I am trying to remote sensing land cover features (bare soil, water, vegetation, cultivated areas) on a 40 km² watershed, located in the Sahel (semi-arid west africa). I am heavily interested in their spatio-temporal trends and patterns. As such, I found Landsat images to be potentially good candidates. Free available Landsat products (C1 and C2 levels) have a resolution of 30 m, i.e the surface being represented in a single pixel is close to 900 m².
I would like to know if this spatial resolution is accurate enough for my task, given the size of my study area (40 km²) ?
Is there a general rule of thumb to follow, or even better, some references discussing the topic ?
How can I account for and estimate mapping errors subsequently ?