Sensitivity of Runoff, Soil Moisture and Reservoir Design to Climate Change in Central Indian River Basins

Climate change due to a doubling of the carbon dioxide in the atmosphere and its possible impacts on the hydrological cycle are a matter of growing concern. Hydrologists are specifically interested in an assessment of the impacts on the occurrence and magnitude of runoff, evapotranspiration, and soil moisture and their temporal and spatial redistribution. Such impacts become all the more important as they may also affect the water availability in the storage reservoirs. This paper examines the regional effects of climate change on various components of the hydrologic cycle viz., surface runoff, soil moisture, and evapotranspiration for three drainage basins of central India. Plausible hypothetical scenarios of precipitation and temperature changes are used as input in a conceptual rainfall-runoff model. The influences of climate change on flood, drought, and agriculture are highlighted. The response of hypothetical reservoirs in these drainage basins to climate variations has also been studied. Results indicate that the basin located in a comparatively drier region is more sensitive to climatic changes. The high probability of a significant effect of climate change on reservoir storage, especially for drier scenarios, necessitates the need of a further, more critical analysis of these effects.     

Assessing the site-specific impacts of climate change on hydrology, soil erosion and crop yields in the Loess Plateau of China

Climate changes may have great impacts on the fragile agro-ecosystems of the Loess Plateau of China, which is one of the most severely eroded regions in the world. We assessed the site-specific impacts of climate change during 2010?C2039 on hydrology, soil loss and crop yields in Changwu tableland region in the Loess Plateau of China. Projections of four climate models (CCSR/NIES, CGCM2, CSIRO-Mk2 and HadCM3) under three emission scenarios (A2, B2 and GGa) were used. A simple spatiotemporal statistical method was used to downscale GCMs monthly grid outputs to station daily weather series. The WEPP (Water and Erosion Prediction Project) model was employed to simulate the responses of agro-ecosystems. Compared with the present climate, GCMs projected a ?2.6 to 17.4% change for precipitation, 0.6 to 2.6°C and 0.6 to 1.7°C rises for maximum and minimum temperature, respectively. Under conventional tillage, WEPP predicted a change of 10 to 130% for runoff, ?5 to 195% for soil loss, ?17 to 25% for wheat yield, ?2 to 39% for maize yield, ?14 to 18% for plant transpiration, ?8 to 13% for soil evaporation, and ?6 to 9% for soil water reserve at two slopes during 2010?C2039. However, compared with conventional tillage under the present climate, conservation tillage would change runoff by ?34 to 71%, and decrease soil loss by 26 to 77% during 2010?C2039, with other output variables being affected slightly. Overall, climate change would have significant impacts on agro-ecosystems, and adoption of conservation tillage has great potential to reduce the adverse effects of future climate changes on runoff and soil loss in this region.     

RCP4.5情景下中国未来干湿变化预估

本文采用国际耦合模式比较计划第五阶段(CMIP5)中21个气候模式的试验数据, 利用土壤湿度以及由其他8个地表气象要素计算所得的干旱指数, 预估了RCP4.5(Representative Concentration Pathway 4.5)情景下21世纪中国干湿变化。结果表明:全球气候模式对1986～2005年中国现代干湿分布具备模拟能力, 尽管在西部地区模式与观测间存在一定的差异。在RCP4.5情景下, 21世纪中国区域平均的标准化降水蒸散发指数和土壤湿度均有减小趋势, 与之对应的是短期和长期干旱发生次数增加以及湿润区面积减小。从2016到2100年, 约1.5%～3.5%的陆地面积将从湿润区变成半干旱或半湿润区。空间分布上, 干旱化趋势明显的区域主要位于西北和东南地区, 同时短期和长期干旱发生次数在这两个地区的增加幅度也最大, 未来干旱化的发生时间也较其他地区要早;只在东北和西南地区未来或有变湿倾向, 但幅度较小。在季节尺度上, 北方地区变干主要发生在暖季, 南方则主要以冷季变干为主。造成中国干旱化的原因主要是由降水与蒸散发所表征的地表可用水量减少。     

西南喀斯特地区中层土壤湿度时空变化特征

本文利用中国西南喀斯特区域内该区域内全部31个农业气候站点1991～2013年50cm层土壤湿度(体积含水量)旬资料，应用线性趋势分析、EOF空间分解方法，详细分析其时空演变特征，进一步认识中国西南喀斯特地区土壤湿度的时空演变特征，结果表明:(1)西南喀斯特地区中层土壤湿度多年平均的空间大小及分布具有明显的区域性差异。(2)1991～2013年季节平均中，中层秋季的土壤湿度整体最高，夏季土壤湿度的低值区范围最大，反映了西南喀斯特地区土壤的独特性。(3)中层土壤湿度年际变化有明显的“南升北降”空间分布特征，相应线性趋势分析和EOF的结果也同样印证了这一主要特征。(4)50cm的年际变化较稳定且波动趋势较小；整体的土壤湿度以夏、秋季最高，春、冬季较低。      

大规模城镇化对黄淮海地区气候及水资源影响的数值试验

黄淮海地区是我国传统的农耕区,也是经济快速发展、城镇化进程快速推进的区域之一,使得该地区植被覆盖发生了明显变化。为研究城镇化对气候与水资源的影响,应用RegCM3区域气候模式,通过控制试验和敏感性试验,在保证积分时间（2001-2005年）的情况下,输出降水、蒸发、温度、湿度、土壤水分、径流、整层水汽含量等资料,利用敏感性试验和控制试验输出量的差值,来分析黄淮海地区城镇化对气候和水资源要素的影响情况。结果表明,城镇化对研究地区气候及水资源造成的影响主要表现在使局地风场减弱、降水减少、地面气温增加、空气湿度减小、水资源总量减少、土壤含水量减少和地表径流增加等方面,从而对气候和水资源造成影响。     

兰江流域近43年气候变化及对水资源的影响

利用累积距平法对兰江流域近43年（1961-2003年）气温、降水量和径流量资料进行分析，研究兰江流域气候变化及其气候变化对水资源的影响。结果显示：兰江流域近43年来气温、降水量总的趋势是上升的；1990年代是兰江流域气温上升和降水增加最显著的时段，主要表现在冬春气温明显上升，夏季降水量明显增加：兰江流域年径流深与年降水量基本保持同步变化。兰江流域过去43年的气候变化对流域内水资源产生了较大的影响，而且由于兰江流域内水资源空间分布差异较大，致使流域内人均水资源占有量较少的金华地区易受气候变化影响而出现供水紧张。     

SOME ADVANCES IN CLIMATE WARMING IMPACT RESEARCH IN CHINA SINCE 1990

Increasing the concentration of greenhouse gases in the atmosphere will strengthen the naturalgreenhouse effect,which could lead to global climate warming and more other changes.China is alargely agricultural country with a large size of population and the relative shortages of farminglands and water resources,thus increasing the importance of climate warming for national economydevelopment.Therefore,Chinese government and scientists have paid great attention to theimpact-assessment of climate warming on national economy in China,especially during the past 10years.This presentation will briefly describe some major issues of climate warming impact researchon national vegetation,agriculture,forest,water resources,energy use and regional sea level forChina,etc.As a result,all climate change scenarios derived by GCMs suggest a substantial change in thecharacteristic natural vegetation types.It is also shown that comparing with the distributionsimulated under the normal time period 1951—1980 as the present climate,by 2050 large changesin cropping systems would occur almost everywhere in China.Climate warming would lead toincrease cropping diversification and multiplication.Unfortunately,the possible net balancebetween precipitation and evapotranspiration would be negative and it would lead to reduce thegrain production in China significantly due to enhanced moisture stress in soil.The most evidentinfluence of climate warming on water resources would happen in Huanghe-Huaihe-Haihe Basin andthe water supply-demand deficit would be substantially enhanced in this area.And also,a warmerclimate for China will alter the energy requirement for domestic heating and cooling,that is,reduce energy use for heating in northern China and increase energy consumption for cooling insouthern China.     

Future African Water Resources: Interactions between Soil Degradation and Global Warming

This study uses a well-established water balance methodology to evaluate the relative impact of global warming and soil degradation due to desertification on future African water resources. Using a baseline climatology, a GCM global warming scenario, a newly derived soil water-holding capacity data set, and a worldwide survey of soil degradation between 1950 and 1980, four climate and soil degradation scenarios are created to simulate the potential impact of global warming and soil degradation on African water resources for the 2010–2039 time period. Results indicate that, on a continental scale, the impact of global warming will be significantly greater than the impact of soil degradation. However, when only considering the locations where desertification is an issue (wet and dry climate regions), the potential effects of these two different human impacts on local water resources can be expected to be on the same order of magnitude. Drying associated with global warming is primarily the result of increased water demand (potential evapotranspiration) across the entire continent. While there are small increases in precipitation under global warming conditions, they are inadequate to meet the increased water demand. Soil degradation is most severe in highly populated, wet and dry climate regions and results in decreased water-holding capacities in these locations. This results in increased water surplus conditions during wet seasons when the soil's ability to absorb precipitation is reduced. At the same time, water deficits in these locations increase because of reduced soil water availability in the dry seasons. The net result of the combined scenarios is an intensification and extension of drought conditions during dry seasons.     

气候变化对中国水安全的影响研究

 全球变暖是目前最重要的环境问题之一,水是全球气候变化最直接和最重要的影响领域。全球气候变暖将加速大气环流和水文循环过程,引起水资源量及其空间分布的变化,进而可能导致水资源短缺问题更加突出、水生态环境问题进一步恶化、洪涝灾害威胁更加严重等一系列问题。本文从防洪安全、供水安全、水生态环境安全和水工程安全4个方面分别阐述气候变化对中国水安全的可能影响。     

气候变化对中国水安全的影响研究

全球变暖是目前最重要的环境问题之一,水是全球气候变化最直接和最重要的影响领域。全球气候变暖将加速大气环流和水文循环过程,引起水资源量及其空间分布的变化,进而可能导致水资源短缺问题更加突出、水生态环境问题进一步恶化、洪涝灾害威胁更加严重等一系列问题。本文从防洪安全、供水安全、水生态环境安全和水工程安全4个方面分别阐述气候变化对中国水安全的可能影响。     

Possible Impacts of Climate Change on Soil Moisture Availability in the Southeast Anatolia Development Project Region (GAP): An Analysis from an Agricultural Drought Perspective

This paper presents probable effects of climate change on soil moisture availability in the Southeast Anatolia Development Project (GAP) region of Turkey. A series of hypothetical climate change scenarios and GCM-generated IPCC Business-as-Usual scenario estimates of temperature and precipitation changes were used to examine implications of climate change for seasonal changes in actual evapotranspiration, soil moisture deficit, and soil moisture surplus in 13 subregions of the GAP. Of particular importance are predicted patterns of enhancement in summer soil moisture deficit that are consistent across the region in all scenarios. Least effect of the projected warming on the soil moisture deficit enhancement is observed with the IPCC estimates. The projected temperature changes would be responsible for a great portion of the enhancement in summer deficits in the GAP region. The increase in precipitation had less effect on depletion rate of soil moisture when the temperatures increase. Particularly southern and southeastern parts of the region will suffer severe moisture shortages during summer. Winter surplus decreased in scenarios with increased temperature and decreased precipitation in most cases. Even when precipitation was not changed, total annual surplus decreased by 4 percent to 43 percent for a 2°C warming and by 8 percent to 91 percent for a 4°C warming. These hydrologic results may have significant implications for water availability in the GAP as the present project evaluations lack climate change analysis. Adaptation strategies – such as changes in crop varieties, applying more advanced dry farming methods, improved water management, developing more efficient irrigation systems, and changes in planting – will be important in limiting adverse effects and taking advantage of beneficial changes in climate.     

近十年来我国气候变暖影响研究的若干进展

近年来，我国政府和科技界十分关注气候王馥棠变暖对我国经济发展可能影响的评估, 开展了许多重大项目和课题的研究。该文仅就气候变暖对我国自然植被、农业、森林、水资源、能源利用和区域海平面上升等领域影响评估研究的若干有意义的初步结果简要归纳和评述如下:取自不同GCM模型的未来气候变化情景下的影响评估模拟表明，我国的特征性自然植被类型将会发生明显的变化。同当前气候（1951~1980年）下的模拟分布相比，到2050年我国几乎所有地方的农业种植制度均将发生较大变化；气候变暖将导致复种指数增加和种植方式多样化，但降水与蒸散之间可能出现的负平衡和土壤水分胁迫的增加以及生育期的可能缩短，最终将导致我国主要作物的产量下降。气候变暖对我国水资源最明显的影响将会发生在黄淮海流域，这个区域的水资源供需短缺将大大提高。同时，气候变暖将改变我国室内取暖和降温的能源需求关系:北方冬季取暖的能源消耗将减少, 而南方夏季降温的能源消耗将会增加。海平面的上升将使我国三个主要沿海低洼脆弱区，即珠江三角洲、长江三角洲和黄河三角洲，面临部分遭受海水淹没的威胁。     

Spatial and Temporal Variability of Water Availability in the Yellow River Basin

The changes in hydrological processes in the Yellow River basin were simulated by using the Community Land Model(CLM,version 3.5),driven by historical climate data observed from 1951 to 2008.A comparison of modeled soil moisture and runoff with limited observations in the basin suggests a general drying trend in simulated soil moisture,runoff,and precipitation-evaporation balance(P-E) in most areas of the Yellow River basin during the observation period.Furthermore,annual soil moisture,runoff,and P-E averaged over the entire basin have declined by 3.3%,82.2%,and 32.1%,respectively.Significant drying trends in soil moisture appear in the upper and middle reaches of the basin,whereas a significant trend in declining surface runoff and P-E occurred in the middle reaches and the southeastern part of the upper reaches.The overall decreasing water availability is characterized by large spatial and temporal variability.     

The implications of climate policy for the impacts of climate change on global water resources

This paper assesses the implications of climate policy for exposure to water resources stresses. It compares a Reference scenario which leads to an increase in global mean temperature of 4 °C by the end of the 21st century with a Mitigation scenario which stabilises greenhouse gas concentrations at around 450 ppm CO₂e and leads to a 2 °C increase in 2100. Associated changes in river runoff are simulated using a global hydrological model, for four spatial patterns of change in temperature and rainfall. There is a considerable difference in hydrological change between these four patterns, but the percentages of change avoided at the global scale are relatively robust. By the 2050s, the Mitigation scenario typically avoids between 16 and 30% of the change in runoff under the Reference scenario, and by 2100 it avoids between 43 and 65%. Two different measures of exposure to water resources stress are calculated, based on resources per capita and the ratio of withdrawals to resources. Using the first measure, the Mitigation scenario avoids 8-17% of the impact in 2050 and 20-31% in 2100; with the second measure, the avoided impacts are 5-21% and 15-47% respectively. However, at the same time, the Mitigation scenario also reduces the positive impacts of climate change on water scarcity in other areas. The absolute numbers and locations of people affected by climate change and climate policy vary considerably between the four climate model patterns.     

具有Horton及Dunne机制的径流模型在VIC模型中的应用(英)

地表径流主要由蓄满(Dunne)和超渗产流(Horton)机制产生;土壤性质的空间变异性、前期土壤水、地形及降水的空间变异性导致不同的径流机制。在研究区域或模型网格内,蓄满产流及超渗产流可能同时出现,缺乏考虑任何一种机制以及土壤性质的次网格空间变率可能导致地表径流的过高或过低估计,从而影响土壤水的计算。利用Philip入渗公式用于时间压缩逼近(TCA)给出了一种径流参数化方法,该方法可以动态实现模型网格中的Horton及Dunne产流机理,它考虑了土壤空间变异性对Horton和Dunne径流的影响。该径流模型应用到基于水文原理的陆面过程模型VIC,在淮河流域及美国宾西法尼亚州的一个流域进行了测试,结果表明:新的参数化方法对地表径流和土壤水分含量的分配起着重要作用,对于改进径流和土壤水的模拟有重要意义。     

土壤湿度年际异常对中国春、夏季气候模拟的影响

基于NCAR大气模式CAM3.1模式,设计了有、无土壤湿度年际异常两组试验对中国区域近40a(1961-2000年)气候进行了模拟。从气候态和年际变率的角度,通过分析两组试验的差值场来探讨土壤湿度年际异常对气候模拟的影响,并初步探讨了影响的可能机制。结果表明:模式模拟的温度和降水对土壤湿度的年际异常非常敏感,土壤湿度的年际变化对中国春夏季气候及其年际变率均有显著影响。当不考虑土壤湿度年际异常时,模式模拟的春夏季平均温度、最高温度、最低温度在我国大范围内降低,春夏季降水在东部大部分地区明显减少,西部增加。而模式模拟的春夏季温度、降水年际变率在中国大部分地区减弱。但当考虑土壤湿度的年际变化,则能在一定程度上提高模式对气候年际变率的模拟能力。在进一步分析表明土壤湿度年际异常时,主要通过改变地表能量通量和环流场,对温度、降水产生影响。当不考虑土壤湿度年际异常时,地表净辐射通量减少,地表温度降低,感热通量减少。感热通量差值场的空间变化和温度差值场的空间变化一致,感热通量对温度有一定影响。而潜热通量差值场的空间变化和降水的差值场的空间变化一致,可见降水受地表潜热通量的影响。土壤湿度年际异常引起的环流场的变化也是导致气候变化的原因之一,地表能量和环流场年际变率的改变对春夏季气候年际变率存在一定影响。     

气候变化及人类活动对西北干旱区水资源影响研究综述

本文回顾了西北干旱区气候变化事实及其对水资源影响的最新研究进展,从气候变化和人类活动两个角度综述了水资源变化的原因,以及未来西北干旱区水资源变化与适应对策。研究表明：1961年以来西北干旱区呈现明显暖湿化趋势,其中冬季增温最快,夏季降水增加速率最大。伊利河谷、塔城等地区增温趋势最大,北疆降水量增加最多。受气候变暖导致冰雪快速消融和山区降水增加的影响,西北干旱区西部河流黑河、疏勒河、塔里木河出山口径流量显著增加。由于东部河流石羊河径流的补给主要靠降水,降水的减少导致径流呈现下降趋势。不合理人类活动造成石羊河、黑河和开都河中下游径流减少。本文提出了西北干旱区亟待深入研究的任务：极端天气气候事件的变化规律及其对水资源影响;未来气候变化和水资源的预估;气候变化归因研究;气候变化-社会经济活动一体化适应策略选择;水资源科学合理定量分配等。     

气候变化对中国水资源影响的适应性评估与管理框架

通过论述气候变化对中国水资源影响的适应性评估与管理框架,提出一个气候变化影响决策评估工具,它包括：未来气候变化对中国水资源潜在影响的定性描述分析、半定量与定量分析以及适应性对策评估。由于不同气候区域所面临的水资源问题不同,选择中国4个典型案例区域,并确定不同的目标进行气候变化适应性管理综合研究,提出了甄别气候变化影响和适应性管理的新的思路、框架与方法论。该项研究为应对未来气候变化影响的水资源规划与风险管理提供了途径与方法。     

气候变化对中国水资源影响的适应性评估与管理框架

 通过论述气候变化对中国水资源影响的适应性评估与管理框架,提出一个气候变化影响决策评估工具,它包括：未来气候变化对中国水资源潜在影响的定性描述分析、半定量与定量分析以及适应性对策评估。由于不同气候区域所面临的水资源问题不同,选择中国4个典型案例区域,并确定不同的目标进行气候变化适应性管理综合研究,提出了甄别气候变化影响和适应性管理的新的思路、框架与方法论。该项研究为应对未来气候变化影响的水资源规划与风险管理提供了途径与方法。     

Mid-Century Ensemble Regional Climate Change Scenarios for the Western United States

To study the impacts of climate change on water resources in the western U.S., global climate simulations were produced using the National Center for Atmospheric Research/Department of Energy (NCAR/DOE) Parallel Climate Model (PCM). The Penn State/NCAR Mesoscale Model (MM5) was used to downscale the PCM control (20 years) and three future(2040–2060) climate simulations to yield ensemble regional climate simulations at 40 km spatial resolution for the western U.S. This paper describes the regional simulations and focuses on the hydroclimate conditions in the Columbia River Basin (CRB) and Sacramento-San Joaquin River (SSJ) Basin. Results based on global and regional simulations show that by mid-century, the average regional warming of 1 to 2.5 °C strongly affects snowpack in the western U.S. Along coastal mountains, reduction in annual snowpack was about70% as indicated by the regional simulations. Besides changes in mean temperature, precipitation, and snowpack, cold season extreme daily precipitation increased by 5 to 15 mm/day (15–20%) along theCascades and the Sierra. The warming resulted in increased rainfall at the expense of reduced snowfall, and reduced snow accumulation (or earlier snowmelt) during the cold season. In the CRB, these changes were accompanied by more frequent rain-on-snow events. Overall, they induced higher likelihood of wintertime flooding and reduced runoff and soil moisture in the summer. Changes in surface water and energy budgets in the CRB and SSJ basin were affected mainly by changes in surface temperature, which were statistically significant at the 0.95 confidence level. Changes in precipitation, while spatially incoherent, were not statistically significant except for the drying trend during summer. Because snow and runoff are highly sensitive tospatial distributions of temperature and precipitation, this study shows that (1) downscaling provides more realistic estimates of hydrologic impacts in mountainous regions such as the western U.S., and (2) despite relatively small changes in temperature and precipitation, changes in snowpack and runoff can be much larger on monthly to seasonal time scales because the effects of temperature and precipitation are integrated over time and space through various surface hydrological and land-atmosphere feedback processes. Although the results reported in this study were derived from an ensemble of regional climate simulations driven by a global climate model that displays low climate sensitivity compared with most other models, climate change was found to significantly affect water resources in the western U.S. by the mid twenty-first century.