Monday, May 7, 2012
Springs ecosystems support diverse and unique biological communities often threatened by development and excessive groundwater pumping. Few hydrogeologic studies have focused on the relation between the geochemical properties; the geomorphology and vegetation cover at springs ecosystems. Understanding the feedbacks between abiotic and biotic factors in springs ecosystems has significant implications for species protection and ecosystem management. Water chemistry influences vegetation type, while vegetation controls the chemical properties of the spring. Furthermore, vegetation change shapes local geomorphology by adjusting erosion rates and channel morphology. Using the extensive Springs Inventory Database of the Springs Stewardship Institute, we determine connections between vegetation cover, water chemistry, and geomorphology of springs with various multivariate statistical techniques. The springs ecosystems of the Spring Mountains National Recreation Area of southern Nevada were used to ground-truth preliminary conclusions and test our methodology.
Local and regional groundwater flow systems can be delineated isotopically. The concentrations of oxygen (δ 18O) and hydrogen (δ2H) isotopes of emerging groundwater are influenced by travel time and the source of infiltration from meteoric water. These isotopic signatures of springs water at emergence zones can act as an indicator of the flow system type. Pairing this chemical approach with an ArcGIS hypsometric analysis (catchment elevations plotted against their relative frequency), especially with those locations suspected to represent regional flow systems, could add a new level of certainty to my conclusions. These results are currently preliminary, and more springs need to be analyzed to confirm our interpretations.