When you intersect two polygon feature classes, the sum of all resulting intersection areas (AREA_NOMINAL) should be equal to the area of the primary feature class. To achieve this, you can perform an adjustment of areas.
The adjustment function calculates the difference between one area of the primary feature class and the related sum of areas of the intersection feature class. Then, the function distributes the difference to the largest resulting area of the intersection feature class.
Example—The difference between the sum of the intersection area_nominal (234) and the area_nominal of the primary feature (235) is greater than the Tolerance Area Nominal. Then, the difference of 1 must be distributed to the intersection area_nominal.
The distribution is executed twice. The first distribution is executed only for the features that have not been excluded using the WHERE clause. Then, if there is still a difference, all features are used for the second distribution.
Example—Intersection between the primary feature class Parcel and the secondary feature class Landuse. Intersection properties and result areas are the following:
In the example the difference must be distributed. Without the WHERE clause it would be added to the largest area of intersection, which is street. With the WHERE clause you exclude the streets from the adjustment. Then, the difference is added to the area of the forest section, because this is the second largest area. If the parcel has only streets sections, the first distribution can not be applied. In the second distribution all features will be considered, and the difference is added to the intersection area_nominal of the largest street section on the parcel.