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Die Aire fliesst sèudlich von Genf durch eine Ebene, die von alters her landwirtschaftlich genutzt wird. Ab Ende des 19. Jahrhunderts wurde der Flusslauf zum Schutz vor Hochwassern nach und nach kanalisiert. 2001 fiel der Entscheid, dem Gewèasser wieder einen natèurlicheren Lauf zu geben. Diese Monografie dokumentiert die vielfach preisgekrèonte Renaturalisierung der Aire am Genfer Stadtrand. Projektskizzen, Fotografien von Bau und neuem Flussverlauf, Essays und Erklèarungen internationaler Autorinnen und Autoren zu den Interventionen zeigen, wie das Gewèasser wieder zu einem wichtigen Bestandteil der Landschaft aufgewertet wurde.

High levels of atmospheric deposition degrade forest ecosystems and cause ecological problems in streams. The amount of atmospheric deposition in Japan has decreased in recent years, but limited information on how stream water chemistry responds to this change is available. We analyzed historical atmospheric sulfur (S) and nitrogen (N) deposition data for Fukuoka City in western Japan from 1992 to 2021 and compared long-term (1986–2023) changes in stream water chemistry at 11 sampling points to evaluate stream water chemistry responses to atmospheric S and N deposition changes. Atmospheric S and N deposition in Fukuoka City increased from the 1990s to the mid-2000s and then decreased to the same as in the 1990s. The sulfate concentration in stream water was significantly lower in 2023 (105 μmol L−1) than 1986 (131 μmol L−1), reflecting changes in atmospheric S deposition. In contrast, the nitrate (NO3−) concentration in stream water was significantly higher in 2023 (107 μmol L−1) than in 1986 (83 μmol L−1) despite atmospheric N deposition decreasing. The calcium counterion concentration was also higher in 2023 (345 μmol L−1) than in 1986 (297 μmol L−1). Partial least squares regression analysis suggested that the NO3− concentration was related to the high percentage of area covered by Japanese cedar trees, which promote calcium leaching. We conclude that large areas of Japanese cedar plantations could attenuate the response of stream NO3− concentrations to the decreased atmospheric N deposition.

The study of water in the landscape is a new and rapidly expanding field. Dr Haslam examines how the quantity, function and ecology of water changes as it moves from watershed to river.

Purpose Life cycle assessment (LCA) distinguishes three types of water use: (1) consumptive water use, (2) degradative water use, and (3) in-stream water use. When it comes to assessing the impact of turbine water use (TWU, major source of in-stream water use) in LCA, so far, no method exists to quantify the related environmental impacts. Here, we developed the first midpoint characterization factors (CFs) with global coverage for turbine water use of storage and pumped storage hydropower power plants. Methods The midpoint CF at the basin scale describes the hydropower regulation potential (HRP) [HDOR·y] per TWU [m 3 ]. The HRP indicates the probability of how strongly the natural flow regime of a river is potentially affected by all upstream reservoir operation, calculated as the quotient between reservoir volume [m 3 ] and the annual river discharge [m 3 /y]. The hydropower degree of regulation (HDOR) thereby equals the unitless m 3 /m 3 fraction. The TWU depends on the electricity production [kWh] and the turbine efficiency [m 3 /kWh]. We tested the sensitivity of the input data on the calculated CFs for four parameters (discharge, turbine efficiency, multipurpose allocation, and plant type). Furthermore, we performed a case study to analyze if consumptive and TWU impacts of producing 1 kWh are correlated or not. Results and discussion The calculated CFs for the 342 basins vary from 1.13E-13 HDOR·y/m 3 to 3.28E10-7 HDOR·y/m 3 . The HDOR values range from 0.0015 to 16.66, and the TWU varies between 0.0030 km 3 and 2824 km 3 . A HDOR ≥ 0.02 can be interpreted as affected basin, and only 23 out of 342 basins have a HDOR below this threshold. This confirms that TWU of hydropower production can have important environmental impacts. The sensitivity analyses revealed that discharge and turbine efficiency are the most sensitive parameters because they are influencing almost all basins. The results of the case study showed that a high consumptive water-use impact does not automatically lead to a high TWU impact and vice versa ( R 2 values of 0.0081 and 0.003). Conclusion Our study highlights that it is important to account for the environmental impacts of in-stream water use in LCA, as otherwise, the environmental impact can be underestimated, which could lead to wrong conclusions. However, the CFs are not meant to replace a local risk assessment of hydropower reservoir operation and should only be used for relative comparison between basins. The CF application in LCA will represent a step forward towards more sustainable hydropower development.

In this study, we have considered the relationship between the spatial configuration of land use and water quality in the Three Gorges Reservoir Area. Using land use types, landscape metrics, and long-term water quality data, as well as statistical and spatial analysis, we determined that most water quality parameters were negatively correlated with non-wood forest and urban areas but were strongly positively correlated with the proportion of forest area. Landscape indices such as patch density, contagion, and the Shannon diversity index were able to predict some water quality indicators, but the mean shape index was not significantly related to the proportions of farmland and water in the study area. Regression relationships were stronger in spring and fall than in summer, and relationships with nitrogen were stronger than those of the other water quality parameters (R ² > 0.80) in all three seasons. Redundancy analysis showed that declining stream water quality was closely associated with configurations of urban, agricultural, and forest areas and with landscape fragmentation (PD) caused by urbanization and agricultural activities. Thus, a rational land use plan of adjusting the land use type, controlling landscape fragmentation, and increasing the proportion of forest area would help to achieve a healthier river ecosystem in the Three Gorges Reservoir Area (TGRA).

The land use and land cover changes in rapidly urbanized regions is one of the main causes of water quality deterioration. However, due to the heterogeneity of urban land use patterns and spatial scale effects, a clear understanding of the relationships between land use and water quality remains elusive. The primary purpose of this study is to investigate the effects of land use on water quality across multi scales in a rapidly urbanized region in Hangzhou City, China. The results showed that the response characteristics of stream water quality to land use were spatial scale-dependent. The total nitrogen (TN) was more closely related with land use at the circular buffer scale, whilst stronger correlations could be found between land use and algae biomass at the riparian buffer scales. Under the circular buffer scale, the forest and urban greenspace were more influential to the TN at small buffer scales, whilst significant positive or negative correlations could be found between the TN and the areas of industrial land or the wetland and river as the buffer scales increased. The redundancy analysis (RDA) showed that more than 40% variations in water quality could be explained by the landscape metrics at all circular and riparian buffer scales, and this suggests that land use pattern was an important factor influencing water quality. The variation in water quality explained by landscape metrics increased with the increase of buffer size, and this implies that land use pattern could have a closer correlation with water quality at larger spatial scales.

Determining the age distribution of water exiting a catchment is important for understanding groundwater storage and mixing. New water‐tagging capabilities within models track precipitation events as they move through simulated storages, yet forward modeling of individual events may not systematically capture the full transit time distribution (TTD). Here, we present a “sequential precipitation input tagging” (SPIT) framework to tag all input precipitation at regular intervals during extended model simulations. Monthly tags over 7 years were applied at six National Ecological Observatory Network sites to calculate TTDs and derive mean virtual tracer age, TV‾$\\overline{{T}_{V}}$ , fractions of young water, Fyw, and hydrologic tracer concentrations (water isotopes δ18O and δ2H) within a tagging enabled version of the Weather Research and Forecast hydrologic model (WRF‐Hydro). Throughout seven simulation years, the fraction of simulated discharge derived from tagged events, Ftag, increased each year, with the final year's Ftag ranging from 66% to 100% and highlights the need to apply SPIT over many years to understand TTDs. When the Ftag was >75%, simulated TV‾$\\overline{{T}_{V}}$ranged 179–923 days and Fyw 0.6%–23.9%, with daily values exhibiting a power‐law relationship with precipitation, discharge, and groundwater. Through implementation of SPIT, we find this hydrologic model configuration performs poorly in estimation of TV‾$\\overline{{T}_{V}}$and Fyw (root mean squared error of 469 days and 14.4% respectively), suggesting it misrepresents subsurface mixing. Thus, the SPIT framework provides a reproducible approach to calculate watershed transit times within tagging enabled models and thereby assess and improve representation of hydrologic processes. Plain Language Summary Understanding how long water stays underground before reaching rivers and streams is important for managing water resources. To study this, tracers are used within rivers and groundwater to help track the movement and age of water. We developed a new method to track precipitation in models as it moves through the environment over several years. By tagging monthly precipitation events, we can see how water flows through different layers of soil and groundwater before it exits as streamflow. Our method was applied at six different ecological research sites across the United States to study how water moves through these landscapes. We found that it can take anywhere from a few weeks to several years for precipitation to become part of the water flowing in rivers. Over time, more and more of the water in rivers comes from these tagged precipitation events, allowing us to better understand how long water is stored underground and how quickly it moves. This new tracking method provides a detailed picture of water movement and helps improve predictions about water availability in the future. It can be used in other locations to improve water management and protect vital water resources. Key Points A novel framework is developed to sequentially tag input precipitation and estimate water transit times and hydrologic tracers Framework is used in a hydrologic model and compared with observed stable water isotope data to assess correlations to model characteristics A substantial time (2–7+ years) needs to be tagged before tagged water significantly contributes to total discharge at six study sites

Low-order streams are important places for river formation and are highly vulnerable to changes in terrestrial ecosystems. Thus, the land-use/land-cover plays an important role in the maintenance of water quality. However, only land-use/land-cover composition may not explain the spatial variation in water quality, because it does not consider land-use/land-cover configuration and forest cover pattern. In this context, the study aimed to evaluate the forest cover pattern effects on water quality on low-order streams located in an agricultural landscape. Applying a paired watershed method, we selected two watersheds classified according to their morphometry and average slope to discard other physical factors that could influence the water quality. Land-use/land-cover pattern was analyzed for composition and forest cover configuration using landscape metrics, including the riparian zone composition. Water quality variables were obtained every two weeks during the hydrological year. This way, watersheds had similar morphometry, slope, and land-use/land-cover composition but differed in forest cover pattern. Watershed with more aggregated forest cover had a better water quality than the other one. The results show that forest cover contributes to water quality maintenance, while forest fragmentation influences the water quality negatively, especially in sediment retention. Agricultural practices are sources of sediment and nutrients to the river, especially in steep relief. Thus, in addition to land-use/land-cover composition, forest cover pattern must be considered in management of low-order streams in tropical agricultural watersheds.

The purpose of the study was to examine the storage and transport of NO3−${\\mathrm{N}\\mathrm{O}}_{3}^{-}$ions through snowpack, soils, and stream water in an acid‐sensitive alpine catchment (Tatra Mountains, Poland) during snowmelt and rain‐on‐snow events. Samples of snowpack layers, near‐surface soil horizons, and stream water were collected in the winter and snowmelt seasons of 2019. A laboratory experiment was conducted to determine the effect of temperature on the rate of soil nitrogen mineralization and nitrification. Our study has shown that snowpack is an important source of NO3−${\\mathrm{N}\\mathrm{O}}_{3}^{-}$ions in the catchment. As the snow melts, the release of NO3−${\\mathrm{N}\\mathrm{O}}_{3}^{-}$ions from snowpack occurs. A gradual and slow melting of snow starts even before the first snowmelt‐induced increase in stream discharge. NO3−${\\mathrm{N}\\mathrm{O}}_{3}^{-}$ions eluted from available snowpack are temporarily stored in soil, which is shown by a large increase in the concentration of water‐soluble NO3−${\\mathrm{N}\\mathrm{O}}_{3}^{-}$in the soil at that time. NO3−${\\mathrm{N}\\mathrm{O}}_{3}^{-}$ions are washed out of soils and supplied to streams during the first snowmelt event. This is demonstrated by a large increase in the stream water NO3−${\\mathrm{N}\\mathrm{O}}_{3}^{-}$concentration, termed an “NO3−${\\mathrm{N}\\mathrm{O}}_{3}^{-}$pulse.” The NO3−${\\mathrm{N}\\mathrm{O}}_{3}^{-}$ion is a key acid anion responsible for the acidification of the studied stream during snowmelt season, as the NO3−${\\mathrm{N}\\mathrm{O}}_{3}^{-}$pulse coincides with a decrease in bicarbonate alkalinity. Our field research and laboratory experiment have shown a minor role of mineralization and nitrification in NO3−${\\mathrm{N}\\mathrm{O}}_{3}^{-}$production in soils in the winter and NO3−${\\mathrm{N}\\mathrm{O}}_{3}^{-}$pulse formation in stream water during the early stages of the snowmelt season. Key Points NO3−${\\mathrm{N}\\mathrm{O}}_{3}^{-}$ions eluted from snowpack in winter are temporarily stored in soils; they are washed out of soils during the first snowmelt event Large supply of NO3−${\\mathrm{N}\\mathrm{O}}_{3}^{-}$at the beginning of snowmelt forms an NO3−${\\mathrm{N}\\mathrm{O}}_{3}^{-}$pulse in stream water which results in stream water acidification The mineralization and nitrification of organic nitrogen play a minor role in NO3−${\\mathrm{N}\\mathrm{O}}_{3}^{-}$production in soils in the winter season