This document discusses the ambivalence of water and its impact on riverine urban areas as both a heritage and natural hazard. It summarizes that water can be seen as a heritage that cities are rediscovering through projects that bring them back to rivers. However, water can also present natural hazards like floods from too much water or desertification from too little water due to climate change. The document provides examples of these hazards and discusses different construction types needed in areas where water presents risks.