GEOL 350 Hydrology/Hydrogeology Past Paper PDF

GEOL 350 Hydrology / Hydrogeology GEOL 350: Hydrology / Hydrogeology Surface Hydrology (Rivers, Stream processes, part 2) Tuesday January 14, 2025 1. QUIZ 2. Slides, part 1 3. BREAK 4. Activity: flood hazard mapping for Calgary 5. BREAK 6. Slides, part 2 (flood mitigation) 7. Homew...

GEOL 350 Hydrology / Hydrogeology GEOL 350: Hydrology / Hydrogeology Surface Hydrology (Rivers, Stream processes, part 2) Tuesday January 14, 2025 1. QUIZ 2. Slides, part 1 3. BREAK 4. Activity: flood hazard mapping for Calgary 5. BREAK 6. Slides, part 2 (flood mitigation) 7. Homework for next class (Unit 2 readings)  Unit 1: Summarize key concepts in hydrology Learning Objectives: ✓ 1.1 Identify hydrogeology as a branch of the field of hydrology ✓ 1.2 Explain the hydrologic cycle and the concept of water balance ✓ 1.3 Describe how groundwater is related to the hydrologic cycle 1.4 Describe rivers as dynamic systems, and interpret hydrographs and calculate flood return periods 1.5 Identify recharge and discharge areas, and describe how surface waters and groundwater interact 1.6 Differentiate between gaining and losing streams, and natural springs 1.7 Define the following terms: porosity, permeability, transmissivity, storativity, and hydraulic conductivity Valleys vs Floodplains No floodplain Discontinuous Continuous floodplain floodplain Floodplain can be large Floodplain the area that is typically covered with water during a large flood http://www.columbia.edu/~vj © 2016, Southern Alberta Institute of Technology 4 d1/streams_basic.htm  A stream’s greatest velocity is usually at bank full stage Sediment begin to be stored Abbotsford BC flooding, Nov 2021 bc.ctvnews.ca Since fine river sediments are deposited on flood plains, they are ideally suited for agriculture, and thus are typically occupied by farms and residences, and in many cases, by towns or cities. (e.g. around Abbotsford from flooding of Fraser River) © 2016, Southern Alberta Institute of Technology 6  Steam longitudinal profile Dominant characteristics of 3 zones: Headwaters Steepest gradient (slope) Sediment erodes and is carried downstream Braided channel pattern Transfer Receives sediment Meandering channel pattern Larger channel and wide floodplains Deposition Shallow gradient Deposit of sediments Highly sinuous channels, broad floodplains Note that erosion, transfer, deposition of sediments occur in all zones delta United States Environmental Protection Agency. Watershed Academy Web Stream Corridor Structure https://cfpub.epa.gov/watertrain/modulePopup.cfm? object_id=656 © 2016, Southern Alberta Institute of Technology 7  Model stream processes with a stream table VIDEO of Stream Table model showing difference between steady stream flow vs. pulsed stream flow (like in a flood): https://www.youtube.com/watch?v=7StgdcPwzms © 2016, Southern Alberta Institute of Technology 8 Streams can erode some particles AND deposit others at the same time! Rather surprisingly, sand grains between 0.2 – 0.5 mm are most easily eroded! Small clay particles have a tendency to stick together Earle, S. (2016)  A Delta A delta forms at a river’s base (where the river flows into a standing body of water) Why? What are characteristics of a delta?  Hydrographs The main purpose of a hydrograph is to show how a watercourse responds to a period of precipitation. A hydrograph is graph that shows the rate of flow (or discharge) of a watercourse over a time period. A hydrograph can show how a watercourse responds to precipitation events, and shows seasonal changes in flow major streams are fitted with a stream gauge to measure the stream’s height (water depth) and velocity directly when the stream is at different stages. must also measure the dimensions of the channel (width, water depth) to make a channel area calculation. Watch a hydrograph develop Watch this short video on hydrograph in a small suburban stormwater channel: https://www.youtube.com/watch?v=xAXyCls7BJc WHAT IS A HYDROGRAPH? WHAT DOES IT MEASURE? DOES IT HAVE A CHARCTERISTIC SHAPE? WHY? © 2016, Southern Alberta Institute of Technology 12  Hydrographs Every hydrograph has a y axis that is discharge and an x axis with time. It also often includes precipitation as a bar graph Flow, synonymous to Discharge, is calculated as area x velocity. Each watercourse has a baseflow, or the near constant day to day flow provided by groundwater seepage During and after a rain event, run-off from the land enters the watercourse. There is a lag time between a precipitation event and when the river discharge is actually increased. Peak discharge is when the river has reached its maximum flow from the precipitation event.  Interpreting a hydrograph Discharge (flow) from a catchment area is variable and the graphical curve which shows this change is called a hydrograph Streamflow is made of two components: Stormflow: from precipitation or snowmelt that reaches the channel over a short time (=constant) frame from run-off into the channel Baseflow: discharges into the channel from a groundwater source. Provides a near constant contribution to streamflow during periods of Source: little precipitation https://cfpub.epa.gov/watertrain/moduleFrame.cfm?parent_object_id=624 &object_id=628#628 © 2016, Southern Alberta Institute of Technology 14  River Flow Hydrograph Discharge = Area x Velocity m3/s m2 m/s (we can predict floods coming) Baseflow In this river, over 40 hours it rained in the first 5-18 hours with Source: https://geographyas.info/rivers/discharge-and-hydrographs/ peak rainfall at hour 12., but peak discharge later at about 22 hours © 2016, Southern Alberta Institute of Technology 15  2013 Flood at Exshaw Creek Braided channel: high sediment load, unstable temporary channels quick to change course, numerous sediment bars within stream Golder, pg. 52 Hydrographs, June 2013 Basin-Wide Hydrology Assessment and 2013 Flood Documentation. Golder Associates. 2013 flood in Calgary area Calgary's River Flood Story https://maps.calgary.ca/riverflooding/ © 2016, Southern Alberta Institute of Technology 18 Human Impacts to River Planform Source: Jon Slaney, City of Calgary Anthropogenic Changes – Flood Plain Development 1924 1948 2015 09/09/2019 Presentation V03 13 © 2016, Southern Alberta Institute of Technology 19 Effect of urbanization Streamflow rate variation for pre-development and post-development scenarios (Schueler, 1992). Hydrology of urban streams changes as natural vegetation is replaced by impervious surfaces due to development. Stormwater run-off is increased after a precipitation event, as infiltration into the subsurface is decreased. © 2016, Southern Alberta Institute of Technology 20  Types of Flood Mapping Flood Inundation Maps Flood Hazard Mapping Show areas at risk for different size floods Regulatory mapping used for development Matched to various river flow rates (discharge) policies, managed by Government of Show areas that could be flooded if local Alberta (https://www.alberta.ca/flood-hazard-identification-program) berms fail Draft Flood Hazard Area map for Calgary Used for emergency response planning and for recently published! (January 2024) infrastructure design Based on 1:100 flood return periods and divided into floodway and flood fringe Flood Awareness Map Application (alberta.ca) https://floods.alberta.ca/?app_code=FI&mapType=Draft Calgary River Valleys Project https://www.calgary.ca/water/flooding/calgary-river-valleys-project.html?redirect=/rivervalleys © 2016, Southern Alberta Institute of Technology 21 Flood Inundation Mapping, QGIS Interactive map with filters for various size of floods (based on return periods) Source: https://mapgallery.calgary.ca/apps/calgary-river-flooding/explore Flood Mechanisms Overland flooding Direct overland flooding where river overtops its banks (“Inundated area”) Areas that could flood if a flood protection barrier failed (“Protected area”) Sewer backup Localized flooding from exceeded stormwater drainage capacity, due to drainage issues, or storm system backups or sewer backups Groundwater Flooding of basements Can lead to overland/surface flooding through seepage / discharge Due to the water table rising, flooding to the ground like basements, toilets.. Water Tubes ACTIVITY See the Activity in Brightspace Unit 1: Calgary Rivers and Floods Explore the interactive websites, and use layer functions to understand Inundation and flood recurrence (probability) Flood Hazard  Calculating Flood Recurrence intervals on the Bow s the d Earle, S. (2016.) Reducing the hazard of river flooding Flood Hazard Mitigation: Mapping flood plains and not building within them (limit development / re- zoning bylaws) Installing flood berms where necessary Monitoring the winter snowpack and the weather and precipitation events Measuring and monitoring stream discharge Educating the public on how to prepare for and respond to the threat of flooding © 2016, Southern Alberta Institute of Technology 27  Mitigation infrastructure for floods Reservoirs Ghost Reservoir operating agreement between GoA and TransAlta modified to hold back more floodwater when required (to a small degree) Gates installed on crest of Glenmore dam in 2020 increasing storage capacity (to help manage high river flow events along the Elbow River Together, designed to downstream of dam) prevent overbank Springbank off-stream reservoir (SR1) will divert water from flooding flooding along Elbow River for temporary storage (expected completion in 2025) Elbow River in Calgary for a 2013-sized flood Flood barriers (berms) Other: Bank / channel reinforcement (strengthen river banks with riparian restoration and/or bioengineering to resist erosion) Calgary’s River Flood Story, https://mapgallery.calgary.ca/apps/calgary-river-flooding/explore 28 Importance of River Floodplains Floodplain – part of the valley floor that is periodically inundated by river floods Storage / Supply area for alluvial sediment (especially finer-grained flood deposits) Unique and diverse ecology and habitat (mixed aquatic and terrestrial) Provides space for river channel to migrate as the river adjusts to changes in sediment and water discharge Contains the extensive, shallow, unconsolidated aquifer (alluvial aquifer) on either side of the river channel © 2016, Southern Alberta Institute of Technology 29  Terms we learned River morphology (planform) Flood inundation maps Tributary Flood recurrence interval Upstream/downstream Confluence Flood frequency River reach Discharge Thalweg Floodway Meander Flood fringe Floodplain channel levees, terraces Watershed (drainage area) Graded stream © 2016, Southern Alberta Institute of Technology 30 Homework (for next lecture class, Tuesday Jan 21) See the Readings under Unit 2 / Learning Activities in Brightspace Quiz to start class on content from this lecture class References Earle, S. (2019). Physical Geology – 2nd Edition. Victoria, B.C.: BCcampus. https://opentextbc.ca/physicalgeology2ed/. Wampler, P. J. (2012) Rivers and Streams — Water and Sediment in Motion. Nature Education Knowledge United States Environmental Protection Agency. Watershed Academy Web Stream Corridor Structure. adapted for the internet from Stream Corridor Restoration: Principles, Processes and Practices written by the Federal Interagency Stream Restoration Work Group. https://cfpub.epa.gov/watertrain/moduleFrame.cfm?parent_object_id=610