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IDProjectCategoryView StatusLast Update
0005966Dwarf FortressDwarf Mode -- Environmentpublic2012-05-28 21:48
ReporterRiloki Assigned To 
PrioritynormalSeverityminorReproducibilityalways
Status newResolutionopen 
PlatformWindows XP 
Product Version0.34.10 
Summary0005966: An error in Aquifer placement code.
DescriptionIt seems that when placing aquifers it will check that there's an [AQUIFER] layer within a number of Z-levels from the surface. If one is found and the biome is one that contains an aquifer, it'll go down several Z-levels (I've been seeing between 3 and 5) and designate that layer an aquifer layer.

Any [AQUIFER] material on that layer will become an aquifer, as will any below it. That's fine. Except it does not check that there are any [AQUIFER] materials on the layer it selects. Therefor it is possible (and common) to have a 'ghost' aquifer, in which the site finder will report an aquifer, but one will not actually be available.

This was tested by turning all stone types into [AQUIFER]-possible materials after discovering that in areas of 'little soil' containing an aquifer, no aquifer will actually be found.
Steps To Reproduce1) Gen a new world (I used a small region)
2) Go to site finder, search for Soil: Little, and Aquifer: Yes.
3) Embark on an area containing only one kind of biome containing the aquifer, and dig. (this is to ensure you are not merely missing the biome the aquifer is contained within)
3a) Please note I used DFHack's reveal function to double check I was not merely unlucky with my exploratory shafts.

Unless you dig into sandstone or conglomerate as your top stone layer, you will almost never actually encounter an aquifer, despite receiving an embark warning of one, and it being listed in the site finder.
Additional InformationI would propose this be fixed simply by finding the lowest aquifer-bearable material within its normal placement range, and placing it there, which would put it in line with real-life groundwater behavior.

If Toady felt particularly adventurous, he could even make there a chance for a 2 wide or more aquifer on areas with low drainage but high rainfall.

Tagsaquifer

Relationships

related to 0007662 assigneduser6 Ocean shores generated with non-porous rock (dacite, shale), no aquifer 

Activities

Riloki

2012-05-28 21:48

reporter   ~0022774

Please note that in some worlds 1 Z-level deep soil on aquifer tiles are more common than others, and finding one may actually prove a little hit and miss, but if you do find one such instance, you may end up with a ghost aquifer as described above.

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Issue History

Date Modified Username Field Change
2012-05-28 21:07 Riloki New Issue
2012-05-28 21:46 Riloki Tag Attached: aquifer
2012-05-28 21:48 Riloki Note Added: 0022774
2014-07-27 15:00 user6 Relationship added related to 0007662