Abstract
Abstract. In this study, we develop a watershed zonation approach for characterizing watershed organization and functions in a tractable manner by integrating multiple spatial data layers. We hypothesize that (1) a hillslope is an appropriate unit for capturing the watershed-scale heterogeneity of key bedrock-through-canopy properties and for quantifying the co-variability of these properties representing coupled ecohydrological and biogeochemical interactions, (2) remote sensing data layers and clustering methods can be used to identify watershed hillslope zones having the unique distributions of these properties relative to neighboring parcels, and (3) property suites associated with the identified zones can be used to understand zone-based functions, such as response to early snowmelt or drought and solute exports to the river. We demonstrate this concept using unsupervised clustering methods that synthesize airborne remote sensing data (lidar, hyperspectral, and electromagnetic surveys) along with satellite and streamflow data collected in the East River Watershed, Crested Butte, Colorado, USA. Results show that (1) we can define the scale of hillslopes at which the hillslope-averaged metrics can capture the majority of the overall variability in key properties (such as elevation, net potential annual radiation, and peak snow-water equivalent – SWE), (2) elevation and aspect are independent controls on plant and snow signatures, (3) near-surface bedrock electrical resistivity (top 20 m) and geological structures are significantly correlated with surface topography and plan species distribution, and (4) K-means, hierarchical clustering, and Gaussian mixture clustering methods generate similar zonation patterns across the watershed. Using independently collected data, we show that the identified zones provide information about zone-based watershed functions, including foresummer drought sensitivity and river nitrogen exports. The approach is expected to be applicable to other sites and generally useful for guiding the selection of hillslope-experiment locations and informing model parameterization.
Highlights
Predictive understanding of watershed functions is often hindered by the heterogeneous and multiscale fabric of watersheds (e.g., Peters-Lidard et al, 2017)
The ratio between the across-hillslope variance and the overall variance (Fig. 2a) is generally high for the elevation, net annual potential solar radiation, peak snow-water equivalent (SWE), and bedrock resistivity up to 0.75, which means that the hillslopeaveraged metrics capture the watershed-scale variability of these variables and that the within-hillslope variability is small compared to the across-hillslope variability
We have developed a watershed zonation approach for characterizing watershed organization and functions based on the bedrock-to-canopy remote sensing and spatial data layers
Summary
Predictive understanding of watershed functions is often hindered by the heterogeneous and multiscale fabric of watersheds (e.g., Peters-Lidard et al, 2017). Heterogeneity exists within each of the watershed compartments, including above-ground compartments (i.e., plant species distribution and plant dynamics, topography) and below-ground compartments (i.e., soil and bedrock structures/properties). Such watershed patterns influence ecohydrological and biogeochemical processes, which in turn affect watershed functions and create emerging patterns as feedback (Sivapalan, 2006). Watershed hydrology modeling studies typically use the grid size from 100 m to 1 km (e.g., Foster et al, 2020; Maina and SiirilaWoodburn, 2020), whereas soil moisture is known to vary on the order of several or several tens of meters (e.g., Engstrom et al, 2005; Wainwright et al, 2015), and biogeochemical dynamics can vary within 1 m or less (e.g., Burt and Pinay, 2005; Groffman et al, 2009)
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
