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<br />FLUCTUATING FLOWS AND BACKWATER HABITATS 1137 <br /> 30 (a) Backwater 5 -0% <br /> ---- 10% <br /> --- 20% <br />0- 20 ----- 30% <br />~ ------40% <br />III <br />... <br />:J <br />- 10 <br />III <br />... <br />III <br />Co <br />E <br />III 0 <br />r- <br /> Jul Aug Sep Oct Nav Dec Jan <br /> Date <br /> 30 (b) Backwater 6 <br />-- 20 <br />0 <br />~ <br />III <br />... <br />:J <br />- 10 <br />III <br />... <br />III <br />Co <br />E " <br />~ 0 <br /> Jul Aug Sep Oct Nav Dee Jan <br /> Date <br /> <br /> <br /> <br /> <br />Figure 7, Simulated mean daily water temperature CC) in backwaters 5 (a) and 6 (b) at 0, 10,20,30 and 40% within-day flow variation <br /> <br />increased, minimum daily wetted area declined substantially. As expected, this decline was particularly noticeable <br />in the shallowest backwaters (backwaters 3, 4 and 5; Figure 9), However, one of the largest, deepest backwaters <br />(backwater 2) was also significantly affected, suggesting that depth alone will not predict the relationship between <br />flow fluctuation magnitude and minimum daily wetted area, <br />Volume of water exchanged with the mainstem, The most dramatic effect of within-day flow fluctuations was on <br />the proportion of the backwat.er's mean daily volume exchanged with the mainstem (Figure 8). At simulated <br />within-day flow fluctuations of 40l!f;, as much as 60cy,:, of the backwater's mean daily volume is exchanged with the <br />mainstem_ Relatively small, shallow backwaters (e. g, 3,4 and 5; see Figure 8) appear to have a larger proportion of <br />their volume exchanged in a fluctuation cycle than larger, deeper backwaters. <br /> <br /> <br />Figure 8, Simulated proportion of the mean daily backwater's volume exchanged with the mainstem for backwater 1,2.3,4,5 and 6 [U 10, 20, 30 <br />and 40% within-day flow variation, Note that at 0% within-day flow variation. backwater volume remains constant <br /> <br />Copyright ,~C) 2006 John Wiley & Sons, Ltd, <br /> <br />River Res, Applic, 22: 1125-1142 (2006) <br />DOl: 10. L002/rra <br />