How to investigate increasing water levels in waterways: Difference between revisions

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When using the [[Water Overlay]], water should generally be in balance. Extraordinary events such as breaches or excessive rainfall may cause an excess of water to be added to (and possibly remain in) the model. But in general, and especially in stationary calculations, you would expect the amount of water flowing into the model to roughly balance the amount of water being removed from the water as well.
When using the [[Water Overlay]], water should generally be in balance. Extraordinary events such as breaches or excessive rainfall may cause an excess of water to be added to (and possibly remain in) the model. But in general, and especially in stationary calculations, you would expect the amount of water flowing into the model to roughly balance the amount of water being removed from the water as well.


==How to check whether water flows properly==
==How to check whether water levels rise==
You may be able to see visually on the overlay where potential issues exist, but by placing a measurement in the waterway you will be able to see more accurately how much water is where in the waterway.
You may be able to see visually on the overlay where potential issues exist, but by placing a measurement in the waterway you will be able to see more accurately whether the water level rises excessively over time.
{{howto|title=check whether water flows properly through a waterway
{{howto|title=check whether water flows properly through a waterway
| Ensure the Water Overlay has a [[Surface last value result type (Water Overlay)|surface last value]] result type and a [[surface elevation result type (Water Overlay)|surface elevation]].
| Ensure the Water Overlay has a [[Surface last value result type (Water Overlay)|surface last value]] result type.
| Open the [[measuring tool]].
| Open the [[measuring tool]].
| Create a line measurement, with one endpoint at the start of the waterway, and the other endpoint at the end of the waterway.
| Create a point measurement, in the location where you suspect the water level rises.
| Set the primary overlay to surface last value, the base overlay to surface elevation, and activate "sum".
| Set the primary overlay to surface last value.
| Set the measurement graph display mode to "fit to graph".
| Set the measurement graph display mode to "fit to graph".
| You now see the water level across the length of the waterway.
| You now see the water level in that location in the waterway, across all timeframes of the simulation.
}}
}}
See if the resulting summed line is (nearly) flat, or if there is a point where the water level suddenly jumps to a different level.
See if the resulting line is relatively flat, which would indicate that water remains more or less balanced. It's natural for the water level to be influences by temporary factors, so the water level going up and down during the simulation is fine. However, if the overal trent is for the water to keep rising, there may be an issue.


==What can you look for when a flow issue occurs==
==What can you look for when a flow issue occurs==
Because inhibited waterflow can have a number of causes, there isn't a single fix for all situations. Check whether any of the following apply to your situation, and interpret in the context of your own use-case what the desirable solution would be.
Because water can flow in and out of any location through a number of routes and have varying origins, it can be quite challenging to find the root cause of the increase of the water (if there even is a single cause). However, a number of avenues of investigation are relevant.
 
===Is there any excessive input?===
Rainfall, inlets, pumps
inundation area
 
===Is the location a bottleneck?===
Terrein height a valley
No (or incorrectly configured) output constructions
Any flow issues
 
 
===Is there an edge of the calculation model nearby?===
* Check what the current [[grid cell size]] is, and check whether the issue occurs near the edge of the project area. Note that the [[Border model (Water Overlay)|outer two cells of the project area are not part of the calculation]].
* Check whether the location of the issue is inside the designated [[Limit rain (Water Overlay)|calculation area]]. You can do so at the weather event step in the configuration wizard, where you can check the configuration for the calculation area. If it is set to water level areas only, check whether the location of the issue is covered by a [[water level area (Water Overlay)|water level area]]. If it is set to specified areas only, check whether the location of the issue is covered by a [[limit area (Water Overlay)|limit area]].
* Check whether the issue takes place near the the [[Edge effects (Water Overlay)|edge of the calculation area]]. The closer to the edge a calculation takes place, the more chance there is of unintended [[Edge effects (Water Overlay)|edge effects]].
===Is it near the calculation area's edge?===

Revision as of 11:51, 2 June 2020

This article is a stub.

When using the Water Overlay, water should generally be in balance. Extraordinary events such as breaches or excessive rainfall may cause an excess of water to be added to (and possibly remain in) the model. But in general, and especially in stationary calculations, you would expect the amount of water flowing into the model to roughly balance the amount of water being removed from the water as well.

How to check whether water levels rise

You may be able to see visually on the overlay where potential issues exist, but by placing a measurement in the waterway you will be able to see more accurately whether the water level rises excessively over time.

How to check whether water flows properly through a waterway:
  1. Ensure the Water Overlay has a surface last value result type.
  2. Open the measuring tool.
  3. Create a point measurement, in the location where you suspect the water level rises.
  4. Set the primary overlay to surface last value.
  5. Set the measurement graph display mode to "fit to graph".
  6. You now see the water level in that location in the waterway, across all timeframes of the simulation.

See if the resulting line is relatively flat, which would indicate that water remains more or less balanced. It's natural for the water level to be influences by temporary factors, so the water level going up and down during the simulation is fine. However, if the overal trent is for the water to keep rising, there may be an issue.

What can you look for when a flow issue occurs

Because water can flow in and out of any location through a number of routes and have varying origins, it can be quite challenging to find the root cause of the increase of the water (if there even is a single cause). However, a number of avenues of investigation are relevant.

Is there any excessive input?

Rainfall, inlets, pumps inundation area

Is the location a bottleneck?

Terrein height a valley No (or incorrectly configured) output constructions Any flow issues


Is there an edge of the calculation model nearby?

Is it near the calculation area's edge?

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