UNDERSTANDING THE IMPORTANCE OF ASPECT ON MOUNTAIN CATCHMENT HYDROLOGY: A CASE STUDY IN THE VALLES CALDERA, NM

Abstract

In surface hydrology, much attention is paid to the effects of changing water fluxes, however there is less of a focus on the effects of changing energy fluxes. These energy fluxes are an important driver of many hydrological processes such as evapotranspiration and snow sublimation/ablation. The hypothesis that varying energy fluxes are important to the hydrological features of a catchment is tested by an experiment that involves calculating mean transit times for a number of catchments that drain different aspects of a large dome located in the Valles Caldera, New Mexico, called Redondo Peak. These catchments have different orientations and therefore receive different amounts of solar radiation. There is a general correlation between mean transit times, as determined by lumped-parameter convolution, and aspect, suggesting that in the Valles Caldera, transit times might be affected by a variety of features that are influenced by exposure to solar radiation, such as slope steepness, vegetation patterns, and soil depth. To put these transit times into context, I also used a distributed physically-based model to simulate a number of factors simultaneously to determine how hydrological features are influenced by aspect. This modeling excercise has illuminated the aspect-dependence of hydrological features such as the timing and intensity of snowmelt and soil moisture patterns, and it has quantified differences in energy and water fluxes on different aspects. These factors affect both water storage and water fluxes, and are therefore tied to transit times.