Potential Effects of Climate Change on Ecologically Relevant Streamflow Regimes

We assessed the climate‐driven changes in ecologically relevant flow regimes expected to occur by the year 2100 in streams across the conterminous United States. We used long‐term daily flow measurements from 601 gauged streams whose watersheds were in relatively natural condition to characterize spatial variation in 16 flow regime variables selected for their ecological importance. Principal component analysis of these 16 variables produced five uncorrelated factors that described patterns of spatial covariation in flow regimes. These five factors were associated with low flow, magnitude, flashiness, timing, and constancy characteristics of the daily flow regime. We applied hierarchical clustering to the five flow factors to classify the 601 streams into three coarses and eight more finely resolved flow regime classes. We then developed a random forest model that used watershed and climate attributes to predict the probabilities that streams belonged to each of the eight finely resolved flow regime classes. The model had a prediction accuracy (per cent correct classification) of 75%. We used the random forest model with downscaled climate (precipitation and temperature) projections to predict site‐specific changes in flow regime classes expected by 2100. Thirty‐three per cent of the 601 sites were predicted to change to a different flow regime class by 2100. Snow‐fed streams in the western USA were predicted to be less likely to change regimes, whereas both small, perennial, rain‐fed streams and intermittent streams in the central and eastern USA were predicted to be most likely to change regime. Copyright © 2016 John Wiley & Sons, Ltd.     

气候变化对降雨侵蚀力的影响研究综述

以全球变暖为主要特征的全球气候变化导致降雨侵蚀力改变,从而影响区域土壤流失过程。因此,研究气候变化对降雨侵蚀力的影响,对适应和预防全球气候变化、争取环境外交主动权、制定农业发展战略具有积极作用。对相关研究成果进行了总结:国外相关研究由侧重单一的降雨量变化对降雨侵蚀力的影响,发展为气候变暖和土地利用类型的变化对土壤侵蚀环境的综合影响;国内相关研究起步较晚,侧重于不同区域降雨侵蚀力的计算,在长江流域,气候变化对降雨侵蚀力影响的相关研究较少。加强相关研究,既可为长江流域降雨侵蚀力的研究提供理论依据,又可为长江流域降雨侵蚀的防治和气候变化下水保措施的制定提供技术支撑。     

Impact of Human Intervention and Climate Change on Natural Flow Regime

According to the ‘natural flow paradigm’, any departure from the natural flow condition will alter the river ecosystem. River flow regimes have been modified by anthropogenic interventions and climate change is further expected to affect the biotic interactions and the distribution of stream biota by altering streamflow. This study aims to evaluate the hydrologic alteration caused by dam construction and climatic changes in a mesoscale river basin, which is prone to both droughts and monsoonal floods. To analyse the natural flow regime, 15 years of observed streamflow (1950–1965) prior to dam construction is used. Future flow regime is simulated by a calibrated hydrological model Soil and Water Assessment Tool (SWAT), using ensemble of four high resolution (~25 km) Regional Climate Model (RCM) simulations for the near future (2021–2050) based on the SRES A1B scenario. Finally, to quantify the hydrological alterations of different flow characteristics, the Indicators of Hydrological Alteration (IHA) program based on the Range of Variability Approach (RVA) is used. This approach enables the assessment of ecologically sensitive streamflow parameters for the pre- and post-impact periods in the regions where availability of long-term ecological data is a limiting factor. Results indicate that flow variability has been significantly reduced due to dam construction with high flows being absorbed and pre-monsoon low flows being enhanced by the reservoir. Climate change alone may reduce high peak flows while a combination of dam and climate change may significantly reduce variability by affecting both high and low flows, thereby further disrupting the functioning of riverine ecosystems. We find that, in the Kangsabati River basin, influence of dam is greater than that of the climate change, thereby emphasizing the significance of direct human intervention.     

Impact of Climate Change on Salinization of Coastal Water Resources

Water Resources Management - A density-dependent numerical model was set up to quantify the actual and future (2050) salinization of a coastal aquifer in the Po Delta (Italy). SEAWAT 4.0 was used...     

Impact of Climate Change on Mediterranean Irrigation Demand: Historical Dynamics of Climate and Future Projections

Global warming is causing important changes in climate conditions, which must be studied in detail and locally in those zones where irrigated agriculture is developed—the major consumer of water worldwide. This study proposes the climatic characterization of a historical series (1971–2000) and its future projections (2011–2099) for an Irrigation District located in the Middle Ebro Valley (Spain), for three different scenarios: low, medium, and high global emission levels of greenhouse gases. Analysis of historical series reveals a significant increase in reference evapotranspiration (3.3 mm/year²; 2.4 ‰) along with a decrease in precipitation (2.5 mm/year²; 5.6 ‰). A comparison was carried out between real historical data and the scenarios produced by the climate models and it was observed that the most adequate climate model to predict climate in the study zone is MPI-ECHAM5. For the XXI century, MPI-ECHAM5 predicts cyclic climate trends but with a general increment in aridity, which intensifies according to the scenario chosen. Changes in climate are affecting agriculture doubly, since evapotranspiration requirements increase at the same time that water resources decrease. These effects are felt especially in irrigated agriculture, since the growing cycles of the main crops coincide with the months most affected by climate change.     

Optimal Ecological Management Practices (EMPs) for Minimizing the Impact of Climate Change and Watershed Degradation Due to Urbanization

Massive deforestation induced by unplanned urbanization in the hilly watersheds of Brahmaputra basin, India, has led to ecological imbalance and is gradually transforming this basin into a multi-hazard zone. Removal of green cover is also becoming a matter of global concern, as it can accelerate the adverse impacts of climate change. People coming in search of work generally reside in the hills, as they cannot afford the high cost of land in plains. This has led to deforestation of the hilly area and has resulted in increased surface erosion from the upper catchments. Though sediment and water yield from these degraded watersheds could have been minimized by implementing ecologically sustainable management practices (EMPs), such as grass land, forest land and detention pond, poor economic conditions of the people stands in the way of field implementation. On the other hand, major industries, which can be held responsible for emission of greenhouse gases, can be asked to finance greenery development in these hilly watersheds through implementation of selected EMPs to earn carbon credit for them. To convert this concept into reality, the EMP combination must be selected in such a way that it restricts sediment and water yield from the watershed within the permissible limit and maximizes its carbon sequestration capacity at minimum possible cost. Such optimal planning is a prerequisite for preparing an acceptable logical agreement between Government and private companies. Keeping this in mind, an optimization model was developed and applied to a micro watershed of Guwahati to explore its applicability in actual field. The model developed in this study provides most logical carbon credit negotiation, subject to the availability of reliable value of CO₂ sequestration for different EMPs.     

Water Structures and Climate Change Impact: a Review

Climate change impact started to play significant role since the last three decades almost in every aspects of life especially on meteorological and climatological events and their impacts on water resources, which are managed by engineering structures. Its effects on hydro-meteorological data are assessed by means of available methodologies, but the climate change impact of engineering water structures (dams, culverts, channels, wells, highways and their side drainages, levees, etc.) are not treated equally. This paper provides the review of the necessary adaptation, combat and mitigation activities against the climate change for protection, construction or augmentation of the engineering water structures design capacity. Additionally, land use practices and geomorphological changes also trigger the climate changes on the engineering water structures. The main aim of this paper is to present the impact of such changes on the engineering water structure capacity, operation and maintenance.

     

Optimal Management of an Overexploited Aquifer under Climate Change: The Lake Karla Case

This paper presents a study for finding the optimal management plan of an overexploited aquifer under global climate change. The study area is the aquifer of the basin of Lake Karla, located in the eastern part of Thessaly in Greece. An optimization method has been used to evaluate the optimum volume of water that can be extracted from the aquifer and the optimum position of the wells with the objective of water table rise to a desirable sustainable level, taking into consideration the climate change forcing. The modelling system consists of a series of interlinked models: a hydrological, a lake-aquifer, a reservoir operation, a groundwater, and an optimization model. The climate change forcing on precipitation and temperature has been evaluated using the outputs of Canadian Centre for Climate Model Analysis General Circulation Model (CGCMa2) and a hybrid downscaling method which combines a multiple regression (MLR) model and a timeseries model for two socioeconomic emissions scenarios. The results of this study show that climate change plays an important role, as it affects the optimum volume of the extracted groundwater and the position of the irrigation wells.     

气候变化对黄河流域地表水资源量的影响评估

为深入认识气候变化对黄河上中游地区地表水资源量的影响,以黄河流域花园口以上区域为研究对象,依据近50 a气象水文要素资料,基于流域年尺度的水量平衡与能量平衡原理,构建了基于Buydko水热耦合平衡的区域地表水资源量模拟模型,以年尺度的简化形式描述流域水循环,从宏观视角识别了研究区水资源量对不同降水和气温变化条件的响应规律。结果表明:若降水条件不变,气温每升高1℃,地表径流深减小6.8%;若气温条件保持不变,每增大10%的降水会导致地表径流深增大21.3%。     

气候变化对喷赤河径流过程的影响研究

为更好地应对气候变化对塔吉克斯坦积雪冰川流域水文水资源的影响,以塔吉克斯坦的喷赤河流域为研究区,采用假设情景法设定气候变化情景,基于融雪型新安江模型对该流域1981—1990年的径流进行模拟,以期定量分析流域径流对气候变化的响应程度。结果表明:1仅气温升高时,该流域多年平均径流随之增大,且1990年增幅最大;仅降水增大或减小20%时,年径流也相应地增大或减小,且1982年的径流受降水影响最明显,1986年受影响较小。2仅气温上升时,各月月均流量相应增大,增幅最大的月份为5月,增幅最小的为1月;仅降水变化时,径流的变化与它完全呈正相关关系,3月径流变化率最大,6月和10月最小。     

The Impact of Climate Change on Hydro-Meteorological Droughts Using Copula Functions

Climate change has made many alterations to the climate of earth, including hydro-climatic extreme events. To investigate the impact of climate change on hydro-meteorological droughts in the Kamal-Saleh dam basin in Markazi province, Iran, proportional to future climate conditions, a new and comprehensive index was developed with the aim of accurately estimating drought in a more realistic condition. This aggregate drought index (ADI) represented the main meteorological and hydrological characteristics of drought. Temperature and precipitation projections for future climates were simulated by five CMIP5 models and downscaled over the study area during 2050s (2040–2069) and 2080s (2070–2099) relative to the baseline period (1976–2005). By fitting five univariate distribution functions on drought severity and duration, proper marginal distributions were selected. The joint distribution of drought severity and duration was chosen from five types of copula functions. The results revealed that in future, severe droughts are expected to frequently occur in a shorter period.

     

白洋淀气候变化及对生态系统的影响

根据1955年-2010年白洋淀地区气象数据及生态资料,研究了气候变化对白洋淀湿地生态系统的影响,以期为白洋淀湿地保护和可持续发展提供依据。结果表明:近56年来,白洋淀地区的气温总体呈现上升趋势,且在2007年达到最高值,而降水量、平均风速和日照时数均呈现下降趋势,其中1996年以后的降水量均低于56年的平均降水量。白洋淀地区降水量和年最高水位呈明显的正相关关系,平均气温和水域面积的变化趋势则相反。水位、水域面积的变化以及人类活动等因素影响了白洋淀水质和生物多样性以及不同土地利用类型的分配比例。     

气候变化对长白山区地方水电的影响与应对策略

气候变化将对直接利用气候资源的地方水电有正、反两方面影响。由于水电具有减少温室气体排放的功能,气候变化对清洁能源的需求不断加大,给地方水电提供了新的发展方向与契机。     

Impact of Future Climate Change on Water Temperature and Thermal Habitat for Keystone Fishes in the Lower Saint John River,Canada

Water temperature is a key determinant of biological processes in rivers. Temperature in northern latitude rivers is expected to increase under climate change, with potentially adverse consequences for cold water-adapted species. In Canada, little is currently known about the timescales or magnitude of river temperature change, particularly in large (≥10⁴ km²) watersheds. However, because Canadian watersheds are home to a large number of temperature-sensitive organisms, there is a pressing need to understand the potential impacts of climate change on thermal habitats. This paper presents the results of a study to simulate the effects of climate change on the thermal regime of the lower Saint John River (SJR), a large, heavily impounded, socio-economically important watershed in eastern Canada. The CEQUEAU hydrological-water temperature model was calibrated against river temperature observations and driven using meteorological projections from a series of regional climate models. Changes in water temperature were assessed for three future periods (2030–2034, 2070–2074 and 2095–2099). Results show that mean water temperature in the SJR will increase by approximately ~1 °C by 2070–2074 and a further ~1 °C by 2095–2099, with similar findings for the maximum, minimum and standard deviation. We calculated a range of temperature metrics pertaining to the Atlantic Salmon and Striped Bass, key species within the SJR. Results show that while the SJR will become increasingly thermally-limiting for Atlantic Salmon, the Striped Bass growth season may actually lengthen under climate change. These results provide an insight into how climate change may affect thermal habitats for fish in eastern Canadian rivers.     

Impact of Climate Change on Water Resources in the Tarim River Basin

The plausible association between climate change and the variability of water resources in the Tarim River basin, west China is investigated in this study. The long-term trend of the hydrological time series including temperature, precipitation, and streamflow are detected by using both parametric and nonparametric techniques. The possible association between the El Niño/Southern Oscillation (ENSO) and these three kinds of time series are tested. This study enhances the knowledge of the climate change impact on water resources in the Tarim River basin. The conclusion obtained in this investigation shows that the temperature experienced a significant monotonic increase at the 5% level of significance during the past 50 yr, and precipitation also exhibited an upward tendency during the past several decades. A significant jump is also detected for both time series around 1986. This may be resulted from the possible impact of climate change, although the interior climate mechanism needs further investigation. Although precipitation and the streamflow from the headwater of the Tarim River exhibited significant increase, decreasing trend has been detected in the streamflow along the mainstream of the river. It implies that anthropogenic activities instead of the climate change dominated the streamflow cessation and the drying-up of the river. Results also showed that no significant association exists between the ENSO and the temperature, precipitation and streamflow in the study area. This conclusion shows that the water curtailment, river desiccation, and ecosystem deterioration in the Tarim River basin may be mainly resulted from the impact of human activities.     

三峡蓄水对局地气候变化的影响

大型水体会对局部地区(局地)气候条件造成影响,三峡工程是当今世界规模最大的水利水电枢纽工程,为了分析三峡蓄水对当地气候变化的影响,以三峡库区10个站点为研究对象,利用气候倾向率、CVM检验等方法,系统分析了三峡库区66 a来气候变化特征以及蓄水对局地气候变化的影响。结果表明,三峡蓄水后局地温度下降,影响大坝附近299.83 km²的地区,影响距离最远距大坝12.65 km,大坝最近的秭归站温度在1997年发生突变,蓄水后20 a秭归站年平均温度较蓄水前20 a下降1.15 ℃;蓄水造成局地降水量增加,影响大坝附近2 914.88 km²的地区,影响距离最远距大坝109.15 km,大坝最近的秭归站降水在1997年突变,蓄水后20 a秭归站平均降水量较蓄水前上升245.90 mm;蓄水造成局地相对湿度增加,秭归、兴山站相对湿度分别在1997年、2003年突变,蓄水后20 a秭归站相对湿度较蓄水前20 a上升5.29%;蓄水造成局地日照时数下降,影响大坝附近2 045.66 km²的地区,影响距离距大坝最远41.06 km,距大坝最近的秭归站日照时数在2002年突变,蓄水后20 a秭归站日照时数较蓄水前20 a下降33.87 h。蓄水对气象要素影响的范围较小,对各要素共同造成影响的范围仅75.27 km²,各要素全部在蓄水期间发生突变的仅秭归一站。     

气候变化对黄河上游流域径流影响分析

近年来在气候变化和人类活动的共同影响下,黄河上游地表水资源偏枯形势严峻,严重影响了我国北方地区经济的可持续发展。为研究气候变化对径流的影响,利用黄河上游14个气象站点的逐月降水、气温和潜在蒸发资料以及唐乃亥水文站和上诠水文站的径流资料,采用线性相关法和Mann-Kendall法分析了气候变化对黄河上游流域径流的影响,结果表明,研究区域降水大致呈不显著递增趋势,气温、蒸发量呈显著递增趋势,径流量呈现显著减少的趋势;径流量发生突变的时间与气象因素的一致性较差,因此,可以得出径流量不仅受气温、降水、蒸发等气候因子的影响,还受到其他因素例如土壤、植被等因素的影响。     

气候变化对流域水资源影响评价中的不确定性问题

<正>确评价气候变化背景下的流域水资源是实现其可持续性开发利用的基础,气候变化对流域水资源影响的评价一般采取气候情景驱动水文循环模型的方法。由于气候系统和水文循环过程的复杂性,该方法在气候情景、水文循环模拟及评价过程中存在很大的不确定性。提高流域气候情景预测精度和完善影响评价模型是降低气候变化影响评价结果不确定性的主要方式。本文介绍了气候变化对流域水资源影响的一般评价方法,分析了影响评价结果不确定性的因素,并讨论了降低评价结果不确定性的方式。     

气候变化对塔里木河流域作物需水量的影响

对塔里木河流域26个气象站1961-2005年的常规气象观测资料进行统计分析,结果表明流域内灌区平均气温近45 a来显著上升,其中2000年以后气温较45 a平均气温升高0.75℃,平均每10 a上升0.28℃,升幅达13.75％.采用FAO-布莱尼-克雷多方法,结合作物系数,计算了流域内主要作物的需水量和农田灌溉需水量,结果表明:流域灌区内现状气温上升的情景下,作物参考蒸散量增加量为24.49 mm,增加幅度为2.83％;灌区小麦、果树、棉花、瓜菜和牧草等作物需水量将分别增加3.39％(70.62 mm)、7.30％(152.35 mm)、3.66％ (76.30 mrn)、2.98％ (62.22 mm)、4.49％(93.58 mm);农田灌溉需水量共增加8.44亿m3.     

Impact of Climate Change on the Hydrology of Upper Tiber River Basin Using Bias Corrected Regional Climate Model

The use of regional climate model (RCM) outputs has been getting due attention in most European River basins because of the availability of large number of the models and modelling institutes in the continent; and the relative robustness the models to represent local climate. This paper presents the hydrological responses to climate change in the Upper Tiber River basin (Central Italy) using bias corrected daily regional climate model outputs. The hydrological analysis include both control (1961–1990) and future (2071–2100) climate scenarios. Three RCMs (RegCM, RCAO, and PROMES) that were forced by the same lateral boundary condition under A2 and B2 emission scenarios were used in this study. The projected climate variables from bias corrected models have shown that the precipitation and temperature tends to decrease and increase in summer season, respectively. The impact of climate change on the hydrology of the river basin was predicted using physically based Soil and Water Assessment Tool (SWAT). The SWAT model was first calibrated and validated using observed datasets at the sub-basin outlet. A total of six simulations were performed under each scenario and RCM combinations. The simulated result indicated that there is a significant annual and seasonal change in the hydrological water balance components. The annual water balance of the study area showed a decrease in surface runoff, aquifer recharge and total basin water yield under A2 scenario for RegCM and RCAO RCMs and an increase in PROMES RCM under B2 scenario. The overall hydrological behaviour of the basin indicated that there will be a reduction of water yield in the basin due to projected changes in temperature and precipitation. The changes in all other hydrological components are in agreement with the change in projected precipitation and temperature.