As I mentioned in my novel Mariner Valley, many of the bases on Mars were built over underground water deposits that facilitated human settlements. Now, thanks to the  Mars Express’s MARSIS radar a major deposit has been found under the surface in the Medusae Fossae Formation. What I had supposed to be a necessity for Martian settlement and colonization has now become reality. Read about it here –

https://www.earth.com/news/mars-has-a-water-reservoir-two-miles-deep-enough-to-fill-earths-red-sea/