Estimated Groundwater Yield following Strip Cutting in Pine Plantations

摘要

Groundwater recharge balances were determined under 40‐acre blocks of a jack pine (Pinus banksiana Lamb) plantation in northwestern lower Michigan during the 4 years following the removal of 50% of the trees in clear‐cut strips. Analyses were made by graphical interpretation of diurnal fluctuations and by use of finite difference equations. In the numerical method, weekly water table elevation measurements over each 40‐acre block were used to determine water table convexity, which was then linearly related to the groundwater inflow‐outflow balance.Results from both methods of analysis showed the effect of strip cutting as increased ground‐water yields. Estimates of water yield by the two methods differed primarily as a result of poor estimates of net evaporative loss from the saturated zone using the graphical method.Three other tests of cutting effects on groundwater recharge supported the budget estimates of treatment effect. Approximately 3 inches per year of additional water was produced as a result of the strip cut during the first 4 years after cutting. The numerical analysis showed that the amount of treatment effect decreased rapidly over th