Different Models Required (Hydrodynamic)

In previous chapter we discussed about the Models required and discussed our first fundamental model (Hydrological Model). In This chapter I will discuss about Hydrodynamic Model:

Hydrodyamic(HD) model deals with the flow of river. For this we need to make river profile(Cross section , banks etc.).  It's easy to work with. You need to find a gis software which will create the basic data for hydrodynamic model and then it will be transferred to HD model of a software. 

To make a river profile you need the DEM, Storage area(reservoir) as well as the river line(derived from DEM or traced using Imagery). I would recommend doing it using High resolution imageries. The river profile is then transferred to HD model(HEC RAS) in this case. 

After zooming we can see the cross section , banks and water flow. You will get river flow after running a simulation. You can see 2D, 3D profile of river.

After this you have to add data to your model. Data you need to add are: 

1) Geometric Data

In geometric data you can edit cross sections (increasing channel width, increasing bank level etc.) . In this you can add more data such as storage areas, structure data (bridges etc.), pumps etc. Data increase accuracy in results.

You have to add Manning values(0 to 1), Channel Length, contraction and expansion coefficients , frictional slope etc.

2) Unsteady Flow

It consist of boundary conditions and Initial Conditions. In boundary conditions all lateral inflows to be added and in initial conditions you have to add the initial flow.

After this you have to link the model with HEC DSS which contains Hydrologic model results. After adding all the data you have to run the unsteady flow analysis or steady flow analysis. It will ask the programs to run , start and ending date, computation and output interval as shown below.

The HD Model improves results significantly . The green line shows HMS results while red line show the computed flow of HD model. The red line follow the blue line(Observed discharge) closely.

That's all for this chapter. In next chapter I will discuss about the Reservoir Model.