Hey everybody,
i got the following issue: The goal is to identify the size of landslides in 3 different zones, per district. Therefore i built a model via the modelbuilder. I calculated the size of each landslide beforehand using the "add geometry tool". The slides, districts, and each zone were my input for the first union (5 inputsi n total). From this Union I select each landslide with with the select tool and an expression like this: Process=Slide AND County=XY AND ZONE1=1 (that was my idea). Afterwards I used "statistics" and SUM in the attribute table for the total area of my landslides. I did the whole process for the total area, but afterwards during the evaluation of the results I realized there was a problem/ i made a mistake:
As long as the Input for the Union are ONLY the Counties and the slides, the slides area (only for each county) is quite realistic. In this case the expression e.g is: "Process=Slide AND County= XY" -> Sum: 9839ha (so far so good, that´s the whole amount of area for the slides located in every zone in the county). Now I DO NOT change the expression, only add some Input layers (the zones) for the Union. And this occurs: Area increases around 5 times, it seems like the areas of the zones are now also included in the calculation. Same happens if I use this expression "Process=Slide AND County=XY AND ZONE1=1" to identify the slides which are located in zone 1 the numbers get quite unrealistic.
Although I would like to have further however only the added area of all landslides which are within the respective zones. In the data frame nothing changes in the display in comparison to "only slides and county input", in the attribute table new objects occur.
How do I write the expression to avoid the "double counting of the zones area"as it seems / make clear that I only want the slides which are located within the different zones (and get the area afterwards)? I use ArcMap 10.5.1. I hope someone understands what I´m trying to say. I´m grateful for every helping comment.
Cheers
Felix
