Authors: C.R. Jackson, S. Wenger, B. Bledsoe, J.M. Shepherd, K. Capps, A. Rosemond, M. Paul, M. Welch-Devine, K. Li, T. Stephens and T. Rasmussen.

Abstract: Rapidly growing cities along the Interstate-85 corridor from Atlanta, GA, to Raleigh, NC, rely on small rivers for water supply and waste assimilation. These rivers share commonalities including water supply stress during droughts, seasonally low flows for wastewater dilution, increasing drought and precipitation extremes, downstream eutrophication issues, and high regional aquatic diversity. Further challenges include rapid growth; sprawl that exacerbates water quality and infrastructure issues; water infrastructure that spans numerous counties and municipalities; and large numbers of septic systems. Holistic multi-jurisdiction cooperative water resource planning along with policy and infrastructure modifications is necessary to adapt to population growth and climate. We propose six actions to improve water infrastructure resilience: increase water-use efficiency by municipal, industrial, agricultural, and thermoelectric power sectors; adopt indirect potable reuse or closed loop systems; allow for water sharing during droughts but regulate inter-basin transfers to protect aquatic ecosystems; increase nutrient recovery and reduce discharges of carbon and nutrients in effluents; employ green infrastructure and better stormwater management to reduce nonpoint pollutant loadings and mitigate urban heat island effects; and apply the CRIDA framework to incorporate climate and hydrologic uncertainty into water planning.

Authors: C. van Rees

Abstract: 21st-century water management is a complex environmental problem marked by burgeoning demand, shrinking supply, diminishing quality, growing risks from floods and droughts, and declining freshwater biodiversity. Tradeoffs between human and environmental water needs, including conflicting uses affecting local water quality and quantity, complicate the application of conventional biodiversity conservation approaches and may make them incompatible with local socioeconomic and cultural contexts. At the same time, new targets and guidance like the Kunming-Montreal post-2020 Global Biodiversity Framework call for increased stakeholder participation and methods for navigating complex water resources tradeoffs. Here, I introduce the term Human-Environment Water Conflict, which as an analytical lens may catalyze much-needed transdisciplinary synthesis and collaboration to simultaneously, and ideally synergistically, manage water resources and biodiversity in the Anthropocene. Advantages of this framework include (1) bridging top-down conservation prioritization approaches with bottom-up, locally relevant and negotiated methods for water management, (2) accelerating the implementation of important practices like e-flows, Other Effective area-based Conservation Measures (OECMs), and Nature-based Solutions, and (3) facilitating the inclusion of marginalized local and Indigenous communities by providing space and representation for their values and worldviews. The paper concludes with a demonstrative application of this analytical lens to the Sacramento-San Joaquin delta of California, the site of a recent high-profile example of Human-Environment Water Conflict. 

Authors: S. Tiegs, K. Capps, J. Schmidt, C. Patrick, J. Follstad Shah and C. Leroy.

Abstract: Rivers and streams contribute to global carbon cycling by decomposing immense quantities of terrestrial plant matter. However, decomposition rates are highly variable and large-scale patterns and drivers of this process remain poorly understood. Using a cellulose-based assay to reflect the primary constituent of plant detritus, we generated a predictive model (81% variance explained) for cellulose decomposition rates across 514 globally distributed streams. A large number of variables were important for predicting decomposition, highlighting the complexity of this process at the global scale. Predicted cellulose decomposition rates, when combined with genus-level litter quality attributes, explain published leaf litter decomposition rates with high accuracy (70% variance explained). Our global map provides estimates of rates across vast understudied areas of Earth and reveals rapid decomposition across continental-scale areas dominated by human activities.