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<br />16 <br /> <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br /> <br />between ranges using the average-end-area method 'to arrive at volumes. These were also <br />compared to get volume changes. <br /> <br />Degradation range locations and graphs of all area and volume calculation results are <br />included in Appendix B. <br /> <br />The results of these analyses show the areal ;changes for Degradation Ranges 1 through <br />3 alternate between aggradation and degradation, Ranges 4 and 5 show only degradation. <br />Ranges 6 and 7 indicate predominantly aggradation; and Range 8 alternates between <br />aggradation and degradation. Range 9 shows aggradation for all surveys. Range 10 shows <br />degradation for all surveys except 1972, Range 11 shows all aggradation, Ranges 12 and 13 <br />alternate between aggradation and degradation, <br /> <br />The volumetric changes for the individual sub-reaches between adjacent Degradation <br />Ranges show low magnitude (about 100 acre-feet) changes in both directions for John Martin <br />Dam to Range 1, Ranges 1 to 2, and Ranges 2 to 3. ,Ranges 3 to 4, 4 to 5, and 5 to 6 all show <br />degradation, up to a maximum of about 600 acre-feet between Ranges 4 and 5, Ranges 6 to 7, <br />7 to 8, and 8 to 9 show predominantly aggradation, up to a maximum of approximately 1,200 <br />acre-feet between Ranges 7 and 8. Between Ranges 9 and 10, there was mostly degradation to <br />a maximum of about 600 acre-feet, although net aggradation of approximately 800 acre-feet <br />was indicated from the 1972 survey, The sub-reaches between Ranges 10 and 11, 11 and 12, <br />and 12 and 13 show mostly aggradation to a maximum of about 3,700 acre-feet between 11 and <br />12, <br /> <br />Cumulative volume changes between the dam and Ranges 1 through 4 show low <br />magnitude oscillations of approximately + 150 acre-feet to -600 acre-feet, with positive values <br />indicating aggradation and negative degradation, Between the dam and ranges 5 through 7, the <br />cumulative net volume changes are almost all negative to a maximum of approximately 1,300 <br />acre-feet, though values generated from the 1972 survey indicate aggradation. Between the <br />dam and Ranges 8 through 13, there is degradation qr slight aggradation (approx. -800 acre-feet <br />to + 150 acre-feet) through the 1962 survey, then significant (approx, 11,000 acre-feet <br />maximum) net aggradation for the subsequent surveys. This substantial change occurred after <br />a large magnitude flood in 1965. It should be noted that the data sets are not complete. Not all <br />of the Degradation Ranges were measured during all of the surveys, <br /> <br />., <br /> <br />Tentative conclusions drawn from this infonnation are that a limited amount of scour <br />and a significant amount of deposition have occurred downstream of John Martin Dam since it <br />began controlling flows, A state of non-equilibrium appears to exist, at least within the reach <br />covered by the Degradation Ranges, Further study will be needed to detennine the specific <br />causes of impacts, <br /> <br />Hydraulic Modeling <br /> <br />Numerical hydraulic models were assembled for each of the problem areas to analyze <br />current conditions, The HEC-2, Water Surface Profiles program (USACE 1990) was used for <br />