Differences in the permeability of urban and rural
land surfaces lead to differences in their hydrographs. Urban streams
have ‘spikey’ hydrographs, that is stream flow goes
up quickly during a rain storm event and then down quickly when
the rain stops. Rural streams have much more ‘gentle’ hydrographs,
with stream flow going up slowly during a rain storm and falling
over a long period after the rain event is over.
In the next page, the accompanying animation
and sound files illustrate the difference between urban and rural
hydrographs. Here, we have converted streamflow data to sound files.
High-pitched tones of long duration indicate high stream flow and
low-pitched tones of short duration indicate low stream flow. Compare
the sound files (as tones or musical instruments) for an urban
stream (the Rouge River in Detroit) and a rural stream (the Sturgeon
River in the Upper Peninsula). Can you ‘hear’ the