provided for 2.a. into a concept map (see example at end of document). See if you can find any additional interconnections between your individual examples and add these including an annotation (label). (3 P.)

Hunain Sindhu 1004444942 EESB20 March 12, 2023 sediments. These sediments consist of the remains of dead organisms and other plant material which transform into rocks over a very long period. • Mineral formation: o Some plants and microorganisms can help form minerals that are then used to make sedimentary rocks. Certain microorganisms and bacteria can precipitate minerals such as calcite and silica which are components of sedimentary rocks. • Fossilization and Fossil Fuels: o Fossilization is when the remains of dead animals and plants get buried and preserved over time. Fossil fuels are derived from the fossils that were buried millions of years ago which were compressed over time and turned into fuels that provide humans with a source of energy. • Weathering and sediment transport o Plants and other organisms can affect the type and rate of weathering. Roots of plants can often break apart bigger rocks which expose them to further weather by wind and water. Plants and organisms can also influence the transport and deposition of sediments within an ecosystem. • Climate change o Climate change is a product of the actions of life on Earth (humans, not so much plants), and it can affect different processes related to sediments and rocks. It can exacerbate chemical and physical weather due to extreme weather conditions that are much more frequent. A lot of biogenic sediment gets deposited from processes related to climate change such as forest fires. b. In your opinion, which of the examples you provided for 3.a. is the most significant relationship compared to the others? Explain. I believe fossilization and fossil fuels are the most significant compared to others because of their ability to affect many processes on Earth. Fossilization are important indicators of the past life and can provide further insight into the evolution of organisms. Fossil fuels are made from deposits of ancient plants and animals which provide energy to humans mainly. Both play a very important role. c. Convert your examples for 3.a. into a concept map (see example at end of document). See if you can find any additional interconnections between your individual examples and add these including an annotation (label). (3 P.)

Hunain Sindhu 1004444942 EESB20 March 12, 2023 Part 4: Groundwater and Sediments/Sedimentary Rocks/Processes: a. How is groundwater related to sediments/sedimentary rocks (rock types, formation, destruction, processes) and how do both influence each other? You may integrate influencing factors in your explanation. Use sketches / diagrams where appropriate. Provide a total of 5 examples and explain each (2 P. each, total 10 P.) Groundwater is related to the formation, destruction and alteration of sediments/sedimentary rocks and plays a few key roles and vice versa: • Alteration of existing sedimentary rocks: o Groundwater flow can alter the composition of some rocks in various ways. Groundwater that is high in carbon dioxide can react with certain minerals in rocks and change the chemical composition of the rock slightly. It can also flow through porous sedimentary rocks that alter the texture or appearance of the rock over time as the water brings in some minerals with it. It can form new minerals or cause dissolution to occur. • Diagenesis:

Hunain Sindhu 1004444942 EESB20 March 12, 2023 Part 5: Methodology and Techniques used in Sedimentology a. Name 5 types of techniques or tools sedimentologists use to describe or analyze sediments/sed. rocks and draw conclusions on sediment types, environments, environmental conditions, and processes. This can include diagrams, graphs, maps, certain types of data collect ion/analysis, … discussed in class or lab. Explain what they are, and why / how each of these are used. (1.5 P each, total 7.5 P.) • Grain-size analysis: o This involves using different techniques such as laser diffraction and sieving to measure and analyze the size distribution of sediment grains. Sedimentologists can deduce information about sediment movement and depositional environment by examining the grain-size distribution. • Stratigraphic analysis: o This is the study of a vertical sequence of the layers of sedimentary rocks in an area. Stratigraphy is useful to reconstruct certain depositional environments and the changes that occur in it over time using the knowledge of which rocks take longer to weather and which are more susceptible to change. • Sedimentary structures analysis:

Hunain Sindhu 1004444942 EESB20 March 12, 2023 o Sedimentary structures analysis includes looking at the physical traits and characteristics of sedimentary structures such as cross-bedding, ripple marks, mud cracks, and bioturbation, which can reveal details about the environment, energy levels, and post-depositional processes that led to their formation. • Ground-penetrating radar: o This involves using electromagnetic waves to penetrate the ground and create images of sedimentary layers and structures. • Remote sensing: o This involves using aerial or satellite imagery to map and analyze sedimentary deposits, such as river systems, coastlines, and deltas. b. Create a concept map that shows how or for what these are used and how they may be related to each other (e.g. used for common goal or separate goals) (3 P.)