Flood Routing: Definition, Purposes and Importance

10 May 2017

The object of this composition is to build a flood routing definition that’s comprehensible. Technical terms will likely pop up occasionally, but the basic concepts should be presented in a legible manner so that anyone can understand the engineering principles. Equations and technical jargon aside, the goal of this engineering study is to ensure an adequate flood protection strategy is in place.

What Exactly is Flood Routing?

This is a science-centric discipline that assesses river and reservoir flood data. The technique uses hydrograph modelling to predict the effects of floodwater at any point along the path taken by a waterway. As for the “hydrograph” identifier, this is a graph type that maps flow rate (In cubic metres per second) against time. The inflow flood hydrograph, perhaps aggravated by a storm, is balanced against the outflow hydrograph at different downstream points to produce a flood-predictive model. Of course, no indiscriminate estimates are used here, not when engineering mathematics are on call. Indeed, the coefficients generated by these formulas will produce dimensional data, so the sizes of channel bordering structures can be estimated.

A Purpose-Driven Flood Management Tool

Again, indiscriminate design techniques aren’t on the cards, not when there are so many factors in motion. The width and depth of the channel changes, and so does the gradient that the water follows. There are sloping hills that funnel more water into the stream as it meanders through the uneven terrain. Land survey plans account for some of these geological shifts, but a flood routing strategy goes deeper. It takes a swift turn into mathematical territory, a theoretical domain that uses outflow and inflow hydrographs to predict floods. When the data is collated, the flood envelope is determined, at which point dams and weirs, storage reservoirs and artificial tributaries can be incorporated into the primary stream so that all future flood scenarios are attenuated.

Many cities class their waterways as key infrastructure segments. They supply power, fill reservoirs, and generally, provide citywide resources. It’s when those water channels overflow that the damage is done, though, for floods can take a heavy toll on a city. Flood routing studies predict potential floods. They use the flow rate of the channel, the velocity of the water, and the local geology to build special graphs (Hydrographs), a channel “fingerprint,” if you like. Then, when this data is plugged into special engineering formulas, floods become forecastable. That means that the behaviour of the water at any point along the river or reservoir is then predictable. The response to the forecast by the infrastructure engineering team is to build the bridges, levees, and overflow channels that attenuate future floods and keep the bordering neighbourhoods dry.

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