The effects of water diversion and climate change on hydrological alteration and temperature regime of karst rivers in central Croatia

Karst rivers in Croatia have been heavily dammed in the past. However, long-term impacts of dams, water diversion and climate change on karst rivers in Croatia have rarely been examined. This study analyzes long-term trends of hydrological and temperature conditions, prior to closure of new large dam, in five connected karst rivers of central Croatia: the sinking rivers Gornja Dobra and Zagorska Mre?nica that have underground connections with the Goja?ka Dobra, Tounj?ica and Mre?nica Rivers. It was established that hydrological conditions of these rivers have been greatly changed after the Gojak HPP, located at spring of Goja?ka Dobra, became operational in 1959. Water diversion from the reservoirs on Zagorska Mre?nica and Gornja Dobra to the Gojak HPP has increased mean annual discharge (52-106%), causing great subdaily fluctuations and overall modification of natural flow regime along the whole course of Goja?ka Dobra. By cutting the connection between Zagorska Mre?nica and Tounj?ica, water diversion has caused a reduction of mean annual discharges of the Tounj?ica (-60%) and Mre?nica (-29%) Rivers. Analyses of long-term trends in water temperature over the last 50 years have revealed significant positive trends in average annual temperature at three gauging stations on three rivers with increase of 0.17, 0.44 and 0.48°C per decade and climate change as the primary cause. The highest significant increasing trend was established at the lower course of Mre?nica where discharge was reduced by water diversion. Mitigation measures for the improvement of hydrological conditions of affected rivers and underground systems are proposed and discussed.     

Sustainability of winter tourism in a changing climate over Kashmir Himalaya

Mountain areas are sensitive to climate change. Implications of climate change can be seen in less snow, receding glaciers, increasing temperatures, and decreasing precipitation. Climate change is also a severe threat to snow-related winter sports such as skiing, snowboarding, and cross-country skiing. The change in climate will put further pressure on the sensitive environment of high mountains. Therefore, in this study, an attempt has been made to know the impact of climate change on the snow precipitation, water resources, and winter tourism in the two famous tourist resorts of the Kashmir Valley. Our findings show that winters are getting prolonged with little snow falls on account of climate change. The average minimum and maximum temperatures are showing statistically significant increasing trends for winter months. The precipitation is showing decreasing trends in both the regions. A considerable area in these regions remains under the snow and glacier cover throughout the year especially during the winter and spring seasons. However, time series analysis of LandSat MODIS images using Normalized Difference Snow Index shows a decreasing trend in snow cover in both the regions from past few years. Similarly, the stream discharge, comprising predominantly of snow- and glacier-melt, is showing a statistically significant declining trend despite the melting of these glaciers. The predicted futuristic trends of temperature from Predicting Regional Climates for Impact Studies regional climate model are showing an increase which may enhance snow-melting in the near future posing a serious threat to the sustainability of winter tourism in the region. Hence, it becomes essential to monitor the changes in temperature and snow cover depletion in these basins in order to evaluate their effect on the winter tourism and water resources in the region.     

The range fraction: an applied method to characterize regional groundwater responses to climate inputs

An important component of ongoing water-resource investigations in the eastern Great Basin, USA, has been to ascertain the impact of future predicted climate change on groundwater availability. As a first step in that analysis, it was hypothesized that potentiometric fluctuations at certain wells would reflect annual-scale precipitation variation. Potentiometric behavior at a well depends on local hydrologic conditions, well construction, and human activities, in addition to natural recharge and regional water levels. Moreover, measurement data are limited for many wells. After preliminarily screening, a large body of well and climate station data, short-term potentiometric responses to annual-scale climate inputs, were identified at 18 wells using a simple visualization methodology developed during the study. For water levels displaying multi-annual trends, the signals were measured as deviations from a linear trendline. Groundwater responses lagged precipitation signals by less than 1 year to as much as 3 years, with most wells showing at most a 1- to 2-year delay. Response amplitude was variable and strongly depended on the hydrologic setting of each well.     

Climate-induced water availability changes in Europe

Water availability changes in Europe are discussed in this paper, as seen in a perspective of climatic change. Such changes will be assessed in terms of the shifts in the watering of terrestrial ecosystems, as well as the shifts in the availability in terrestrial freshwater systems. A changing climate will have a major impact on the availability of water. Both wetter and drier conditions will have major implications for societal activities and land use patterns (e.g., agriculture, urban activities, waste water disposal, etc.).Some future research and monitoring activities are proposed by the authors to assess linkages in hydrological shifts to changes in land use patterns.     

Monitoring the Hydrology of Canadian Prairie Wetlands to Detect the Effects of Climate Change and Land Use Changes

There are millions of small isolatedwetlands in the semi-arid Canadian prairies. These`sloughs' are refuges for wildlife in an area that isotherwise intensively used for agriculture. They areparticularly important as waterfowl habitat, with morethan half of all North American ducks nesting inprairie sloughs. The water levels and ecology of thewetlands are sensitive to atmospheric change and tochanges of agricultural practices in the surroundingfields. Monitoring of the hydrological conditions ofthe wetlands across the region is vital for detectinglong-term trends and for studying the processes thatcontrol the water balance of the wetlands. Suchmonitoring therefore requires extensive regional-scaledata complemented by intensive measurements at a fewlocations. At present, wetlands are being enumeratedacross the region once each year and year-roundmonitoring is being carried out at a few locations. Theregional-scale data can be statistically related toregional climate data, but such analyses cast littlelight on the hydrological processes and have limitedpredictive value when climate and land use arechanging. The intensive monitoring network has providedimportant insights but it now needs to be expanded andrevised to meet new questions concerning the effects ofclimate change and land use.     

Spatiotemporal analysis of the effect of climate change on vegetation health in the Drakensberg Mountain Region of South Africa

The impact of climate change on mountain ecosystems has been in the spotlight for the past three decades. Climate change is generally considered to be a threat to ecosystem health in mountain regions. Vegetation indices can be used to detect shifts in ecosystem phenology and climate change in mountain regions while satellite imagery can play an important role in this process. However, what has remained problematic is determining the extent to which ecosystem phenology is affected by climate change under increasingly warming conditions. In this paper, we use climate and vegetation indices that were derived from satellite data to investigate the link between ecosystem phenology and climate change in the Namahadi Catchment Area of the Drakensberg Mountain Region of South Africa. The time series for climate indices as well as those for gridded precipitation and temperature data were analyzed in order to determine climate shifts, and concomitant changes in vegetation health were assessed in the resultant epochs using vegetation indices. The results indicate that vegetation indices should only be used to assess trends in climate change under relatively pristine conditions, where human influence is limited. This knowledge is important for designing climate change monitoring strategies that are based on ecosystem phenology and vegetation health.     

Study of the Climate Change Impacts on Water Quality in the Upstream Portion of the Cau River Basin,Vietnam

This paper presents simulations of climate change impacts on water quality in the upstream portion of the Cau River Basin in the North of Vietnam. The integrated modeling system GIBSI was used to simulate hydrological processes, pollutant and sediment wash-off in the river basin, and pollutant transport and transformation in the river network. Three projections for climate change based on emission scenarios B1, B2, and A2 of IPCC Special Report on Emission Scenarios (SRES) were considered. By assuming that the input pollution sources and watershed configuration were constant, based on 2008 data, water quality in the river network was simulated up to the terminal year 2050. For each climate change scenario, patterns of precipitation in wet and dry year were considered. The change in annual and monthly trends for dissolved oxygen (DO), biochemical oxygen demand (BOD), and ammonium ions (NH4+) load and concentration for different portions of the watershed have been analyzed. The results of these simulations show that climate change has more impact on changing the seasonal water quality parameters than on altering the average annual load of the pollutants. The percent change and change pattern in water quality parameters are different for wet and dry year, and the changes in wet year are smaller than those in dry year.     

长江源区水生态系统健康研究进展

对截止至2021年6月报道的长江源区气候、水资源、水质、藻类、大型无脊椎动物和鱼类资源等水生态系统健康相关研究进行了综述,以期为进一步开展长江源区水生态系统健康研究与生态保护提供参考和依据。研究结果表明:①长江源区水生态相关研究主要关注于气候变化,其次为水资源变化和草地退化。②1948—2019年,长江源区全年平均气温呈上升趋势,增长速度为0.2~0.5℃/10 a;春季和冬季降水量呈增加趋势,增长速度分别为1.1~26.6 mm/10 a和0.2~9.1 mm/10 a;全年平均径流量呈增加趋势,增长速度为11.8~79.6 m³/(s·10 a);蒸发量呈增加趋势,增长速度为7.6~71.6 mm/10 a。③1969—2002年,冰川面积减少了68.1 km²,年均减少2.0 km²。1969—2015年,格拉丹东冰川面积减少了14.9~79.0 km²,减少速度为0.5~10.0 km²/a。1975—2015年,湖泊面积增加了2.7~831.6 km²,增速为0.3~96.2 km²/a。④1986—2015年,大部分河段水质为Ⅱ类及以上,且无明显年际变化。⑤针对水生生物的调查和研究非常匮乏。总体而言,长江源区水生态系统健康状况良好。近年来其气象因子以及水资源状况有所改变,未来气候变化可能会进一步影响长江源区水生态系统健康状况。今后亟须加强对长江源区的本底调查,完善基础数据,关注气候变化对水资源和水质的影响,并探索气候变化对水生生物的影响。     

Hydrology of mountainous areas in the upper Indus Basin, Northern Pakistan with the perspective of climate change

Mountainous areas in the northern Pakistan are blessed by numerous rivers that have great potential in water resources and hydropower production. Many of these rivers are unexploited for their water resource potential. If the potential of these rivers are explored, hydropower production and water supplies in these areas may be improved. The Indus is the main river originating from mountainous area of the Himalayas of Baltistan, Pakistan in which most of the smaller streams drain. In this paper, the hydrology of the mountainous areas in northern Pakistan is studied to estimate flow pattern, long-term trend in river flows, characteristics of the watersheds, and variability in flow and water resource due to impact of climate change. Eight watersheds including Gilgit, Hunza, Shigar, Shyok, Astore, Jhelum, Swat, and Chitral, Pakistan have been studied from 1960 to 2005 to monitor hydrological changes in relation to variability in precipitation, temperature and mean monthly flows, trend of snow melt runoff, analysis of daily hydrographs, water yield and runoff relationship, and flow duration curves. Precipitation from ten meteorological stations in mountainous area of northern Pakistan showed variability in the winter and summer rains and did not indicate a uniform distribution of rains. Review of mean monthly temperature of ten stations suggested that the Upper Indus Basin can be categorized into three hydrological regimes, i.e., high-altitude catchments with large glacierized parts, middle-altitude catchments south of Karakoram, and foothill catchments. Analysis of daily runoff data (1960-2005) of eight watersheds indicated nearly a uniform pattern with much of the runoff in summer (June-August). Impact of climate change on long-term recorded annual runoff of eight watersheds showed fair water flows at the Hunza and Jhelum Rivers while rest of the rivers indicated increased trends in runoff volumes. The study of the water yield availability indicated a minimum trend in Shyok River at Yogo and a maximum trend in Swat River at Kalam. Long-term recorded data used to estimate flow duration curves have shown a uniform trend and are important for hydropower generation for Pakistan which is seriously facing power crisis in last 5 years.     

Environmental water demand assessment under climate change conditions

Measures taken to cope with the possible effects of climate change on water resources management are key for the successful adaptation to such change. This work assesses the environmental water demand of the Karkheh river in the reach comprising Karkheh dam to the Hoor-al-Azim wetland, Iran, under climate change during the period 2010–2059. The assessment of the environmental demand applies (1) representative concentration pathways (RCPs) and (2) downscaling methods. The first phase of this work projects temperature and rainfall in the period 2010–2059 under three RCPs and with two downscaling methods. Thus, six climatic scenarios are generated. The results showed that temperature and rainfall average would increase in the range of 1.7–5.2 and 1.9–9.2%, respectively. Subsequently, flows corresponding to the six different climatic scenarios are simulated with the unit hydrographs and component flows from rainfall, evaporation, and stream flow data (IHACRES) rainfall-runoff model and are input to the Karkheh reservoir. The simulation results indicated increases of 0.9–7.7% in the average flow under the six simulation scenarios during the period of analysis. The second phase of this paper’s methodology determines the monthly minimum environmental water demands of the Karkheh river associated with the six simulation scenarios using a hydrological method. The determined environmental demands are compared with historical ones. The results show that the temporal variation of monthly environmental demand would change under climate change conditions. Furthermore, some climatic scenarios project environmental water demand larger than and some of them project less than the baseline one.     

Modeling economy-wide climate change impacts on Egypt: A case for an integrated approach

This study looks at the role of biophysical sectors and world markets on an integrated economic assessment of climate change impacts on Egypt. Using the outcome from Global Circulation Models (GCMs) and a global model of world food trade (the Basic Linked System; BLS) — changes in crop yields; crop water demands; water and land resource availability; and world market prices were applied to a dynamic, computable general equilibrium model of Egypt (the Standard National Model of the BLS). Modeling results consistently showed that the net effect of climate change on the macro indicator of per capita GDP was not great — regardless of the level of integration. This outcome was only realized through autonomous economic adjustments which implied significant socio-economic and structural change. Including or excluding certain biophysical sectors and world markets influenced the development path and the nature of the autonomous adjustments. The importance of a particular biophysical sector or of world markets was also dependent upon the specific climate change scenario.     

The Biodiversity Crisis and Adaptation to Climate Change: A Case Study from Australia's Forests

If current trends continue, human activities will drastically alter most of the planet's remaining natural ecosystems and their composite biota within a few decades. Compounding the impacts on biodiversity from deleterious management practices is climate variability and change. The Intergovernmental Panel on Climate Change (IPCC) recently concluded that there is ample evidence to suggest climate change is likely to result in significant impacts on biological diversity. These impacts are likely to be exacerbated by the secondary effects of climate change such as changes in the occurrence of wildfire, insect outbreaks and similar disturbances. Current changes in climate are very different from those of the past due to their rate and magnitude, the direct effects of increased atmospheric CO₂ concentrations and because highly modified landscapes and an array of threatening processes limit the ability of terrestrial ecosystems and species to respond to changed conditions. One of the primary human adaptation option for conserving biodiversity is considered to be changes in management. The complex and overarching nature of climate change issues emphasises the need for greatly enhanced cooperation between scientists, policy makers, industry and the community to better understand key interactions and identify options for adaptation. A key challenge is to identify opportunities that facilitate sustainable development by making use of existing technologies and developing policies that enhance the resilience of climate-sensitive sectors. Measures to enhance the resilience of biodiversity must be considered in all of these activities if many ecosystem services essential to humanity are to be sustained. New institutional arrangements appear necessary at the regional and national level to ensure that policy initiatives and research directed at assessing and mitigating the vulnerability of biodiversity to climate change are complementary and undertaken strategically and cost-effectively. Policy implementation at the national level to meet responsibilities arising from the UNFCCC (e.g., the Kyoto Protocol) and the UN Convention on Biological Diversity require greater coordination and integration between economic sectors, since many primary drivers of biodiversity loss and vulnerability are influenced at this level. A case study from the Australian continent is used to illustrate several key issues and discuss a basis for reform, including recommendations for facilitating adaptation to climate variability and change.     

A System to Monitor Climate Change with Epilithic Lichens

The issue of biological monitoring of the local consequences of anticipated global climate change is considered for the Central Negev Highlands, Israel. Epilithic lichens are suggested as biological monitors. The proposed methodology of such monitoring consists of a sampling scheme, including lichen measurement along transects on flat calcareous rocks, and construction of a trend detection index (TDI). TDI is a sum of lichen species cover with coefficients chosen so as to ensure maximum ability to detect global climate trends. Coefficients have been estimated in a study of lichens along an altitudinal gradient from 500 to 1000 m a.s.l. The gradient study demonstrated that the TDI index is performed better than other integrated indices. Recommendations on this system to monitor climate change with epilthic lichens are given. Measuring, for instance, a hundred transects in fifty plots (two transet per plot scheme) allows one to detect a climate-driven change in the epilithic lichen community corresponding to a 0.8 °C shift in annual mean temperature. Such resolution appears sufficient in view of global warming of 2.5 °C considered by the Intergovernmental Panel on Climate Change as a realistic prediction for the end of the next century.     

Climate Change Impacts and Human Settlements in Africa: Prospects for Adaptation

Climate change impacts on African human settlements arise from a number of climate change-related causes, notably sea level changes, impacts on water resources, extreme weather events, food security, increased health risks from vector home diseases, and temperature-related morbidity in urban environments.Some coastlines and river deltas of Africa have densely populated low-lying areas, which would be affected by a rise in sea level. Other coastal settlements will be subjected to increased coastal erosion. Recent flooding in East Africa highlighted the vulnerability of flood plain settlements and the need to develop adaptive strategies for extreme weather events management and mitigation. In the semi arid and arid zones many settlements are associated with inland drainage water sources. Increases in drought will enhance water supply related vulnerabilities. Inter-basin and international water transfers raise the need for adequate legal frameworks that ensure equity among participating nations.Similarly, water supply and irrigation reservoirs in seasonal river catchments might fail, leading to poor sanitation in urban areas as well as food shortage. Hydroelectric power generation could be restricted in drought periods, and where it is a major contributor to the energy budget, reduced power generation could lead to a multiplicity of other impacts. States are advised to develop other sources of renewable energy.Temperature changes will lead to altered distribution of disease vectors such as mosquitoes, making settlements currently free of vector borne diseases vulnerable. Rapid breeding of the housefly could create a menace associated with enteric disorders, especially in conditions of poor sanitation.The dry savannahs of Africa are projected as possible future food deficit areas. Recurrent crop failures would lead to transmigration into urban areas. Pastoralists are likely to undertake more trans-boundary migrations and probably come into conflict with settled communities.Adaptive measures will involve methods of coastal defences (where applicable), a critical review of the energy sector, both regionally and nationally, a rigorous adherence to city hygiene procedures, an informed agricultural industry that is capable of adapting to changing climate in terms of cropping strategies, and innovations in environment design to maximise human comfort at minimum energy expenditure. In the savannah and arid areas water resource management systems will be needed to optimise water resource use and interstate co-operation where such resources are shared.Climate change issues discussed here raise the need for state support for more research and education in impacts of climate change on human settlements in Africa.     

Climate dynamics and extreme precipitation and flood events in Central Europe

Past changes and possible future variations in the nature of extreme precipitation and flood events in Central Europe and the Alpine region are examined from a physical standpoint. An overview is given of the following key contributory physical processes: (1) the variability of the large-scale atmospheric flow and the associated changes of the North-Atlantic storm track; (2) the feedback process between climate warming and the water cycle, and in particular the potential for more frequent heavy precipitation events; and (3) the catchment-scale hydrological processes associated with variations in major river flooding events and that are related to land-use changes, river training measures, and shifts in the proportion of rain to snowfall. In this context an account is provided of the possible future forecasting and warning methodologies based upon high-resolution weather prediction and runoff models. Also consideration is given to the detectability of past (future) changes in observed (modeled) extreme events. It is shown that their rarity and natural fluctuation largely impedes a detection of systematic variations. These effects restrict trend analysis of such events to return periods of below a few months. An illustration using daily precipitation from the Swiss Alps does yield evidence for pronounced trends of intense precipitation events (return period 30 days), while trends of stronger event classes are not detectable (but nevertheless can not be excluded). The small detection probability for extreme events limits possible mitigation of future damage costs through an abatement of climate change alone, and points to the desirability of developing improved early forecasting/warning systems as an additional no-regret strategy. This revised version was published online in July 2006 with corrections to the Cover Date.     

Murres, capelin and ocean climate: inter-annual associations across a decadal shift

To ensure energy demands for reproduction are met, it is essential that marine birds breed during periods of peak food availability. We examined associations of the breeding chronology of common murres (Uria aalge) with the timing of the inshore arrival of their primary prey, capelin (Mallotus villosus) from 1980 to 2006 across a period of pervasive change in the Northwest Atlantic ecosystem. We also assessed the influence of ocean temperature and the North Atlantic Oscillation (NAO; an index of winter climate and oceanography) on these interactions. We found a lagged linear relationship between variations in murre breeding chronology and the timing of capelin arrival in the previous year. On a decadal level, we found a non-linear threshold relationship between ocean temperature and the timing of capelin arrival and murre breeding. Centennially anomalous cold water temperatures in 1991 generated a marked shift in the timing of capelin spawning inshore and murre breeding, delaying both by more than 2 weeks. By the mid-1990s, ocean temperatures returned to pre-perturbation levels, whereas the temporal breeding responses of capelin and murres were delayed for a decade or more. Oceanographic conditions (temperature, NAO) were poor predictors of the timing of capelin arrival inshore in the current year compared to the previous one. Our findings suggest that knowledge of the timing of capelin availability in the previous year provides a robust cue for the long-lived murres, allowing them to achieve temporal overlap between breeding and peak capelin availability.     

Land Use and Climate Change Impacts on the Hydrology of the Bago River Basin,Myanmar

Assessment of land use and climate change impacts on the hydrological cycle is important for basin scale water resources management. This study aims to investigate the potential impacts of land use and climate change on the hydrology of the Bago River Basin in Myanmar. Two scenarios from the representative concentration pathways (RCPs): RCP4.5 and RCP8.5 recommended by the Intergovernmental Panel on Climate Change, Fifth Assessment Report (IPCC AR5) were used to project the future climate of 2020s, 2050s, and 2080s. Six general circulation models (GCMs) from the Coupled Model Intercomparison Project Phase 5 (CMIP5) were selected to project the future climate in the basin. An increase of average temperature in the range of 0.7 to 1.5 °C and 0.9 to 2.7 °C was observed under RCP 4.5 and RCP 8.5, respectively, in future periods. Similarly, average annual precipitation shows a distinct increase in all three periods with the highest increase in 2050s. A well calibrated and validated Soil and Water Assessment Tool (SWAT) was used to simulate the land use and climate change impacts on future stream flows in the basin. It is observed that the impact of climate change on stream flow is higher than the land use change in the near future. The combined impacts of land use and climate change can increase the annual stream flow up to 68 % in the near future. The findings of this study would be beneficial to improve land and water management decisions and in formulating adaptation strategies to reduce the negative impacts, and harness the positive impacts of land use and climate change in the Bago River Basin.     

钱塘江南源流域异常水质预测及影响因素分析

基于数据驱动的水质预测模型存在局限性,对突发水质异常事件的预测效果不佳。该研究选取钱塘江南源流域马戍口监测断面为研究对象,综合采用相关性分析方法对水质异常事件的主要影响因素进行分析,明确流域内、外因及土壤条件对水质异常指标的影响程度,探究造成模型局限性的深层原因。结果表明:异常水质的影响因素及其耦合机制复杂多变,异常浊度受降雨量、径流量的直接影响更大,异常高锰酸盐指数与温度、降雨量相关关系更明显,而总磷、总氮的异常变化与相对湿度、降雨量、径流量具有相关关系。研究结果对于提高气候变化背景下的水质预报能力具有重要的参考价值,可为自然流域水污染防治提供科学参考。     

Tropical cyclone losses in the USA and the impact of climate change — A trend analysis based on data from a new approach to adjusting storm losses

Economic losses caused by tropical cyclones have increased dramatically. Historical changes in losses are a result of meteorological factors (changes in the incidence of severe cyclones, whether due to natural climate variability or as a result of human activity) and socio-economic factors (increased prosperity and a greater tendency for people to settle in exposed areas). This paper aims to isolate the socio-economic effects and ascertain the potential impact of climate change on this trend. Storm losses for the period 1950–2005 have been adjusted to the value of capital stock in 2005 so that any remaining trend cannot be ascribed to socio-economic developments. For this, we introduce a new approach to adjusting losses based on the change in capital stock at risk. Storm losses are mainly determined by the intensity of the storm and the material assets, such as property and infrastructure, located in the region affected. We therefore adjust the losses to exclude increases in the capital stock of the affected region. No trend is found for the period 1950–2005 as a whole. In the period 1971–2005, since the beginning of a trend towards increased intense cyclone activity, losses excluding socio-economic effects show an annual increase of 4% per annum. This increase must therefore be at least due to the impact of natural climate variability but, more likely than not, also due to anthropogenic forcings.