New Mexico Geological Society Annual Spring Meeting — Abstracts

The partitioning of water into runoff and infiltration is not well understood in the Sevilleta National Wildlife Refuge. Aspect and solar radiation inputs control soil development and the amount and type of vegetation on each hillslope. The differences in the hillslopes are reflected in the runoff processes that control water partitioning, the type of vegetation that is present, and the differences in soil development of each slope. Because of the presence of vegetation and the organisms that live in the islands formed by vegetation, there are higher rates of infiltration on north facing slopes allowing greater infiltration and deep percolation. In contrast, on south facing slopes there is less vegetation, more bare ground, less activity from microorganisms, and consequently, lower infiltration rates. These differences in infiltration and runoff enhance soil development on north slopes and inhibit soil development on south hillslopes. Therefore, it is expected that north slopes will have less runoff due to increased infiltration and decreased distance between flow obstructions. The opposite is true for south hillslopes. Since these processes are intricately coupled, this research project will focus on the influence of hillslope aspect and its controls over slope stability due to differences in infiltration and runoff in a semiarid landscape.

To complete these objectives, several runoff plots will be constructed to observe the amount of runoff and sediment generated during storms. However, data for this poster will come from plots that were constructed and monitored in the summer of 2006. Four plots were constructed, two on the north facing hillslope and two on the south facing hillslope at the Red Tanks area of the Sevilleta NWR. Bulk runoff samples were collected from these plots for the duration of the summer. Runoff budgets for the hillslopes were determined using the bulk runoff amounts, infiltration rates and precipitation data also collected at the study hillslopes. These plots will be used to supplement data that will be collected from future runoff plots that will be built in a well-instrumented hillslope. These data will be used to examine the complex relationships of runoff and infiltration on the hillslope scale and to gain a greater understanding of water partitioning in a semi-arid environment.