# NDR Output: Interpreting n\_export.tif **URL:** \ **Category:** Science, Research & Data\ **Tags:** ndr\ **Created:** [November 16, 2021, 10:37pm UTC](https://community.naturalcapitalalliance.org/t/ndr-output-interpreting-n-export-tif/2316 "2021-11-16T22:37:50Z")\ **Posts on this page:** 4\ **Page:** 1
**Author:** ![atershy](https://yyz1.discourse-cdn.com/flex031/user_avatar/community.naturalcapitalalliance.org/atershy/32/1763_2.png) [@atershy](https://community.naturalcapitalalliance.org/u/atershy)\ **Post date:** [November 16, 2021, 10:37pm UTC](https://community.naturalcapitalalliance.org/t/ndr-output-interpreting-n-export-tif/2316/1 "2021-11-16T22:37:50Z")
Hello, fellow InVEST users! šŸŒ± I am using the NDR model to estimate nutrient retention in riparian habitat for an M.S thesis. I am exploring the model output and trying to understand the logical connection between two outputs: the n\_export.tif and the stream.tif. I understand that the stream.tif is the stream network computed from the DEM. In the InVEST documentation, the n\_export.tif is defined as " A pixel-level map showing how much load from each pixel eventually reaches the stream." In my n\_export.tif output, the highest values of n export are the pixels that are also a part of the stream network. Photos 1 and 2 visualize how the highest n\_export values match up perfectly with the stream.tif. ![n_export](https://canada1.discourse-cdn.com/flex031/uploads/naturalcapitalproject/original/2X/c/c920a49cbf344977266d25a8267e98aa166808f1.jpeg) (photo 1: n\_export map with red representing the highest n export.) Could not upload photo 2 because I am a new user. photo 2: stream.tif with streams in green and land with no color, overlaid on n\_export) **My Question:** How should I interpret the n\_export.tif? Does n\_export.tif simply show the accumulation and export of N in streams? Iā€™m confused because I interrupted the n\_export.tif to show how much **load from each pixel eventually reaches the stream**. I assumed that only **land pixels** would contribute n loads that would reach the stream so that land pixels would have the highest N export values. My sense is that n\_export.tif is indeed a simple display of stream pixels that have high values of n export, but I wanted to check here for clarification. Thank you! ---
**Author:** ![atershy](https://yyz1.discourse-cdn.com/flex031/user_avatar/community.naturalcapitalalliance.org/atershy/32/1763_2.png) [@atershy](https://community.naturalcapitalalliance.org/u/atershy)\ **Post date:** [November 16, 2021, 10:38pm UTC](https://community.naturalcapitalalliance.org/t/ndr-output-interpreting-n-export-tif/2316/2 "2021-11-16T22:38:26Z")
![stream_tif](https://canada1.discourse-cdn.com/flex031/uploads/naturalcapitalproject/original/2X/2/2caa5767bdfe973346f88d0be647d2f0120d81be.jpeg) photo 2: stream.tif with streams in green and land with no color, overlaid on n\_export) ---
**Author:** ![jesseG](https://yyz1.discourse-cdn.com/flex031/user_avatar/community.naturalcapitalalliance.org/jesseg/32/1068_2.png) [@jesseG](https://community.naturalcapitalalliance.org/u/jesseG)\ **Post date:** [November 18, 2021, 1:10am UTC](https://community.naturalcapitalalliance.org/t/ndr-output-interpreting-n-export-tif/2316/3 "2021-11-18T01:10:36Z")
Hi @atershy , Welcome to the Forum! Your interpretation on the ā€œ_n\_export\_{SUFFIX}.tif_ā€ output is correct in that it should display spatial patterns of nitrogen ā€œ_load from each pixel that eventually reach the stream_.ā€ As such, values \>0 should appear on the landscape, and not actually in any streams, so something went wrong with this model run. From looking at your screenshots, one thought is that perhaps your spatial extent may somehow be limited to only the streams themselves. What does your Watersheds input vector look like? It should consist of polygon(s) that cover your entire area of interest, like the beige underlying polygon in your screenshots; it should not be a linear stream layer. Please upload your log file (ending in _.txt_) here too. That will help us to further diagnose what went wrong. Thanks, Jesse ---
**Author:** ![atershy](https://yyz1.discourse-cdn.com/flex031/user_avatar/community.naturalcapitalalliance.org/atershy/32/1763_2.png) [@atershy](https://community.naturalcapitalalliance.org/u/atershy)\ **Post date:** [November 25, 2021, 9:35pm UTC](https://community.naturalcapitalalliance.org/t/ndr-output-interpreting-n-export-tif/2316/4 "2021-11-25T21:35:20Z")
Hi Jesse, Thank you for your insight! Iā€™m not quite sure what the issue was, but I think it likely could have been a faulty DEM reconditioning that I did. I fixed the reconditioned DEM, re-ran my model, and got the correct output for n\_export ![image](https://canada1.discourse-cdn.com/flex031/uploads/naturalcapitalproject/original/2X/4/4165c9e6fd26af9dcb6d21f5308b4e0a08059fd8.jpeg) Thanks again for your time and expertise!