rapidless

adjective2

1. •
   Without rapids.

   • "The river itself is flat and picks up quite a bit of current in highest flows, but otherwise it is a straightforward, rapidless section of beginner water." — 2009
2. •
   having no fast rivers or streams

   • The Zambezi contains at least 14 species that were not found in the Kwando River; ten of these species are strongly rheophilic, explaining their absence in the rapidless and rockless Kwando-Linyanti. — 1986