Citation:

Kaushal, S., C. Maas, P. Mayer, Tamara Newcomer Johnson, S. Grant, M. Rippy, R. Shatkay, J. Leathers, A. Gold, C. Smith, E. McMullen, S. Haq, R. Smith, S. Duan, J. Malin, A. Yuculak, J. Reimer, K. Delaney Newcomb, A. Sides Raley, D. Collinson, J. Gallella, M. Grese, G. Sivirichi, T. Doody, P. Vikesland, S. Bhide, L. Krauss, M. Daugherty, C. Stavrou, M. Etheredge, J. Ziegler, A. Kirschnick, W. England, AND K. Belt. Longitudinal stream synoptic monitoring tracks chemicals along watershed continuums: a typology of trends. Frontiers in Environmental Science. Frontiers, Lausanne, Switzerland, 11:1122485, (2023). https://doi.org/10.3389/fenvs.2023.1122485

Impact/Purpose:

Many water quality studies focus on routine monitoring at a few fixed locations or large random sampling designs.  Often, these simplistic sampling approaches cannot capture the complexity of patterns of stream biogeochemistry that are important to assess condition or recovery after restoration. We present a more comprehensive but feasible approach for stream and watershed monitoring designed to collect data from across flowpaths which can provide a more holistic picture of water quality.  We show that the resulting data, called “synoptic sketches”, can reveal sources of anthropogenic impacts as well as improvements in water quality after conservation or restoration.  We present synoptic sketches of carbon, nutrients, greenhouse gasses, salts, and metals from data collected among multiple studies conducted in the Chesapeake Bay region.  Results synoptic sketches of multiple parameters revealed water quality trends, pollution sources and sinks, and fate and transport of chemical cocktails en route to receiving waters, drinking water supplies, and coastal zones.

Description:

There are critical challenges in evaluating the effects of management, conservation, and restoration efforts on water quality due to spatial heterogeneity in sources, transport, and transformation of contaminants along human-impacted watersheds.  Many water quality studies focus on routine monitoring at a few fixed locations or large random sampling designs.  We explore an approach for analyzing multiple chemical parameters along flowpaths using synoptic surveys designed to provide a holistic picture of water quality called ‘synoptic sketches.’  Synoptic sketches consider hydrologic flowpaths as major units of study.  Analyzing watershed synoptic data can reveal if: (1) anthropogenic impacts on land spread downstream to receiving waters, and (2) downstream changes in land use, conservation, or restoration can reverse water quality degradation.  We present synoptic sketches of carbon, nutrients, greenhouse gasses, salts, and metals concentrations along 10 watershed flowpaths draining 1,765 km2 of the Chesapeake Bay region.  These 10 watershed flowpaths are drained by stream reaches experiencing either urban degradation, forest and wetland conservation, or stream and floodplain restoration.  Across the 10 watershed flowpaths, we synoptically surveyed over 300 total sampling sites along a combined stream length of 337 km. Results from synoptic surveys illustrated: (1) increasing, decreasing, stepwise, piecewise, and other trends in chemical concentrations with increasing distance downstream, which provide insights into water quality processes along flowpaths; (2) rates of downstream changes in chemical concentrations can be quantified along stream reaches in units such as increases or decreases in mg/L per km of stream length or upstream watershed area/forest cover/impervious surface cover, etc.; (3) downstream trends, transitions, and rates of changes in chemical mixtures tracked pollution sources and processes such as nutrient uptake, greenhouse gas production, and salt ion exchange; (4) nutrients, metals, and salts were often attenuated along hydrologic flowpaths, which extended into conservation and restoration areas with surrounding forests and wetlands.  Synoptic sketches outline emerging water quality patterns and their rates of changes with distance downstream that would not be discovered using only routine monitoring or random sampling.  A watershed synoptic sketch approach:  (1) reveals water quality trends and transitions across expanding spatial scales, land use and management, geology and hydrology; (2) accurately pinpoints ‘hot spots’ of pollution sources and sinks along watershed flowpaths; (3) evaluates effects of watershed management beyond stream reach scales; and (4) tracks rates of change per distance downstream in the sources, transport, and transformations of chemical cocktails en route to sensitive receiving waters including drinking water supplies and coastal zones.

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