Jain_Dhruv_Tutorial2

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Simon Fraser University *

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Feb 20, 2024

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Name: Dhruv Jain Tutorial Section (Day/Time): D105 Tutorial #2: Using the Scientific Method to Investigate Streamflow and Flooding Adapted from http://www.hartnell.edu/tutorials/biology/scimethod.html and Kortz & Smay (2008) Instructions: Download this worksheet to your computer, and save the file as Your Last Name_First Name_Tutorial2 (e.g. Holland_Tara_Tutorial2). Type your answers directly onto this worksheet. Upload your completed worksheet to Canvas Assignments Tutorial 2 as a .pdf attachment. This tutorial is graded out of 25 marks. Point values are given in parentheses after each question Learning Goals: List the steps of the scientific method, and explain how science works Analyze hydrographs with respect to processes in the hydrologic cycle, especially precipitation, surface runoff, and infiltration Apply the scientific method to generate and test hypotheses about environmental and human factors that influence flooding Resources on Canvas : Video: How Science Works (10 min): https://youtu.be/JH0_xC7q9tU Stream Hydrology primer https://runoff.modelmywatershed.org/ Context: In this tutorial, you will apply the scientific method to an analysis of streamflow (discharge) graphs as related to the hydrologic cycle and human activity. Diagram of the Hydrologic (Water) Cycle Holland EVSC 100 2024 Tutorial 2
River Flow and Flooding The amount of water moving down a river at a given time and place is referred to as its discharge , or streamflow, and is measured as a volume of water per unit time, typically cubic meters per second (m 3 /s). The discharge at any given point in a river can be calculated as width (in m) times the average depth (in m) times average velocity (in m/s). The vast majority of rivers are known to exhibit considerable variability in flow over time because inputs, in the form of rain events, snowmelt, groundwater seepage, etc., vary over time. Some rivers respond quickly to rainfall runoff or snow melt, while others respond more slowly depending on the size of the watershed, steepness of the hillslopes, ability of the soils to (at least temporarily) absorb and retain water, and the amount of storage in lakes and wetlands. Floods are rare events in which a body of water temporarily covers land that is normally dry. River floods are typically caused by excessive rainfall and/or sudden melting of snow and ice. Most rivers overflow their banks with small floods about once every two years. Human activities such as development in the watershed and modifications of the river channel can change the frequency and severity of floods. Description of the Scientific Method One of the goals of science is to come up with explanations about how the natural world (all the things we see or experience) functions. It is important to note that there are also other important systems for understanding and explaining the world around us, such as Indigenous ways of knowing. Scientific explanations are based on patterns in nature that are objective (do not depend on faith, authority, or opinion), are testable (can be demonstrated with experiments), and are consistent (the same conditions produce the same results). The 4 Steps of the Scientific Method* To learn about the natural world, scientists use a four-step procedure called the scientific method. The four steps of the scientific method are listed below. Step 1: Observations & Questions Observe something in the natural world and ask a question about how it works. Step 2: Hypothesis Holland EVSC 100 2024 Tutorial 2
Make a hypothesis (an educated guess) that attempts to answer the question. A useful hypothesis is a testable statement. Step 3: Experiment Design and carry out an experiment that is capable of testing the hypothesis. In other words, the experiment must be designed so that it will produce results that either clearly support or clearly falsify (disprove) the hypothesis. It helps to use “If-Then” predictions based on your hypothesis. Step 4: Analyze Results and State Conclusions Reject the hypothesis if the results are not consistent with the hypothesis, or accept the hypothesis as possibly true if the results are consistent with the hypothesis. Notice that the hypothesis is not “proven to be true”, even if the results do support it. This is because there may be explanations other than the hypothesis for the experimental result. If the experimental results do not support the hypothesis, the hypothesis may be modified and additional experiments may be done to test the new or revised hypothesis. *Although we represent the scientific method as a somewhat linear process, it is important to recognize that science in reality is much more complex. The video on Canvas “How Science Works” will give you an idea of how the scientific method works “in real life”. Part 1: Rainfall Look at the cross section below showing the ground surface and water table (top level of where water is stored underground) during a short, powerful rainstorm. This diagram represents a watershed , which is the area from which rainfall flows into a stream, lake, or reservoir. For more background on how water reaches a stream, consult the Stream Hydrology primer on Canvas. Imagine that you are outside watching this storm happen. 1) Make an observation : (1) What two possible things will happen to Raindrop A when it hits the ground? Raindrop A may contribute to surface runoff and move downstream toward the stream when it hits the ground, or it may infiltrate into the ground and travel through the subsurface layers, ultimately going into the stream. 2) Draw or insert arrows showing the directions that surface water and ground water are flowing. (1) Holland EVSC 100 2024 Tutorial 2
3) Ask (and propose and answer to) a question : (1) Where will Raindrop A eventually end up? If Raindrop A hits the ground on the hill slope during the storm, it will eventually end up in the stream due to the steep slope of the surface. Part 2: Streamflow Analysis The graph below (called a hydrograph ) shows the level of water in the stream from Part 1. The black box indicates the duration of the short, powerful rainstorm. Rainwater reaches the stream by flowing along the ground surface (called runoff ) and/or by soaking into the ground (called infiltration ) and slowly traveling underground to the stream. 4) Observation : (1) Is the flood at its highest during the rain storm (highlight one)? Yes No The flood is not at its highest during the rainstorm. There is a distinct lag phase, indicating a delay between the onset of the rainstorm and the peak of the flood. Holland EVSC 100 2024 Tutorial 2
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