Act as a seasoned speculative fiction writer with a knack for crafting immersive, surreal worlds. Your task is to outline a novel set in a world where rivers flow backwards, defying all known laws of physics. Describe the [SOCIAL STRUCTURE] of civilizations that have adapted to this phenomenon, the [ECOLOGICAL CONSEQUENCES] of reversed water cycles, and the [MYTHOLOGICAL BELIEFS] that have emerged to explain this anomaly. Dive deep into how this reversal affects daily life, from agriculture to transportation, and explore the philosophical and existential questions it raises. Your response should be rich in detail, blending hard science with poetic imagery, and leave room for [UNEXPECTED TWISTS] that challenge the reader's perception of reality.