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Changing suspended sediment in United States rivers and streams: linking sediment trends to changes in land use/cover, hydrology and climate

Between 1992 and 2012, concentrations of suspended sediment decreased at about 60 % of 137 US stream sites, with increases at only 17 % of sites. Sediment trends were primarily attributed to changes in land management, but streamflow changes also contributed to these trends at > 50 % of sites. At many sites, decreases in sediment occurred despite small-to-moderate increases in the amount of anthropogenic land use, suggesting sediment reduction activities across the US may be seeing some success.

Temperature controls production but hydrology regulates export of dissolved organic carbon at the catchment scale

Lateral carbon fluxes from terrestrial to aquatic systems remain central uncertainties in determining ecosystem carbon balance. This work explores how temperature and hydrology control production and export of dissolved organic carbon (DOC) at the catchment scale. Results illustrate the asynchrony of DOC production, controlled by temperature, and export, governed by flow paths; concentration–discharge relationships are determined by the relative contribution of shallow versus groundwater flow.

The millennium-old hydrogeology textbook The Extraction of Hidden Waters by the Persian mathematician and engineer Abubakr Mohammad Karaji (953 CE–1029 CE)

We revisit and shed light on the textbook The Extraction of Hidden Waters by the Persian mathematician and engineer Abubakr Mohammad Karaji. Ground-breaking ideas and descriptions of hydrological and hydrogeological perceptions such as components of the hydrological cycle, groundwater quality and driving factors for groundwater flow were presented in the book. We speculate that Karaji’s book is the first of its kind to provide a construction and maintenance manual for an engineering project.

Surface water as a cause of land degradation from dryland salinity

Secondary dryland salinity is a global land degradation issue. Our understanding of causal processes is adapted from wet and hydrologically connected landscapes and concludes that low end-of-catchment runoff indicates land clearing alters water balance in favour of increased infiltration and rising groundwater that bring salts to the surface causing salinity. This study shows surface flows play an important role in causing valley floor recharge and dryland salinity in low-gradient landscapes.

Global catchment modelling using World-Wide HYPE (WWH), open data, andstepwise parameter estimation

How far can we reach in predicting river flow globally, using integrated catchment modelling and open global data? For the first time, a catchment model was applied world-wide, covering the entire globe with a relatively high resolution. The results show that stepwise calibration provided better performance than traditional modelling of the globe. The study highlights that open data and models are crucial to advance hydrological sciences by sharing knowledge and enabling transparent evaluation.

Seasonal partitioning of precipitation between streamflow and evapotranspiration, inferred from end-member splitting analysis

Perhaps the oldest question in hydrology is “Where does water go when it rains?”. Here we present a new way to measure how the terrestrial water cycle partitions precipitation into its two ultimate fates: “green water” that is evaporated or transpired back to the atmosphere and “blue water” that is discharged to stream channels. Our analysis may help in gauging the vulnerability of both water resources and terrestrial ecosystems to changes in rainfall patterns.

Distinct stores and the routing of water in the deep critical zone of a snow-dominated volcanic catchment

This paper examines the influence of the subsurface structure on water routing, water residence times, and the hydrologic response of distinct groundwater stores and further investigates their contribution to streamflow. We conclude that deep groundwater from the fractured aquifer system, rather than shallow groundwater, is the dominant source of streamflow, which highlights the need to better characterize the deep subsurface of mountain systems using interdisciplinary studies such as this one.

Benchmarking the predictive capability of hydrological models for river flow and flood peak predictions across over 1000 catchments in Great Britain

We evaluated four hydrological model structures and their parameters on over 1100 catchments across Great Britain, considering modelling uncertainties. Models performed well for most catchments but failed in parts of Scotland and south-eastern England. Failures were often linked to inconsistencies in the water balance. This research shows what conceptual lumped models can achieve, gives insights into where and why these models may fail, and provides a benchmark of national modelling capability.

Global-scale human pressure evolution imprints on sustainability of river systems

A simple and effective index for the quantitative estimation of the evolution of human pressure on rivers at global scale is proposed. This index, based on nightlights and river discharge data, shows a significant increase from 1992 to 2013 worldwide. The most notable changes are found in river basins across Africa and Asia, where human pressure on rivers is growing markedly. This index identifies priority areas that can be targeted for the implementation of mitigation strategies and plans.

Summary and synthesis of Changing Cold Regions Network (CCRN) research in the interior of western Canada – Part 1: Projected climate and meteorology

This article examines future atmospheric-related phenomena across the interior of western Canada associated with abusiness-as-usualclimate scenario. Changes in large-scale atmospheric circulation and extent of warming vary with season, and these generally lead to increases, especially after mid-century, in factors associated with winter snowstorms, freezing rain, drought, forest fires, as well as atmospheric forcing of spring floods, although not necessarily summer convection.

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