The Critical Zone (CZ) is the zone between the upper branches of trees and the depths of groundwater. Humans are changing this zone at geologically unprecedented rates. Maintaining ecosystems will require the ability to project the future of the CZ. Only with concerted efforts to measure and model the landscape will it be possible to make forward projections or "earthcasts" of the CZ.
In the Susquehanna Shale Hills Critical Zone Observatory (CZO), scientists are working to earthcast the CZ by modeling aspects of the atmosphere, land surface, biota, soil, rocks and water. In addition, the models will eventually incorporate impacts of human activity. These models for water, energy, sediment, and solute (WESS) fluxes will be used to project changes spanning from 10^-3 y (water) to 10^6 y (soil). For the sedimentary rocks underlying the CZO, the models will be used to explore how the geological past has impacted today?s land surface, and, in turn, how this structure contributes toward controlling today's water and gas fluxes.
The central focus of the CZO is the forested Shale Hills watershed (~0.1 km2) but investigations will include the multiple-landuse Shavers Creek watershed (165 km2). These nested watersheds will comprise the expanded Susquehanna Shale Hills Observatory (SSHO). This upscaling will force a transition from measuring "everything everywhere" to measuring "only what is needed" in a larger watershed with multiple rock types and land use. The CZO will be used to test the over-arching hypothesis: To project CZ evolution into the future requires knowledge of geological history, observations of CZ processes today, and scenarios of human activities tomorrow.
An important focus of the CZO will be to transfer knowledge to nonCZO scientists and to the public. For example, the CZO will develop hydrological models for two PA watersheds in the region of drilling and hydrofracking for shale gas in western and northern Pennsylvania. The public will also be engaged through a "CZO Four Seasons" music concert, where Penn State musicians will create a music score from many years of watershed data at the CZO.
