Science Article

Before choosing the specific watershed you plan to study, think about: 

• the amount of time available to do the work
• the number of people ready to help
• the extent of their interest
• the size of the upstream section from your starting point

Define the Watershed—the base map
 Locate the water body: What area does your group have an interest in? Find it on a map. In order to define your watershed, you need to locate the high ground that divides your watershed from the ones around it.

Establish the direction of water flow and find the bottom of your watershed—where the river empties into a large lake.

To trace surface water, trace upstream from the watershed bottom until you hit intermittent streams, ponds, or wetlands. To show the height of land from your watershed to the next watershed, trace around the highest contour between the two water bodies.

Creating the Map Overlays
Keep these elements consistent on all maps: scale, legend, north arrow, reference points.

Land Use Overlay

Use information provided on topographical maps to show ways people have used the land. Use many colors, but keep it simple for clarity. Include the following: agricultural activities, forestry/wood lots, urban areas, landfills, mining activities (including gravel pits and quarries), underground reservoirs and groundwater pumping, industrial and commercial areas, and areas of cultural or natural interest (golf courses, parks, camp sites, etc.).

Since maps are often out of date, confirm your information by taking a field trip to check any areas in question. During fieldwork be careful to respect any properties you cross and work on. Check if permission is needed to go on them.

Landscape Overlay
Label soil types and study the topography of the area. Check soil and land inventory maps and ask experts in the area to find out as much as you can. Mark the areas of sand/gravel, clay/silt, no soil, and peat using a thin black marker and different hatching techniques.

Divide the area of your watershed into one of three classes of topography: flat, rolling, or steep and rugged. Use different colors to show each area on your map. Determine your bedrock type by finding out if it is either volcanic rock (such as granite) or sedimentary rock (such as limestone).

It is easy to find the level of erosion sensitivity by identifying the slope of an area and the soil type. Silt erodes at a slope of 5% or steeper. Clay erodes at a slope of 15% or steeper. Sand and gravel erode at a slope of 40% or steeper.

Water Pathways and Storage Overlay
Draw surface-water features in thin blue lines on the overlay. Mark any breaks, such as dams, flood-control structures, and urbanized areas where water is fed through storm sewers.

Look for areas where the water flow has been straightened (ditches, canals, reservoirs) or that have abrupt angles. Mark these areas in thick red bars. Mark any sand or gravel deposits in the landscape overlay—these are groundwater recharge areas.

Mark any wells or water pumping stations—these wells access groundwater storage.

Look for isolated ponds and wetlands. If they have streams only coming out of them but not into them, they are areas fed by groundwater. Also mark any springs or artesian wells.

Plant and Animal Community Overlay
Draw on the overlay aquatic communities such as lake, stream, and wetland vegetation. Draw on the overlay terrestrial communities such as forests, grasslands, forest plantations, croplands, barren lands, scrublands, etc.

You have successfully mapped your watershed. Now you can add potential impact flags!