Climate change and urbanization are key factors affecting the future of water quality in urbanized catchments. The work reported in this paper is an evaluation of the combined and relative impact of ...climate change and urbanization on the water quality of receiving water bodies in the context of a highly urbanized watershed served by a combined sewer system (CSS) in northern Italy. The impact is determined by an integrated modelling study involving two years of field campaigns. The results obtained from the case study show that impervious urban surfaces and rainfall intensity are significant predictors of combined sewer overflows (CSOs) and consequently of the water quality of the receiving water body. Scenarios for the year 2100 demonstrate that climate change combined with increasing urbanization is likely to lead to severe worsening of river water quality due to a doubling of the total phosphorus load from CSOs compared to the current load. Reduction in imperviousness was found to be a suitable strategy to adapt to these scenarios by limiting the construction of new impervious areas and decreasing the existing areas by only 15%. This information can be further utilized to develop future designs, which in turn should make these systems more resilient to future changes in climate and urbanization.
Display omitted
•Impervious surfaces and rainfall intensity are significant predictors of CSOs.•Urbanization and climate change impacts on surface water quality are addressed.•The coupled scenarios show a TP load from CSOs double than the current one.•Reduction of imperviousness is a suitable adaptation strategies for these scenarios.
The presence of SARS-CoV-2 in raw wastewaters has been demonstrated in many countries affected by this pandemic. Nevertheless, virus presence and infectivity in treated wastewaters, but also in the ...receiving water bodies are still poorly investigated. In this study, raw and treated samples from three wastewater treatment plants, and three river samples within the Milano Metropolitan Area, Italy, were surveyed for SARS-CoV-2 RNA detection by means of real time RT-PCR and infectivity test on culture cells. SARS-CoV-2 RNA was detected in raw, but not in treated wastewaters (four and two samples, respectively, sampled in two dates). The isolated virus genome was sequenced, and belonged to the strain most spread in Europe and similar to another found in the same region. RNA presence in raw wastewater samples decreased after eight days, probably following the epidemiological trend estimated for the area. Virus infectivity was always null, indicating the natural decay of viral pathogenicity in time from emission. Samples from receiving rivers (three sites, sampled in the same dates as wastewaters) showed in some cases a positivity to real time RT-PCR, probably due to non-treated, or inefficiently treated discharges, or to the combined sewage overflows. Nevertheless, also for rivers infectivity was null. Risks for public health should be limited, although a precautionary approach to risk assessment is here advocated, giving the preliminary nature of the presented data.
Display omitted
•SARS-CoV-2 RNA presence and infectivity in wastewaters and receptors was assessed.•Viral RNA was detectable in the inflow but not in the outflow wastewaters.•Viral RNA was present in receptors due to sewage overflows or inefficient treatment.•SARS-CoV-2 infectivity was null both in wastewaters and receptors.•A precautionary approach in the assessment of contagious risk is advocated.
The Paris Agreement presents new fields of research related to the adaptation strategies to climate change. A challenge for future research consists in developing context-specific guidelines to ...support adaptation. This Special Issue on “Adaptation strategy to climate change for water resources” is born in this context. It contains 15 scientific studies facing a diversity of issues inherent to the adaptation strategies for water resources. This editorial analyses how the authors of this collection of papers decided to develop and present their research in order to identify criteria to contribute defining, in a near future, standardized approaches and practices for adaptation studies. Papers have been categorized in two major fields: “Studies for the development of adaptation scenarios” and “Studies for the development of adaptation solutions”. Papers belonging to both categories are generally found missing to treat the ‘uncertainty’ issues arising and the implementation of the proposed adaptation strategies. Studies investigating future adaptation scenarios are generally found to be unbalanced in favor of the assessment of future impacts on water resources and less towards the provision of adaptation scenarios. When these studies do not provide elements to manage the specific uncertainty related to the proposed adaptation solutions, at least exploring the uncertainty related to the climatic and impact scenarios is strongly recommended. Studies providing methodological and/or procedural examinations on adaptation solutions are recommended to suitably report the climatic, environmental, and social context for which the action has been developed. A reduction of uncertainty and an easier implementation of proposed measures could be induced from this.
What are the main morphological factors that control the heterogeneous responses of debris-covered glaciers to climate change in the southern central Himalaya? A debate is open whether thinning rates ...on debris-covered glaciers are comparable to those of debris-free ones. Previous studies have adopted a deterministic approach, which is indispensable, but is also limiting in that only a few glaciers can be monitored. In this context, we propose a statistical analysis based on a wider glacier population as a complement to these deterministic studies. We analysed 28 glaciers situated on the southern slopes of Mt. Everest in the central southern Himalaya during the period 1992–2008. This study combined data compiled by three distinct studies for a common period and population of glaciers for use in a robust statistical analysis. Generally, surface gradient was the main morphological factor controlling the features and responses of the glaciers to climate change. In particular, the key points that emerged are as follows. 1) Reduced downstream surface gradient is responsible for increased glacier thinning. 2) The development of supraglacial ponds is a further controlling factor of glacier thinning: where supraglacial ponds develop, the glaciers register further surface lowering. 3) Debris coverage and thickness index were not found to be significantly responsible for the development of supraglacial ponds, changes in elevation, or shifts in snow line altitude.
•Downstream surface gradient is the main factor controlling changes in mass balance, surface, SLA, pond density.•Reduced downstream surface gradient is responsible for increased glacier thinning.•Where supraglacial ponds develop the glaciers register further glacier thinning.•Debris coverage and thickness were not found significantly responsible for changes in glacier elevation.
This study explores the link between area increase of Imja Tsho (Lake) and changes of Imja Glacier (area ~25km2) under the influence of climate change using multitemporal satellite imagery and local ...climate data. Between 1962 and 2013, Imja Lake expanded from 0.03±0.01 to 1.35±0.05 km2 at a rate of 0.026±0.001 km2 a-1. The mean glacier-wide flow velocity was 37±30ma-1 during 1992–93 and 23±15ma-1 during 2013–14, indicating a decreasing velocity. A mean elevation change of –1.29±0.71ma-1 was observed over the lower part of the glacier in the period 2001–14, with a rate of –1.06±0.63ma-1 in 2001–08 and –1.56±0.80ma-1 in 2008–14. We conclude that the decrease in flow velocity is mainly associated with reduced accumulation due to a decrease in precipitation during the last few decades. Furthermore, glacier ablation has increased due to increasing maximum temperatures during the post-monsoon months. Decreased glacier flow velocities and increased mass losses induce the formation and subsequent expansion of glacial lakes under favourable topographic conditions.
Until robust in situ sensors for total phosphorus (TP) are developed, continuous water quality measurements have the potential to be used as surrogates for generating high frequency estimates. Their ...use has widespread implications for water quality monitoring programmes considering that TP, in particular, is generally recognised as the limiting factor in the process of eutrophication. Surrogate measures for TP concentration, such as turbidity, have proved useful within natural and agricultural contexts, but their predictive capability for urban watersheds is considered more difficult, due to the different sources of TP, though a strict relationship with turbidity/suspended matter has been clearly described even for these environments. In this context, we investigated this still unresolved problem for high frequency estimation of TP concentration in urban environments by monitoring a medium-sized (71 km2) urban watershed (Lambro River watershed, north Italy) in which we detected 60 active combined sewer overflows, and an its natural sub-basin for comparison. We found two different relationships between turbidity and TP concentration in the investigated urban watershed that differently describe the prevalence of TP from point sources (domestic wastewaters) or diffuse origin (surface runoff). In this regard, we first characterise the prevailing sources of TP by using a marker for detecting domestic wastewater contamination (caffeine), then we describe the mutual relationships amongst the continuously monitored variables (in our case the occurrence of the First Flush and the clockwise turbidity/discharge hysteresis). Afterwards we discriminate, by observing variables that are continuously monitored (in our case, the discharge and the turbidity), amongst the continuous surrogate records according to their sources. In conclusion, we are able to apply the relevant turbidity/TP regression equations to each turbidity record and, thus, estimate the respective TP concentrations with high frequency. If traditional grab sampling techniques had been employed, the contributions of point sources (up to 34% across 237 monitored days) to the total estimated loads would not have been correctly evaluated, whilst the high frequency monitoring is able to catch the dynamics that occur over time scales of a few hours. We conclude that the reasonable uncertainty obtained in this study can be achieved in other urban watersheds, but further studies are required for watersheds of differing sizes and degrees of urbanisation.
•Turbidity is investigated as a means to provide high frequency estimates of TP in urban watershed.•We found two different relationship between turbidity and TP concentration in an urban watershed.•Caffeine can be used to discriminate between point and non-point sources of TP.•We used surrogate measurements for distinguishing the TP sources.
This article describes how the concept of Tourism Carrying Capacity (TCC) has shifted from a uni-dimensional approach to incorporating environmental, social and political aspects. This shift is ...demonstrated by a study of a large, internationally popular protected area used by trekkers, the Mt. Everest Region, where qualitative data collected from visitors was combined with environmental modeling using a participatory framework. Tourist satisfaction showed positive margins for further tourist industry expansion, but current environmental conditions limit growth and further development. Space and time dimensions were also considered. We observed that the limits on growth and further development can be manipulated, with a certain degree of flexibility, through investments and regulatory measures. We hypothesized that TCC can play an important role in the management of protected areas only if it is viewed as a systematic, strategic policy tool within a planning process rather than as a unique, intrinsic number that is not modifiable. We conclude that to translate the strategy into action using standard measures, further investigation is needed to balance the various TCC components as a part of a decision-making framework that includes the integration of different cultural approaches and policy needs.
•We examine both Social and Environmental Carrying Capacities in a protected area.•We contribute to revive the present debate on growth limits in tourist destinations.•Tourism Carrying Capacity is a multi-dimensional, systematic, strategic policy tool.•The growth limit can be modified by management policies.•A protected area could present multiple growth limits both temporally and spatially.
ABSTRACT
The South Asian summer monsoon brings abundant precipitation and associated latent heat release to the south of central Himalaya, and alters hydrothermal conditions of this region. This ...study explored the impact of South Asian summer monsoon on the elevation‐dependence of meteorological variables along the south slope of Mt. Everest in the central Himalaya, which is crucial to modelling the glacio‐hydrological processes in this elevated region. The data were collected at five stations deployed at 2660–5600 m above sea level (asl) along the slope during 2007–2011. Major findings are the following: (1) The amount of precipitation during the monsoon season usually decreases with elevation but it is relatively uniform between 3600 and 5000 m asl. This uniform profile may be attributed to the monsoon–terrain–land interactions, particularly to the retard effect of glacier cooling on daytime upvalley wind; (2) Cloud shielding effects cause lower solar radiation and higher downward longwave radiation in the monsoon than in the other seasons. In particular, higher elevations have more clouds in the afternoon, resulting in an abnormal elevation‐dependence of solar radiation (i.e. higher elevations receive less solar radiation); (3) Strong daytime upvalley wind and moist convection homogenizes the vertical distributions of air mass along the slope, causing a constant lapse rate of both surface air temperature and dew‐point temperature (representing humidity) during typical monsoon months, but this phenomenon is not found in the other seasons. These findings provide critical guidance for extrapolating the meteorological variables from lower to higher elevations in this region.
South Asian summer monsoon greatly affects the elevation‐dependence of meteorological variables along the steepest valley in the world (south of Mt. Everest). Strong daytime upvalley winds and deep convection during the monsoon season cause a uniform precipitation profile between 3500 and 5000 m above sea level, an abnormal elevation‐dependence of solar radiation (higher elevations receive less solar radiation), and a constant vertical gradient of near‐surface air temperature and dew‐point temperature.
Over the past two decades, we observed a substantial rise in ionic content that was mainly determined by the sulfate concentration at 20 remote high elevation lakes located in central southern ...Himalaya. At LCN9, which was monitored on an annual basis for the last 20 years, the sulfate concentrations increased over 4-fold. Among the main causes, we exclude a change in the composition of wet atmospheric deposition, as well as a possible influence of decrease in seasonal snow cover duration, which could have exposed larger basin surfaces to alteration processes. Glacier retreat likely was the main factor responsible for the observed increase of sulfate concentrations. We attribute this chemical changes mainly to the sulfide oxidation processes that occur in subglacial environments. Moreover, we observe that the weakened monsoon of the past two decades has only partially contributed to the lakes enrichment through runoff waters that are more concentrated in solutes or lowering the water table, resulting in more rock exposed to air and enhanced mineral oxidation.
The interaction of climate with aquatic ecosystems is a multidisciplinary field of research involving water quantity and quality issues and having strong socio-economic implications. This special ...issue hosts 10 studies undertaken in 7 countries of 4 continents: Asia, Africa, Europe, and North America. The issue provides a wide spectrum of natural and artificial case-studies and covers a broad range of climatic conditions. Most of the studies adopted a modelling (50%) or a field (40%) approach and focused on water-quantity (60%), while the remaining were equally subdivided between water-quality and biogeochemistry. Forty percent of the papers directly face climate change. The diversity of approaches and case studies is the main aspect characterizing this special issue. Despite this high diversification, in relation to water-quantity related issues, we can identify the following messages: high attention to extreme meteorological events, drought in particular, even in regions once considered rich in water (e.g., northern Italy); fragility of agricultural and water supply systems in the face of extreme weather events, in particular in low-income countries (e.g., Madagascar); more attention to climate change compared to land cover/use change but importance of natural land cover to efficiently face the incoming climate change, in particular, in agriculture ecosystems. From a water quality biogeochemistry point of view, we can point out: sensitivity of lakes to climate change with the risk of biodiversity loss; need to reduce nutrient loads to mitigate eutrophication related problems, exacerbated by climate change; in particular, reduction of nitrogen loads from agriculture run-off, to reduce N2O emissions in large-shallow Chinese environments.
PDF
