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<br />side of a cross section, if possible, so that the remaining conveyance <br />at the incrementally higher water surface elevation is the same as the <br />conveyance of the natural section at the natural water surface elevation. <br />There is one restriction to the encroachment process; the program will <br />not encroach into the channel as defined by the left and right bank <br />stations. If there is insufficient conveyance in one of the over- <br />banks, the program will automatically try to reduce the conveyance on <br />the other overbank to make up the deficit. Once the encroachment <br />staions (left and right) are set, the program computes the water sur- <br />face elevation for the encroached cross-section. A simple example <br />hand calculation (Appendix I) shows the steps involved. <br />A variation of the above procedure for determining the stations <br />of encroachment has been added to the program as Modification 58. <br />Instead of eliminating an equal percent of the increased conveyance <br />from each side of a cross section, this procedure distributes the <br />percent of conveyance reduction based on the distribution of conveyance <br />in the two overbanks. For example, if the left overbank of a cross <br />section had twice as much conveyance as the right overbank, this pro- <br />cedure would eliminate 67% of the increased conveyance from the left <br />overbank and 33% from the right. This procedure would reduce the <br />instances where the program completely eliminates a cross section <br />overbank because the overbank has less than half the increase in conveyance. <br />This revised procedure will work with Method 3 or 4 by using a negative <br />input value on the ET card (ET card input is presented on page 10). <br />However, this procedure is not consistent with the current requirements <br /> <br />~' <br /> <br />" <br /> <br />, <br /> <br />6 <br />