Alabama Soil and Water Blog Spot

  Many E&SC practices like a silt fence are to be placed mostly on a contour to pond water and allow coarse particles time to settle and be captured.  So, my question is “What do you call a silt fence that is NOT on the contour?”  The answer is “A Diversion”.  This runoff water funnels down the edge of the silt fence often washes out the backfill and results in undermining of the silt fence.   Perry L Oakes, PE Alabama’s Erosion and Sediment Control Program Manager

I often hear the statement that “It’s flooding like I have NEVER seen it flood before”.  Sometimes it is easy to blame this on Climate Change , but it can be caused by land use changes.  For example, a watershed that changes from a Runoff Curve Number of 70 (a lot of woods and green space) to 95 (urbanized) can experience flooding more often. In this scenario, the runoff from a 2-year, 24-hour (50% chance of occurrence) event in the urbanized watershed can resemble the runoff from a 25-year, 24-hour (4% chance of occurring) event in the green watershed . So, it floods more frequently.  Something to think about!   Perry L Oakes, PE Alabama’s Erosion and Sediment Control Program Manager