**5. Application of EDHM**

EDHM is qualitatively and quantitatively evaluated by comparing its results with the output from DHM, for two test simulations. The focus was to check if the EDHM solution resembles DHM output for these two cases for varying inflow and other model parameters.

#### *Case 1: Flow in a transition.*

Open channel flow through a linear contraction under the framework of twodimensional flow is a common phenomenon and has drawn the attention of many experimental and numerical studies. The flow characteristics in the contraction depend on the Froude number at the upstream end. Flow in a contraction has acted as a benchmark simulation in investigations [12] that compared the performance of various CFD and hydraulic models. **Figure 1** is the definition sketch of the test problem. The rectangular channel is 380 ft. long and 260 ft. wide. The constriction

**Figure 1.** *Definition sketch of the test problem (channel length = 380 ft., channel width = 260 ft., cell size = 20 ft).*

**47**

**Figure 3.**

**Figure 2.**

*Examination of Hydrologic Computer Programs DHM and EDHM*

nents) was observed across other longitudinal sections.

*Case 2: Overland flow.*

portion of the channel is 60 ft. x 60 ft. The channel length before and after constriction is 120 ft. and 200 ft., respectively. The cell size in the domain is 20 ft., and the total number of cells are 239. **Figure 2** illustrates the cell numbers in the domain. The elevation of cells along the north and south boundaries was assigned a high value to physically denote that they are walls. The flow is confined within these boundaries. At the upstream end, cells 3-11 (nine cells) were specified with a constant inflow of 33.33 cfs. At the downstream end, a free outfall boundary was

**Figure 3** plots the water depth profile for the two models along the channel centerline at time = 0.9 hours for a channel bottom Manning's roughness value of 0.015. The close agreement of results gives confidence that the changes made to arrive at EDHM did not lead to different output data. The analysis over varying inflow discharge and bottom roughness values did not change the trend of the results. **Figures 4** and **5** compare the depth profile for the roughness coefficient of 0.024 and 0.04. A similar agreement in output data (including velocity compo-

Overland flow over a hill slope generated by a rainfall event is characterized by varying hydraulic properties, roughness values, topography, and physical features in the domain. For predicting the hydraulic and hydrologic properties of flow, various models that solve a range of equations from a one-dimensional hydrodynamic equation for homogeneous place surfaces [13, 14] to 2D full non-linear shallow water Equations [15] have been applied. **Figure 6** shows the flow domain. The number of cells in the domain is 56 and are 30 ft. in size. The roughness value ranged between 0.015 to 0.03Inflow hydrograph (**Figure 7**) was applied at cells 1 and 15. The transient model was run until time = 2 hours. The elevation drop along the north and south end of the domain is 26 ft., and the drop along the west and east boundaries is 5 ft. Cells 42 to 56 were specified as critical depth outflow

*Flow domain with the cell numbers. The wall boundaries are identified by orange-colored cells. There are 239 cells in the domain. The centerline cells (7,20,..220,233) where the depth profiles are compared are highlighted.*

*Comparison of depth profiles along the centerline of the channel at time = 0.9 hours (roughness =* 0.015)*.*

specified. The transient simulation was carried out until time = 1 hour.

*DOI: http://dx.doi.org/10.5772/intechopen.94283*

#### *Examination of Hydrologic Computer Programs DHM and EDHM DOI: http://dx.doi.org/10.5772/intechopen.94283*

portion of the channel is 60 ft. x 60 ft. The channel length before and after constriction is 120 ft. and 200 ft., respectively. The cell size in the domain is 20 ft., and the total number of cells are 239. **Figure 2** illustrates the cell numbers in the domain. The elevation of cells along the north and south boundaries was assigned a high value to physically denote that they are walls. The flow is confined within these boundaries. At the upstream end, cells 3-11 (nine cells) were specified with a constant inflow of 33.33 cfs. At the downstream end, a free outfall boundary was specified. The transient simulation was carried out until time = 1 hour.

**Figure 3** plots the water depth profile for the two models along the channel centerline at time = 0.9 hours for a channel bottom Manning's roughness value of 0.015. The close agreement of results gives confidence that the changes made to arrive at EDHM did not lead to different output data. The analysis over varying inflow discharge and bottom roughness values did not change the trend of the results. **Figures 4** and **5** compare the depth profile for the roughness coefficient of 0.024 and 0.04. A similar agreement in output data (including velocity components) was observed across other longitudinal sections.

*Case 2: Overland flow.*

*Hydrology*

**4.2 Minor enhancements**

**4.3 Compiler details**

responding line numbers, is shown in **Table 1**.

x86 compatible CPUs such as those from AMD.

**5. Application of EDHM**

other model parameters.

*Case 1: Flow in a transition.*

The two minor enhancements that were made in DHM code are (a) to accommodate the increased number of cells in EDHM, the fixed format output descriptor has been expanded by one digit and (b) to better align the variables in the output file, the inter variable spacing was decreased by one digit. A detailed listing of all the major and minor changes made in the DHM source code, along with the cor-

After reviewing the currently available compilers in Windows for Fortran 77 codes, we have chosen the Intel Fortran Compiler within the Microsoft Visual Studio integrated development environment (IDE) to make the enhancements in DHM and for generating the.EXE file. This interface is ideal to debug and execute Fortran 77 programs. The compiler can optimize the performance of source codes for Intel CPUs. It offers broad support for current and previous Fortran standards and also tools by which a robust, high-performance code can be created in serial and parallel environments. The Math Kernel Library (Intel MKL) and the Debugger tools in the compiler, creates a solid foundation for building robust, high-performance codes. The end executable file (.EXE) although optimized for Intel CPUs, can also run on

EDHM is qualitatively and quantitatively evaluated by comparing its results with the output from DHM, for two test simulations. The focus was to check if the EDHM solution resembles DHM output for these two cases for varying inflow and

Open channel flow through a linear contraction under the framework of twodimensional flow is a common phenomenon and has drawn the attention of many experimental and numerical studies. The flow characteristics in the contraction depend on the Froude number at the upstream end. Flow in a contraction has acted as a benchmark simulation in investigations [12] that compared the performance of various CFD and hydraulic models. **Figure 1** is the definition sketch of the test problem. The rectangular channel is 380 ft. long and 260 ft. wide. The constriction

*Definition sketch of the test problem (channel length = 380 ft., channel width = 260 ft., cell size = 20 ft).*

**46**

**Figure 1.**

Overland flow over a hill slope generated by a rainfall event is characterized by varying hydraulic properties, roughness values, topography, and physical features in the domain. For predicting the hydraulic and hydrologic properties of flow, various models that solve a range of equations from a one-dimensional hydrodynamic equation for homogeneous place surfaces [13, 14] to 2D full non-linear shallow water Equations [15] have been applied. **Figure 6** shows the flow domain. The number of cells in the domain is 56 and are 30 ft. in size. The roughness value ranged between 0.015 to 0.03Inflow hydrograph (**Figure 7**) was applied at cells 1 and 15. The transient model was run until time = 2 hours. The elevation drop along the north and south end of the domain is 26 ft., and the drop along the west and east boundaries is 5 ft. Cells 42 to 56 were specified as critical depth outflow


**Figure 2.**

*Flow domain with the cell numbers. The wall boundaries are identified by orange-colored cells. There are 239 cells in the domain. The centerline cells (7,20,..220,233) where the depth profiles are compared are highlighted.*

**Figure 3.** *Comparison of depth profiles along the centerline of the channel at time = 0.9 hours (roughness =* 0.015)*.*

**Figure 4.** *Comparison of depth profiles along the centerline of the channel at time = 0.9 hours (roughness =* 0.024*).*

**Figure 5.** *Comparison of depth profiles along the centerline of the channel at time = 0.9 hours (roughness =* 0.04*).*

**49**

**Figure 9.**

*Examination of Hydrologic Computer Programs DHM and EDHM*

nodes. **Figures 8** and **9** compare the transient depth profiles from DHM and EDHM (time = 0 to 2 hours) at cells 36 and 26, respectively. The trend of the depth and velocity values at other cells also indicated the close agreement of flow data from

*DOI: http://dx.doi.org/10.5772/intechopen.94283*

the two models.

**Figure 7.**

**Figure 8.**

*Transient depth profiles at cell 36.*

*Transient depth profiles at cell 26.*

*Inflow hydrograph data at cells 1 and 15.*

**Figure 6.** *Overland flow domain with the cell numbers. The domain has 56 cells.*

nodes. **Figures 8** and **9** compare the transient depth profiles from DHM and EDHM (time = 0 to 2 hours) at cells 36 and 26, respectively. The trend of the depth and velocity values at other cells also indicated the close agreement of flow data from the two models.

**Figure 7.** *Inflow hydrograph data at cells 1 and 15.*

*Hydrology*

**Figure 4.**

**Figure 5.**

**48**

**Figure 6.**

*Overland flow domain with the cell numbers. The domain has 56 cells.*

*Comparison of depth profiles along the centerline of the channel at time = 0.9 hours (roughness =* 0.024*).*

*Comparison of depth profiles along the centerline of the channel at time = 0.9 hours (roughness =* 0.04*).*

**Figure 8.** *Transient depth profiles at cell 36.*

**Figure 9.** *Transient depth profiles at cell 26.*
