Long-term Surface Water Research Articles

The variability of surface water quality indicators in relation to watercourse typology, Czech Republic

This paper examines the relationships between watercourse typology and selected indicators of long-term surface water quality for rivers in the Czech Republic. The parameters used to define watercourse typology are in accord with the Water Framework Directive 2000/60/EC outlined by the European Commission. The relationships were tested using descriptive and multivariate statistical analysis, namely cluster analysis and canonical correspondence analysis. It was found that only some of the typological parameters have a close association with indicators of surface water quality. Specifically, the parameters of altitude and geology show clear relationships with pH, calcium content, and the saprobity index of macroinvertebrates. Conversely, parameters that are strongly influenced by anthropogenic pollution show weak relationships with indicators of surface water quality. These depend instead on the presence of pollution sources rather than on natural environmental conditions.

Hydrochloric Acid: An Overlooked Driver of Environmental Change

Research on the ecosystem impacts of acidifying pollutants, and measures to control them, has focused almost exclusively on sulfur (S) and nitrogen (N) compounds. Hydrochloric acid (HCl), although emitted by coal burning, has been overlooked as a driver of ecosystem change because most of it was considered to redeposit close to emission sources rather than in remote natural ecosystems. Despite receiving little regulatory attention, measures to reduce S emissions, and changes in energy supply, have led to a 95% reduction in United Kingdom HCl emissions within 20 years. Long-term precipitation, surface water, and soil solution data suggest that the near-disappearance of HCl from deposition could account for 30-40% of chemical recovery from acidification during this time, affecting both near-source and remote areas. Because HCl is highly mobile in reducing environments, it is a more potent acidifier of wetlands than S or N, and HCl may have been the major driver of past peatland acidification. Reduced HCl loadings could therefore have affected the peatland carbon cycle, contributing to increases in dissolved organic carbon leaching to surface waters. With many regions increasingly reliant on coal for power generation, HCl should be recognized as a potentially significant constituent of resulting emissions, with distinctive ecosystem impacts.

The Atmospheric Water Balance over the Semiarid Murray–Darling River Basin

Abstract The atmospheric water balance over the semiarid Murray–Darling River basin in southeast Australia is analyzed based on a consecutive series of 3- to 24-h NWP forecasts from the Australian Bureau of Meteorology’s Limited Area Prediction System (LAPS). Investigation of the LAPS atmospheric water balance, including comparison of the forecast precipitation to analyzed rain gauge observations, indicates that the LAPS forecasts capture the general qualitative features of the water balance. The key features of the atmospheric water balance over the Murray–Darling Basin are small atmospheric moisture flux divergence (at daily to annual time scales) and extended periods during which the atmospheric water balance terms are largely inactive, with the exception of evaporation, which is consistent and very large in summer. These features present unique challenges for NWP modeling. For example, the small moisture fluxes in the basin can easily be obscured by the systematic errors inherent in all NWP models. For the LAPS model forecasts, there is an unrealistically large evaporation excess over precipitation (associated with a positive bias in evaporation) and unexpected behavior in the moisture flux divergence. Two global reanalysis products (the NCEP Reanalysis I and the 40-yr ECMWF Re-Analysis) also both describe (physically unrealistic) long-term negative surface water budgets over the Murray–Darling Basin, suggesting that the surface water budget cannot be sensibly diagnosed based on output from current NWP models. Despite this shortcoming, numerical models are in general the most appropriate tool for examining the atmospheric water balance over the Murray–Darling Basin, as the atmospheric sounding network in Australia has extremely low coverage.

California's evolution toward integrated regional water management: a long-term view

Water resources sustainability hinges on interrelated physical, chemical, biological, and human processes, all of which may affect the quantity and quality of available water supplies. California's decades-long transition process from intensive and often unmanaged groundwater development toward more effective, sustainable integrated water resources management has resulted in important lessons. The process offers insights to other countries that seek to achieve sustainability. Long-term systematic groundwater and surface water monitoring programs and ongoing assessment of regional groundwater systems are an integral part of management. On local to global scales, the need for fundamental data, regional resources assessments, and increased support for scientific and technological advances is becoming increasingly apparent. The scientific community must enhance society's understanding of the essential links between basic data needs and the advancement and application of scientific approaches for effective water management. Correspondingly, scientific and political communities must coordinate common interests in endeavors toward sustainable management. Public outreach is a necessary complement to achieve sustainability goals and garner support for the programs needed to develop water policies based on sound science, manage water resources, and meet future water demands while avoiding unacceptable impacts.

Acidification trends in surface waters in the international program on acidification of rivers and lakes

We applied trend analyses to data from the International Cooperative Programme forAcidification of Rivers and Lakes in an attempt to discover regional patterns of long-term changesin surface water chemistry both in Europe and North America, and to relate these changes totrends in deposition. Decreases in surface water SO 3 - concentrations predominated at European sites in theFederal Republic of Germany, The Netherlands, and in Norway, and at the North American sitesin Ontario, Canada, the Adirondacks and Catskill Mountains of New York, U.S.A. Otherpredominating trends in the European sites were decreasing Ca2+ concentrations at many of thesites in The Netherlands, Norway, and Sweden. Increases in NO 3 - were observed at several sites in southern Norway, and in theAdirondack and Catskill regions of eastern New York. This, combined with an increasedoccurrence of declining base cation concentrations may well be responsible for the lack ofdocumented surface water recovery from acidification. Despite region-wide trends in severalvariables of importance in acidification, no correlations between surface water trends and changesin deposition were found using these data.