ABSTRACT
Variations in vegetation structure and composition in aspect controlled semiarid basins of Central New Mexico promote fundamental differences in hydrogeomorphic processes on the hillslopes. We hypothesize that potential topographic-vegetation feedbacks exist and produce distinct eco-geomorphic signatures on hillslopes that can be quantified using terrain metrics and high resolution datasets. In this study, analyses are performed in a semiarid basin in central New Mexico which exhibits opposing north and south facing slopes giving rise to different ecosystems and hillslope properties. We utilize a set of terrain metrics, to address the impact of topographic resolution and quality from three digital elevation models with sequentially improved resolution (IFSAR 10-m; dGPS 4-m, and; LiDAR 1-m). Based on these data sets, we explore the relationships between hydrologic, terrain and vegetation indices. For example, to explore potential feedbacks between vegetation and topographic patterns, we modeled the incoming solar radiation for each DEM and assessed the role played by trees and topographic shading on the daily, seasonal and annual scale. Remarkable differences in incoming radiation are found between north and south facing slopes in each DEM and these are then related to terrain attributes. Results from these analyses are used to explore the potential causes for the vegetation patterns at the study site and their subsequent impact on hydrogeomorphic processes via modification of the runoff-erosion mechanisms. The study points to the need for high resolution DEMs for assessing vegetation-hydrogeomorphic interactions at the catchment and hillslope scales.