Water, like air, is one of the key fluids that helps to move energy and matter around on Earth. Water is endlessly cycled on Earth from the oceans up into the atmosphere, and down onto the land by the power of the sun. Fresh water on land is a critical nutrient for all life, as well as creating habitat for life through the water in the soil, deeper in the ground, in rivers and in lakes. Physically, water acts to erode sediments, and chemically, it carries dissolved materials back to the ocean. Earth’s ice caps and glaciers act as massive stores of fresh water. All the phases that water can take on (gas, liquid, solid) are interconnected as one seamless whole, endlessly circulating.
This lab explores the different flow processes of water within a single watershed and examines how those processes interact. It examines what happens to the natural water cycle when humans choose to divert water from its natural flow, and to use it for another purpose. Any water pumped from either surface water or from groundwater eventually leads to a decrease in the surface water flow within the watershed. Students will demonstrate their understanding of the different flow processes by plotting graphs of precipitation, groundwater level, and streamflow, and by observing and explaining the interactions between these components.
After completion of this lab, you will be able to:
- Describe the distribution of water and freshwater on Earth.
- Explain the link between the energy cycle and the water cycle.
- Plot precipitation on a daily or annual basis.
- Plot surface water flow using a hydrograph.
- Plot groundwater levels and determine changes in groundwater storage.
- Use a spreadsheet to create graphs of values over time using multiple scales.
- Describe how the pumping of surface water or groundwater affects surface water flow.
- Appreciate an integrated approach to water management at the watershed scale.·
Graphing Using a Spreadsheet
The lab requires that you be able to download data on precipitation, streamflow and groundwater levels from different BC and Federal government sources. The data will be collected together in a spreadsheet, and then graphed over time. You should be familiar with spreadsheets and how to open a file, copy and paste data, save a spreadsheet, and plot data as an x-y graph of a value plotted over time. Please complete the spreadsheet tutorial.
The Water Cycle
Most Physical Geography textbooks will have suitable chapters covering elements of the water cycle. This may be split into a broad introduction to the water cycle within the early chapters when the hydrosphere (liquid water) and cryosphere (frozen water) are introduced. Later chapters on water resources typically include a more detailed explanation of the water cycle, and in particular, the processes that occur at the soil surface, the generation of runoff to streams, and infiltration to groundwater.
A series of short videos also introduce the major terms and concepts:
You should be familiar with the following key terms: precipitation, rainfall, snowfall, evaporation, transpiration, evapotranspiration, runoff, infiltration, percolation, soil water storage, net infiltration, water table, groundwater, groundwater recharge, groundwater discharge, groundwater pumping.
This lab examines hydrograph data. Students should be familiar with how streamflow is measured and how hydrographs are created.
United States Geological Survey, How Streamflow is Measured, Accessed June 18, 2020. https://www.usgs.gov/special-topic/water-science-school/science/how-streamflow-measured?qt-science_center_objects=0#qt-science_center_objects
A summary of hydrographs and the impact of different types of watersheds on hydrographs can be found at:
You should be familiar with the following key terms: watershed, hydrograph, discharge, stage, quickflow, baseflow, lag time, peak discharge
Groundwater, the Water Table, and Groundwater Pumping.
A good introductory summary of groundwater can be found in the following publication from the United States Geological Survey:
“Groundwater and the rural homeowner” – You should read from the beginning to the end of the “Increased Pumping in the Immediate Area” section. You can read from Quality of Water onwards just for interest sake if you wish.
You should be familiar with the following key terms: net infiltration, recharge, soil water, unsaturated zone, saturated zone, water table, aquifer, porosity, permeability.
This lab examines the ground-based components of the water cycle at the scale of a watershed. It is based on the watershed of the Nicomekl river near Langley, British Columbia, located to the east of Vancouver in the Fraser Valley. Data will be downloaded on precipitation, groundwater levels, and stream flow. These data will be plotted using a spreadsheet to examine changes over time. You will then examine how human usage of water within the watershed influences the geography of the water drainage features and the water budget of the area.
Location of the Watershed
A watershed is the land area drained by a surface water feature such as a stream or a river. In this exercise, you will use a BC Provincial water data web portal to examine the overall geography of the watershed, and to access the particular data on precipitation, streamflow and groundwater levels.
Data for water resources in British Columbia are collected by a variety of different organizations. Environment and Climate Change Canada is the federal government ministry that looks after weather and climate stations and is responsible for the Water Survey of Canada who maintain Canada’s network of streamflow measuring stations and prepares streamflow hydrographs. Groundwater data is collected by the BC Ministry of the Environment. The BC Government has created a web-based portal, the BC Water Tool, to allow the public to easily access all of the water-related data in a convenient place.
The BC Water Tool collects together basic hydrology, satellite imagery, streamflow, groundwater and climate data in one interactive web map. Open the BC Water Tool website, and navigate to the Water Portal for the South and Coast Area (link near the top of the home page). You may have to accept a data licence agreement. Zoom the map into the area of Vancouver, and to the Fraser Valley located to the east, and locate the sub-area outlined in Figure 18.1.
Functions in the BC Water Tool
At the top left hand side of the BC Water Tool screen, you will see a series of buttons that change the way data is presented on the screen. The + and – buttons allow the screen to be zoomed in and out. The normal “hand” icon allows you to use a mouse to drag the screen to new locations. The disk icon below the +/- allows you to save your current view as a url, or to download the data on the screen to a file. Under that is a folded paper icon. Click on this to change the character of the map. “Default” is likely the best scheme to use to see all the drainage features. You will also find “Satellite”. Click on this view, and the simplified map will be replaced with a detailed colour satellite image. Try out some of the different view types. At the bottom of that column of icons is a small “i”. Clicking on this his information icon will show the map legend.
As you navigate around the map, you may also <rightclick> using a mouse at any location. A small dialog box will open on the screen that will indicate the latitude and longitude of the location clicked expressed in decimal degrees.
Further to the left are a second series of buttons arranged vertically. Click on each button in turn, and see how the data presented on the screen changes. From top to bottom, what will be displayed are the following:
- Book icon: watershed reporting;
- Upwards trending graph icon: surface water hydrometric stations;
- S: surface water quality measurement stations;
- G: groundwater quality monitoring stations;
- Downward trending graph icon: groundwater level monitoring stations;
- Cloud icon: climate stations.
On each different data screen, different markers are used to indicate currently active stations, and inactive stations for which there is historical data, but not current data. You can click on the ‘i’ information icon to activate the map legend display. You may find that the top book icon (watershed reporting) does not work in this area.
Take 15 minutes and explore the watershed the BC Water Tool. You may wish to alternate your map view between the default line map view, and the satellite view. If you are familiar with Google Earth, you may also wish to explore the watershed using Google Earth.
Locate the Nicomekl River at the point where it flows east to west to the ocean at the hydrograph station to the left of Figure 18.1 (49.06917N or 49 04’ 09”N; 122.82500W or 122 49’ 30”W). Starting from this point, trace the river to the east where it passes through the City of Langley to the hydrograph station to the right of Figure 18.1 (49.10417N or 49 06’ 15” N; 122.6603W or or 122 39’ 37” W). Further to the east, the river may become difficult to trace. Examine some of the major tributaries of the Nicomekl as well. The Nicomekl has two side creeks that branch off to the south of the river—Anderson Creek just west of Langley, and another the branches off southeast of Langley.
Once you have taken some time to explore the watershed, answer the following questions:
- Describe the types of land uses within the watershed. Use the BC Water Tool default map view and the satellite image view to estimate the approximate proportions of the land within the Nicomekl watershed that is covered by farmland, urban land, and natural land.
- Examine the character of the side creeks from the Nicomekl river on the south side of the river in the area of Highway 15 (from 168th to 164th St). Compare this area in the satellite view, or using Google Earth. What is the dominant land use? Describe how the land use and drainage pattern go together.
- Examine the area of Langley city center (approx. 49.104, -122.657; the intersection of Glover Road or 203rd Street and the Fraser Highway). The urban area is bounded on the north by the Langley Bypass of Highway 10, on the south by the Nicomekl. On the west by 192nd Street and on the east by 208th Street and the Langley Bypass. What pattern do creeks show on the north side of the main Nicomekl channel compared to south of the main channel? Explain why.
Summary: At the end of this exercise, you should be familiar with the location of the Nicomekl river watershed, and the types of land use occurring within the watershed.
In this exercise, we will visit a series of data sources with the BC Water Tool, and collect data on climate and precipitation, streamflow in the Nicomekl, and groundwater levels. These data will be used in Exercise 3. In each case, you should save the gathered data to somewhere you can access it for use in the next set of Lab Exercises. If you find that you are unable to complete this step, contact your instructor, who will have a set of data downloaded that you can use.
Precipitation and Climate Data
Click on the Cloud icon on the left of the screen. Click on the information icon (an “i”) to see the legend (red circles are active stations, blue circles are historical data only). Zoom out until you locate the closest active climate station which will be south of the watershed close to the United States border in White Rock BC. Click on the station on the map and information will load on the right of the screen for White Rock station 1108910. Also on the right of the screen, you will see a large blue button to <Download Data>. Click here to download the data from this station. Save the file using the name suggested (station-data-12418.csv) to a folder you can find.
On the bottom right of the screen, you will see panels indicating graphs for Temperature, Precipitation, Snow on Ground and others. Click on the panel for Precipitation. You should now see a graphic displaying precipitation such as the one shown in Figure 18.2. The graphic has the following features:
- Precipitation amount is plotted on the y-axis and date is plotted on the x-axis.
- The black horizontal line in each month indicates the median value in that month.
- Dark shading indicates the more common historical ranges of data in that month of the year
- Light grey shading indicates the more extreme variations in historical data.
- Blue graphs show the cumulative amount of precipitation for each month in the current year.
Visually trace the black line across the figure, and take note of which months have, on average, typically record higher precipitation and which months have lower precipitation. To exit this screen, you must click on the X located in the top right of the screen.
Click on the upwards trending graph icon to activate the display of the locations of hydrographic stations. Locate the active hydrograph station located near the center of Langley (Nicomekl River At 203 Street, Langley, 08MH155, 49 06’ 15” N, 122 39’ 37” W). On the right of the screen, click to <Download data> and save the file (station-data-4268.csv) to your folder.
On the right of the screen, click on the <7 Day Flow>. You will see a graph similar to Figure 18.3. The streamflow discharge is plotted on the y-axis in m3/s. The date is plotted on the x-axis. As with the previous figure, the black line indicates the median flow on that particular day of the year, and the areas in dark and light grey show the range of values that are more commonly (dark grey) or less commonly (light grey) recorded on that day. As you move the cursor across the screen, the values of the median value of streamflow on that day, and the range over time will be displayed. The orange line shows the actual flow over the last 1 year period.
Visually trace the black line across the figure, and note which months have, on average, higher streamflow and which have lower streamflow. Follow the yellow line across the graphic, and look at how streamflow over the last year has changed. To exit this screen, you must click on the X located in the top right of the screen.
Zoom out, click on the downward trending graph icon to active groundwater level monitoring stations. Locate the two groundwater monitoring well locations (red dot in Figure 1) to the south of Langley close to Anderson Creek. Zoom in, and locate the eastern (right hand) of the two wells at this location (Langley 196 St near 36 Ave, Observation Well #353). Click on this well, and then click on the <Download Data> button and save the data to your folder (station-data-8309.csv).
Click on the <Level> button on the right. You will see a graph similar to Figure 18.4. The black line shows the median value of depth to water for that month, and the dark and light grey show the ranges of historical data. Notice that the groundwater data is plotted as depth to water on the y-axis, but it has been plotted as increasing downwards. This is how water levels are measured, using a specialized tape measure to record the depth to water downwards from the ground surface. A large depth to water therefore means a lower water elevation.
Trace the black line across the figure, and note which months have, on average, higher groundwater levels (small depth to water) and which have lower groundwater levels (large depth to water). To exit this screen, you must click on the X located in the top right of the screen.
Your instructor will have prepared a set of mean monthly data for you covering the calendar year prior to your lab. Examine the data and answer the questions relating to the monthly data.
- Examine the annual pattern of rainfall data. Which 2 months represent the peak inputs of water to the watershed from precipitation? When are inputs the lowest?
- Which 2 months represent the peak streamflow discharge out of the watershed? When is the lowest?
- Which 2 months represent the peak groundwater elevation? When is the lowest elevation? (Note: the data record depth from surface; the largest depth to groundwater indicates the lowest groundwater level). How much does the groundwater level change by over a year? What does this water level change represent?
- What is the lag time between peak precipitation and peak streamflow? What is the lag time between peak precipitation and peak groundwater level.
Summary: At the end of this exercise, you should have a folder containing three data files in .csv format for precipitation, streamflow and groundwater level. You will have examined the data on an annual basis to note the months with high precipitation, streamflow, and groundwater levels. Precipitation moves through the watershed either as runoff or interflow to become surface water directly. Or, precipitation may infiltrate to the groundwater, where it raises the groundwater level and is stored in the pores spaces in the ground. Groundwater then gradually flows underground to discharge to surface water.
Examine the folder where you saved your data files in Exercise 2. There should be three files there representing the precipitation, streamflow and groundwater level data. These will have file endings of .csv indicating they are text files where the different data points are separated by commas. If you have a spreadsheet program (e.g., Excel or OpenOffice Calc) installed on your computer, it should automatically open this type of file.
Open the file for climate data (Station-data-12418.csv) by double clicking on the file. If need be, you may have to start your spreadsheet program first, and then use <File> <Open> to open the precipitation file. Have a look at the data available in this file. Note that there is precipitation data, then snowfall data, and then a number of temperature data. You only need to look at the precipitation data, and can delete everything after the precipitation data if you wish.
Open the file for hydrometric data (Station-data-4268.csv). Have a look at the data available in this file. Note that there is both discharge and water level data. You only need the discharge data, and can delete the water level data if you wish.
Open the file for groundwater level data (Station-data-8309.csv). Have a look at the data available in this file.
Open up the EX3 spreadsheet (in Worksheets). Here you will note that the station data for precipitation, discharge, and groundwater level have been provided from 2004-09-10 to 2021-02-22. You will also note two graphs. First, a graph of precipitation and streamflow for the 2019/2020 water year (October 1, 2019 to September 30, 2020) on a single graph, plotting precipitation as a column, and streamflow as a XY type joined by a line. An example is shown in Figure 18.5.
Second, you will see a graph of precipitation and groundwater level for the 2019/2020 water year on a single graph, plotting precipitation as a column, and groundwater level as an X-Y scatter plot joined by a line. An example is shown in Figure 18.6.
The instruments used to derive the precipitation, discharge, and groundwater level happened to all malfunction on three specific days in the 2019/2020 water year and gave values that do not make sense. Search through the values in the EX3 spreadsheet between the dates October 1, 2019 and September 30, 2020 for three dates where the values for each parameter (precipitation, discharge and groundwater level) all seem wrong to you…
Answer the following questions:
- What are the three dates in the 2019/2020 water year where the instruments malfunctioned? Using your .csv station data file downloads (which have the correct values for these dates), correct these dates in your copy of the EX3 spreadsheet for precipitation, discharge, and groundwater level.
- Your two graphs should have automatically adjusted when you corrected the values in 8. Copy/screenshot/snip your corrected graphs and submit these graphs with your assignment.
- What time lag typically occurs between larger rainfall events in the winter, and changes in streamflow? You may wish to note some larger rainfall events on an annual graph, and adjust the x-axis so that you can zoom in on those dates only. Choose one such event that demonstrates your answer. Provide a copy of this graph with your assignment.
- Examine the graph plotting precipitation and groundwater level data. Does the groundwater level respond to precipitation on a daily basis? Choose a range of data on the graph of precipitation and groundwater level that supports your conclusion. Provide a copy of this graph with your assignment.
- Groundwater levels rise and fall on a seasonal basis. What happens to the water stored in groundwater between September and February?
Summary: In Exercise 2, you examined the way in which water moved into and out of the watershed on an annual basis. Exercise 3 required you to examine the response time between precipitation, streamflow, and groundwater level on a daily basis. You should have an understanding of how quickly streamflow responds to runoff and interflow, compared to groundwater flow.
Exercise 1 showed you that some of the surface water features within the watershed have been altered by land use within the watershed. Exercises 2 and 3 examined a streamflow response within a watershed without considering ways in which human beings may have altered the natural water cycle. In this exercise, we will examine some of the water users within this watershed, and consider what affect their usage has on the streamflow, and upon the overall nature of the water balance in the watershed.
On the input side of the water balance, precipitation is the main input of water to a watershed, and land use type can affect how much precipitation ends up as runoff, and how much water ends up infiltrating into the ground to become groundwater. Exercise 3 examined responses of streamflow to precipitation in a general way. Much more sophisticated analysis would be required to determine any effects of human alteration of the watershed on the streamflow.
The output side of a water balance is also affected. Humans may extract water from surface water or groundwater to provide domestic water supply (a single household), to supply drinking water (a water utility supplying many houses), to provide irrigation water, or for commercial purposes. This water may be returned to places within the watershed after it has been used (for example, some domestic water use is collected, treated, and discharged back to surface water), or water volume may be lost from the watershed if the water is evapotranspired by plants back to the atmosphere through use of the water for agricultural irrigation or for watering household lawns and gardens.
The hydrograph and groundwater levels within the Nicomekl river watershed are affected by the use of water by humans living within the watershed. Drinking water usage tends to be consistent year round. Irrigation water usage peaks in summer time. Commercial uses can vary over the year. Water extracted directly from a surface water feature will immediately reduce the streamflow or water level in that feature. Water extracted from groundwater either intercepts groundwater that was on its way to discharging to surface water as groundwater baseflow, or, the groundwater pumping may lower the water level enough to cause water to flow out of surface water and into the groundwater. Both effects lower the amount of surface water flow.
The following maps indicate surface water and groundwater water users within the Nicomekl river watershed (Figure 18.7).
Using these maps, answer the following questions:
- Which areas of the watershed use the most surface water? What usage type do you think these water licences are used for? (domestic, water supply, irrigation, commercial). Explain your answer.
- Which areas of the watershed have single households (domestic use) that rely upon groundwater for their water supply? Explain your answer.
- Based on the distribution of all of the surface licences and groundwater wells, can you determine which areas of the watershed have their drinking water supplied from a large water supplier? Explain your answer.
- Which area of the watershed do you think is the most environmentally sensitive? Why did you pick this area?
Summary: This exercise introduces the complexity of the real water balance within a watershed.
In the lab exercises, we saw that precipitation in a watershed leads to a response in surface water flow on short time scales in surface water. Precipitation can also infiltrate into the ground, percolate down to the water table, and become groundwater. The groundwater system stores up water in pore spaces, and then it flows slowly to discharge into surface water bodies, providing baseflow to streams year-round.
Three farmers have asked permission to pump water to irrigate their crops in July and August. One farmer has a pump that removes water directly from the river. The second farmer has a groundwater well located 10 metres from the river. The third farmer has a well located 2000 m from the nearest stream. The local fisheries officer is worried about low water flows in the river in late summer and fall as the river and creeks provide habitat for salmon and freshwater trout.
You are tasked with deciding if they should all get a water licence to extract water. What things would you need to consider in making your decision?
Click here to download the spreadsheet for Exercise 3 (Lab18_Ex3_Spreadsheet_2021.xlsx)
- Figure 18.1 Location of Nicomekl River Watershed © DataBC adapted by Craig Nichol is licensed under a CC BY-NC-SA (Attribution NonCommercial ShareAlike) license
- Figure 18.2 Precipitation data from White Rock climate station 1108910 © Foundry Spatial is licensed under a CC BY-NC-SA (Attribution NonCommercial ShareAlike) license
- Figure 18.3 Streamflow in Nicomekl River at Station 08MH155 © Foundry Spatial is licensed under a CC BY-NC-SA (Attribution NonCommercial ShareAlike) license
- Figure 18.4 Groundwater levels at BC Obs Well 353 © Foundry Spatial is licensed under a CC BY-NC-SA (Attribution NonCommercial ShareAlike) license
- Figure 18.5 Precipitation and streamflow in the Nicomekl watershed © Craig Nichol is licensed under a CC BY-NC-SA (Attribution NonCommercial ShareAlike) license
- Figure 18.6 Precipitation and groundwater level in the Nicomekl watershed © Craig Nichol is licensed under a CC BY-NC-SA (Attribution NonCommercial ShareAlike) license
- Figure 18.7 Water usage within the Nicomekl watershed © DataBC adapted by Craig Nichol is licensed under a CC BY-NC-SA (Attribution NonCommercial ShareAlike) license