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Abstract Seawater intrusion (SWI) affects coastal landscapes worldwide. Here we describe the hydrologic pathways through which SWI occurs ‐ over land via storm surge or tidal flooding, under land via groundwater transport, and through watersheds via natural and artificial surface water channels—and how human modifications to those pathways alter patterns of SWI. We present an approach to advance understanding of spatiotemporal patterns of salinization that integrates these hydrologic pathways, their interactions, and how humans modify them. We use examples across the East Coast of the United States that exemplify mechanisms of salinization that have been reported around the planet to illustrate how hydrologic connectivity and human modifications alter patterns of SWI. Finally, we suggest a path for advancing SWI science that includes (a) deploying standardized and well‐distributed sensor networks at local to global scales that intentionally track SWI fronts, (b) employing remote sensing and geospatial imaging techniques targeted at integrating above and belowground patterns of SWI, and (c) continuing to develop data analysis and model‐data fusion techniques to measure the extent, understand the effects, and predict the future of coastal salinization. 

A substantial increase in predictive capacity is needed to anticipate and mitigate the widespread change in ecosystems and their services in the face of climate and biodiversity crises. In this era of accelerating change, we cannot rely on historical patterns or focus primarily on long-term projections that extend decades into the future. In this Perspective, we discuss the potential of near-term (daily to decadal) iterative ecological forecasting to improve decision-making on actionable time frames. We summarize the current status of ecological forecasting and focus on how to scale up, build on lessons from weather forecasting, and take advantage of recent technological advances. We also highlight the need to focus on equity, workforce development, and broad cross-disciplinary and non-academic partnerships. 

A growing body of research focuses on climate change and Indigenous peoples. However, relatively little of this work focuses on Native American tribes living in the Atlantic Coastal Plain of the United States. The Lumbee Tribe of North Carolina is a large (60,000 member) Native American tribe located on the Coastal Plain in present day North Carolina (U.S.). The tribe has deep connections to the Lumbee River, which flows through a watershed dominated by extensive forested wetlands. In this paper, I outline key issues associated with climate change and water in the region, and I use long‐term climatic and hydrologic datasets and analysis to establish context for understanding historical climate change in the Lumbee River watershed. Downscaled climate model outputs for the region show how further changes may affect the hydrologic balance of the watershed. I discuss these changes in terms of environmental degradation and potential impacts on Lumbee culture and persistence, which has remained strong through centuries of adversity and has also experienced a resurgence in recent years. I close by acknowledging the especially vulnerable position of the Lumbee Tribe as a non‐federal tribe that lacks access to certain resources, statutory protections, and policies aimed at helping Native American tribes deal with climate change and other environmental challenges. 

Shallow groundwater responses to rainfall in forested headwaters can be highly variable, but their relative strengths of influences remain poorly understood. We investigated the roles of storms and landscape characteristics on short‐term, shallow groundwater responses to rainfall in forested headwater catchments. We used field observations of shallow groundwater combined with random forest modeling to identify the factors that affect shallow groundwater responses and the relative influences of key response drivers. We found that the rainfall thresholds required for groundwater responses were only met by the largest quartile of events, suggesting that most events contributed to unsaturated soil storage or were lost to evaporation. Significantly higher rainfall thresholds and longer response times for south facing catchments as opposed to north facing catchments highlighted the role of insolation in setting antecedent conditions that influenced the groundwater response. During storms, there were significantly larger increases in water table height in catchments dominated by coniferous forests compared to deciduous forests, indicating that local spatial characteristics of hillslopes could be more important factors for groundwater response than catchment wetness. The random‐forest analysis revealed that total rainfall amount had the greatest influence on most groundwater responses, but the relative influence of topography and local antecedent wetness was more pronounced as events progressed, indicating a shift in hydrological processes during different stages of the groundwater response. These results have implications for our understanding of runoff generation processes, including processes that determine hydrologic connectivity between stream and hillslopes. 

In the 1970s, Forest Service and academic researchers clearcut the forest in Watershed 7 in the Coweeta Basin to observe how far the perturbation would move the ecosystem and how quickly the ecosystem would return to its predisturbance state. Our long-term observations demonstrated that this view of resistance and resilience was too simplistic. Forest disturbance triggered a chain of ecological dynamics that are still evolving after 40 years. Short-term pulses in dissolved inorganic nitrogen (DIN) (3 years) and streamflows (4 years) were followed by several years in which the system appeared to be returning to predisturbance conditions. Then however, changes in forest composition triggered a regime change in DIN dynamics from biological to hydrological control as well as persistent high stream DIN levels mediated by climatic conditions. These forest composition changes also led to later reductions in streamflow. These long-term observations of streamflows, stream DIN concentrations, stream DIN exports, and stand composition have substantially advanced our understanding of forest ecosystem dynamics; and they demonstrate the value of long-term observational data in revealing ecosystem complexities and surprises, generating new hypotheses, and motivating mechanistic research. Shorter observational records from this experiment would have produced incomplete or erroneous inference.