Degree of Anthropogenic Land Disturbance Controls Fluvial Sediment Hysteresis

Abstract

Storm events dominate sediment delivery to stream corridors, but the effects of anthropogenic disturbances on altering the sources, pathways, and timing of delivery remain uncertain. To address this knowledge gap, we analyzed 849 events from over a decade of high-frequency turbidity data across five watersheds in an urbanization gradient. Sensing results suggested that hysteresis patterns evolved with land use from clockwise (low-rural) to figure-eight (high-rural) to counter-clockwise (high-urban), indicating a disturbance-driven shift of sediment provenance from proximal to distal. Sediment loading pathways in the lowest-disturbance rural watershed were dominated by a single hysteresis shape (>90% of export by clockwise events), whereas the mostdisturbed urban basin had the greatest variability in loading pathways (∼25% of export by clockwise, counter-clockwise, figure-eight, and complex events, respectively). Finally, wastewater treatment facilities modulated the release of "hungry-water" baseflow, causing more-rapid periods of high streamflow variance in catchments with a treatment facility (∼4 h period) than in those without (∼6 h period). Together, our results indicate that anthropogenic disturbances, including tile drainage, impervious surfaces, and roadway density, increase the connectivity of distally located sediment that wouldin undisturbed basinsdeposit along the sediment cascade. This information is important to watershed managers as they mitigate erosion in developing basins.

Plutonium Isotopes: An Effective Tool for Fluvial Sediment Sourcing in Urbanized Catchments

“…This pathway is plausible as tile‐drained area in the rural watersheds ranges from 12.2% to 18.6% (Figure 1). On the other hand, in urban watersheds, low‐intensity events fall on impervious surfaces, which deliver high‐energy sediment‐free flows to ditches and tributaries where substantial bank erosion occurs (Russell et al., 2019; Zarnaghsh & Husic, 2021). Further, wastewater treatment facilities discharge sediment‐starved water, which have a high capacity for erosion, directly into streams (Lawler et al., 2006).…”

“…Much of the Earth's land surface is experiencing anthropogenically driven land use change and erosion at unprecedented rates (Owens, 2020; Russell et al., 2017; Shi et al., 2021). The rapid conversion of natural and rural landscapes into urban systems has diminished agricultural productivity, increased sediment pollution, and has counteracted urban sustainability (Chang et al., 2020; Zarnaghsh & Husic, 2021). The global urban population is expected to double by 2050 (Bettencourt et al., 2018), which will be met with increasing urban development as well as agricultural activity to satisfy population demands.…”

Hydro-Chemical Responses at Different Scales in a Rural Catchment, UK, and Implications for Managing the Unintended Consequences of Agriculture

“…Mean seasonal HI were all >0 (0.00 to 0.29) indicating that clockwise loops patterns were still dominant, typical of low-disturbance rural catchments (Zarnaghsh and Husic, 2021).…”

“…This could be caused by a combination of a greater variety of Summer antecedent conditions which can affect hysteresis (Perks et al, 2015) and an increase in catchment 'urban' hard surfaces (e.g. Zarnaghsh and Husic, 2021) (when compared to Catchment 1) which can cause higher variability in timings. In the Winter, when the catchment was predominantly 'saturated', hydrological connectivity to the drainage network was high.…”

Inferring drivers of nitrate and sediment event dynamics from hysteresis metrics for two large agricultural watersheds

“…Typically, analysis of hysteretic patterns is carried out via a bivariate plot to highlight the response of one variable to variations in another (Zuecco et al, 2016). Concentration–discharge ( c–q ) relationships can provide rich insight into the complex interactions between watershed hydrological functioning and solute and particulate biogeochemical responses during events (Aguilera & Melack, 2018; Lloyd et al, 2016a; Rose et al, 2018; Zarnaghsh & Husic, 2021) and can assist in formulating watershed management strategies aimed at reducing solute and particulate export into streams. To date, larger watersheds (>100 km 2 ) have been minimally studied with more emphasis focused on smaller homogenous watersheds (<10 km 2 ; Gao & Josefson, 2012).…”