SWMM 5 Weir RTC Rules

 SWMM 5 Weir RTC Rules

This SWMM 5 model exemplifies how Real-Time Control (RTC) rules can be used to manage weir flow based on the depth at the upstream node. Here's how it's set up:

Rules for Weir Control:

Multiple rules are defined to close a weir (WEIR) when the depth at the node WeirNode exceeds specific thresholds by 0.25 feet increments. The rules are as follows:

• RULE Weir100:
  IF Node  WeirNode Depth > 1.75
  AND Node WeirNode Depth
  THEN WEIR WEIR Setting = 0.0
  Priority 2

• RULE Weir101:
  IF Node  WeirNode Depth > 2.25
  AND Node WeirNode Depth
  THEN WEIR WEIR Setting = 0.0
  Priority 2

• RULE Weir102:
  IF Node  WeirNode Depth > 2.75
  AND Node WeirNode Depth
  THEN WEIR WEIR Setting = 0.0
  Priority 2

• RULE Weir103:
  IF Node  WeirNode Depth > 3.25
  AND Node WeirNode Depth
  THEN WEIR WEIR Setting = 0.0
  Priority 2

• RULE Weir104:
  IF Node  WeirNode Depth > 3.75
  AND Node WeirNode Depth
  THEN WEIR WEIR Setting = 0.0
  Priority 2

Explanation:

• Triggering Condition: Each rule checks if the depth at WeirNode exceeds a specific level (e.g., 1.75, 2.25, etc.). The AND Node WeirNode Depth condition in the rules seems to be incomplete or typographical; it's likely meant to be a condition like AND Node WeirNode Depth <= 2.00 for the first rule to specify a range, but here it's interpreted as simply checking if there's any depth.
• Action: When the depth condition is met, the weir setting is adjusted to 0.0, effectively closing the weir and stopping flow over it.
• Priority: All rules have a priority of 2, meaning these rules will be executed in the order they are listed if multiple conditions are met simultaneously, but since they check for different depth thresholds, they would activate at different times.

Visual Analysis:

• Figure 1 (Scatter Graph of Weir Flow vs. Weir Node Depth): This graph would show:
  • Normal flow over the weir at various depths until the depth thresholds are hit.
  • Sharp drops in flow to zero at the specified depth points (1.75, 2.25, 2.75, 3.25, 3.75 feet), indicating when the weir is closed by the RTC rules.

Figure 1.  Scatter Graph of Weir flow versus Weir Node Depth.