Thesis (Ph.D., Water Resources) -- University of Idaho, December 2014 | In the tropics, ongoing departure from the long-term climate average is more rapid and significant than anywhere on the planet, predicted to reach unprecedented conditions as early as 2020. Moreover, low latitudes harbor the majority of developing nations with limited capital available for monitoring water resources and climate change. As climate change intensifies, the interaction between altered precipitation regimes and modified vegetation and soil associated with expanding agricultural and pastoral land use can reduce the intrinsic resilience of watersheds and the ecosystems and societies they support.
We provide insight into how climate change and land use affect watershed hydrology and channel morphology in the data-poor humid mountain tropics. We identified an expression of geomorphic equilibrium in mountain river channels unique relative to conventional metrics of geomorphic balance derived from temperate and semi-arid regions. Then, using physically based modeling of surface and subsurface hydrology paired with field-based channel measurements, we evaluated the response exhibited by watersheds in tectonically active steep mountain terrain under existing and altered climate and land cover scenarios. Our efforts provide a rapid and inexpensive procedure for deciphering the effects of land use and climate change without need for long-term datasets or a spatially comprehensive description of subsurface heterogeneity, allowing local resource management efforts to broaden to the watershed scale.