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20 I I , I II I I I I I I I I I I I I I I Examination of the profile indicated by the s\n"vey shows widely varying slopes between adjacent cross-sections. The reach-length weighted average slope for the problem area is 0.00097, but the individual values range from a relatively steep 0,00476 to an adverse- 0,00140, More disturbingly, the values change sign quite often, with six consecutive cross- sections being the longest stretch of positive slope within the model, and two to three sections being typicaL Tellingly, the portion with the most frequent directional changes in slope, i,e" positive to negative or vice versa, coincides with an irrea heavily encroached upon by agriculture. Aerial photography indicates numerous :old river scrolls within the cropland, and shows a large meander bend truncated by encroachment. At the upstream end of this bend the river is oversteep and then bounces frequently between positive and adverse slopes to near the bottom of the reach, It is probable that the encroachment is most responsible for the radically varying slope, This likely occurred as a combination of the actual excavation (and probable over-excavation) performed to move the river channel from the potential agricultural land and the river's adjustment to the imposed disequilibriun\:ofunstable channel and planform geometry, A profile plot of this area is shown in Plate 2. Problem Area 4 is suspected to be aggrading,' although this can not be stated with certainty at this point. This is consistent with the apparent downstream movement of an aggradational trend observed in the degradation rangelines, The "JR2" particle size distribution was used:for this sub-reach for sediment transport calculations, The sediment yield for this problem area under existing conditions was 5,600 tons/yr with a mean daily load of 15 tons/day. Problem Area 5. Hydraulic modeling of Problem Area 5 indicated that the capacity within the active channel banks is approximately 1,500 cfs, This is the value above which flow begins to significantly inundate the overbank areas adjacent to the river channeL Only one cross-section (out of 75) within the model indicates flows in excess of 4,000 cfs could cause damage to the adjacent agricultural area though, again, much of the flow area for lesser flows is outside the chaunel proper. The next potentially damaging flow occurs at approximately 6,000 cfs, with a substantial portion of the model sections ip.dicating potential damage at flows above this amount. The 3,000 cfs operational discharge was modeled to indicate potential problem areas under current conditions, The flow area extents for this discharge were not plotted for this area, since it did not indicate potential surface w!lter damages. The area with its cross, sections is shown on Sheet 3, .. Examination of the profile indicated by the survey shows varying slopes between adjacent cross-sections, though not to the degree of area 4. The reach-length weighted average slope for the problem area is 0,00118, but the individual values range from a relatively steep 0,00742 to an adverse -0.00059, This steep slope is !lssociated with an irrigation diversion within the reach, Another steep value of 0.00682 along with an adverse value of -0,00032 occurs just upstream of a bridge crossing and is the result of the flow constriction there, The steepest value not related to a known structure is 0,00421, but is again associated with human activities. This value occurs where a meander loop has been cut-off by mechanical means, The adverse slopes are infrequent and not alarming for a natural channeL Compared to other