This is fantastic work. I'll be following your account from here on out.
I get the attraction for ephemeral art. In the arts group that I run, we make wooden sculptures with the intent on burning them at a big celebration party when they are finished.
Your post reminds me of a snow sculpture that a friend of mine did this past winter. He did it in a very busy public park and it lasted for days before the snow melted. I kept an eye on the park in Instagram, and it was cool to see his work being photographed and shared around on different people's instagram feeds, and to see comments from people that had never met the guy.
Here's a pic of the snowman that my friend made.
RE: Reflections of a mermaid - sand sculpture