Warnings (Water Overlay): Difference between revisions

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| auto=
| auto=
| resolve=Change the applicable threshold(s), so they are further below the [[elevation model|terrain height]], or remove them entirely.
| resolve=Change the applicable threshold(s), so they are further below the [[elevation model|terrain height]], or remove them entirely.
}}
{{warning fix | level= ==== | title=The lower threshold is not functional for this System Outlet, because water is never added. Use an upper threshold instead.
| description=This [[Inlet (Water Overlay)|Inlet]] only has negative [[inlet q (Water Overlay)|inlet q]]('s) configured, meaning water will only flow out, not in. However, the configured [[inlet lower threshold (Water Overlay)|lower threshold]] can only affect the proces of water flowing in.
| auto=
| resolve=Check whether the [[inlet q (Water Overlay)|inlet q]] is configured correctly. If it should facilitate water flowing in, change the value. If water flowing only out is correct, use a [[Inlet upper threshold (Water Overlay)|upper threshold]] instead.
}}
{{warning fix | level= ==== | title=The upper threshold is not functional for this System Inlet, because water is never removed. Use a lower threshold instead.
| description=This [[Inlet (Water Overlay)|Inlet]] only has positive [[inlet q (Water Overlay)|inlet q]]('s) configured, meaning water will only flow in, not out. However, the configured [[inlet upper threshold (Water Overlay)|upper threshold]] can only affect the proces of water flowing out.
| auto=
| resolve=Check whether the [[inlet q (Water Overlay)|inlet q]] is configured correctly. If it should facilitate water flowing out, change the value. If water flowing only in is correct, use a [[Inlet lower threshold (Water Overlay)|upper threshold]] instead.


}}
}}

Revision as of 09:13, 21 June 2021

This is a listing of all possible warnings which may be encountered when working with the Water Overlay.

Calculation warnings

When the Water Overlay is selected in the Editor, a number of warnings may appear in the right panel when a calculation is performed.

Calculation was cancelled

The calculation did not run to completion, because it was cancelled by the user. Depending on the calculation being performed, partial results may be available.

Calc too long forced timeout

The calculation exceeded the allowed calculation time. During business hours (9-17, GMT+1, during weekdays), there is a maximum calculation time of 1 hour. If during business hours a calculation has been calculating for an hour, the calculation times out automatically. Depending on the calculation being performed, partial results may be available.

Error in GPU calculation

During the calculation, an unknown error has occurred. This may be due to an unexpected configuration of the specific calculation, or an internal error in the calculation infrastructure. Please contact support with a description of the calculation and its related settings to further investigate the issue.

Prequel

When a Grid Overlay encounters an error, its results may not be valid. Any other Grid Overlay which uses that first Grid Overlay as a prequel will warn about that error in one of the prequels taking place. Subsequent Grid Overlays relying on that one will also report the error.

Limited cycles. Inaccurate results

It took too many calculation cycles to perform the calculation. The maximum amount of calculation cycles is 2147483647. The amount of cycles is dictated by the complexity, size, and duration of the simulation. More water with a higher maximum impulse across a larger calculation area over a longer period of time requires more computational cycles to accurately compute.

To resolve: Reduce the complexity of the calculation. Prioritize reducing the calculation time, and consider running the Water Overlay calculation in low impulse mode.

Invalid constructions

One or more constructions used in the calculation are invalid. They may be incorrectly configured, or interfered with by the presence of other Constructions. More information for the individual Constructions with errors can be found in the Water Overlay Wizard, or under the Construction warnings header.

To resolve: Open the Water Overlay configuration wizard, continue to the step of the Constructions, and investigate the warnings (highlighted yellow) or errors (highlighted red) of Constructions on an individual basis. If applicable, fixes are proposed with the tool icon. By clicking on the icon the fix can be automatically solved. See also: How to apply fixes for multiple components in the Water Overlay Wizard

Warning in the wizard, there is a fix proposed. By clicking on the icon, the fix can be applied when accepted.

Large cell size. Inacurate results

The grid cell size has been configured as greater than 4 meters. This means water may have difficulty flowing into alleys or through fair-sized waterways, and other accuracy-related artifacts may present themselves in the calculation results.

To resolve: Reduce the grid cell size.

Heightmap resolution is too low

The resolution of the heightmap is lower than the grid cell resolution, meaning that even though more accurate results might be expected, it's not possible to refine the detail of water flow to the configured accuracy. The only way to enhance the heightmap accuracy is to load in a new Project with a more detailed DEM resolution.

To resolve: As a stop-gap measure, increase the grid cell size. For a more permanent resolution, recreate the Project with a more detailed DEM resolution.

General warnings

These warnings are general warnings and are related to hydrological features and hydraulic structures

... is already recognized as a ...

This hydraulic structure or hydrological feature has 2 or more Attributes which match Overlay Keys identifying different structures or features, so the Water Overlay cannot determine which of the two or more features or structures this Item is intended to represent. The Item will only be recognized as one of the possible features or structures.

To resolve: Determine as which type of structure or feature this Item should be treated, and remove the Attribute(s) which match Overlay Keys identifying it as other structures or features.

... does not have a geometry ...

This hydrological feature or hydraulic structure does not have a geometry and therefore no location in the 3D world.

Automatic fix proposed: A fix is proposed to remove the Item from the Project.

To resolve manually: Either select the Item, and draw its location in the 3D world, or remove the structure or feature from the project.

... cannot be placed in the grid raster

The hydrological feature or hydraulic structure cannot be placed in the raster with the current grid cell size. The following situations will all trigger this warning:

  • The center or either of the endpoints of the structure are on an inactive cell.
  • The center or either of the endpoints share a cell with the center or endpoint of another structure.
  • The structure should be a line, but the endpoints are on the same cell.

To resolve: Either change the grid cell size, or redraw the Item. You can also check the advanced options in the Water Overlay Wizard, that object correction is active, which will allow the Tygron Platform to automatically attempt to fix this issue for all Constructions.

... time value of attribute ... at index ... (...) is smaller than at index ... (...). Values after this index will not be used by the water calculations.

The hydrological feature or hydraulic structure has an Attribute which supports time sequences, but the time sequence configured is improper. Specifically, one of the time values indicates a moment in the past of one of the earlier time values. The Water Overlay cannot continue interpreting the sequence if the times are out of order.

To resolve: If the time sequence was imported, check the file which was imported and verify that the time values are in order. Then reïmport the file.

... of ... time value intervals of attribute ... fall outside the simulation time range [ 0 - ... seconds].

The hydrological feature or hydraulic structure has an Attribute which supports time sequences, but the time sequence indicates times which fall outside of the simulation time as defined by the Weather's RAIN_M Attribute. Times and their related values beyond the definition of the simulation time are ignored, as those times are never reached. All times and values which are within the simulation time are treated as normal.

To resolve: Either increase the simulation time of the Water Overlay, or reïmport a time sequence for this Item which does not have time values beyond the simulation time.

Feature warnings

For individual hydrological features, warnings may be presented when they are improperly configured.
See also more information about the feedback and the automatic proposed fixes.

Water Area

Below a list of warnings related to Water areas.

The water level is located ... above the highest shoreline height: ...

The water level is much higher than the average height of the terrain. The effect in the model is that water will be initialized in waterways as a high block exceeding the average terrain height, so the simulation will start with a sudden flood emanating from the waterways.

To resolve: A fix is proposed to provide a value to set the water level below the highest shoreline.

The water level is located ... below the water bottom: ...

The water level is much lower than the water bottom. The effect in the model is that waterways will be initialized with excessively low water levels, if they are even deep enough to contain any water.

To resolve: A fix is proposed to provide a value to set the water level below the highest shoreline.

This Water Area consists of multiple disconnected polygons

This water area is a multipolygon which is not allowed.

To resolve: A fix is proposed to automatically split the multipolygon into single polygons.

This ... has at least ... overlap with area ... and ... level difference.

The water area overlaps with another area. This overlap has now two different water levels.

To resolve: Remove the overlapping part from one of the two water areas.

Inundation Area

Below a list of warnings related to Inundation areas.

The inundation level for this area is ... higher than the average land height: ...

The inundation level is much higher than the average height of the terrain. The effect in the model is that water will be initialized on the surface many meters high, which is an unrealistic starting situation.

To resolve: A fix is proposed to provide a value above the terrain height to place the inundation area.

The inundation level for this area is ... below the average land height: ...

The inundation level is much lower than the average height of the terrain. The effect in the model is that no water will be placed on the surface.

To resolve: A fix is proposed to provide a value above the terrain height to place the inundation area.

Sewer Area

Below a list of warnings related to Sewer areas.

This Sewer Area has an invalid storage

The Sewer area has an invalid sewer storage. All sewer storage must be strictly positive and non-zero.

To resolve: A fix is proposed to provide a new value for the Sewer storage.

The storage is very small

The Sewer area has a very small sewer storage, which is unlikely to be correct.

To resolve: Check the value for the Sewer storage to see if the value is realistic.

The Q Discharge is negative ..., which is not allowed

The Sewer area is configured to have a negative sewer pump speed. This would mean water is structurally pumped into the sewer. Sewer pump speeds must be 0 or positive.

To resolve: Check your Sewer area and adjust the sewer pump speed values where possible.

This Sewer Area has no Q Discharge or Sewer Overflow, water cannot leave

The Sewer area does not have a sewer pump speed set and also no Sewer overflow. This means water cannot leave the sewer area.

To resolve: Set a sewer pump speed or add a Sewer overflow for this Sewer area.

This Sewer Area has %s Sewer Overflows (only 1 allowed)

This Sewer area has multiple Sewer overflows, which is not allowed.

To resolve: Remove the abundant Sewer overflows.

This ... has at least ... overlap with area ....

The Sewer Area overlaps with another Sewer Area. This means there is an overlapping location where it's uncertain which sewer a specific cell belongs to.

To resolve: Redraw either Sewer Area, so that the two polygons no longer overlap.

Aquifer

Below a list of warnings related to Aquifers.

This Aquifer Area has a negative KD value. Horizontal groundwater flow in this area will be calculated as freatic.

The Aquifer is configured to have a negative hydraulic conductivity, which directly dictates maximum flow speed. The hydraulic conductivity must be positive and not zero, otherwise the underground flow speed would be similarly negative or zero.

To resolve: A fix is proposed to adjust the aquifer kd value to a positive value.

This Aquifer Area has a zero KD value. Horizontal groundwater flow in this area will be calculated as freatic.

The hydraulic conductivity must be positive and not zero, otherwise the underground flow speed would be similarly negative or zero.

To resolve: A fix is proposed to provide a new aquifer kd value.

This Aquifer Area is positioned lower than the ground bottom datum: ... > ...

The aquifer height is set too low, meaning the Aquifer is not functioning.

To resolve: A fix is proposed to raise the aquifer by an entered value below the surface datum.

Breach

Below a list of warnings related to Breaches.

This Breach Area shares its input area with breach area "...", which is not allowed.

The Breach is properly connected to an input area, but another Breach is connected to the same input area. Make sure every Breach using an input area has its own input area.

To resolve: Either change the input area of this Breach, or find the other Breach which refers to the same input area and change the input area of that Breach.

This Breach Area uses an input area which is empty. This breach will not work propertly.

The Breach is properly connected to an input area, but the input area is not a polygon in the 3D World.

To resolve: Ensure that the input area has a polygon in the 3D World.

This Breach Area has an invalid input area with id ..

The Breach refers to an Area as input area, but the referred Area is not configured to be an input area.

To resolve: Add a breach input area Attribute to the area the Breach uses as input area. Alternatively, use the Water Overlay configuration wizard to select a different (or no) input area.

Breach uses an external area as input, but it is not allowed to be empty

The Breach does not have a configured breach input area, and therefor defaults to using an external area. However, the external area's size is no a non-zero positive integer.

To resolve: Change the externa area Attribute to a positive value.

Construction warnings

For individual hydraulic structures, warnings may be presented when they are improperly configured.
See also more information about the feedback and the automatic proposed fixes.

For some warnings, clear steps can be followed to resolve them.

All structures

All hydraulic structures are checked for whether they can be related to the grid properly.

The polygon of the ... is too complex to calculate a center line from

This warning means that the polygon is too complex to create a center line from, for line based constructions. This means it's not possible to determine what the end-points of the structure are, and thus which cells are connected through this structure.

To resolve: Simplify the geometry, so that it is easier to compute a center line. This can be done manually by redrawing it, or possibly automatically via a GIS application such as ArcGIS or QGIS, via a WFS connection.

Weirs

Below a list of warnings related to Weirs.

This Weir is not connecting two different Water Areas

The Weir is only connected to a single Water Area. This can mean only one endpoint of the Weir intersects with a Water Area and the other doesn't, or that both endpoints intersect with the same Water Area. This may in some situations be intentional, but as Weirs are usually a construction to separate two water levels, this may be the result of data error.

To resolve: If neccesary and appropriate, move the Weir so that its endpoints lay in two distinct Water Areas.

This Weir is situated ... higher than the average land height: ...

The Weir is many meters higher than the average terrain height, so water needs to be equally excessively high to flow across it.

To resolve: Make sure that the weir height is set to a realistic value.

This Weir is situated ... lower than the average land height ...

The Weir's height is that low, meaning water can almost certainly always flow across the Weir.

To resolve: Make sure that the weir height is set to a realistic value.

This Weir has a very small width of ...

The Weir width value is very small which restricts the flow of water over the weir.

To resolve: A fix is proposed to provide a new Weir width value.

This Weir has no width, no water will flow through it

The Weir width of the Weir is unset, or not a positive, non-zero value. This means it has no capacity to have water flow through.

Automatic fix proposed: A fix is proposed to set a value for the Weir's width.

To resolve manually: Ensure the Weir's width is a positive, non-zero value.

This Weir has no defined angle

The Weir angle value is not set. This means the Tygron Platform cannot automatically orient the Weir. Weirs are often defined as point-data, in which case an angle is the only way to determine how the Weir is meant to be oriented, and generate a structure perpendicular to the direction of flow to prevent water flowing past it without being limited by the Weir. If the Weir is drawn as a line, the Tygron Platform will be able to place the Weir based on its center-line. However, even then it is still probably neccessary to generate a flow-blocking structure, for which a configured angle is required,

Automatic fix proposed: A fix is proposed to automatically let the Tygron Platform generate the Weir angles.

To resolve manually: Set a value in the range of 0-360 for the Weir angle.

The downstream Water Area level is ... higher than the datum height: ...

The water level on the downstream side of the Weir (the side with the lower water level), is (much) higher than the height of the weir itself. If the weir is only slightly lower, this may be intentional. However, if the difference is multiple meters, it's likely the result of data error.

Automatic fix proposed: A fix is proposed to automatically change the weir's height to match the upstream water level.

To resolve manually: Change the weir's height, or the water level on the downstream side of the weir, so that the weir is higher than or at the same level as the water.

The upstream Water Area level is ... lower than the datum height: ...

The water level on the upstream side of the Weir (the side with the higher water level), is (much) lower than the height of the weir itself. If the weir is only slightly higher, this may be intentional. However, if the difference is multiple meters, it's likely the result of data error.

Automatic fix proposed: A fix is proposed to automatically change the weir's height to match the upstream water level.

To resolve manually: Change the weir's height, or the water level on the upstream side of the weir, so that the weir is lower than or at the same level as the water.

Culverts

Below a list of the warnings related to culverts.

This Culvert does not have a diameter, no water will flow through it.

The culvert diameter of the culvert is unset, or not a positive, non-zero value. This means it has no capacity to have water flow through.

Automatic fix proposed: A fix is proposed to set a value for the diameter.

To resolve manually: Ensure the culvert diameter is a positive, non-zero value.

This Culvert is situated ... above the water levels: ... and...

The culvert's threshold is placed higher than initial water levels on either side of the culvert. This means that water will initially not be able to flow through.

To resolve: Change the culvert threshold to a value below the water levels of the adjacent Water Areas.

This Culvert connects two Water Areas with significantly different water levels: ... and ...

The culvert lies on the border of two water areas with very different initial water levels. This means the initial water situation is probably not realistic, as there is a great difference between what are effectively adjacent water levels.

To resolve: If the adjacent water bodies should indeed be connected by a Culvert, verify that their water levels are correct. Otherwise, consider removing the culvert to avoid rapid water flow directly following the start of the simulation.

This Culvert has a very small diameter of ...

The culvert diameter value is very small and unlikely to be a valid value.

Automatic fix proposed: A fix is proposed to set a value for the diameter.

To resolve manually: Ensure the culvert diameter is a positive, non-zero value, larger than its current value.

This Culvert has a very small rectangular height of ...

The culvert rectangular height value is very small and unlikely to be a valid value.

Automatic fix proposed: A fix is proposed to set a value for the rectangular height.

To resolve manually: Ensure the culvert rectangular height is a positive, non-zero value, larger than its current value.

This Culvert has a negative Manning friction value

The culvert n value is negative which is not a valid value for a manning value.

Automatic fix proposed: A fix is proposed to set a new value for the culvert's manning value.

To resolve manually: Ensure the culvert's manning value is a positive, non-zero value.

The height of this Culvert is ... higher that the average land height (...)

The culvert threshold value is too high in relation to the average terrain height. This means the culvert is probably situated too high, and water is unlikely to flow through.

To resolve: Change the culvert threshold to a value closer to the terrain height. Commonly, the value should be higher than the bottom of the waterway, and below the height of the terrain surrounding the waterway.

The height of this Culvert is ... below the average land height (...)

The culvert threshold value is too low in relation to the average terrain height. This means the culvert is would be effectively buried (according to the data). The culvert will be automatically raised to the terrain/water bottom, but the discrepancy indicates likely data error.

To resolve: Change the culvert threshold to a value closer to the terrain height. Commonly, the value should be higher than the bottom of the waterway, and below the height of the terrain surrounding the waterway.

Inlets

Below a list of warnings for Inlets.

A threshold is near surface level: ..., this threshold cannot be reached.

This message only applies to inlets which are configured to interact with the ground water. If the lower threshold or upper threshold of the inlet are configured to be near or above the terrain height, it is not possible to ever reach those thresholds, leaving the inlet permanently active or inactive, depending on its configuration.

To resolve: Change the applicable threshold(s), so they are further below the terrain height, or remove them entirely.

The lower threshold is not functional for this System Outlet, because water is never added. Use an upper threshold instead.

This Inlet only has negative inlet q('s) configured, meaning water will only flow out, not in. However, the configured lower threshold can only affect the proces of water flowing in.

To resolve: Check whether the inlet q is configured correctly. If it should facilitate water flowing in, change the value. If water flowing only out is correct, use a upper threshold instead.

The upper threshold is not functional for this System Inlet, because water is never removed. Use a lower threshold instead.

This Inlet only has positive inlet q('s) configured, meaning water will only flow in, not out. However, the configured upper threshold can only affect the proces of water flowing out.

To resolve: Check whether the inlet q is configured correctly. If it should facilitate water flowing out, change the value. If water flowing only in is correct, use a upper threshold instead.

The lower threshold is not functional for this System Outlet, because water is never added. Use an upper threshold instead.

This Inlet only has negative inlet q('s) configured, meaning water will only flow out, not in. However, the configured lower threshold can only affect the proces of water flowing in.

To resolve: Check whether the inlet q is configured correctly and use a upper threshold instead.

The upper threshold is not functional for this System Inlet, because water is never removed. Use a lower threshold instead.

This Inlet only has positive inlet q('s) configured, meaning water will only flow in, not out. However, the configured upper threshold can only affect the proces of water flowing out.

To resolve: Check whether the inlet q is configured correctly and use a lower threshold instead.

Pumps

Below a list of warnings related to Pumps.

This Pump has no defined angle

The Pump angle value is not set. This means the Tygron Platform cannot automatically orient the pump. Pumps are often defined as point-data, in which case an angle is the only way to determine how the pump is meant to be oriented. If the pump is drawn as a line, the Tygron Platform will be able to place the pump based on its center-line.

Automatic fix proposed: A fix is proposed to automatically let the Tygron Platform generate the Pump angles.

To resolve manually: Set a value in the range of 0-360 for the Pump angle.

This Pump has a negative capacity

The Pump capacity value is negative. This means water can never be pumped through, as the maximum amount of water to be pumped is always already exceeded.

Automatic fix proposed: A fix is proposed to make the Pump capacity positive, by removing the minus sign from the value.

To resolve manually: Ensure the Pump capacity is set to a positive, non-zero value, or remove the Pump capacity entirely.

Drainage

Below a list of warnings related to Drainage.

This Drainage is missing a valid datum height

The drainage datum value is empty. This means the exact height of the drainage cannot be determined, and as such whether water can flow through or that the water level on the other side, underground or otherwise, is higher than the drainage.

Automatic fix proposed: A fix is proposed to provide a valid drainage datum value.

To resolve manually: Ensure that the drainage has a drainage datum value configured.

The override overflow threshold is lower than the waterbottom: ... < ...

The drainage overflow threshold is lower than the waterbottom. If the drainage is configured as active drainage, no water will be pumped to the waterway since the threshold assumed to be extremely low and as such already met.

Automatic fix proposed: A fix is proposed to provide a height above the waterbottom to fix the drainage overflow threshold.

To resolve manually: Either configure a valid threshold, or reconfigure the drainage as passive drainage, so that the threshold not required.

This Drainage is missing overlap with land

Drainage should consist of two polygons where one overlaps with land and one overlaps with water. The overlap with land is missing, so there is no location where this drainage interacts with the groundwater. (Generally meaning: there is no location to drain water from.)

To resolve: Redraw the polygon of the Drainage, so that it intersects with both a section of land and a section of water.

This Drainage is missing overlap with water

Drainage should consist of two polygons where one overlaps with land and one overlaps with water. The overlap with surface water is missing, so there is no location where this drainage interacts with surface water. (Generally meaning: there is no location to drain water to.)

To resolve: Redraw the polygon of the Drainage, so that it intersects with both a section of land and a section of water.

This Drainage is positioned higher than the average land datum: ... > ...

The Drainage is placed higher than the average terrain height, meaning the drainage would be flying above the surface. Drainage should be at least partially below the surface, and partially above the water bottom of Water Terrain.

To resolve: Ensure that the drainage has a drainage datum value configured. This should be lower than the surface height of the land, but higher than the water bottoms height.

Sewer overflows

Below a list of warnings for Sewer Overflows.

The height of this Sewer Overflow is situated ... above the average land height: ...

The Sewer Overflow is location high above the average terrain height, meaning the sewer overflow is modeled as either an above-ground sewer, or as a construction rising high up from the ground to allow sewer water to overflow.

Automatic fix proposed: A fix is proposed to provide a height better in line with the terrain height.

To resolve manually: Ensure the Sewer Overflow's height is set to a realistic value, relative to the terrain height.

The height of this Sewer Overflow is situated ... below the average land height: ...

The Sewer Overflow is location far below the average terrain height, meaning the sewer overflow is modeled as buried underground.

Automatic fix proposed: A fix is proposed to provide a height better in line with the terrain height.

To resolve manually: Ensure the Sewer Overflow's height is set to a realistic value, relative to the terrain height.

The water level at this Sewer Overflow is ... higher than the Sewer Overflow's height: ...

The water level at the sewer overflow is (much) higher than the sewer overflow itself, meaning that water is unlikely to be able to flow out of the sewer as the sewer overflow is under water.

Automatic fix proposed: A fix is proposed to provide a height better in line with the water level.

To resolve manually: Ensure the Sewer Overflow's height is set to a realistic value, relative to the water level.

The water level at this Sewer Overflow is ... lower than the Sewer Overflow's height: ...

The water level at the sewer overflow is (much) lower than the sewer overflow itself, meaning that water flowing out of the sewer will fall from relatively high. Although not strictly, impossible, such a configuration could indicate a data error.

Automatic fix proposed: A fix is proposed to provide a height better in line with the water level.

To resolve manually: Ensure the Sewer Overflow's height is set to a realistic value, relative to the water level.

This Sewer Overflow is not connected to a Sewer Area. It is therefore not functional

Sewer Overflows move water from a Sewer Area to the surface. This requires that the Sewer Overflow overlaps with a Sewer Area. This Sewer Overflow does not, meaning the Sewer Overflow does not have a Sewer Area to remove water from.

To resolve: Check that Sewer Areas are loaded in correctly. Check whether a Sewer Area should be expanded so that it overlaps with the Sewer Overflow or the Sewer Overflow should be moved to intersect with the Sewer Area.

This Sewer Overflow has a negative Q Discharge, which is not allowed

Sewer Overflows move water from a Sewer Area to the surface, with a speed configured by their sewer overflow speed. This must be a positive value, or zero to indicate there is no limit to the rate of discharge. It cannot be negative, as that would imply the water would flow into the sewer instead, which is not allowed.

To resolve: Change the sewer overflow speed to a positive value, or to zero.

... shares the Sewer Area with another Sewer Overflow and is the inactive one

The Sewer Area which this Sewer Overflow intersects, intersects with more Sewer Overflows which is not allowed. Only one of the Sewer Overflows is actually active, and the other Overflows are inactive. The Sewer Overflow this message appears for is considered inactive.

To resolve: Ensure that the Sewer Area only has one Sewer Overflow. Either remove this Overflow, or the other one(s), or move this Overflow (or the other(s)) to a different location and Sewer Area.