Abstract. The hydrological and biogeochemical response of rivers carries information about solute sources, pathways, and transformations in the catchment. We investigate long-term water quality data of 11 Swiss catchments with the objective to discern the influence of major catchment characteristics and anthropic activities on delivery of solutes in stream water. Magnitude, trends, and seasonality of water quality samplings of different solutes are evaluated and compared across catchments. Subsequently, the empirical dependence between concentration and discharge is used to classify the solute behaviors. While the anthropogenic impacts are clearly detectable in the concentration of certain solutes (i.e., Na+, Cl−, NO3, DRP), the influence of single catchment characteristics such as geology (e.g., on Ca2+ and H4SiO4), topography (e.g., on DOC, TOC, and TP), and size (e.g., on DOC and TOC) is only sometimes visible, which is also because of the limited sample size and the spatial heterogeneity within catchments. Solute variability in time is generally smaller than discharge variability and the most significant trends in time are due to temporal variations of anthropogenic rather than natural forcing. The majority of solutes show dilution with increasing discharge, especially geogenic species, while sediment-bonded solutes (e.g., total phosphorous and organic carbon species) show higher concentrations with increasing discharge. Both natural and anthropogenic factors affect the biogeochemical response of streams, and, while the majority of solutes show identifiable behaviors in individual catchments, only a minority of behaviors can be generalized across the 11 catchments that exhibit different natural, climatic, and anthropogenic features.

Solutes in rivers often come from multiple sources, notably precipitation (above) and generation from the subsurface (below). The question of which source is more influential in shaping the dynamics of solute concentration cannot be easily addressed due to the general lack of input data. An analysis of solute concentrations and their dependence on discharge across 585 catchments in nine countries leads us to hypothesize that both the timing and the vertical distribution of the solute generation are important drivers of solute export dynamics at the catchment scale. We test this hypothesis running synthetic experiments with a tracer‐aided distributed hydrological model. The results reveal that the depth of solute generation is the most important control of the concentration‐discharge (C‐Q) relation for a number of solutes. Such relation shows that C‐Q patterns of solute export vary from dilution (Ca2+, Mg2+, K+, Na+, and Cl−) to weakly enriching (dissolved organic carbon). The timing of the input imposes a signature on temporal dynamics, most evident for nutrients, and adds uncertainty in the exponent of the C‐Q relation.

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Invasions of water bodies by floating vegetation, including water hyacinth (Eichhornia crassipes), are a huge global problem for fisheries, hydropower generation, and transportation. We analyzed floating plant coverage on 20 reservoirs across the world's tropics and subtropics, using [ 30 year time-series of LANDSAT remote-sensing imagery. Despite decades of costly weed control, floating invasion severity is increasing. Floating plant coverage correlates with expanding urban land cover in catchments, implicating urban nutrient sources as plausible drivers. Floating vegetation invasions have undeniable societal costs, but also provide benefits. Water hyacinths efficiently absorb nutrients from eutrophic waters, mitigating nutrient pollution problems. When washed up on shores, plants may become compost, increasing soil fertility. The biomass is increasingly used as a renewable biofuel. We propose a more nuanced perspective on these invasions moving away from futile eradication attempts towards an ecosystem management strategy that minimizes negative impacts while integrating potential social and environmental benefits. Keywords Biological invasions Á Dams Á Google earth engine Á Land cover change Á Urbanization Á Water-energy-food nexus Electronic supplementary material The online version of this article (

Scientific literature has mostly focused on the analysis of climate change impacts on hydropower operations, underrating the consequences of energy policies, for example, increase in Variable Renewable Sources (VRSs) and CO2 emission permit price, on hydropower productivity and profitability. We contribute a modeling framework to assess the impacts of different climate change and energy policies on the operations of hydropower reservoir systems in the Alps. Our approach is characterized by the following: (i) the use of a physically explicit hydrological model to assess future water availability; (ii) the consideration of electricity price scenarios obtained from an electricity market model accounting for the future projected European energy strategies; and (iii) the use of optimization techniques to design hydropower system operations in response to the projected changes. Through the application to the Mattmark system, a snow‐ and ice‐dominated hydropower system in Switzerland, we demonstrate how the framework is effective in exploring the sensitivity of Alpine hydropower to changes in water availability and electricity price, in quantifying the uncertainties associated to these projections and in identifying the value of reoperation strategies. Results show that energy policies may have more significant impacts on hydropower operations than climate change and, as such, are worth considering in impact assessments studies. The reduction of water availability due to climate change is expected to induce a loss in electricity production down to −27% by 2050. Changes in electricity price, instead, may have up to 6 times stronger impact than climate change, leading to an increase in hydropower revenue up to about +181%.