The aspect of the land surface in mid and high latitudes control hydrological response through differences in energy fluxes, prevailing winds, snow processes, evaporation and transpiration. In the Valles Caldera National Preserve (VCNP) in northern New Mexico, recent research has shown that north facing terrains accumulate thicker snow packs, the snow cover duration is longer, the soil moisture content is higher and hillslopes have longer water transit times. These findings suggest that catchments with a predominant north facing aspect are expected to have more water available and consequently a different hydrological response than catchments characterized by a different land orientation. This poster presents four years (2008-2011) of hydrological data in the VCNP and shows the hydrological response to interannual climate variability in mountainous catchments draining along different aspects. This investigation focuses on three perennial catchments draining Redondo Peak (3435m): La Jara (LJ, 3.67 km2), History Grove (HG, 2.42 km2) and Upper Jaramillo (UJ, 3.06 km2). The three catchments range in elevation between 2680 m and 3429 m. They share similar topographic characteristics, climate, vegetation and a complex geology. The most predominant north facing catchment is UJ, HG and LJ have both a predominant east facing aspect. This study is based on empirical observations of basin response and it has been carried out by way of monitoring physical amount, intensity and timing of water entering and leaving the catchments using the available meteorological data in the region and the instrumented network installed by the Jemez River Basin and Santa Catalina Mountains Critical Zone Observatory (http://www.czo.arizona.edu/). The climate in the region is semi-arid, continental and highly variable. For the water years (WY) 2008 and 2011 annual precipitation was 86% and 71% below the mean (P=711.5mm), and during WY 2009 and 2010, annual precipitation was 4% and 1% above the mean. Within the period of analysis the ratio of winter precipitation to annual precipitation varied from 59.4% to 39.4%. The maximum snow water equivalent (SWE) was equal to 303 mm and 53 mm during the years 2010 and 2011. Preliminary results show that the north facing catchment (UJ) had the highest annual discharge during the four years. Water yield (Q/P) for UJ was the highest and ranged between 0.10 during the driest year 2011 and 0.27 for the wettest year 2010. UJ shows the highest peak of specific discharge and it happens with a few days of delay with respect to the other catchments. UJ retains water for a longer time and it shows during dry and wet years the lowest variability between the flow percentiles Q15 and Q90 suggesting that north facing catchments are less susceptible to climate variability.
Zapata X., Troch P.A., McIntosh J.C., Broxton P.D., Brooks P.D. (2012): The Effect of Terrain Aspect on Interannual Variability of Hydrologic Response In Mountainous Catchments in New Mexico. Abstract B23H-0541 presented at 2012 Fall Meeting, AGU, San Francisco, Calif., 3-7 Dec (Poster).