Aligning HRUs by property boundaries?

[Maggie Armstrong]

Hi all,

I am still learning SWAT+ (using QGIS) and could use some help in understanding how to align the HRUs by property boundaries. The catchment area I am looking at is primarily agriculture, with the pastures of different properties touching each other. We want to separate out HRUs by property boundaries so we can simulate the different management actions that the individual land owners have undertaken. There are some similar concepts that we found in literature but they were done 

a) at different physical scales (pasture scale – Sheshukov et al., 2016; Kalcic et al., 2015) and/or 

b) with different programs (ArcGIS). 

 

Has anyone done this before? Or does anyone know how to make the HRU adjustments? My colleagues and I have tried three things:

 

Divide Land Use Map by property boundaries

I created a land use map that divided up the land by property boundaries. Rather than having the pastureland as one big polygon throughout the catchment, it was broken up into multiple smaller polygons. Within the pasture polygons were the other land uses such as forest and houses.

This did not have a big effect of the HRUs when it was used with the original soil map or with the ones mentioned below.

 

 

Divide Soil Map by property boundaries and soil type.

There are two types of soil in the catchment. The first attempt at adjusting the soil map was done with creating polygons based on where the soil types were found and again divided into polygons based on the property boundaries. The soil file was adjusted to maintain the correct characteristics of the soil but with different, unique names for each polygon.

 

Divide Soil Map by property boundaries.

The most recent adjustment was creating polygons purely based on the property boundaries and using the soil values of the most prominent soil type found within the area. Unique names were also used for each polygon.

 

 

Whether the approach did not work because the idea wasn't fundamentally sound or if there was something else (like the layer wouldn’t rasterize), we have run into issues. I appreciate any and all insight on this as we have been stuck on this problem for a long time. I hope that I can continue the conversation with whoever has insight into this as I am eager to learn more about the program and how to resolve this. I can send screenshots of the different layers if that would be useful.

Thanks,

Maggie