Controls on the chemistry of runoff from an upland peat catchment

This study uses 2 years of data from a detailed weekly water sampling programme in a 11·4 km² upland peat catchment in the Northern Pennines, UK. The sampling comprised precipitation, soil‐water samples and a number of streams, including the basin outlet. Samples were analysed for: pH, conductivity, alkalinity, Na, K, Ca, Mg, Fe, Al, Total N, SO₄, Cl and colour. Principal component analysis (PCA) was used to identify end‐members and compositional trends in order to identify controls on the development of water composition. The study showed that the direct use of PCA had several advantages over the use of end‐member mixing analysis (EMMA) as it combines an analysis of mixing and evolving waters without the assumption of having to know the compositional sources of the water. In its application to an upland peat catchment, the study supports the view that shallow throughflow at the catotelm/acrotelm boundary is responsible for storm runoff generation and shows that baseflow is controlled by cation exchange in the catotelm and mixing with a base‐rich groundwater. Copyright © 2003 John Wiley & Sons, Ltd.     

The Effects of Climate Change on Water Resources in the West: Introduction and Overview

The results of an experimental `end to end' assessment of the effects of climate change on water resources in the western United States are described. The assessment focuses on the potential effects of climate change over the first half of the 21st century on the Columbia, Sacramento/San Joaquin, and Colorado river basins. The paper describes the methodology used for the assessment, and it summarizes the principal findings of the study. The strengths and weaknesses of this study are discussed, and suggestions are made for improving future climate change assessments.     

Watershed structural influences on the distributions of stream network water and solute travel times under baseflow conditions

Watershed structure influences the timing, magnitude, and spatial location of water and solute entry to stream networks. In turn, stream reach transport velocities and stream network geometry (travel distances) further influence the timing of export from watersheds. Here, we examine how watershed and stream network organization can affect travel times of water from delivery to the stream network to arrival at the watershed outlet. We analysed watershed structure and network geometry and quantified the relationship between stream discharge and solute velocity across six study watersheds (11.4 to 62.8 km²) located in the Sawtooth Mountains of central Idaho, USA. Based on these analyses, we developed stream network travel time functions for each watershed. We found that watershed structure, stream network geometry, and the variable magnitude of inputs across the network can have a pronounced affect on water travel distances and velocities within a stream network. Accordingly, a sample taken at the watershed outlet is composed of water and solutes sourced from across the watershed that experienced a range of travel times in the stream network. We suggest that understanding and quantifying stream network travel time distributions are valuable for deconvolving signals observed at watershed outlets into their spatial and temporal sources, and separating terrestrial and in‐channel hydrological, biogeochemical, and ecological influences on in‐stream observations. Copyright © 2016 John Wiley & Sons, Ltd.     

Scale impacts on spatial variability in reference evapotranspiration

ABSTRACT

Evapotranspiration (ET) is one of the most important components in the hydrological cycle, and a key variable in hydrological modelling and water resources management. However, understanding the impacts of spatial variability in ET and the appropriate scale at which ET data should be incorporated into hydrological models, particularly at the regional scale, is often overlooked. This is in contrast to dealing with the spatial variability in rainfall data where existing guidance is widely available. This paper assesses the impacts of scale on the estimation of reference ET (ETo) by comparing data from individual weather stations against values derived from three national datasets, at varying resolutions. These include the UK Climate Impacts Programme 50 km climatology (UKCP₅₀), the UK Met Office 5 km climatology (UKMO₅) and the regional values published in the Agricultural Climate of England and Wales (ACEW). The national datasets were compared against the individual weather station data and the UKMO₅ was shown to provide the best estimate of ETo at a given site. The potential impacts on catchment modelling were then considered by mapping variance in ETo to show how geographical location and catchment size can have a major impact, with small lowland catchments having much higher variance than those with much larger areas or in the uplands. Some important implications for catchment hydrological modelling are highlighted.

Editor D. Koutsoyiannis; Associate editor L. Ruiz     

Another Year of Record Heat for the Oceans

Changes in ocean heat content(OHC), salinity, and stratification provide critical indicators for changes in Earth’s energy and water cycles. These cycles have been profoundly altered due to the emission of greenhouse gasses and other anthropogenic substances by human activities, driving pervasive changes in Earth’s climate system. In 2022, the world’s oceans, as given by OHC, were again the hottest in the historical record and exceeded the previous 2021 record maximum.According to IAP/CAS data, ...     

Time series analysis of the world's longest fluvial nitrate record: evidence for changing states of catchment saturation

Processes that drive the occurrence of nitrate concentrations in surface waters are known to operate over many decades longer than the available observations. This study considers the world's longest water quality record of nitrate concentrations in the River Thames (1868–2009) in order to understand whether the nature of the time series has changed with time and such external drivers as climate change and land use of hydrology. The study considers the linear trend, the seasonality, the memory and the impulsivity relative to river flow of the time series for moving windows of 6 years in length. The study can show that:

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Introduction: Interaction between environment and fisheries—The role of stakeholder participation

This paper is an introduction to the special issue on a role of participation in dealing with the interactions between environment and fisheries. In this introduction, we explore the recent discussion on the ecosystem-based approach to fisheries management (EBAFM) and extract important points for implementation of EBAFM from the social science literature on participation and participatory processes in environmental management. The introduction finishes by describing the analytical framework for studying participatory processes.