this functions loads the data from the sheet "surface_areaType" within the data entry excel file
Arguments
- data.dir
The directory of the entry data table.
- filename
Name of the R2Q-Excel File including ".xlsx".
- residential_suburban, residential_city, commercial, main_road, no_runoff
vectors of 3 containing 1) fD value of the landuse type, 2) the proportion of the landuse type within the catchment area in percent and 3) a value of if 1 if the landuse tyoe should be considered as connected to the separate sewer system or 0 if not.