Flood Routing

Flood Routing can be demonstrated as a method for describing the processes in a watercourse and for forecasting the temporal and geographical variation of a flood wave at one or more places along the watercourse (river or channel). The identifier “hydrograph” is also described as a graph type that plots flow rate, (this flow rate is explained in the terms of cubic meters per second) which is unparalleled or opposite to the time.

Along with this, the inflow flood hydrograph is maintaining equilibrium in opposition to the outflow hydrograph, this equilibrium is maintained at different downstream points for facilitating a flood-predictive version or model, which a storm may exacerbate. In other words, Flood routing is a method of estimating the flood hydrograph of different water bodies by observing or analyzing the activities of these water bodies. It collects data from different upstream sections and makes predictions.

Flood Routing Definition

Flood routing is a science-based specialty that evaluates flood data from rivers and reservoirs. The method of flood routing uses hydrograph modeling to forecast floodwater effects at every point along a waterway’s route.

Applications of Flood Routing

Let’s understand the basic applications of flood routing. 

• Flood routing is used in hydrology for forecasting the variations occurring under the oceans and other water bodies, by observing their current activities. 
• Along with this prediction, Flood routing also forecasts how fast the hail will be. It also predicts the speed in centimeters of rain. Scientists and weather researchers can easily find out whether the rain will be fatal or normal through flood routing. 
• Furthermore, Flood routing also helps in anticipating the form of the hydrograph and consequently the likelihood for lowland flooding after many rainfall events. 
• Reservoir and channel design, floodplain studies, and watershed simulations are just a few other routing applications.

Flood routing Equation 

The basic equation in all hydrologic routing is the equation of continuity, which stipulates that the difference between the input and outflow rates is equal to the rate of change of storage, i.e., the outflow hydrograph’s peak will be smaller than the inflow hydrograph’s peak.

Hydrologic routing equation

A flood hydrograph’s journey through reservoir or canal reach is characterized by a variable, unstable flow. In hydrologic routing methods, the equation of continuity is as follows:

If we assume a hydrologic system with the input I(t), storage S(t), and output O(t), the continuity equation in hydrologic routing methods is as follows:

ds/dt = l – O 

Because both O and S are unknown, you cannot solve this equation directly to obtain the outflow hydrograph, O(t), even if the input hydrograph, I(t), is known.

To connect S, Q, and I, a second relation, the storage function, is required. The storage equation’s specific form is determined by the system, such as a river reach or a reservoir.

Flooding Routing Algorithm

The static routing algorithm is flooding. Every incoming packet is broadcast on all outgoing lines except the one on which the flooding routing algorithm was received in this procedure.

Types of Flooding Routing Algorithms

• Dynamic Routing or static
• Centralised
• Single path or Multipath
• Hierarchical
• Inter-Domain
• Distance Vector

Methods Of Flood Routing

Let’s learn about the different methods of flood routing. 

Modified Puls

The Modified puls routing approach is perhaps most commonly used for reservoir routing, but it can also be used for river routing in some cases. The storage indication approach is another name for it.  

Kinematic Wave

Hydraulic routing is the most basic form of kinematic wave channel routing, in which the continuity equation is combined with a reduced version of the equations of St.Venant. The bed slope is assumed to be equal to the friction slope in kinematic wave routing.

Muskingum Method of flood Routing

Muskingum method of flood routing uses an inflow hydrograph routed using a mass conservation approach. Most rivers have “looped” storage vs. outflow relationships, which the Muskingum method of flood routing can account for (i.e., hysteresis).

The Muskingum method of flood routing is based on the single stage-to-discharge assumption.

In lamest terms, there can only be one height for each given discharge, Q.

For a particular flow, Q, the slope of friction on the rising side of a hydrograph may be significantly different from the friction slope on the side of the recession of the hydrograph for the same flow, Q.

Muskingum-Cunge

The derivation of Muskingum-Cunge starts with the continuity equation and contains the momentum equation of the diffused form, similar to the Muskingum type derivation.

Dynamic wave

Because it considers all of the terms of the momentum equation, the dynamic wave model is one of the best approaches for predicting the characteristics of floods during their propagation in natural rivers.

Conclusion

Flood routing is a science-based specialty that evaluates flood data from rivers and reservoirs. The method uses hydrograph modeling to forecast floodwater effects at every point along a waterway’s route. Flood routing is a method of analyzing flood flow data from one or more upstream sections. The most basic form of hydraulic routing is kinematic wave channel routing, which combines the continuity equation with a reduced version of the St.Venant equations. The Muskingum-Cunge method uses conservation of mass approach to route an inflow hydrograph. So, from this article, we learn about flood routing.