This document discusses 4 key ecohydrological principles for modeling water resources in drylands: 1. The response of dryland ecohydrology is slow due to long time scales and residence times of hydrological systems. 2. Dryland ecohydrological systems are nested hierarchical systems with different scaling properties than agronomy and meteorology. 3. Ecohydrological processes have strong feedbacks and non-linear responses, as actions can change the overall system. 4. It is important to balance the cycles of water and solutes to achieve sufficiency, sustainability, efficiency and resilience, as seen in the water and solute cycles of an example system in Windhoek.