Laserfiche WebLink
<br />I - 18 <br /> <br />1.5 <br /> <br />TECHNICAL ASPECTS <br /> <br />Effects of river development, flood control measures and channel structures <br />built during the last century have proven the need for takin'J into account delayed <br />and far-reachin'J effects of any alteration man makes in a natural alluvial river <br />system. <br />Because of the complexity of the processes occurring in natural flows and t.he <br />erosion and deposition of material, an analytical approach to the problem is very <br />difficult and time consuming. Most of our river process relations have been derived <br />empirically. Nevertheless, if a Ljreater understanding of the principles <JoverninLj the <br />processes of river formation is to be '-pined, the empirically derived relations must <br />be put in the proper context by employing the analytic;][ approach. In that way the <br />distinct limitations of the empirical relations can be removed. <br />Mankind's attempts at controlling large rivers has often led to tilt; situaLion <br />described by J_ 1100ver Mackin (1937) when he wrote: <br /> <br />"the engineer who alters natur<ll equilibrium <br />relations by diversion or damming or channel <br />improvement measures will often find that he has <br />the bull by the tail and is unable to let go. _ _ _ _ _ as <br />he continues to correct or suppress undesirable <br />phases of the chain reaction uf the stream to the <br />initial 'stress' he will necessarily place increasing <br />emphasis on study of the 'Jenetic aspects of the <br />equilibrium in order that he may work with riv,;rs, <br />rather than merely on them." <br /> <br />1 hrourJh such cxperiences, man realizes that, to prevent Dr reduce the <br />detriment<1l effects of any modification Df the natur<11 processe,; and state of <br />equilibrium on a river, he must (pin an understanding of the physical laws governing <br />them, and become knowled'Jeable Df the far -reaching effects of any attempt to <br />control or monify a river's course. <br /> <br />1.5.1 Variables Affectinq River Behavior <br />Variables affecting alluvial river channels are numerous and interrelated. Tt",ir <br />naturt; is such that, unlike rigid boundary hydraulic problems, it is not pDssihle to <br />isolate and study the role of any individual vari<lble. <br /> <br />I <br />J <br />I <br /> <br />I <br /> <br />I <br />I <br /> <br />I <br />I <br /> <br />I <br /> <br />.- <br />I <br />I <br />I <br /> <br />I <br />I <br />I <br /> <br />I <br />.. <br />.' <br />