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at given elevation and distance from the line sink and parallel to it. The <br />equation used is dependent on the degree of excavation of the sink. The time <br />required for the distance of influence to intercept the boundary is computed <br />by equation 7 (McWhorter 1981). The flow to this type of sink remains <br />constant after the time calculated by equation 7. <br />Line Sink Downdip Equation 8 is used for the special case of a line sink <br />parallel to strike in an aquifer of nonzerodip angle. In successive time <br />steps, the line sink is moved progressively downdip. This solution addresses: <br />o The change in head in the unit from an initial value to a final <br />value.' <br />o A number of bench cuts associated with this change in head. <br />o The start and stop times of each bench cut. <br />• <br />Line Sink with Head Adjustment If the distance of influence of a line sink <br />intersects a barrier or nor flow boundary, the unit cannot be treated as <br />infinite in extent. These conditions are addressed by adjusting the initial <br />head used in the basic line sink equation. This head adjustment is depenaent <br />on the initial and final head at the boundary (Equation 9). Equations l0a and <br />lOb represent modifications to the standard line sink equations for conditions <br />in which no-~ow boundaries affect flow to the sink. The inflow rate to the <br />sink depends on the physical properties of the boundary zone: its specific <br />yield, width, initial head, and distance from the boundary to the sink. <br />Again, equations l0a and lOb represent different solutions for time before and <br />r <br />after the sink reaches its full length. <br /> <br />3 <br />