Southern Sierra Critical Zone Observatory (SSCZO): impact of changing climate on soil hydrology in the Sierra Nevada mountains of California

Abstract

The Southern Sierra Critical Zone Observatory (SSCZO) is a community platform for research on critical-zone (CZ) processes along a steep elevation transect where precipitation grades from dominantly rain to dominantly snow and ecosystems range from oak savannah biomes to subalpine forests. Spatial gradients in CZ properties and processes permit substitution of space for time, making the SSCZO an excellent natural laboratory for studying how the CZ responds to disturbance and how the water cycle drives CZ processes. The SSCZOs goals include: i) expand process-based understanding of the CZ in a sensitive, societally crucial ecosystem; ii) establish a foundation for long-term physical, biogeochemical and ecological studies; and iii) develop a framework for improving Earth System Models. Proposed research builds on past results and involves a core SSCZO team from 6 campuses, plus collaborators and cooperators from other institutions who use SSCZO data and other resources in their research. SSCZO resources include 4 focal sites spanning a 3000-m elevation range with gradients in climate, regolith properties, soils, vegetation and material cycles. Measurements are intensive and detailed, including 4 flux towers, meteorological stations, soil lysimeters, groundwater wells, and over 1000 continuous sensors for snow depth, soil moisture, streamflow, water quality and sap flow. Contributing to SSCZO purpose, the goal of this research is to evaluate the water and nutrients distribution and storage in the soil, depths of 20, 30, 60 and 90 cm, through monitoring soil water content and electrical conductivity at representative areas of steep elevation transect, SSCZO. The project is focused particularly about soil intermediate layer, which different soils types are in non-saturated conditions. We believed to influence significantly in the hydrology, soil formation process and also in soil water storage capacity for minimizing the drought effect. The research will involve a schedule for soil characterization and continuous monitoring of water potential, moisture, soil electrical conductivity, rainfall/snow, temperature, relative humidity and evapotranspiration. Expected of results to calculate the water balance, water storage and water and nutrients flow in the soil from September 2016 until June 2017 to provide valuable and applicable information for operational hydrological interest. (AU)