Global warming intensifies the hydrological cycle by altering the rate of water fluxes to and from the terrestrial surface, resulting in an increase in extreme precipitation events and longer dry spells. Prior hydrological intensification work has largely focused on precipitation without joint consideration of evaporative demand changes and how plants respond to these changes. Informed by state‐of‐the‐art climate models, we examine projected changes in hydrological intensification and its role in complicating water resources management using a framework that accounts for precipitation surplus and evaporative demand. Using a metric that combines the difference between daily precipitation and daily evaporative demand (surplus events) and consecutive days when evaporative demand exceeds precipitation (deficit time), we show that, globally, surplus events will become larger (+11.5% and +18.5% for moderate and high emission scenarios, respectively) and the duration between them longer (+5.1%; +9.6%) by the end of the century, with the largest changes in the northern latitudes. The intra‐annual occurrence of these extremes will stress existing water management infrastructure in major river basins, where over one third of years during 2070–2100 under a moderate emissions scenario will be hydrologically intense (large intra‐annual increases in surplus intensity and deficit time), tripling that of the historical baseline. Larger increases in hydrologically intense years are found in basins with large reservoir capacity (e.g., Amazon, Congo, and Danube River Basins), which have significant populations, irrigate considerable farmland, and support threatened and endangered aquatic species. Incorporating flexibility into water resource infrastructure and management will be paramount with continued hydrological intensification.

Rain-on-snow (ROS) melt events reduce the amount of water stored in the snowpack while also exacerbating flooding. The hydrologic implications of changing ROS events in a warming climate, however, are still uncertain. This research used a calibrated and validated Soil and Water Assessment Tool (SWAT) hydrologic model, modified with energy budget equations to simulate ROS melt and forced with a climate model ensemble representing moderate greenhouse gas concentrations, to simulate changes to ROS melt in the North American Great Lakes Basin from 1960–2069. The changes to ROS events between the historic period (1960–1999) and mid-century (2040–2069) represent an approximately 30 % reduction in melt in warmer, southern subbasins but less than 5 % reduction in melt in colder, northern subbasins. Additionally, proportionally more rainfall reduces the formation of snowpacks, with area-weighted combined winter and spring rain-to-snow ratios rising from approximately 1.5 historically to 1.9 by the mid-21st century. Areas with historic mean combined winter and spring air temperatures lower than −2 ^∘C have ROS regimes that are resilient to mid-21st century warming projections, but ROS occurrence in areas that have mean combined winter and spring temperatures near the freezing point are sensitive to changing air temperatures. Also, relationships between changes in the timing of ROS melt and water yield endure throughout spring but become weak by summer. As the influence of ROS melt events on hydrological systems is being altered in a changing climate, these conclusions are important to inform adaptive management of freshwater ecosystems and human uses in regions of the globe that are sensitive to changes in ROS events.

Streambank erosion is difficult to quantify; models and field methods are needed to assess this important sediment source to streams. Our objectives were to (1) evaluate and compare three techniques for quantifying streambank erosion: erosion pins, total station, and laser scanning, (2) spatially assess streambank erosion rates in the Indian Mill Creek watershed of Michigan, USA, and (3) relate results with modeling of nonpoint source pollution. We found large absolute and relative errors between the different measurement techniques. However, we were unable to determine any statistically significant differences between techniques and only observed a correlation between total station and laser scanner. This suggests that the three methods have limited comparability and differences between measurements were largely not systemic. Further, the application of each technique should be dependent on site conditions, project goals, desired resolution, and resources. The laser scanner collected high-resolution data on clear, barren streambanks, but the erosion pin and total station were more representative of complex vegetated banks. Streambank erosion rates varied throughout the watershed and were influenced by fluvial processes. We estimate that streambank erosion contributed 28.5% of the creek’s total sediment load. These findings are important to address sources of watershed impairments related to sedimentation, as choosing an applicable technique for individual purposes can help reduce the challenges and costs of a streambank erosion study.

Most readily available land use/land cover (LULC) data are developed using growing season remote sensing images often at annual time steps, but seasonal changes in remote sensing data can lead to inconsistencies in LULC classification, which could impact geospatial models based on LULC. We used the Dynamic World near-real-time global LULC dataset to compare how geospatial environmental models of water quality and hydrology respond to LULC estimated from growing vs. non-growing season data for temperate watersheds of the eastern United States. Non-growing season data resulted in LULC classifications that had more built area and less tree cover than growing season data due to seasonal impacts on classifications rather than actual LULC changes (e.g., quick construction or succession). In mixed-LULC watersheds, seasonal LULC classification inconsistencies could lead to differences in model outputs depending on the LULC season used, such as differences in watershed nitrogen yields simulated by the Soil and Water Assessment Tool. Within reason, using separate calibration for each season may compensate for these inconsistencies but lead to different model parameter optimizations. Our findings provide guidelines on the use of near-real-time and high-temporal-resolution LULC in geospatial models.

The 2021 emergence of the 17‐year Brood X cicadas (Magicicada septendecim,M. cassinii, andM. septendecula) saw billions of cicadas emerge from the soil throughout the midwestern and eastern United States. The emergence left connected burrows visible at the surface, which are hypothesized to affect near surface hydrologic processes. To investigate these processes, we used single‐ring, dual head infiltrometers to measure field saturated hydraulic conductivity (K_fs,n = 70) across patterns of emergence and land use in south‐central Indiana, USA. Our experimental design included locations with and without cicada burrows in forested (undisturbed) and urbanized (disturbed) areas. Across undisturbed sites, we found a significant 80.8% increase inK_fsbetween soils with (median = 14.1 cm/h;n = 20) and without (median = 7.8 cm/h;n = 20) cicada burrows. At disturbed sites, we found no significant difference inK_fsbetween sites with (median = 4.2 cm/h;n = 18) and without (median = 4.4 cm/h;n = 12) cicada burrows. We found a significant correlation between the number of burrows present at the surface andK_fsrates for undisturbed sites ( = 0.42;p = 0.008), while no correlation was found for the disturbed sites ( = −0.09;p = 0.62). Our measurements suggest that the effect of burrows onK_fsis minimized in urbanized areas, potentially due to compaction and other impacts from human disturbance that mitigate the presence of macropores left by cicadas. In contrast, surface‐connected macroporosity from Brood X cicada burrows in undisturbed areas act as a conduit for precipitation into the soil profile and bypass flow into deeper horizons and the shallow groundwater table, with implications for runoff dynamics, soil and groundwater recharge and quality, and nutrient cycling.