Variability of stream extents controlled by flow regime and network hydraulic scaling

Abstract

Stream networks expand and contract through time, impacting chemical export, aquatic habitat, and water quality. Although recent advances improve prediction of the extent of the wetted channel network (L) based on discharge at the catchment outlet (Q), controls on the temporal variability of L remain poorly understood and unquantified. Here we develop a quantitative, conceptual framework to explore how flow regime and stream network hydraulic scaling factors co-determine the relative temporal variability in L (denoted here as the total wetted channel drainage density). Network hydraulic scaling determines how much L changes for a change in Q, while the flow regime describes how Q changes in time. We compiled datasets of colocated dynamic stream extent mapping and discharge to analyze all globally available empirical data using the presented framework. We found that although variability in L is universally damped relative to variability in Q (i.e., streamflow is relatively more variable in time than network extent), the relationship is elastic, meaning that for a given increase in the variability in Q, headwater catchments will experience greaterthan-proportional increases in the variability of L. Thus, under anticipated climatic shifts towards more volatile precipitation, relative variability in headwater stream network extents can be expected to increase even more than the relative variability of discharge itself. Comparison between network extents inferred from the L-Q relationship and blue lines on USGS topographic maps shows widespread underestimation of the wetted channel network by the blue line network.

Hierarchical climate-driven dynamics of the active channel length in temporary streams

“…based on multiple field surveys. This could help the reconstruction and the modeling of channel network dynamics, especially in cases where active length statistics can be indirectly inferred from rainfall and/or discharge observations 12 , 27 , 28 , 32 .…”

Analysing river network dynamics and active length - discharge relationship using water presence sensors

“…Catchments can be seen as dynamical systems where the discharge at the outlet and the active length co-evolve in time in response to the underlying climatic forcing. In this study, we seek to use high frequency ER data to evaluate the robustness of an empirical model often proposed in the literature, linking the wet length and the corresponding discharge using a power-law relationship (Godsey and Kirchner, 2014;Jensen et al, 2017;Lapides et al, 2021):…”

“…In the search of a mathematical synthesis of the coevolution of network dynamics and the hydrological response of catchments, observed variations of the active channel length were frequently compared to the corresponding discharge values observed at the catchment outlet (Godsey and Kirchner, 2014;Jensen et al, 2017Jensen et al, , 2019Lapides et al, 2021). This led to the formulation of a power-law model connecting the active channel length L and the catchment streamflow Q, which was often used to get a simple mathematical description of the hydrologic dynamics involved both in rainfall-runoff mechanisms and river network dynamics.…”

Controls on Stream Water Age in a Saturation Overland Flow‐Dominated Catchment

“…This trend is likely to make overland flow more important in catchments where overland flow occurs. Increased precipitation volatility is also likely to result in increased relative variability in wetted channel extent (Lapides et al., 2021), which may apply to saturated area as well. Future studies might consider these interactions and their consequences for kinetic‐rate controlled processes like chemical weathering.…”