Add minor reservoirs to hydrology (old ticket #1123)

[doucla]

Include a representation of minor reservoirs.

[james-bruten-mo]

[Automatic Update]

The Code Review deadline for the Spring 2026 has passed. As this issue does not have a linked pull request it has been removed from the milestone. Please review this issue and either select a new milestone or close it as appropriate. Please contact @MetOffice/ssdteam if you think there has been an error.

Thanks

[james-bruten-mo]

[Bulk Update]

The Code Review deadline for the Summer 2026 milestone has passed. As this issue does not have a linked pull request it has been removed from the milestone. Please review this issue and either select a new milestone or close it as appropriate. Please contact MetOffice/ssdteam if you think there has been an error.

Thanks