Impact of climate change and water use policies on hydropower potential in the south-eastern Alpine region

Techno-ecological synergies of hydropower plants: Insights from GHG mitigation

Hydropower is a source of climate-friendly energy; however, its ecological impacts have been criticized. Few studies have considered the greenhouse gas (GHG) emissions resulting from ecosystem restoration. This study proposes a techno-ecological synergy framework based on life cycle assessment (LCA) to evaluate 34 hydropower plants (HPs) in the upper reaches of the Yangtze River from GHG supply and demand side perspectives. Our results show that the demand unit carbon footprint of the 34 HPs ranged from 5.43 to 49.36 g CO₂-eq/kWh, while the imputed GHG emissions from ecosystem restoration occupied 1.22 % to 30.35 %. The unit carbon footprint of large HPs were larger than those of small HPs, and both were positively correlated with the installed capacity of the HPs. All the HPs were unsustainable at the local scale and relied on regional ecosystem supplies. The Sobol' sensitivity analysis and Monte Carlo simulations demonstrated the reliability of our results. Finally, our results were used to consider the related policy implications.

Directions and Extent of Flows Changes in Warta River Basin (Poland) in the Context of the Efficiency of Run-of-River Hydropower Plants and the Perspectives for Their Future Development

This paper presents changes in the flow of 14 rivers located in the Warta River basin, recorded from 1951 to 2020. The Warta is the third-longest river in Poland. Unfortunately, the Warta River catchment area is one of the most water-scarce regions. It hosts about 150 hydropower plants with a capacity of up to 5 kW. The catchment areas of the 14 smaller rivers selected for the study differ in location, size, land cover structure and geological structure. The paper is the first study of this type with respect to both the number of analyzed catchments, the length of the sampling series and the number of analyzed flow characteristics in this part of Europe. The analysis of changes in the river flows was performed with reference to low minimum, mean and maximum monthly, seasonal and annual flows. Particular attention was paid to 1, 3, 7, 30 and 90-day low flows and durations of the flows between Q50 and Q90%. In addition, the duration of flows between Q50 and Q90% were analysed. Analysis of the direction and extent of particular flow types was performed by multitemporal analysis using the Mann–Kendall (MK) and Sen (S) tests. The analysis of multiannual flow sequences from the years 1951–2020 showed that the changes varied over the time periods and catchments. The most significant changes occurred in the low flows, while the least significant changes occurred in the high flows. From the point of view of the operation of the hydropower sector, these changes may be unfavourable and result in a reduction in the efficiency of run-of-river hydropower plants. It was established that local factors play a dominant role in the shaping of river flows in both positive and negative terms, for the efficiency of the hydropower plants.

Projected hydrologic changes over the north of the Iberian Peninsula using a Euro-CORDEX multi-model ensemble

This study explores the impacts of climate change on the hydrology of the headwater areas of the Duero River Basin, the largest basin of the Iberian Peninsula. To this end, an ensemble of 18 Euro-CORDEX model experiments was gathered for two periods, 1975-2005 and 2021-2100, under two Representative Concentration Pathways (RCP4.5 and RCP8.5), and were used as the meteorological forcings of the Variable Infiltration Capacity (VIC) during the hydrological modelling exercise. The projected hydrologic changes for the future period were analyzed at annual and seasonal scales using several evaluation metrics, such as the delta changes of the atmospheric and land variables, the runoff and evapotranspiration ratios of the overall water balance, the snowmelt contribution to the total streamflow and the centroid position for the daily hydrograph of the average hydrologic year. Annual streamflow reductions of up to 40% were attained in various parts of the basin for the period 2071-2100 under the RCP8.5 scenario, and resulted from the precipitation decreases in the southern subwatersheds and the combined effect of the precipitation decreases and evapotranspiration increases in the north. The runoff and the evapotranspiration ratios evinced a tendency towards an evaporative regime in the north part of the basin and a strengthening of the evaporative response in the south. Seasonal streamflow changes were mostly negative and dependent on the season considered, with greater detriments in spring and summer, and less intense ones in autumn and winter. The snowmelt contribution to the total streamflow was strongly diminished with decreases reaching -80% in autumn and spring, thus pointing to a change in the snow regime for the Duero mountains. Finally, the annual and seasonal changes of the centroid position accounted for the shape changes of the hydrograph, constituting a measure of seasonality and reflecting high correlations degrees with the streamflow delta changes.

Machine Learning-Based Small Hydropower Potential Prediction under Climate Change

As the effects of climate change are becoming severe, countries need to substantially reduce carbon emissions. Small hydropower (SHP) can be a useful renewable energy source with a high energy density for the reduction of carbon emission. Therefore, it is necessary to revitalize the development of SHP to expand the use of renewable energy. To efficiently plan and utilize this energy source, there is a need to assess the future SHP potential based on an accurate runoff prediction. In this study, the future SHP potential was predicted using a climate change scenario and an artificial neural network model. The runoff was simulated accurately, and the applicability of an artificial neural network to the runoff prediction was confirmed. The results showed that the total amount of SHP potential in the future will generally a decrease compared to the past. This result is applicable as base data for planning future energy supplies and carbon emission reductions.

Analysis of Small Hydropower Generation Potential: (2) Future Prospect of the Potential under Climate Change

The interest in renewable energy to replace fossil fuel is increasing as the problem caused by climate change has become more severe. In this study, small hydropower (SHP) was evaluated as a resource with high development value because of its high energy density compared to other renewable energy sources. SHP may be an attractive and sustainable power generation environmental perspective because of its potential to be found in small rivers and streams. The power generation potential could be estimated based on the discharge in the river basin. Since the river discharge depends on the climate conditions, the hydropower generation potential changes sensitively according to climate variability. Therefore, it is necessary to analyze the SHP potential in consideration of future climate change. In this study, the future prospect of SHP potential is simulated for the period of 2021 to 2100 considering the climate change in three hydropower plants of Deoksong, Hanseok, and Socheon stations, Korea. The results show that SHP potential for the near future (2021 to 2040) shows a tendency to be increased, and the highest increase is 23.4% at the Deoksong SPH plant. Through the result of future prospect, we have shown that hydroelectric power generation capacity or SHP potential will be increased in the future. Therefore, we believe that it is necessary to revitalize the development of SHP to expand the use of renewable energy. In addition, a methodology presented in this study could be used for the future prospect of the SHP potential.

Priority and emerging organic microcontaminants in three Mediterranean river basins: Occurrence, spatial distribution, and identification of river basin specific pollutants

There is a worldwide growing use of chemicals by our developed, industrialized, and technological society. More than 100,000 chemical substances are thus commonly used both by industry and households. Depending on the amount produced, physical-chemical properties, and mode of use, many of them may reach the environment and, notably, the aquatic receiving systems. This may result in undesirable and harmful side-effects on both the human and the ecosystem's health. Mediterranean rivers are largely different from Northern and Central European rivers in terms of hydrological regime, climate conditions (e.g. air temperature, solar irradiation, precipitation), and socio-economics (e.g. land use, tourism, crop types, etc.), with all these factors leading to differences in the relative importance of the environmental stressors, in the classes and levels of the pollutants found and their environmental fate. Furthermore, water scarcity might be critical in affecting water pollution because of the lowered dilution capacity of chemicals. This work provides raw chemical data from different families of microcontaminants identified in three selected Mediterranean rivers (the Sava, Evrotas, and Adige) collected during two sampling campaigns conducted in 2014 and 2015 in three different matrices, namely, water, sediments, and biota (fish). More than 200 organic micropollutants were analyzed, including relevant groups like pharmaceuticals, personal care products, perfluorinated compounds, pesticides, pyrethroid insecticides, flame retardants, and persistent organic pollutants. Data obtained were summarized with some basic statistics for all compound families and matrices analyzed. Observed occurrence and spatial patterns were interpreted both in terms of compound physical-chemical properties and local environmental pressures. Finally, their spatial distribution was examined and their ecotoxicological risk in the water phase was assessed. This allowed locating, at each basin, the most polluted sites ("hot spots") and identifying the respective river basin specific pollutants (RBSPs), prioritizing them in terms of the potential ecotoxicological risk posed to the aquatic ecosystems.

Long-Term Changes of Morphodynamics on Little Ice Age Lateral Moraines and the Resulting Sediment Transfer into Mountain Streams in the Upper Kauner Valley, Austria

Since the end of the Little Ice Age (LIA), formerly glaciated areas have undergone considerable changes in their morphodynamics due to external forces and system-internal dynamics. Using multi-temporal high-resolution digital elevation models (DEMs) from different remote sensing techniques such as historical digital aerial images and light detection and ranging (LiDAR), and the resulting DEMs of difference (DoD), spatial erosion and accumulation patterns can be analyzed in proglacial areas over several decades. In this study, several morphological sediment budgets of different test sites on lateral moraines and different long-term periods were determined, covering a total period of 49 years. The test sites show high ongoing morphodynamics, and therefore low vegetation development. A decrease as well as an increase of the mean annual erosion volume could be demonstrated at the different test sites. All test sites show a slope–channel coupling and a decrease in the efficiency of sediment transport from slopes to channels. These developments are generally subject to conditions of increasing temperature, decreasing short-term precipitation patterns and increasing runoff from adjacent mountain streams. Finally, the study shows that sediment is still available on the investigated test sites and the paraglacial adjustment process is still in progress even after several decades of deglaciation (~133 years).

Understanding the Hydropower and Potential Climate Change Impact on the Himalayan River Regimes—A Study of Local Perceptions and Responses from Himachal Pradesh, India

The Himalayas have become synonymous with the hydropower developments for larger electricity demands of India’s energy sector. In the Himachal Himalayas though, there are only three large storage dams with more than 1000 megawatts (hereafter MW) capacity that have very serious environmental issues. However, hundreds of small runoff-river hydropower plants across the Himachal Himalayas are a serious threat to the river regimes and Himalayan biota. There are 965 identified hydropower projects (hereafter HPPs) having a potential capacity of 27,436 MW in the Himachal Pradesh as of December 2019 as per the Directorate of Energy of the state. Out of the 965 identified, 216 are commissioned, including less than 5 MW plants, with an installed capacity of 10,596 MW, and were operational by December 2019. Only 58 projects are under construction among the identified with an installed capacity of 2351 MW, 640 projects are in various stages of clearance and investigation with an installed capacity 9260 MW, 30 projects are to be allotted with 1304 MW installed capacity, and merely four projects are disputed/cancelled with installed capacity of 50.50 MW. The large number of HPPs are sanctioned without proper consideration of negative environmental and geohazard impacts on the Himalayan terrestrial biota. In this work, our focus was on the hydropower and climate change impact on the Himalayan river regimes of the Chenab, the Ravi, the Beas, the Satluj, and the Yamuna river basins. We analyzed basin-wise rainfall, temperature, and soil moisture data from 1955 to 2019 to see the trend by applying the Mann–Kendall test, the linear regression model, and Sen’s slope test. A basin-wise hazard zonation map has been drawn to assess the disaster vulnerability, and 12 hydropower sites have been covered through the primary survey for first-hand information of local perceptions and responses owing to hydropower plants.

Impacts of climate change on reservoir water availability, quality and irrigation needs in a water scarce Mediterranean region (southern Portugal)

Future climate for the Mediterranean climatic region is expected to bring an increase in temperatures, decrease in the precipitation quantity and shifts in the seasonal precipitation pattern. Although the impacts of climate change on water resources have been relatively well explored for the Mediterranean climatic region, the specific consequences for reservoirs and, in particular, water availability and irrigation issues have been less studied. The objective of this work is two-fold: (i) to assess the impacts of future climate changes on water resources availability, quality (focusing on phosphorus loads as this is the limiting nutrient for eutrophication) and irrigation needs for two multipurpose reservoirs in southern Portugal; (ii) to suggest climate change adaptation strategies, especially for the agricultural sector. To this end, the SWAT model was first calibrated against existing data on reservoir inflows as well as phosphorus loads. Then, SWAT was run with climate derived EURO-CORDEX models (RCA4/RACMO22E) for four periods (1970-2000, 2010-2040, 2040-2070 and 2070-2100). Water availability was analysed using the Water Exploitation Index (WEI) that was calculated for both reservoirs combining changes of inflows and irrigation requirements. The results indicated that climate change will negatively impact water availability in both reservoirs, especially under RCP8.5. In the case of the Monte Novo reservoir, future domestic water supply could be constrained by water quality problems related with phosphorus loads. For Vigia reservoir, the high water exploitation will lead to water scarcity problems, mainly as this reservoir on present-day conditions is restrictive on irrigation requirements. Adaptation strategies such as the implementation of high end technology (e.g. soil moisture and plant water stress probes, satellite imagery and drones to evaluate water stress - NDVI) as well as the renewal of the irrigation network and adequate crop selection can help attenuating the effects of climate change on the water resources in this region.

Headwaters’ Isotopic Signature as a Tracer of Stream Origins and Climatic Anomalies: Evidence from the Italian Alps in Summer 2018

Glaciers are shrinking due to global warming, resulting in a diminishing contribution of ice and snowmelt to headwaters and subsequent consequences to freshwater ecosystems. Within this context, we tested whether water-stable isotopes are spatio-temporal tracers of (i) water in high altitude periglacial environments, being the isotopic signature of surface water inherited from the snow/icemelt, groundwater, and rainfall; and (ii) regional (year-specific) meteorological conditions, being the isotopic signature of precipitations affected by air temperature, humidity and aqueous vapour origin, ascribing stable isotopes to the list of “essential climate variables″ (ECVs). To this end, we investigated the ionic and isotopic composition (δ18O and δ2H) of six high-altitude streams and one pond in the Italian Alps (Noce and Sarca basins) during the ablation season in 2018. Differences between habitat types (pond, kryal, rhithral, krenal) were detected. More negative values of δ18O and δ2H were recorded in the kryal and glacio-rhithral sites, dominated by ice and snowmelt, in early summer. Less negative values were recorded in these sites in late summer, as well as in the krenal sites, which were dominated by groundwater and rainfall inputs. The isotopic results also show that the complex alpine orography influences air masses and moisture, ultimately resulting in isotopic differences in the precipitations of neighboring but distinct catchments (Sarca and Noce basins). On average, less negative values were recorded in the Sarca basin, characterized by a higher contribution of precipitation of Mediterranean origin. In general, isotopic results of the entire water population appeared to be strongly influenced by the regional climatic anomaly of 2018, which was anomalously warm. Therefore, the study will provide additional information for the climate change debate, proposing water isotopes as ECVs for assessing change in a warmer future.

Convenient use of electrical conductivity measurements to investigate hydrological processes in Alpine headwaters

Developing effective hydrological models for streamflow generation in Alpine catchments is challenging due to the inherent complexity of the intertwined processes controlling water transfer from hillslopes to streams and along the river network. Over the past decades, studies have proposed complementing traditional hydrological information with environmental tracer data, e.g. stable isotopes or electrical conductivity (EC), for different purposes such as the separation of streamflow components or the estimation of catchment mean residence time. In particular EC has been applied in Alpine environments mainly for hydrograph separation but also, more recently, considered as a possible proxy for streamflow (Q) prediction. The reason is simple: EC data loggers are convenient because of their relative low cost, easiness of installation and low maintenance, unlike traditional water stage gauges. However, EC time series require careful interpretation since electrical conductivity is influenced by a number of geochemical processes not always introduced in the analysis since these can be difficult to parametrize. Likewise, the relationship between EC and Q is very complex because it is characterized by hysteresis loops and often site specific. This study shows how the continuous monitoring of EC in Alpine catchments can be useful specifically for: hydrograph separation, including a proper quantification of uncertainty; process understanding of catchment functioning through the interpretation of hysteresis loops and time lags between EC and Q signals; and finally, water discharge estimation through calibrated functional EC-Q relationships. We discuss advantages and limitations of the use of EC in hydrology and provide information to encourage its use in studies dealing with streamflow generation dynamics in snow-dominated catchments.

Water-Energy Nexus for an Italian Storage Hydropower Plant under Multiple Drivers

Climate change has repercussions on the management of water resources. Particularly, changes in precipitation and temperature impact hydropower generation and revenue by affecting seasonal electricity prices and streamflow. This issue exemplifies the impact of climate change on the water-energy-nexus, which has raised serious concern. This paper investigates the impact of climate change on hydropower with a multidisciplinary approach. A holistic perspective should be favored as the issue is complex, consequently, we chose to investigate a specific case study in Italy. It allows grasping the details, which matters in mountainous area. We integrated a hydrological model, hydropower management model, nine climate scenarios, and five electricity scenarios for a specific storage hydropower plant. Independently from the scenarios, the results show a glacier volume shrinkage upward of 40% by 2031 and minimum of 50% by 2046. The reservoir mitigates losses of revenue that reach 8% in the worst case, however, are lower compared with run-of-the-river configuration. Changes in price seasonality amplitude also determine modifications in revenues, while temporal shifts appear to be ineffective. For run-of-the-river, any variation in hydrological cycle immediately translates into revenue. Comparing the results of all future scenarios with the base scenario, it can be concluded that an increase in temperature will slightly improve the performances of hydropower.

Effects of Climate Change and Flow Regulation on the Flow Characteristics of a Low-Relief River within Southern Boreal Climate Area

We investigated how hydro-climatological changes would affect fluvial forces and inundated area during a typical high-flow situation (MHQ, mean high discharge), and how adaptive regulation could attenuate the climate change impacts in a low-relief river of the Southern Boreal climate area. We used hydrologically modeled data as input for 2D hydraulic modeling. Our results show that, even though the MHQ will increase in the future (2050–2079), the erosional power of the flow will decrease on the study area. This can be attributed to the change of timing in floods from spring to autumn and winter, when the sea levels during flood peaks is higher, causing backwater effect. Even though the mean depth will not increase notably (from 1.14 m to 1.25 m) during MHQ, compared to the control period (1985–2014), the inundated area will expand by 15% due to the flat terrain. The increase in flooding may be restrained by adaptive regulations: strategies favoring ecologically sustainable and recreationally desirable lake water levels were modeled. The demands of environment, society, and hydropower are not necessarily contradictory in terms of climate change adaptation, and regulation could provide an adaptive practice in the areas of increased flooding.

The impact of climate variability and change on the energy system: A systematic scoping review

The energy system is a vital infrastructure which can be vulnerable to climate variability and change (CV&C) impacts. Understanding the impacts can prevent disruption and inform policy decision making. This study applied a scoping review in a systematic manner following the Joanna Briggs Institute guidelines to identify consistent patterns of CV&C impacts on the energy system, map and locate research gaps in the literature. A total of 176 studies were identified as eligible for inclusion in the review. This study found evidence of consistent increase in energy demand for Africa, the Americas and Asian continent. Consistent decrease was found in Northern and Eastern Europe, while increase in residential demand was projected in Oceania. There was evidence of consistent decrease in thermal power plant output globally. Solar photovoltaic showed a robust consistent pattern of increase in the Caribbean and Central America, Northern and Southern Africa and Oceania. As the global climate is changing in a future that is highly uncertain, the energy system should also evolve in order to adapt to the changing climate. Future impact assessment must integrate the impact of CV&C on power demand and supply while consider socioeconomic dynamics, cross-sectoral linkages and back-loops in a complete energy system model.

Relevance and Scale Dependence of Hydrological Changes in Glacierized Catchments: Insights from Historical Data Series in the Eastern Italian Alps

Glaciers have an important hydrological buffering effect, but their current rapid reduction raises concerns about future water availability and management. This work presents a hydrological sensitivity analysis to different climatic and glacier cover conditions, carried out over four catchments with area between 8 and 1050 km2, and with glacierization between 2% and 70%, in the Italian Alps. The analysis is based on past observations, and exploits a unique dataset of glacier change and hydro-meteorological data. The working approach is aimed at avoiding uncertainties typical of future runoff projections in glacierized catchments. The results highlight a transition from glacial to nival hydrological regime, with the highest impacts in August runoff over smaller catchments. The buffering effect of current glaciers has largely decreased if compared to the Little Ice Age, up to 75% for larger catchments, but it is still important during warm and dry summers like 2003. We confirm a non-linear relationship between glacier contribution in late summer and catchment area/percent glacierization. The peak in runoff attributable to glacier melt, expected in the next 2–3 decades on highly glacierized alpine catchments, has already passed in the study area.

Hydropower Future: Between Climate Change, Renewable Deployment, Carbon and Fuel Prices

Hydropower represents an interesting technology: affordable, renewable, and flexible. However, it must cope with climate changes and new energy policies that jeopardize its future. A smooth transition to sustainability requires decision makers to assess the future perspectives of hydropower: about its future revenue and related uncertainty. This investigation requires a multidisciplinary approach as both streamflow and energy mix will evolve. We simulated future streamflow based on eight climate scenarios using a semi-distributed hydrological model for our case study, the Tremorgio hydropower plant located in southern Switzerland. Next, using a hydropower management model we generated income according to these streamflows and twenty-eight electricity price scenarios. Our results indicate that climate change will modify the seasonality of inflows and volumes exploitable for hydropower generation. However, adaptive strategies in the management of reservoirs could minimize revenue losses/maximize revenue gains. In addition, most market scenarios project an increase in revenues, except in the case of high wind and solar energy penetration. Markets do not provide the right incentive, since the deployment of intermittent energy would benefit from more flexible hydropower.

Coupling hydrological modeling and support vector regression to model hydropeaking in alpine catchments

Water management in the alpine region has an important impact on streamflow. In particular, hydropower production is known to cause hydropeaking i.e., sudden fluctuations in river stage caused by the release or storage of water in artificial reservoirs. Modeling hydropeaking with hydrological models, such as the Soil Water Assessment Tool (SWAT), requires knowledge of reservoir management rules. These data are often not available since they are sensitive information belonging to hydropower production companies. In this short communication, we propose to couple the results of a calibrated hydrological model with a machine learning method to reproduce hydropeaking without requiring the knowledge of the actual reservoir management operation. We trained a support vector machine (SVM) with SWAT model outputs, the day of the week and the energy price. We tested the model for the Upper Adige river basin in North-East Italy. A wavelet analysis showed that energy price has a significant influence on river discharge, and a wavelet coherence analysis demonstrated the improved performance of the SVM model in comparison to the SWAT model alone. The SVM model was also able to capture the fluctuations in streamflow caused by hydropeaking when both energy price and river discharge displayed a complex temporal dynamic.

The Impact of Climate Change on Swiss Hydropower

Hydropower represents an important pillar of electricity systems in many countries. It not only plays an important role in mitigating climate change, but is also subject to climate-change impacts. In this paper, we use the Swiss electricity market model Swissmod to study the effects of changes in water availability due to climate change on Swiss hydropower. Swissmod is an electricity dispatch model with a plant-level representation of 96% of Swiss hydropower plants and their interrelations within cascade structures. Using this detailed model in combination with spatially disaggregated climate-change runoff projections for Switzerland, we show that climate change has ambiguous impacts on hydropower and on the overall electricity system. Electricity prices and overall system costs increase under dry conditions and decrease under average or wet conditions. While the change of seasonal patterns, with a shift to higher winter runoff, has positive impacts, the overall yearly inflow varies under hydrological conditions. While average and wet years yield an increase in inflows and revenues, dry years become drier, resulting in the opposite effect. Even though different in magnitude, the direction of impacts persists when applying the same changes in inflows to the 2050 electricity system.

Uncertainty of modelled flow regime for flow-ecological assessment in Southern Europe

Sustainable water basin management requires characterization of flow regime in river networks impacted by anthropogenic pressures. Flow regime in ungauged catchments under current, future, or natural conditions can be assessed with hydrological models. Developing hydrological models is, however, resource demanding such that decision makers might revert to models that have been developed for other purposes and are made available to them ('off-the-shelf' models). In this study, the impact of epistemic uncertainty of flow regime indicators on flow-ecological assessment was assessed at selected stations with drainage areas ranging from about 400 to almost 90,000km² in four South European basins (Adige, Ebro, Evrotas and Sava). For each basin, at least two models were employed. Models differed in structure, data input, spatio-temporal resolution, and calibration strategy, reflecting the variety of conditions and purposes for which they were initially developed. The uncertainty of modelled flow regime was assessed by comparing the modelled hydrologic indicators of magnitude, timing, duration, frequency and rate of change to those obtained from observed flow. The results showed that modelled flow magnitude indicators at medium and high flows were generally reliable, whereas indicators for flow timing, duration, and rate of change were affected by large uncertainties, with correlation coefficients mostly below 0.50. These findings mirror uncertainty in flow regime indicators assessed with other methods, including from measured streamflow. The large indicator uncertainty may significantly affect assessment of ecological status in freshwater systems, particularly in ungauged catchments. Finally, flow-ecological assessments proved very sensitive to reference flow regime (i.e., without anthropogenic pressures). Model simulations could not adequately capture flow regime in the reference sites comprised in this study. The lack of reliable reference conditions may seriously hamper flow-ecological assessments. This study shows the pressing need for improving assessment of natural flow regime at pan-European scale.

Assessing water scarcity in agricultural production system based on the generalized water resources and water footprint framework

An indicator, agricultural water stress index (AWSI), was established based blue-green water resources and water footprint framework for regional water scarcity in agricultural production industry evaluation. AWSI is defined as the ratio of the total agricultural water footprint (AWF) to water resources availability (AWR) in a single year. Then, the temporal and spatial patterns of AWSI in China during 1999-2014 were analyzed based on the provincial AWR and AWF quantification. The results show that the annual AWR in China has been maintained at approximately 2540Gm³, of which blue water accounted for >70%. The national annual AWF was approximately 1040Gm³ during the study period and comprised 65.6% green, 12.7% blue and 21.7% grey WFs The space difference in both the AWF for per unit arable land (AWFI) and its composition was significant. National AWSI was calculated as 0.413 and showed an increasing trend in the observed period. This index increased from 0.320 (mid-water stress level) in 2000 to 0.490 (high water stress level) in the present due to the expansion of the agricultural production scale. The Northern provinces, autonomous regions and municipalities (PAMs) have been facing high water stress, particularly the Huang-Huai-Hai Plain, which was at a very high water stress level (AWSI>0.800). Humid South China faces increasingly severe water scarcity, and most of the PAMs in the region have converted from low water stress level (AWSI=0.100-0.200) to mid water stress level (AWSI=0.200-0.400). The AWSI is more appropriate for reflecting the regional water scarcity than the existing water stress index (WSI) or the blue water scarcity (BWS) indicator, particularly for the arid agricultural production regions due to the revealed environmental impacts of agricultural production. China should guarantee the sustainable use of agricultural water resources by reducing its crop water footprint.

Examining global electricity supply vulnerability to climate change using a high-fidelity hydropower dam model

An important and plausible impact of a changing global climate is altered power generation from hydroelectric dams. Here we project 21st century global hydropower production by forcing a coupled, global hydrological and dam model with three General Circulation Model (GCM) projections run under two emissions scenarios. Dams are simulated using a detailed model that accounts for plant specifications, storage dynamics, reservoir bathymetry and realistic, optimized operations. We show that the inclusion of these features can have a non-trivial effect on the simulated response of hydropower production to changes in climate. Simulation results highlight substantial uncertainty in the direction of change in globally aggregated hydropower production (~-5 to +5% change in mean global production by the 2080s under a high emissions scenario, depending on GCM). Several clearly impacted hotspots are identified, the most prominent of which encompasses the Mediterranean countries in southern Europe, northern Africa and the Middle East. In this region, hydropower production is projected to be reduced by approximately 40% on average by the end of the century under a high emissions scenario. After accounting for each country's dependence on hydropower for meeting its current electricity demands, the Balkans countries emerge as the most vulnerable (~5-20% loss in total national electricity generation depending on country). On the flipside, a handful of countries in Scandinavia and central Asia are projected to reap a significant increase in total electrical production (~5-15%) without investing in new power generation facilities.

Contamination sources and distribution patterns of pharmaceuticals and personal care products in Alpine rivers strongly affected by tourism

Knowledge regarding the impact of tourism on the emergence of pharmaceuticals and personal care products (PPCPs) in Alpine river waters is limited and scarce. Therefore, a study on the occurrence patterns and spatiotemporal variability of 105 PPCPs in an Alpine river basin located in the Trentino-Alto Adige region (North-Eastern Italy) has been conducted. We observed that the total concentration of analyzed PPCPs was generally higher in all sampling sites during winter than in the summer. The analysis of tourist data revealed that during both sampling campaigns the number of tourists was lower in the downstream sites in comparison with the upstream area of the basin (Val di Sole). Particularly, sampling sites located near important tourist resorts have shown the highest abundance of the PPCPs during winter, being analgesics/anti-inflammatories, antihypertensives and antibiotics the most abundant pharmaceutically active compounds (PhACs). Diclofenac showed the highest concentration amongst PhACs, reaching concentrations up to 675ngL^-1 in the sampling site situated downstream of the Tonale wastewater treatment plant (WWTP). Antihypertensives were found at concentrations >300ngL^-1, while antibiotics were quantified up to 196ngL^-1, respectively. Amongst personal care products (PCPs), the most abundant compound was octyl-dimethyl-p-aminobenzoic acid (ODPABA) with concentrations reaching up to 748ngL^-1 in the sampling site situated within the Rotaliana district. In general, concentrations and detection frequencies were higher in water than in the sediment samples. The most frequently detected PhACs in sediments from both sampling campaigns were antibiotics, while amongst PCPs in sediments, octocrylene (OC) showed the highest concentration in both sampling campaigns. As a result, this study highlights the potential impact of tourism on the water quality of the Alpine aquatic ecosystems.

Combined impacts of climate and socio-economic scenarios on irrigation water availability for a dry Mediterranean reservoir

The impacts of climate and associated socio-economic changes on water availability, including supply and demand, quality, and storage volume, were evaluated for the Vale do Gaio reservoir in southern Portugal, located in a dry Mediterranean climate and already under drought stress. The SWAT model was applied with 6 scenarios for 2071-2100, involving two storylines (A1B and B1) with individual changes in climate (-9% rainfall, increasing in winter by +28 to +30%), socio-economic conditions (an increase in irrigation demand by 11%, and a replacement of cereals and pastures by sunflower), and a combination of both. Most future scenarios resulted in lower water availability, due to lower supply (-19 to -27%) combined with higher irrigation demand (+3 to +21%). This resulted in more years with limited irrigation supplies (presently: 28%; scenarios: 37 to 43%), although limitations were mitigated by lower losses to excess discharge. Land-use changes also decreased quality by increasing P concentrations (+29 to +93%). Impacts were more severe in scenario A1B than in B1, and in combined changes than in climate or socio-economic changes only. Water availability was resilient to climate change, as impacts led only to a moderate aggravation of present-day conditions. Lower future water availability could be addressed by supply and demand management strategies and, in the most extreme scenario, by water transfers from regional water reserves; water quality issues could be addressed through land-use policies. Results also highlighted the importance of taking the characteristics of water supply systems into account when designing adaptation measures for future changes.

Longitudinal assessment of hydropeaking impacts on various scales for an improved process understanding and the design of mitigation measures

Hydropeaking is one of the main pressures on the aquatic ecology in alpine rivers. Beside studies on abiotic process and biotic response on the local scale there is a lack in process understanding on the reach scale. Especially longitudinal changes of hydropeaking impacts based on retention processes have not been studied yet. Thus, based on unsteady one-dimensional and two-dimensional depth averaged modelling it was targeted to investigate possible changes in vertical ramping velocity for the discussion of possible mitigation measures at the local scale. Here, we compared artificial and natural sheltering habitats in terms of peak flow. Additionally, the hydropeaking assessment on various river scales was supported by an evaluation of tributaries in an alpine river system. Based on the modelling results and the discussion of the impact assessment of hydropeaking in different case studies we state, that on the first 5km downstream of the turbine outlet a significant decrease in vertical ramping velocity occurs. In this reach, habitat improvements should focus on increasing retention processes considering the higher risk of stranding for juvenile fish and macroinvertebrates. For morphological mitigation measures at the local scale, it turned out that self-formed, near-natural morphology should be targeted in terms of mitigation measure design compared to artificial sheltering habitats. Abundance and biomass of macroinvertebrates are directly linked to substrate variability in self-formed sheltering habitats downstream of gravel bars. Moreover, we ascertained that tributaries are able to contribute to the 'ecological potential' in multi-stressed hydropeaking rivers by providing spawning and rearing habitats for fish. However, for a sustainable improvement of the aquatic environment on all relevant scales, both sediment and flood dynamics have to be considered as important drivers to establish self-formed sheltering habitats in terms of hydropeaking.

Evaluation of precipitation input for SWAT modeling in Alpine catchment: A case study in the Adige river basin (Italy)

Precipitation is often the most important input data in hydrological models when simulating streamflow. The Soil and Water Assessment Tool (SWAT), a widely used hydrological model, only makes use of data from one precipitation gauge station that is nearest to the centroid of each subbasin, which is eventually corrected using the elevation band method. This leads in general to inaccurate representation of subbasin precipitation input data, particularly in catchments with complex topography. To investigate the impact of different precipitation inputs on the SWAT model simulations in Alpine catchments, 13years (1998-2010) of daily precipitation data from four datasets including OP (Observed precipitation), IDW (Inverse Distance Weighting data), CHIRPS (Climate Hazards Group InfraRed Precipitation with Station data) and TRMM (Tropical Rainfall Measuring Mission) has been considered. Both model performances (comparing simulated and measured streamflow data at the catchment outlet) as well as parameter and prediction uncertainties have been quantified. For all three subbasins, the use of elevation bands is fundamental to match the water budget. Streamflow predictions obtained using IDW inputs are better than those obtained using the other datasets in terms of both model performance and prediction uncertainty. Models using the CHIRPS product as input provide satisfactory streamflow estimation, suggesting that this satellite product can be applied to this data-scarce Alpine region. Comparing the performance of SWAT models using different precipitation datasets is therefore important in data-scarce regions. This study has shown that, precipitation is the main source of uncertainty, and different precipitation datasets in SWAT models lead to different best estimate ranges for the calibrated parameters. This has important implications for the interpretation of the simulated hydrological processes.

Evaluation of eight high spatial resolution gridded precipitation products in Adige Basin (Italy) at multiple temporal and spatial scales

This study provides a comprehensive evaluation of eight high spatial resolution gridded precipitation products in Adige Basin located in Italy within 45-47.1°N. The Adige Basin is characterized by a complex topography, and independent ground data are available from a network of 101 rain gauges during 2000-2010. The eight products include the Version 7 TRMM (Tropical Rainfall Measuring Mission) Multi-satellite Precipitation Analysis 3B42 product, three products from CMORPH (the Climate Prediction Center MORPHing technique), i.e., CMORPH_RAW, CMORPH_CRT and CMORPH_BLD, PCDR (Precipitation Estimation from Remotely Sensed Information using Artificial Neural Networks-Climate Data Record), PGF (Global Meteorological Forcing Dataset for land surface modelling developed by Princeton University), CHIRPS (Climate Hazards Group InfraRed Precipitation with Station data) and GSMaP_MVK (Global Satellite Mapping of Precipitation project Moving Vector with Kalman-filter product). All eight products are evaluated against interpolated rain gauge data at the common 0.25° spatial resolution, and additional evaluations at native finer spatial resolution are conducted for CHIRPS (0.05°) and GSMaP_MVK (0.10°). Evaluation is performed at multiple temporal (daily, monthly and annual) and spatial scales (grid and watershed). Evaluation results show that in terms of overall statistical metrics the CHIRPS, TRMM and CMORPH_BLD comparably rank as the top three best performing products, while the PGF performs worst. All eight products underestimate and overestimate the occurrence frequency of daily precipitation for some intensity ranges. All products tend to show higher error in the winter months (December-February) when precipitation is low. Very slight difference can be observed in the evaluation metrics and aspects between at the aggregated 0.25° spatial resolution and at the native finer resolutions (0.05°) for CHIRPS and (0.10°) for GSMaP_MVK products. This study has implications for precipitation product development and the global view of the performance of various precipitation products, and provides valuable guidance when choosing alternative precipitation data for local community.

Evaluation of genotoxic potential throughout the upper and middle stretches of Adige river basin

In this study a comprehensive genotoxicological survey throughout the upper and middle stretches of Adige river basin is presented. The study was carried out at 7 sites located along the Adige main course and one the most significant tributaries, the Noce creek, both presenting different levels of pollution pressure. To give an insight into the nature of the genotoxic activity we employed the battery of prokaryotic and eukaryotic assays. Mutagenicity in water samples was evaluated by SOS/umuC test in Salmonella typhimurium TA1535/pSK1002. The level of DNA damage as a biomarker of exposure (comet assay) and biomarker of effect (micronucleus assay) and the level of oxidative stress as well (Fpg - modified comet assay) were studied in blood cells of Salmo cenerinus Nardo, 1847 and Salmo marmoratus Cuvier, 1829. Within the applied bioassays, comet assay showed the highest potential for discriminating the sampling sites which are under lesser extent of pressure (sampling sites 1-Barnes at Bresimo and 4-Noce downstream S. Giustina) from the sites under high pressure (sampling sites 5-Noce at Mezzolombardo and 6/7-Adige upstream and downstream municipality of Trento). Significant correlation between the standard and Fpg - modified comet assay indicated that oxidative stress could be a major contributor to observed DNA damage in collected specimens.

Global assessment of heat wave magnitudes from 1901 to 2010 and implications for the river discharge of the Alps

Heat waves represent one of the most significant climatic stressors for ecosystems, economies and societies. A main topic of debate is whether they have increased or not in intensity and/or their duration due to the observed climate change. Firstly, this is because of the lack of reliable long-term daily temperature data at the global scale; secondly, because of the intermittent nature of such phenomena. Long datasets are required to produce a reliable and meaningful assessment. In this study, we provide a global estimate of heat wave magnitudes based on the three most appropriate datasets currently available, derived from models and observations (i.e. the 20th Century Reanalyses from NOAA and ECMWF), spanning the last century and before. The magnitude of the heat waves is calculated by means of the Heat Wave Magnitude Index daily (HWMId), taking into account both duration and amplitude. We compare the magnitude of the most severe heat waves occurred across different regions of the world and we discuss the decadal variability of the larger events since the 1850s. We concentrate our analysis from 1901 onwards, where all datasets overlap. Our results agree with other studies focusing on heat waves that have occurred in the recent decades, but using different data. In addition, we found that the percentage of global area covered by heat wave exceeding a given magnitude has increased almost three times, in the last decades, with respect to that measured in the early 20th century. Finally, we discuss the specific implications of the heat waves on the river runoff generated in the Alps, for which comparatively long datasets exist, affecting the water quality and availability in a significant portion of the European region in summer.

Hydroclimatic and water quality trends across three Mediterranean river basins

Water resources are under pressure from multiple anthropogenic stressors such as changing climate, agriculture and water abstraction. This holds, in particular, for the Mediterranean region, where substantial changes in climate are expected throughout the 21st century. Nonetheless, little attention has been paid to linkages between long-term trends in climate, streamflow and water quality in Mediterranean river basins. In the present study, we perform a comparative analysis of recent trends in hydroclimatic parameters and nitrate pollution in three climatologically different Mediterranean watersheds (i.e., the Adige, Ebro and Sava River Basins). Mann-Kendall trend analyses of annual mean temperature, precipitation and streamflow (period 1971 to 2010) and monthly nitrate concentrations, mass fluxes and flow-adjusted concentrations (period 1996 to 2012) were performed in these river basins. Temperature is shown to have increased the most in the Ebro followed by the Sava, whereas minor increases are observed in the Adige. Precipitation presents, overall, a negative trend in the Ebro and a positive trend in both the Adige and Sava. These climatic trends thus suggest the highest risk of increasing water scarcity for the Ebro and the lowest risk for the Adige. This is confirmed by trend analyses of streamflow time series, which indicate a severe decline in streamflow for the Ebro and a substantial decline in the Sava, as opposed to the Adige showing no prevailing trend. Concerning surface water quality, nitrate pollution appears to have decreased in all study basins. Overall, these findings emphasize progressive reduction of water resources availability in river basins characterized by continental climate (i.e., Ebro and Sava). This study thus underlines the need for adapted river management in the Mediterranean region, particularly considering strong feedbacks between hydroclimatic trends, freshwater ecosystem services and water resources availability for agriculture, water supply and hydropower generation.