Natural Catchment #

A catchment is an area where water is collected by the natural landscape.

The outside edge of a catchment is always the highest point. Gravity will causes all rain and runoff in the catchment to run downhill where it naturally collects in rivers, lakes or oceans.

The system of of streams which transport water, sediment and other material form a catchment is called a drainage network

Manually, you can trace your catchment boundaries and drainage network from a topographical (topo) map onto tracing paper, and to examine the pattern of streams and rivers that cover the reaches of your catchment.

Digital Elevation Model (DEM) Analysis parameter #

Nc #

To enhance visual clarity and presentation quality, when unticked, some catchments may appear rough, coarse or incomplete. This option will smooth out all catchment edges and fill in any gaps for a cleaner and more polished presentation.

DEM Grid: Cell Size #

The smaller the value, more sub-catchments will be introduce and more precise terrain as well as more refined the whole DEM will be generated.

Below are are some examples when using different cell sizes with and without Nc:

1. Cell Size: 5

2. Cell Size: 2

3. Cell Size: 0.1

TauDEM: Threshold #

For user to have better control on the streamline generation, the smaller the value, more streamline will be generated which will make it easier for user to identify catchment and flow for drainage design

Below are are some examples when using different threshold values:

1. Threshold: 50

2. Threshold: 30

3. Threshold: 5

However, we no longer need that extra work anymore as now we have ‘watershed delineation’ feature in latest MiTS 2.

Steps & procedure on how to use ‘watershed delineation’ #

1. Create new project / open existing MiTS project file
2. Import survey points for newly created project file
3. Go to Earthwork > Terrain > Click ‘Watershed’
4. Software will generate the watershed delineation
5. User may also refer video tutorial below

How ‘WATERSHED DELINEATION’ works in MiTS #

• Streamlines will be generated based on the terrains and flow gravitationally from highest point area to lowest point area.
• User can identify the streamline of the collected water by adjusting the ‘streamline – line type scale’ for software to shows which catchment area receive the most flow by streamline thickness
• Streamline which shows thick line shows more flow collected compare to fine line
• For further understanding, user may refer video tutorial below

Advantages of having watershed delineation #

• Save time and hassle free to generate streamline
• Watershed delineation can be used as reference for catchment flow in drainage network and in Earthwork