Oh you pesky “worth a dam” tree and beaver-huggers. You don’t understand that planting trees in our creek can slow the water down and cause significant flooding problems. Sure roots hold the soil, but trees get in the way, so you can’t plant any near the water, or near the channel. There are important safety issues at stake here, and these larger concerns matter more than your silly beavers.
HYDRAULIC CHARACTERISTICS OF CALIFORNIA NATIVE RIPARIAN PLANT SPECIES (SANDBAR WILLOWS) UNDER FLOOD CONDITIONS IN A FLUME1
• “The willows decreased velocity at the bottom and increased it at the top of the flow profile.”
• “The willows decreased bottom erosion.”
Please look closely at the following graph from L.K Kavvas at UC Davis. The left axis indicates erosion, and you can see that the bare creek produced much much higher erosion, which means more landloss and greater silt in the water. The right axis indicates velocity, or the speed at which the water moved through the flume. The willow creek not only had less erosion, it had demonstrably faster water, and moved more water through at a quicker rate, leaving less water backed up to hang around and cause flooding.
Too bad the city moved all those trees last year.
1Riparian Habitat Joint Venture: Dec 2007 Section 2 Page 40
M.L. KAVVAS, Z.Q. CHEN,
H. BANDEH, M. CAYAR, N. OHARA,
D. COCHERELL, JOSEPH CECH, JR.
UNIVERSITY OF CALIFORNIA, DAVIS
STEPHAN LORENZATO, TED FRINK
DEPARTMENT OF WATER RESOURCES
JOHN CARLON AND TOM GRIGGS
