CZO: Boulder Creek Critical Zone Observatory--Weathered Profile Development in a Rocky Environment and Its Influence on Watershed Hydrology and Biogeochemistry

University Of Colorado At Boulder, Boulder CO

Investigators

Abstract

This project will implement a new Critical Zone Observatory in the Boulder Creek watershed (BcCZO) in the Front Range of the Rocky Mountains in Colorado. The Earth's critical zone lies between the top of the vegetation and unweathered rock (NRC, 2001); it is in essence our living environment. Design and instrumentation of the BcCZO is driven by a suite of Earth science investigations to understand the transformation of rock into soil, and to quantify how the relevant processes are modulated by and coupled to both external forcings (e.g. climate) and intrinsic properties of the critical zone. The BcCZO extends from the continental divide to the range front, encompassing slightly more than 1000 km2 (~400 square miles) and a range of 2600 m (~8500 ft) in altitude. The relatively large drop in elevation within a single watershed provides an important contrast in climate and ecological regimes, which in turn provides a critical contrast in erosional processes. As a consequence, the properties and structure of the critical zone vary across the watershed, constituting a natural experiment on critical zone evolution and function. Three subcatchments of the BcCZO representing different states of critical zone development will be densely monitored via a networked infrastructure of geophysical, geochemical, and hydrological instrumentation. Intrinsic properties of the rock-soil column, including microbial biomass and activity, will be measured at multiple localities. The BcCZO will also leverage extant data and instrumentation from partners in the same and neighboring watersheds (e.g., NSF's Long-term Ecological Research (LTER) site, Niwot Ridge), including the unparalleled 50-year Mountain Climate Program. These data, coupled with high-resolution digital topography, cosmogenic nuclide analyses, and numerical hydrochemical models will allow development of the first mechanistic and quantitative description of processes that generate the critical zone. Simulations will be developed to explore the effect of critical zone properties on hydrologic and biogeochemical fluxes. The BcCZO will exploit intersections with the Niwot Ridge LTER site (which is the National Ecological Observatory Network Core Site, and with the Community Surface Dynamic Modeling System. The observatory will position itself as a resource to the broader scientific community through competitive graduate field fellowships, open science meetings, and maintenance of accessible data and sample archives. Results will be disseminated widely in journal publications, presentations at scientific meetings, and through web pages. The observatory will support the community-based BASIN.org environmental information network, viewed by more than 150,000 unique visitors per year. Through partnership with Science Discovery at UC Boulder, K-12 classroom, field programs, and curriculum will be developed for elementary-middle schoolers. A graduate level course using BcCZO field sites, and a field trip offered during the Geological Society of America annual meeting will extend the impact of the BcCZO within the scientific community.