Practical Road Drainage Design with SewerGEMS – Step by Step

Follow a step-by-step approach to design a road drainage network using SewerGEMS, delineating road catchments and inlets, and applying a 25-year, 24-hour UAE rainfall with rational method guidance.

Learn to delineate the road boundary in QGIS by creating a center line, median buffers, and ten-by-ten meter catchments with inlet assignments for Abu Dhabi road drainage.

Convert a DEM to LandXML in Autodesk Civil 3D by importing a geotiff surface from QGIS, building a grid and points, and exporting the surface as LandXML.

Import road boundary shapefiles into Civil 3D, assign UTM coordinates, explode layers to polygons, color road and median, and prepare for creating inlets on both sides.

This lecture shows creating inlet locations and manholes in Autodesk Civil 3D, trimming road edges to form inlet paths, and placing inlets every 10 m and manholes every 100 m.

Create catchments in Autodesk Civil 3D by dividing roads into ten-meter grids, assigning inlets, using the road centerline, and building boundary polygons for road and median catchments.

Import exported data from Autodesk Civil 3D into QGIS, convert road polylines and catchments to polygons, create centroid points for inlets and manholes, and import data into SewerGEMS Model Builder.

Import shapefiles into SewerGEMS via ModelBuilder, map polylines, polygons, manholes, and inlets, set coordinate unit as meters, and apply Abu Dhabi curve numbers for asphalt and median catchments.

Learn to automatically assign catchment outfalls to the nearest inlet in QGIS by joining attributes by nearest and saving a permanent connected catchment file.

Create conduit networks by laying lines and manholes, then connect five inlets to the main line. Build a pipe catalog with sizes, materials, and inlet types for road drainage design.

Validate the SewerGEMS model by setting accurate ground and invert elevations, creating the correct outfall, and configuring the rational method with IDF tables for 5-year, 10-year, and 25-year events.

Explore GVF-rational run by selecting new physical alternatives, adjusting pipe sizes and velocities, and color-coding pipes while rerunning to verify inlet elevations, ground elevations, and outfall options.

Analyze a road drainage network in SewerGEMS using dynamic wave solver and unit hydrograph; adjust pipe sizes and slopes to reduce overflow and continuity error, and create main-line profiles.

Learn to optimize invert elevations to achieve a linear crown profile in sewer networks by adjusting manhole inverses and pipe start elevations, re-running the model to reduce profile error.

Relabel and renumber network elements in SewerGEMS, including inlets, gateways, and conduits, using analytic and dendritic forms, then optimize the model and prepare for 3D export.

Modify profile in SewerGEMS by adjusting scale, updating conduits, and configuring annotation parameters for length, slope, and elevation; rename structures with the dendritic method to reveal network connections.

Export the drainage network to a .dxf file format, add length and slope annotations to pipes with offset controls, and prepare the file for Civil 3D export and further editing.