Predicting Streamflow Elasticity Based on Percolation Theory and Ecological Optimality

How much terrestrial precipitation is used by vegetation and how runs off, represents central issues in hydrologic science, ecology, climate change, even geopolitics. We present a theory for the water balance to predict fractional change streamflow due given changes temperature precipitation. The involves single parameter whose value derived under conditions of neither energy- nor water-limitations and, therefore, not an adjustable parameter. By comparison with extensive data elasticity ϵp at global scale, we find that captures key trends variations median aridity index AI. In contrast shortcoming classical Budyko phenomenology, namely, convergence = 4 large AI, our yields 2 all AI > 1, accord major river basins, as well summaries continental sets. Incorporating effects annual storage leads ability range observed values function index, or its inverse, humidity run-off ratio. When are neglected, more accurate predictions drainages than small watersheds, particularly if basin spans various regimes such, integration over climates tends reduce relative storage.