Estimation of watershed width function: a statistical approach using LiDAR data
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ORIGINAL PAPER
Estimation of watershed width function: a statistical approach using LiDAR data Prashanta Bajracharya1
•
Shaleen Jain1,2
Ó Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract Terrain variability and channel network characteristics critically influence the hydrologic response of watersheds. Width function represents this response under idealized flow conditions of constant velocity and absence of losses, and can be estimated solely using the terrain data. However, the width function, in its graphical form, is less tractable for further analytical applications such as in the derivation of link-based geomorphological instantaneous unit hydrograph. In this study, we systematically redress these issues in the following manner: (a) develop a framework for the functional estimation of width functions using a mixture of truncated skew-normal distributions that captures a wide variety of distribution shapes, (b) provide a basis for model selection based on the Bayesian Information Criterion, (c) demonstrate the utility of a functional estimation approach by identifying hydrologically similar watersheds based on divergence measures applied to the width function estimates, and (d) illustrate the utility of efficient statistical estimation of geomorphic functions and metrics, which affords data reduction and can be scaled to very-large terrain datasets. Keywords Width function Instantaneous unit hydrograph Hydrologic response Hydrologic similarity Skew-normal Divergence measures
1 Introduction Recent proliferation of high resolution terrain data has the potential to transform analysis and modeling of land-surface hydrological processes (Liu and Zhang 2011; Biron et al. 2013; Yang et al. 2014). For instance, higher spatial resolution afforded by Light Detection and Ranging (LiDAR) data (often at 2 m resolution, as compared to the routinely available 30-m Digital Elevation Model data) is poised to enable advancements in: (a) delineation of Electronic supplementary material The online version of this article (https://doi.org/10.1007/s00477-020-01846-5) contains supplementary material, which is available to authorized users. & Prashanta Bajracharya [email protected] Shaleen Jain [email protected] 1
Department of Civil and Environmental Engineering, University of Maine, Orono, ME 04469–5711, USA
2
Climate Change Institute, University of Maine, Orono, ME 04469–5711, USA
channel networks (Sahoo and Jain 2018) and wetlands (Wu and Lane 2017), (b) understanding of runoff generation processes (Degetto et al. 2015), and (c) analytical modeling using the geomorphological unit hydrographs (Rodriguez-Iturbe and Valdes 1979; Gupta et al. 1980; Cheng 1982; Gupta and Mesa 1988; Troutman and Karlinger 1988). The availability of high-resolution terrain elevation data is of particular interest in improving geomorphological instantaneous unit hydrograph (GIUH) theory-based derivations of hydrologic response (Rodriguez-Iturbe and Valdes 1979; Kirshen and Bras 1983; Bras 1990; R
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