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Natural water treatment systems have long been recognized as sources of ancillary benefits in the form of cultural ecosystem services. To date, there is a lack of quantitative understanding of the extent and welfare impact of such benefits. This paper investigates 166 natural treatment systems worldwide and provides the first quantitative assessment of their recreational and educational benefits. The public use is highly influenced by the type of recreational activities, presence of recreational and educational facilities, and accessibility of the systems. Using value transfer techniques, we estimate the mean and median monetary values of recreational benefits in 8397 and 530 €/ha/year, respectively. We compare such value flows with operation and management costs and other ecosystem services provided by these systems. [ABSTRACT FROM AUTHOR]

Abstract: Shading by riparian vegetation affects incident solar radiation and water temperature in small- and moderate-size streams, and is thus an important component in the influence of forested riparian buffers on streams. The water quality effects of riparian shading are largely unknown. A simulation study was carried out to evaluate the effect of shading on six water quality variables in a moderate-size Belgian river stretch. A dynamic modelling approach making use of the River Water Quality Model No. 1 was chosen to represent the system. The scenarios developed indicate that shading may be an effective tool in controlling stream eutrophication (44% reduction in phytoplankton productivity in the simulated stretch) but has a limited effect on dissolved oxygen, chemical oxygen demand, nitrates, ammonium nitrogen, and phosphates. Results suggest that shading can effectively be implemented as a direct management strategy to improve water quality conditions in small and moderate-size watercourses that are exposed to excessive algal growth during summer periods. [Copyright &y& Elsevier]