Part One – Determining Flow Directions using a DEM

Question 1 (5 points)

Constructing a Flow Direction Map

1. Open the Flow Diagram word document.

2. Flow direction can only be calculated from nodes where the nearest eight neighbour nodes (immediately adjacent nodes) are visible. You cannot start a flow path at the edge of the map however finishing a flow path at an edge is possible.

3. It is best to start a flow path at the highest elevation. In this lab assignment you will begin in the southwest (bottom-left) corner at the node with an elevation of ‘101’.

4. After identifying this node, look at the elevation of the eight neighbouring nodes. Which has the lowest elevation?

5. Draw a straight line with an arrow indicating the direction of water movement between your node and the neighbouring node with the lowest elevation. This is the flow path water would take.

6. Now find the next neighbouring node with the lowest elevation and repeat step 5, until you reach the edge of the map or find all the neighbouring nodes have a higher or similar elevation. In the latter case, your flow path has entered a pit; label this area “Pit”.

7. Pick a node adjacent to your first node and repeat the process, until flow paths are originating from all the nodes with the exception of those along the edge of the map.

There are several ways to complete this question:

· You can complete it by hand by printing the diagram out, hand-draw the arrows, then upload a photo of the page. The photo should be either JPG or PNG format ***

· You can Draw arrows digitally in Word using either:

· Insert Tab -> Shapes, then choose the straight line with an arrow.

· Draw Tab -> choose a pen, then draw an arrow with your cursor

***Do not upload an image where the marker needs to download or convert a file to view (i.e. .HEIC or otherwise), you may need to convert your image.

Part Two – GIS Layers and Spatial Information Analysis

Problem One

GIS uses different “layers” of information for spatial analysis. In this part of the lab, we will use different layers of information in the form of maps (spatial information) to analyze theoretical groundwater contamination problems on Mayne Island. The process is similar to that used by computer based GIS systems; however, this lab uses layers created in Quantum GIS and imported as KMZ files into Google Earth Pro.

The lab package includes ten layers, named Mayne_Island_”LAYER NAME”. Use these Mayne_Island_”layer” to complete the analysis and answer the associated questions.

· Mayne_Island_20m_contours & groundwater_flow – flow direction map and elevation contours, derived from a DEM (Mayne Island DEM). The groundwater_flow layer was derived using the same methodology you employed in Part 1 of this lab.

· Mayne_Island_groundwater_wells – the location of groundwater wells on Mayne Island

· Mayne_Island_wetlands — the location of wetlands on Mayne Island

· Mayne_Island_stream & _lakes – the location of streams and lakes on Mayne Island

· Mayne_Island_Airfield — the location of the airport on Mayne Island

· Mayne_Island_polygon – improves the viewing of certain layers by shading the satellite image

· Mayne_Island_Place_Names – improves your understanding of various locations

· Mayne_Island_DEM – a raster-based image and was used to create the flow directions and contour lines

Problem One

In this theoretical exercise, contaminants have been observed in the stream, lake, and wetland that drain into Campbell Bay. The source of these contaminants is unknown. One possibility is that contaminants are being introduced from a polluted well. Your task is to identify which wells might be contaminated and potentially causing the contamination.

This will require three steps:

1. Identify the area that is receiving the contaminants — the “target area”

2. Identify the area that could be contributing the contaminants — the “source area”

3. Identify wells locate within the source area

Identifying watershed “Source Area”

· Locate Campbell Bay using the _place_names layer

· Locate the lake, stream, and wetland that flow into Campbell Bay. This is your target area.

· Using the groundwater_flow layer arrows that indicate the direction water will flow, trace the watershed or source area for contaminants that may be found in Campbell Bay by using the Add -> Polygon function (see instruction video). This may be easiest by starting at the mouth of the stream, creating a polygon that encompasses all of the arrows that point toward the wetland, lake, or stream. (Hint: the boundary of a watershed can be identified by arrows going in opposite directions.) Name this polygon “Campbell Bay watershed_Source Area”.

· Tip: The watershed boundary should occur where flow arrows are pointing in opposite directions on either side of the boundary

Example:

https://d2l.langara.bc.ca/content/enforced/224841-11372.202210/PastedImage_4k2da029nk5by41lbjm20f5ccj5obs2700146357024.png?_&d2lSessionVal=vWS7MiEGeYlyxrL7uxIvs5mIO

For the next step, you will be creating a map in Google Earth showing the watershed layer (Campbell Bay watershed_Source Area) that you just created. To make your map, follow these steps:

· Create a Placemark that labels the watershed layer “Campbell Bay watershed_Source Area”

· Turn on the groundwater_wells layer and notice the number of groundwater wells that may be contaminating the wetland, lakes, and streams flowing into Campbell Bay.

· Your map should have the following layers displayed. Make sure these layers are checked in the Places Panel in Google Earth:

· Wetlands

· Lakes

· Streams

· Campbell_Bay_Watershed_Source_Area

· Groundwater_Wells

· Click Save Image and save it to a folder on your computer.

· Ensure the map has the following components:

· Title: Campbell Bay watershed and Groundwater Wells

· Description: Groundwater wells that may be contributing to pollution of Campbell Bay via wetland, stream, and lake

· Legend

· Scale

· Compass

Question 2 (5 points)

Upload your map of the Campbell Bay watershed and Groundwater Wells, use the Add File button in the text box below.

Problem Two

Question 3 (5 points)

Problem One used a methodology where you determined the areas upstream of the contaminated “target” area. Problem Two will determine areas downstream of the potential source of contamination.

Imagine that hypothetically the airport’s fuel storage facility were to leak, spilling fuel along the Mayne Island Airfield (the long white line). If this were to happen, the fuel would not necessarily all stay exactly along the airfield (white line), but rather some of the fuel could potentially travel from the airfield to nearby locations. If the Airport’s fuel storage facility were to leak; what groundwater areas, and wells would be contaminated?

· Use a methodology similar to Problem One. Create a polygon around the area affected by a leaking Airport Fuel storage facility and label it, “Wells possibly contaminated by Airport fuel leaks”

· You should now have two polygons; one illustrating the area possibly contributing to the contamination of the wetland, streams, or lakes upstream of Campbell Bay, and another illustrating the area and well potentially affected by a leaking fuel storage facility at the Mayne Island Airfield.

· Produce a map showing the wells possibly contaminated by Airport fuel leaks. This map should show the second polygon you made (illustrating the area and wells potentially affected by a leaking fuel storage facility at the Mayne Island Airfield), the contours layer from the kmz file, the groundwater flow arrows, well locations, the airfield, and relevant place names. Change the title and description of the map appropriately, then save it to your folder.

· Use the Add File button in the text box below to upload your map of the Mayne Island Air Field and possible contamination area

Question 4 (1 point)

Do the people living in Miners Bay, Village Bay, or Bennet Bay need to be concerned about their wells being affected by the contaminants affecting Campbell Bay? Explain your answer.

Question 5 (1 point)

Some people in Campbell Bay claim the contamination is coming from the Airport. Do you think this is likely? Explain?

Question 6 (1 point)

Hydrocarbon contamination is evident at trace levels in wells located near Village Bay. They say this is evidence that Airport fuel is leaking into their wells. The Airport administrators say the source of contamination may exist outside of the Airport area, and may be a result of the BC Ferries site located in Village Bay. What does your analysis show? Explain where you think the source area is?

Part Three: Groundwater Level Changes Over Time

Some groundwater supplies suffer from overuse. The monitoring of groundwater levels on Mayne Island is conducted using provincial government observation wells. The levels of these wells are continuously monitored.

The graph attached below illustrate the monthly variation in the groundwater levels of two monitored wells between 1972 and 2002. The third graph illustrates the monthly precipitation record from Victoria International Airport. The Airport is the closest area with long term precipitation records.

Download the Observation well graphs document to answer the following questions

Question 7 (1 point)

In the southern Gulf Islands and in Victoria precipitation is generally greater in the winter and decreases in the summer. This trend is noticeable in the graph. Do the groundwater wells exhibit a similar monthly trend?

Tip: The X axis labels have different date formats, but each X axis label indicates one year. It may be difficult tell exactly which months peak precipitation and depth to groundwater occurs. However, when answering this question, try to focus on the general trend.

Question 8 (1 point)

What do the patterns suggest about the relationship between precipitation and groundwater levels on Mayne Island? Why do you think this relationship exists

Question 9 (1 point)

Do you notice any long term trends? Describe these trends.

Question 10 (1 point)

Observation Well 125 is located in a primarily residential area. The land use around Observation Well 126 is a mix between agriculture and forest. Mayne Island and the Gulf Islands in general, have experienced an increase in population growth in the past. Does this aid in explaining the different trends seen in the groundwater levels of these wells? Explain why?

Question 11 (1 point)

Something to Consider: Mayne Island relies on groundwater exclusively for its domestic and agricultural water. No other sources exist. With Canada’s changing demographics there is an increase in the demand for property on Mayne Island and an increase in development (i.e. retirees love this area); moreover, climate change models predict a reduction in winter precipitation in the southern Gulf Island area. What are the implications to groundwater levels and what would be a strategy to mitigate this issue?