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and consumptive use issues. Consumptive use estimates for <br />particular sites could be made using the Jensen /Raise or Blaney- • <br />Criddle equations, calibrated with lysimeter data collected from <br />each site (Quinlan 1984). The measurement of actual ET from <br />undisturbed, excavated, and reclaimed areas may play an important <br />role in deciding water rights issues. <br />Peat extraction affects the hydrology of a pea }land in <br />several ways. The fundamental factor underlying all of the <br />impacts is that the excavation process removes all of the active <br />layer, and most of the inactive humified layer. Typically, what <br />remains is a thin layer of the most humified sapric material. <br />Not only does this change the thickness of the deposit, but <br />topography, microrelief, hydraulic conductivity, oxidation - <br />reduction, and pH are also affected. These then result in a <br />reduction in storage capacity, which in turn increases stream <br />flow, flooding, and erosion. <br />These represent changes to both the physical and chemical <br />character of the peatland. The material remaining after <br />excavation has a much lower fiber content and much higher bulk <br />density than does the original peat cover. Since the size (and <br />volume) of the pore spaces in the remaining sapric material is so <br />small, vertical and horizontal water flow and the amount of <br />active storage space essentially go to zero (Verry and Boelter <br />1978). Figure 3 and Figure 4, when viewed in terms of the <br />relative flow and storage capabilities of peat at different bulk <br />densities and fiber contents, show graphically the trends that <br />38 • <br />