Activity 2 Investigating how water moves through Tucson
We can learn a lot about how water flows through Tucson by just looking at maps and
photos. In this activity you’ll use maps and photos to investigate how water gets into
rivers, the direction of water flow and the size of water flow.
Materials
The Basics
Watershed
Aerial photograph
Drainage network sketch
Ruler
Colored pencils
Calculator
The upstream area from where a river gets all of its water. All of the
precipitation (rain or snow) that falls in a particular watershed funnels into
a particular river. The upstream area from where a river gets all of its
water.
Gradient
The slope of a river (change in elevation divided by distance between 2
points on a river).
Discharge
The volume or amount of water that passes through a point along a river
at one moment in time.
Get oriented
The circled numbers (1 through 7) on the map are points along Tucson water channels
that will help direct your study of the different watersheds in Tucson.
1. An elevation value for each point is marked next to the circled numbers. Use
these elevations to determine the direction that water flows at each point. Mark
the direction with an arrow. The direction for Point (1) is marked.
[Hint: Which way does water flow? Downhill or uphill? Does elevation increase
or decrease when you go downhill?]
2. Identify the watersheds. For each numbered point, outline the watershed where
that point gets all of its. Use a different color for each watershed you outline and
make sure to clearly mark which color corresponds to which number. The
watershed for Point (1) is marked.
[Hint: Remember that watersheds are always upstream (or uphill) from a given
point.]
3. a) Rank Points (1), (3), (5) and (6) in increasing order of their watershed size.
b) Rank Points (1), (3), (5) and (6) in increasing order of discharge (amount of
water that passes through that point) after it rained consistently over the whole
map area.
c) Rank Points (1), (3), (5) and (6) in increasing order of their channel width.
d) How do watershed size, discharge and channel width relate to each other?
4. Use the following chart to calculate the gradient between Points (1) and (3) and
between (2) and (5).
Points
#1
Elev
#2
Elev
#3
Elevation
change
(#2 - #1)
#4
Map dist
(in inches)
#5
# miles in 1
map inch
#6
Distance in
miles
(#4 x #5)
(1) and (6)
(example)
(1) and (3)
(2) and (5)
Gradient = (elevationpoint a - elevationpointb) / (distance between point a
and point b)
Use the elevation values given on the map.
Use the scale bar on the map and a ruler to determine distance
between points.
Fill out chart. See example between Point (1) and Point (6).
Gradient
#3 / #6