Creating catchments in Civil 3D involves defining areas that contribute runoff to a specific location, such as a drainage structure or pond. Here's a step-by-step guide:<br /><br />Steps to Create Catchments in Civil 3D<br />1. Set Up the Drawing<br />Open a drawing that contains a surface or create a new surface for your project.<br />Ensure the drainage structures or target locations (like inlets) are defined in your drawing.<br />2. Open the Catchment Creation Tools<br />Navigate to the Home tab.<br />In the Create Design panel, select Catchments > Create Catchment.<br />3. Select a Target Structure<br />In the Create Catchment dialog box:<br />Choose the Target Structure from the dropdown menu. This is the structure where runoff will flow.<br />If no structure exists, you can create one in the Pipe Network first.<br />4. Define the Catchment Method<br />Choose the method for defining the catchment:<br />By Surface: Automatically creates catchments using the surface drainage pattern.<br />By Polyline: Converts a manually drawn polyline into a catchment.<br />5. Set Catchment Parameters<br />Specify the Name and Style for the catchment.<br />Define key parameters:<br />Runoff Coefficient (C): Reflects the land cover's runoff characteristics.<br />Time of Concentration (Tc): Time it takes for water to travel from the farthest point in the catchment to the outlet.<br />Rainfall Intensity: Define the storm event for the catchment.<br />6. Create the Catchment<br />If using the By Surface method:<br />Click on the surface in the drawing. Civil 3D calculates flow paths and delineates the catchment.<br />If using the By Polyline method:<br />Draw or select a closed polyline that outlines the desired catchment area.<br />7. Review the Catchment<br />The catchment will appear in the drawing, connected to the target structure.<br />Civil 3D automatically calculates catchment area, flow paths, and related parameters.<br />8. Edit Catchment Properties<br />Select the catchment and open the Properties palette to modify:<br />Runoff Parameters (C value, Tc, etc.).<br />Area (can be manually overridden if needed).<br />Connection to different structures.<br />9. Generate Reports (Optional)<br />Use the Analyze tab to run hydrology reports for the catchments.<br />Export the data to spreadsheets or integrate it into hydrologic models.<br />Tips<br />Use the Surface Flow Analysis tools before creating catchments to understand the drainage patterns.<br />Ensure the surface has proper contouring and elevation data for accurate results.<br />Assign appropriate styles to distinguish between different catchment areas in your drawings.
