Hydrologist - an hydrologist studies water and its movement.

Introduction: On this field trip, the hydrologists will measure the speed of water flowing in the stream. When people divert water from a stream, build dams, or channelize the stream channel, the flow of the water changes. In Hawaii, the speed of the water is important since fast-flowing water can flush out introduced stream animals and allow native animals to live. Channelized sections of the stream flow faster than natural sections of the stream. The speed of the water also affects how much oxygen is in the water. Information on water flow is important to use with the data from the other scientists to determine the health of the ecosystem.

Materials: a cork, stopwatch, tape measure, and pencil.

Methods: The hydrologists will measure the speed of the water by timing a cork floating downstream. First mark off a section of the stream 5 meters long. One of the hydrologists will hold a cork in the fast flowing part of the stream at the upstream and of the 5 meters. Another hydrologist will be watching the stopwatch and recording the time in seconds. When the hydrologist upstream releases the cork, start the stopwatch and time the movement of the cork until it reaches the other end of the 5 meter section. Repeat 2 more times. Now repeat this series of three measurements with the cork floating close to the stream bank.

FAST FLOWING SECTION
Time 1 = ________ Time 2= ________ Time 3= _________
Total Time /3= ________average time in seconds

Velocity = 5 meters/ average time = ________meters/second
(velocity = distance/time)


SIDE OF STREAM
Time 1= ________ Time 2= ________ Time 3= ________
Total Time /3 = ________ average time in seconds

velocity = 5 meters/average time = ________meters/second


Is there a difference in velocity from the side of the stream to the fast flowing part of the stream? Why do you think this is? What do you think the velocity of the water would be like on the bottom of the stream?