PLAN341 Lecture Notes - Lecture 4: Shear Strength, Slope Stability, Alidade
20 Mar 2016
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Document Summary
Productivity: carbon produced per m2 per unit of time. Water quality problems are often coupled with erosion and sedimentation. Without knowledge or regulation of slopes, placement of structures occurs on unstable slopes. When we cut out slopes we are disturbing and destabilizing the river/slope environment, can result in failure. Overland flow leading to soil erosion: vegetated slopes provide resistance to water, reduces erosion and stabilizes slopes, water repellent soils occur at 0 to 5 cm, and creates a tin-roof effect. Surface erosion from overland flow causes sediment bulking in gullies/channels. Summer thunderstorm with intensity of 10mm/hr for 30 minutes can cause debris flows or flooding. Slope measurement: contour maps - connect points of equal elevation, survey techniques abney level alidade transit. Percent slope = change in elevation x 100. Disturbance of stable slope may result in: failure, accelerated erosion, ecological deterioration of slope.
