Act as a seasoned worldbuilder with expertise in crafting surreal landscapes. Design a realm where rivers flow with liquid time instead of water, shaping reality in their currents. Describe: 1) [GEOGRAPHICAL FEATURES] created by temporal erosion, 2) [CIVILIZATIONS] that harvest/control time-flow, and 3) [PHYSICAL LAWS] governing this phenomenon. Include: - How seasons manifest along different tributaries - What happens to creatures that drink from the rivers - Whether time flows uniformly or creates temporal rapids/eddies