Input data for ndr

Dear Community,

I am new to InVEST NDR and I need your help. I am expected to run NDR for a watershed in Zambia.
I have read the manual, but I still have the following difficulties because InVEST cannot read all my inputs for the watershed.

How best can I download files that will be recognised by InVEST and run the model successfully?
Do I have to use another Model to processes then before taking them to InVEST.
What websites would you recommend for me to download LULC?

Thank you

Welcome to the forum @Joseph_Mphande!

Are you seeing an error when putting your inputs into the Workbench interface? If so, please post a screenshot of the window showing the error message. If the errors are produced after you hit Run, please post the entire log file (.txt with a long name) that is created in the Workspace. That contains a lot more information that might help us debug.

We provide several resources that help with data and formatting. The User Guide Introduction and Getting Started section talks about data formatting, and also introduces the sample data, which we recommend using as an example for how to format your own data.

The NDR model chapter also has a Data Sources Appendix that provides pointers to some global data sources, plus some additional guidance. For LULC in particular, I’d recommend seeing if there is a national LULC map for Zambia, which is often provided by the government. If there isn’t a national one, then you could look at the global sources referenced in the Appendix, and see which one is the most accurate for your watershed.

Being proficient with GIS is a requirement for preparing the data that goes into the models, and there are a lot of tutorials and guides on the internet that can help with that too. While we don’t generally teach GIS, we do have a small series of videos called GIS for InVEST that may be helpful.

~ Stacie

Dear Stacie,

Thank you for your timely response and the information you provided.
I realised that there was a lot of things that I didn’t know, and your guidance and Videos have been very helpful so far. For instance, I was not merging the tiles into mosaic, not projecting according to the coordinate systems of my place and other preparatory steps of InVEST NDR input data.

I have one more question, when creating watersheds, I have seen from your presentation that I need to have two major inputs for the DelineateIT tool which are Filled DEM and DAM.intake.shp file.
How can I come up with a dam shp file? I understand this is the output point of the dam or reservoir or in my case Lake Kariba which was created after damming Zambezi River.
This is the major question I have now otherwise, the videos and the guidance you provided has been very helpful. Thank you so much.

Hi @Joseph_Mphande -

The dam outlet location might already exist, whether in a shapefile or in the form of latitude/longitude data provided by the government, or the dam operators or some other source. If the location isn’t provided, you can digitize the point yourself by creating a new point vector file in a GIS, looking at the dam in a satellite basemap, and creating a new point in the vector file at the location where you see the dam in the basemap.

~ Stacie

Dear Stacie,

Thank you for the guidance given. I am working on the inputs now. I hope they will run perfectly once they are loaded in InVEST NDR.

Hi Stacie,

I managed to pre-process the inputs for NDR and managed to run the model successfully, thank you for your guidance.

I want to find out the following.

Within my watershed of interest, I have Tree Cover, Shrubland, grassland, cropland, built up, Bare or Spare vegetation, Permanent water bodies and Herbaceous wetland.
I have the phosphorus exported from these LULC because I just have one watershed.

My question is, If I want to know how much phosphorus each of the above LULC is contributing to the total exported phosphorus how can I go about it?.

Your guidance and help will be appreciated.

(Attachment screenshot.docx is missing)

Hi @Joseph_Mphande -

You could aggregate the sediment export results by LULC class using a GIS tool like Zonal Statistics.

~ Stacie