# Understanding inputs for the model
**URL:** https://community.naturalcapitalalliance.org/t/understanding-inputs-for-the-model/5960
**Category:** Science, Research & Data
**Tags:** coastal-vulnerability
**Created:** [April 28, 2025, 8:34am UTC](https://community.naturalcapitalalliance.org/t/understanding-inputs-for-the-model/5960 "2025-04-28T08:34:08Z")
**Posts on this page:** 3
**Page:** 1
### Author:  [@n-marine](https://community.naturalcapitalalliance.org/u/n-marine)
#### Post date: [April 28, 2025, 8:34am UTC](https://community.naturalcapitalalliance.org/t/understanding-inputs-for-the-model/5960/1 "2025-04-28T08:34:08Z")
Hi
I have a few inquires. (context: i am trying to perform the model for an island in the red sea)
1- i wanted to know if anyone knows of any open source platforms i can get inputs for the coastal vulnerability model
2- I noticed the seagrass habitat is added as a .tif file instead of a .shp file like the rest of the habitats. Why is that? Will i need to add my seagrass as .tif as well?
3- I see the maximum fetch distance on the grand Bahamas is quite short, why is that? To my understanding the max fetch distance is the length from a point which take the path of the wind to the closest land mass. For my island, i created a point on the edge of the island and, based off of what i found from papers which show the wind direction of the red sea, i created a line that extends and hits the closest landmass which was 88.1 miles away (or 142 kms). This is quite big and i read in the guide that my bathymetry will need to go from my AOI to the max fetch distance. I do not have such wide bathymetry information. Can i pick a shorter value for the distance? I dont understand why the fetch rays created for the bahamas island in the sample files is so short. You could say my island is sort of similar in distance as grand bahamas is to florida and then there is the open ocean on its opposite side. So wouldn’t my fetch distance be small too?
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### Author:  [@dave](https://community.naturalcapitalalliance.org/u/dave)
#### Post date: [April 29, 2025, 3:57pm UTC](https://community.naturalcapitalalliance.org/t/understanding-inputs-for-the-model/5960/2 "2025-04-29T15:57:39Z")
Hi @n-marine , I can address some of your questions,
> [@n-marine](#):
>
> 2- I noticed the seagrass habitat is added as a .tif file instead of a .shp file like the rest of the habitats. Why is that? Will i need to add my seagrass as .tif as well?
This demonstrates the fact that your habitat layers may be rasters (for example .tif) or vectors (for example shp). Choose whichever format is convenient for you.
> [@n-marine](#):
>
> To my understanding the max fetch distance is the length from a point which take the path of the wind to the closest land mass. For my island, i created a point on the edge of the island and, based off of what i found from papers which show the wind direction of the red sea, i created a line that extends and hits the closest landmass which was 88.1 miles away (or 142 kms). This is quite big and i read in the guide that my bathymetry will need to go from my AOI to the max fetch distance. I do not have such wide bathymetry information. Can i pick a shorter value for the distance?
This is the right idea, but, yes, you can pick a shorter distance. The `max_fetch_distance` refers to the maximum distance the model will extend lines in search of other landmasses that could offer protection from open-ocean waves. How close does the nearest land need to be to offer protection from open-ocean waves? 1km? 10km? 100km? Choose the largest distance (or slightly larger) that still offers protection to the coastline. If there are bays, or inlets that you know for sure offer protection to the opposing coastline, you could measure the distance across to make sure you choose a fetch distance _larger_ than those spans.
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### Author:  [@swolny](https://community.naturalcapitalalliance.org/u/swolny)
#### Post date: [April 29, 2025, 5:43pm UTC](https://community.naturalcapitalalliance.org/t/understanding-inputs-for-the-model/5960/3 "2025-04-29T17:43:24Z")
@n-marine, have you looked at the [Data Sources Appendix](https://storage.googleapis.com/releases.naturalcapitalproject.org/invest-userguide/latest/en/coastal_vulnerability.html#appendix-2-data-sources) in the Coastal Vulnerability chapter of the User Guide? It suggests sources for datasets, which are freely available, but have differing usage rights, so you’ll need to check each one’s licensing, so that it is appropriate for your use.
~ Stacie