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<br />n <br />Qi=( I Qu)+Qr>' <br />u=l <br /> <br />where: Q.=discharge at node i, <br />1- <br /> <br />Q =discharge at adjacent nodes immediately upstream from node i, <br />u <br /> <br />n=number of adjacent nodes immediately upstream from node i, and <br /> <br />(1) <br /> <br /> <br />002~66 <br /> <br />An output node is any node at which there is an interest in observing <br />the model estimates through time and examining differences in these estimates <br />with various anticipated mining activities. The most downstream node (node 6 <br />in fig. 2) usually would be an output node. If the cumulative effects of coal <br />mining in the area upstream from node 4 (fig. 2) are of interest, node 4 also <br />could be an output node. <br /> <br />At any node, the surface-water quantity component, which is mean monthly <br />discharge in cubic feet per second, is calculated by the equation: <br /> <br />Q =incremental discharge (increase or decrease) within the reach <br />r between node i and adjacent nodes immediately upstream. <br /> <br />The estimate of incremental discharge within the reach can be obtained by <br />reading observed data or by estimating the data by the equation: <br /> <br />Qr=a+bQs' <br /> <br />where: Q =incremental discharge (increase or decrease) within the reach, <br />r <br />and b=the regression coefficients from simple linear regression, and <br /> <br />(2) <br /> <br />Q =discharge at some nearby streamflow-gaging stations. <br />s <br /> <br />In the model several stream reaches have both an upstream and a down- <br />stream node with a streamflow-gaging station. In these situations, Q could <br />be measured directly and observed discharge data were used. In thoser>situa- <br />tions where observed data were not available, Qr> was initially set to zero <br />and modified by altering the regression coefficients in equation 2 during <br />calibration. <br /> <br />For each anticipated mining activity the Mined Land Reclamation Division <br />estimated the quantity of water discharging to the stream. This discharge <br />input was made at nodes identified in figure 1. If the estimated water dis- <br />charge was runoff discharged from sediment ponds or from water migrating <br />through spoil material from a surface mine, this water was not considered <br />"new" water to the system but rather part of the water present in the <br />observed data. If the estimated discharge was from dewatering activities, it <br />was considered new water. It may be argued that surface mining increases the <br />streamflow by reducing evapotranspiration and by the addition of a new <br />ground-water storage zone (the reclaimed area). If this increase in discharge <br /> <br />6 <br />