|
Caption: This chart shows surface erosion (tons) by decade from harvested areas within sub-watersheds of the Upper Trinity Planning Watershed. The first time period category includes data prior to 1950. The different colored bars represent tons of surface erosion per decade, while the total length of the bars show the total mass of sediment resulting from harvested areas during the period of pre-1950 to 2000. Erosion rates were assigned as follows: pre-1970 12 tons/acre, 1970 period one half of acreage at 12 tons/acre and one half at 4 tons/acre, 1980 and later 4 tons/acre. For areas in each watershed underlain by erodible Shasta Bally Batholith, rates were increased by a factor of 10. Data are from Graham Mathews and Associates Trinity River Sediment Source Analysis (2001). See Info Links for more information.
|