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<br />FLOOD CONTROL
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<br />sediment calculations for Mail Creek, a
<br />tributary to Fossil Creek, had to be re-
<br />calculated for the Fossil Creek study
<br />since they were originally done in sepa-
<br />rate report for Mail Creek; basically a
<br />duplication of effort,
<br />Additionally, since rivers are part of
<br />a system, reach-by-reach studies may
<br />overlook significant variables, with
<br />regard to continuity between reaches,
<br />that would have been accounted for by
<br />taking a watershed approach. The City
<br />will be revising the 1982 Master Plan in
<br />the coming year and will verify continu-
<br />ity between the studies for the fluvial
<br />system.
<br />In addition, expertise may be diffi.
<br />cult to find, Although there is an
<br />increasing number of skilled consultants
<br />with the expertise in geomorphology,
<br />there is still a general shortage of people
<br />with specialized training, The applica-
<br />tion of geomorphology to real world sit-
<br />uations requires personal practical expe-
<br />rience in addition to academic qualifica-
<br />tions.
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<br />Conclusions
<br />Results of the stability analysis
<br />included development of practical
<br />improvements for mitigating adverse sta-
<br />bility conditions in the stream, as well as
<br />delineating minimum set backs and
<br />"erosion buffer limits" for future devel-
<br />opment. By using setbacks and selec-
<br />tive stabilization, naturalistic channels
<br />can provide protection to adjacent prop-
<br />erty similar to that provided by hard-
<br />lined channels while recognizing natural
<br />river processes, Obviously, this
<br />approach only works if development
<br />has not already encroached upon the
<br />channel.
<br />The stability studies are used as a
<br />basis for floodplain management. In
<br />many areas the erosion buffer limits are
<br />wider than the lOo-year floodplain, In
<br />such cases, if lOO-year floodplain delin-
<br />eation was the only criteria used, devel-
<br />opment would be susceptible to proper-
<br />ty damage through meander migration,
<br />bank erosion and failure, Therefore,
<br />lOO-year floodplain delineation is used
<br />for regulation in addition to the erosion
<br />buffer limits; whichever delineation is
<br />more conservative is used to regulate
<br />development.
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<br />There are no structures located
<br />within the lOO-year floodplain or ero-
<br />sion buffer limits of Fossil Creek. The
<br />wisest approach to land management
<br />along alluvial river channels, such as
<br />Fossil Creek, is to maintain natural con-
<br />ditions by discouraging development in
<br />the geomorphic floodplain,
<br />Bridging the disciplines of engineer-
<br />ing and geology, by recognizing that
<br />there are significant geologic and geo-
<br />morphic controls on rivers that influence
<br />river stability, is an area that deserves
<br />considerable attention in floodplain
<br />studies and management, Fluvial sys-
<br />tems are either adjusting to altered con.
<br />ditions or in the state of dynamic equilib-
<br />
<br />rium with present conditions, In either
<br />case, natural or man-induced changes
<br />can initiate responses that may be prop-
<br />agated over long periods of time and
<br />large areas, Therefore, the analysis of
<br />even localized problems and develop-
<br />ment of practical solutions must consid-
<br />er both modem and past conditions for
<br />the entire fluvial system. Lt?IW
<br />For more information, contact Mike
<br />Grimm, Floodplain Division Manager,
<br />Stormwater Utility, 235 Mathews Street,
<br />Fort Collins, CO 80522, (970) 224-
<br />6036
<br />
<br />Free
<br />Prairie Restoration
<br />Fact Sheet
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<br />Iand and Water
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<br />For More Information, Circle #36
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<br />MarchIApriI1996-37
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