Calculation points

Updated on 21 Jun 2024
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Calculation points refer to specific locations within a catchment area where statistical and rainfall-runoff analyses are conducted for flood estimation purposes. A Calculation point typically represents the outlet of the catchment of interest.

Calculation points can be created from any FEH catchment imported into your database.

Details

This tab displays the administrative details of the Calculation point.

The following fields are provided on this tab:

Field in interface	Description
Calculation point name	User-provided name of the Calculation point. This field allows you to assign a unique name or identifier to the Calculation point. It helps you keep track of different points within your model.
Save	Saves the Calculation point details (description and comments).
Calculation point description	User-provided description of the Calculation point. The user can provide additional information or context about the Calculation point. It’s useful for documenting the purpose or significance of the point in your analysis.
Comments	Allows you to add any relevant notes or remarks related to the Calculation point. You can use it to capture specific details, assumptions, or considerations.
Basin location	The system automatically selects the geographic location of the catchment area. It determines the location (country, area) based on where the majority of the catchment area is situated. This is used when applying climate change uplifts. The value can be adjusted in the hydrograph library.
Associated catchment	This field links the Calculation point to a specific catchment or sub-catchment. It defines the area from which runoff flows to the point. By associating the Calculation point with a catchment, you can perform hydrological calculations and analyse the impact of rainfall events.
Associated gauge	The associated gauge refers to a flow gauge or monitoring station located near the calculation point. It provides observed flow data, which can be used for calibration, validation, or comparison with model results. If available, linking the calculation point to an actual gauge improves the accuracy of your simulations.

Catchment descriptors

Fields related to the catchment descriptors are repeated on the left and right sides of this tab.

Left-hand-side: The latest saved version of the catchment descriptors are displayed by default. The drop-down can be used to view previous versions.

Right-hand-side: An editable copy of the version selected on the left. Edits appear in red until this is saved as a new version.

The following fields are provided on this tab:

Field in interface	Description
Version	Version number of the catchment descriptors. Original descriptors will be automatically named version 1 and each subsequent modification will save as a new version.
Comment	The comment provided for the select version of the catchment descriptors.
Table of catchment descriptors	Table of all FEH catchment descriptors, with any edits and comments made.
Only show modified rows	Checkbox to only display modified rows in the tables of catchment descriptors.
Save	Saves any modifications made to the Calculation Point.

ReFH2

The ReFH2 tab provides the option to initiate a new ReFH2 analysis. For each analysis performed, a new version is automatically created and displayed on the tab.

The left-hand-side of the tab lists all completed analyses. For each analysis, the following options are available:

Field in interface	Description
Version details	Various details are provided. This field allows you to specify the ReFH2 engine version to use. You can choose between different versions based on your requirements. For example: If the field is blank in an existing unit, the default version might be 2.2. For newly created units, the recommended version is 2.3.
Set as preferred	This option allows you to mark a specific Calculation point as the preferred one. It’s useful when you have multiple Calculation points, and you want to prioritize one over the others.
Review in ReFH2	Clicking this option opens the ReFH2 software (if you have a licensed installation) and allows you to review and fine-tune the parameters associated with this Calculation point. You can adjust settings related to rainfall-runoff modelling and hydrograph generation.
Delete	If you no longer need this version of your ReFH2 analysis, you can use this option to remove it from your model. Be cautious, as deleting a point is irreversible.
Export ReFH2 to CSV	This feature allows you to export the ReFH2 parameters and associated data for the selected Calculation point to a CSV (Comma-Separated Values) file. You can use this exported data for further analysis or documentation, for example applying direct rainfall to a 2D simulation.
Initiate New ReFH2 Analysis	When you initiate a new ReFH2 analysis, you are starting a process to generate hydrographs based on rainfall data and catchment characteristics. It accommodates the hydrograph associated with the Calculation point.

At the bottom of the list of versions on the left-hand side of the window, the 'Initiate New ReFH2 Analysis' option enables you to start a new ReFH analysis. This analysis is separate from any existing ones but utilizes the catchment descriptors of your Calculation point. Please bear in mind that initiating this action necessitates a ReFH2 license and its subsequent installation.

The right-hand-side of the tab displays essential functionality for configuring and analysing flood hydrographs.

A toolbar along the top of the graph provides the following functionality:

Field in interface	Description
Chart options	This setting allows you to customise the appearance of the graph. You can choose different display options, such as line colours, markers, and grid lines. It helps you visualise the ReFH2 hydrograph in a way that suits your preferences.
Line Width	The line width option controls the thickness of the hydrograph line on the graph. Adjusting this value can make the hydrograph more prominent or subtle, depending on your needs.
Return Periods	Return periods refer to the frequency of a specific rainfall event. In hydrology, we often analyse rainfall events based on their recurrence interval. Common return periods include 2-year, 10-year, 50-year, and 100-year events. By selecting a return period, you can view the corresponding hydrograph for that specific rainfall intensity.
Rural	Allows you to view the hydrograph considering rural land use characteristics. Rural areas typically have different runoff behaviour compared to urban areas due to natural surfaces (e.g., grass, soil). Choosing this option adjusts the hydrograph parameters accordingly.
Urban	This option considers land use characteristics typical of urban areas (e.g., pavement, buildings). Urban hydrographs account for faster runoff due to impervious surfaces. Selecting this option adjusts the hydrograph parameters to reflect urban conditions.

WINFAP

The WINFAP tab provides the option to initiate a new WINFAP analysis. For each analysis performed, a new version is automatically created and displayed on the tab.

The left-hand-side of the tab lists all completed analyses. For each analysis, the following options are available:

Field in interface	Description
Version details	The version option allows you to specify the version of WINFAP to use. Different versions may have varying features, improvements, or bug fixes. Choose the appropriate version based on your requirements.
Set as preferred	By marking a Calculation point as preferred, you prioritise it over others. It’s useful when you have multiple points and want to focus on specific ones during analysis.
Show On Plot	This feature enables the display of Flood Frequency Curves (FFC) or Growth Curves on the plot, even if the version is not the preferred one, allowing for an easier comparison between WINFAP versions.
Review in WINFAP	Clicking this option opens the WINFAP software (if you have it installed and licensed). You can review and fine-tune the parameters associated with this calculation point using WINFAP. Adjustments made here impact the flood frequency analysis.
Delete	If you no longer need a this version of your WINFAP analysis, use this option to remove it from your model. Be cautious, as deletion is irreversible.
Initiate New WINFAP Analysis	Enables you to start a new statistical analysis. This analysis is separate from any existing ones but utilizes the catchment descriptors of your Calculation point. Please bear in mind that initiating this action necessitates a WINFAP license and its subsequent installation.

The right-hand-side of the tab displays essential tools for the flood frequency analysis and understanding the relationship between peak flows and return periods.

A toolbar along the top of the graph provides the following functionality:

Field in interface	Description
Chart options	This setting allows you to customize the appearance of the graph associated with the calculation point. You can adjust line colours, markers, and other visual elements for better clarity.
Line Width	The line width option controls the thickness of the hydrograph or curve line on the graph. Adjusting this value affects the visual representation.
Curve (FFC and Growth)	This section likely refers to the Flood Frequency Curve (FFC) and Growth Curve. The FFC represents the relationship between flood magnitude (usually peak flow) and its recurrence interval (return period). The Growth Curve shows how the flood magnitude increases with increasing return periods. These curves are essential for flood risk assessment.
Distribution	The distribution dropdown allows you to select the probability distribution function (PDF) for flood frequency analysis. Common distributions include Log-Pearson Type III, Generalized Extreme Value (GEV), and Log-Normal. The choice of distribution impacts the shape of the FFC.
Flood Frequency Curve-Rural	The table at the bottom of the graph displays the FFC data specifically for rural conditions. It shows the peak flow values corresponding to different return periods.

Hydrograph library

The Hydrograph library tab serves as a valuable resource for managing and accessing pre-defined hydrographs and includes functionality to reconcile ReFH hydrographs to WINFAP peak flows, apply climate change uplifts and custom alterations. The Hydrograph library is designed to store a collection of hydrographs that represent various flow scenarios, such as rainfall events, runoff patterns, or specific catchment conditions. These hydrographs serve as templates or reference curves for modelling and analysing streamflow behaviour.

The right-hand-side of the main area in the Hydrograph library includes following options:

Item in interface	Description
Add hydrograph	Opens the Scaling tool enabling you to reconcile your data and add scaling factors, to create hydrographs to add to your hydrograph library. By clicking on this button, you can define the hydrograph’s characteristics, such as peak flow values, time intervals, and other relevant parameters. The added hydrograph becomes part of the library and can be reused for various modelling scenarios.
View hydrograph	Clicking this option allows you to examine the details of a hydrograph that is currently stored in the library. You can view the shape of the hydrograph, its peak flow values, and the corresponding time intervals. Use this option to analyse existing hydrographs or compare them with other hydrographs in your model.
Export hydrograph	The “Export Hydrograph” option enables you to save a hydrograph from the library to an external file (e.g., CSV, Excel). You might export hydrographs for documentation, sharing with colleagues, or further analysis outside the modelling software. After exporting, you can import the hydrograph into other Flood Modeller projects or tools, for example the 1D simulation interface.

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Calculation point view

Table of contents

Details
Catchment descriptors
ReFH2
WINFAP
Hydrograph library