Characterizing hydrologic thresholds using multiple meteorological factors
Abstract
Nonlinear hydrologic response is a common observation in studies that characterize precipitation-runoff relationships for individual catchments. This has prompted interest in emergent properties, like thresholds, in precipitation-runoff relationships: these are critical moments in time that coincide with a significant change in runoff behavior. Thresholds have typically been identified using two-dimensional scatter plots that compare meteorological inputs to hydrologic response. However, this approach inherently assumes that hydrologic response is controlled by a single factor, which is at odds with ecohydrological process conceptualizations that depict multiple meteorological factors, like rainfall volume and rainfall intensity, as important controls. While hydrologists have not yet devised ways to identify thresholds in multi-factor relationships, ecologists have characterized such thresholds (in ecological response) using three-dimensional response surfaces. The goal of the present study was, therefore, to borrow three-dimensional response surface methods from ecology to assess possible interactions between rainfall volume and rainfall intensity that may lead to nonlinear hydrologic response. Rainfall-runoff event data from the HJ Andrews Experimental Forest (United States) and the Mahurangi Catchment (New Zealand) were used. Three-dimensional response surfaces were modeled to show event-specific hydrologic response as a function of rainfall volume and rainfall intensity. The abruptness of thresholds for response surfaces showing nonlinear changes were quantified using a threshold strength metric that measures response surface bimodality and monotonicity. Different types of response surface geometry were also examined for clues about rainfall volume-intensity interactions. Preliminary results from response surface analysis show evidence of interactions between rainfall volume and rainfall intensity that lead to threshold behavior in hydrologic response for some relationships. These nonlinear changes in hydrologic response differ in abruptness, as illustrated by highly variable threshold strength values.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2020
- Bibcode:
- 2020AGUFMH215.0004R
- Keywords:
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- 1804 Catchment;
- HYDROLOGY;
- 1813 Eco-hydrology;
- HYDROLOGY;
- 1860 Streamflow;
- HYDROLOGY;
- 1879 Watershed;
- HYDROLOGY