If I remember correctly, we have discussed facets of this issue under different headings previously. It is an important one during the time of the effects of warming climate with all the associated instabilities and extremes. There are several NAP publications dealing with the science and engineering of flood problems, remedies/protections, risks and effects, see, for example 1995 NAP 4969 and 2012 NAP 13393.
There are many others – one can always check in: Hydraulic Design of Flood Control Channels, USACE EM 1110-2-1601; Hydrologic Frequency Analysis, USACE EM 1110-2-1415; and Design and Construction of Levees, USACE EM 1110-2-1913. In my article Flood Barrier Systems, I have attempted to look into it from a broader perspective – but focusing primarily on Storm Surge Barriers. Different aspects of Water Actions that warrant protection were identified – together with discussing the Flood Barrier Hydraulics. They were followed by highlighting some major Storm Surge Barriers around the world.
------------------------------Dr. Dilip Barua, Ph.D, P.Eng, M. ASCEVancouver, BC, Canada------------------------------
I just happened to run across this thread and thought to share my thoughts.Retarding flows has been a classic approach in reducing/controlling the amount of flow to downstream channels. There are two types of retarding basins 1) the Classic online (flow-through) retarding basin and 2) the offline (flow-by) basin. An example of an online basin is a reservoir behind a dam. Offline retarding basins divert flows over a side-weir and into the retarding basin, once the water surface in the channel exceeds the weir crest. Therefore, the basin remains empty until a few hours into the storm. In essence, the required flood storage volume is significantly smaller in contrast with online retarding basins. This also results in significant savings by reducing the required land area needed. They are far more environmentally-friendly than classic online basins and require far less maintenance. They allow sediment transport to the downstream system, which reduces scour and erosion, and allow free fish-passage to the upstream of the system. In addition to their flood control function, such systems often serve secondary purposes such as water quality enhancement, percolation and recreation.
I developed the Basin Analysis Software, B.A.S. over two decades ago and it still represents the state-of-the-art in modeling side-weirs and offline retarding systems. While the development of B.A.S. absorbed several years of programming, debugging and verification of results, many more years of hydraulic expertise are behind the theoretical concepts used in the program. If anyone is interested to learn more, you can visit www.hyd-solutions.com or email me at nmajaj@....