Modeling of the Mendoza river watershed as a tool to study climate change impacts on water availability

Unmitigated anthropogenic climate change is set to exacerbate current stresses on water resources management and creates the need to develop strategies to face climate change impacts on water resources, especially in the long term. Insufficient information on possible impacts on water availability limits the organization and promotion of efforts to adapt and improve the resilience and efficiency of water systems. To document the potential impacts of climate change in the region of Mendoza, Argentina, we perform a hydrological modeling of the Mendoza River watershed using a SWAT model and project climate change scenarios to observe hydrological changes. The results show the impact of higher temperature on glaciers as river flow increases due to glacier melting; at the same time, runoff decreases as precipitation is reduced. Furthermore, the runoff timing is shifted and an earlier melting becomes more important in more pronounced climate change scenarios. Scenarios show a reduction in water availability that ranges between 1 and 10%. An additional scenario under stronger climate change conditions without glaciers data shows a reduction of the river flow by up to 11.8%. This scenario would correspond to a future situation in which glaciers have completely melted. These situations would imply a reduction in the water availability and the possibility of future unsatisfied water uses, in particular for irrigation, which received most of the available water in Mendoza, on which agricultural activities and regional economy depends.     

气候变化对中国黄淮海农业区小麦生产影响模拟研究

研究首先利用1980-2000年黄淮海农业区10个站点的农业数据对CER ES-W heat动态机理作物模型进行详细的验证,然后将CERESW-heat模型与两个全球气候模式(G ISS和H adley)结合,同时考虑到CO2对小麦的直接施肥作用,模拟了黄淮海农业区10个站点在IPCC SR ES A 2和B2两个气候情景下雨养和灌溉小麦产量和水分利用的变化趋势。得到如下结论:在不考虑CO2直接肥效的情况下,黄淮海农业区雨养小麦全面减产,空间分布特点是西部减产幅度大,东部减产幅度小;在充分灌溉的情况下,灌溉小麦产量维持了现有水平,但灌溉水量增加。因此,在未来该地区水资源短缺的情况下,如何合理利用有限的水资源将成为黄淮海农业区主要面临的问题。在考虑CO2直接肥效的情况下,雨养和灌溉小麦产量都全面增产,雨养小麦的增产幅度明显偏高,灌溉小麦约增产10%～30%,但CO 2的肥效能否充分实现还需要进一步研究证明。     

Adaptation to changing water resources in the Ganges basin, northern India

An ensemble of regional climate model (RCM) runs from the EU HighNoon project are used to project future air temperatures and precipitation on a 25 km grid for the Ganges basin in northern India, with a view to assessing impact of climate change on water resources and determining what multi-sector adaptation measures and policies might be adopted at different spatial scales.The RCM results suggest an increase in mean annual temperature, averaged over the Ganges basin, in the range 1–4 °C over the period from 2000 to 2050, using the SRES A1B forcing scenario. Projections of precipitation indicate that natural variability dominates the climate change signal and there is considerable uncertainty concerning change in regional annual mean precipitation by 2050. The RCMs do suggest an increase in annual mean precipitation in this region to 2050, but lack significant trend. Glaciers in headwater tributary basins of the Ganges appear to be continuing to decline but it is not clear whether meltwater runoff continues to increase. The predicted changes in precipitation and temperature will probably not lead to significant increase in water availability to 2050, but the timing of runoff from snowmelt will likely occur earlier in spring and summer. Water availability is subject to decadal variability, with much uncertainty in the contribution from climate change.Although global social-economic scenarios show trends to urbanization, locally these trends are less evident and in some districts rural population is increasing. Falling groundwater levels in the Ganges plain may prevent expansion of irrigated areas for food supply. Changes in socio-economic development in combination with projected changes in timing of runoff outside the monsoon period will make difficult choices for water managers.Because of the uncertainty in future water availability trends, decreasing vulnerability by augmenting resilience is the preferred way to adapt to climate change. Adaptive policies are required to increase society's capacity to adapt to both anticipated and unanticipated conditions. Integrated solutions are needed, consistent at various spatial scales, to assure robust and sustainable future use of resources. For water resources this is at the river basin scale. At present adaptation measures in India are planned at national and state level, not taking into account the physical boundaries of water systems. To increase resilience adaptation plans should be made locally specific. However, as it is expected that the partitioning of water over the different sectors and regions will be the biggest constraint, a consistent water use plan at catchment and river basin scale may be the best solution. A policy enabling such river basin planning is essential.     

降水和人类活动对松花江径流量变化的贡献率

为了估算自然因素和人类活动对松花江流域径流量变化的相对影响程度,采用累积距平、有序聚类等方法,对松花江干流6 个水文站1955-2010 年径流量序列进行了分析,揭示了径流量变化过程中各站都存在3 个突变点及被其分割的4 个变化阶段。应用累积量斜率变化率比较方法,在不考虑蒸散影响时定量估算了不同阶段降水和人类活动对径流量的贡献率。结果表明:与基准期相比,之后三个时期降水对径流量的贡献率约为26%~35%、0.1%~10%和25%~43%,而人类活动对径流量的贡献率分别约为65%~74%、90%~99.9%和57%~75%。可见人类活动是松花江流域径流量变化最主要的影响因素。虽然在国内大多数流域仍在增强,但在松花江流域自1999年以来已明显小于之前两个时期,却仍然高于降水量的影响程度。     

我国东部河流水文水质对气候变化响应的研究

基于A2和B2气候变化情景,采用统计降尺度模型SDSM,将由3个国际上流行的大气环流模式GCMs(Had CM3、CSIRO-Mk2和CGCM2)模拟的未来我国东部长乐江流域的气温和降水,与水土评价模型SWAT相耦合,分析了该流域水文水质对气候变化的响应,并比较了3个大气环流模式模拟结果的异同.结果表明,所有气候情景下,TN浓度有明显的升高趋势;TP浓度有增有减,总体上仍呈微弱增加趋势.河川径流呈微弱减少趋势,而营养物负荷量呈微弱增加趋势,说明该流域水文水质状况受气温升高的影响大于降水微弱增加的影响.另外,在不同的气候变化情景下,年内径流和营养物负荷变化情况存在较大差异.研究结果可为理解河流水环境对气候变化的响应及其应对管理提供理论依据.     

气候变化对莱州湾地区水资源脆弱性的影响

论文首先分析了在现状年(1993年)供水能力和需水条件下,1960～1993年的气候波动对莱州湾地区水资源供需平衡和脆弱性的影响。然后根据未来气候情景分析了在2000规划年和2020规划年供水能力和需水要求下,未来气候变化(2000～2042年)对水资源供需平衡及脆弱性的影响。在农业需水保证率50%时,2000～2019年水资源供需基本平衡,但2020～2042年水资源短缺20～57亿m³。若考虑未来气温的上升,则水资源短缺进一步加大。因此,2020年以后需在调入56亿m³客水资源基础上,从区外调入更多稳定的水量以保证该地区社会经济的可持续发展。     

Impacts of Global Climate Change on Mediterranean Agrigulture: Current Methodologies and Future Directions. An Introductory Essay

Current trends in Mediterranean agriculture reveal differences between the Northern and Southern Mediterranean countries as related to population growth, land and water use, and food supply and demand. The changes in temperature and precipitation predicted by general circulation models for the Mediterranean region will affect water availability and resource management, critically shaping the patterns of future crop production. Three companion papers analyze in detail future impacts of predicted climate change on wheat (Triticum aestivum L.) and maize (Zea mays L.) production in Spain, Greece, and Egypt, and test farm- level adaptation strategies such as early planting and cultivar change with the aid of dynamic crop models. Strategies to improve the assessment of the potential effects of future climate change on agricultural production are discussed.     

Impact of climate change on regional irrigation water demand in Baojixia irrigation district of China

Water scarcity in China would possibly be aggravated by rapid increase in water demand for irrigation due to climate change. This paper focuses on the mechanism of climate change impact on regional irrigation water demand by considering the dynamic feedback relationships among climate change, irrigation water demand and adaptation measures. The model in implemented using system dynamics approach and employed in Baojixia irrigation district located in Shaanxi Province of China to analyses the changes in irrigation water demand under different climate change scenarios. Obtained results revealed that temperature will be the dominant factor to determine irrigation water demand in the area. An increase of temperature by 1 °C will result in net irrigation water demand to increase by about 12,050?×?10⁴ m³ and gross water demand by about 20,080?×?10⁴ m³ in the area. However, irrigation water demand will not increase at the same rate of temperature rise as the adaptation measures will eventually reduce the water demand increased by temperature rise. It is expected that the modeling approach presented in this study can be used in adopting policy responses to reduce climate change impacts on water resources.     

The role of rainfed agriculture in securing food production in the Nile Basin

A better use of land and water resources will be necessary to meet the increasing demand for food in the Nile basin. Using a hydro-economic model along the storyline of three future political cooperation scenarios, we show that the future of food production in the Basin lies not in the expansion of intensively irrigated areas and the disputed reallocation of water, but in utilizing the vast forgotten potential of rainfed agriculture in the upstream interior, with supplemental irrigation where needed. Our results indicate that rainfed agriculture can cover more than 75% of the needed increase in food production by the year 2025. Many of the most suitable regions for rainfed agriculture in the Nile basin, however, have been destabilized by recent war and civil unrest. Stabilizing those regions and strengthening intra-basin cooperation via food trade seem to be better strategies than unilateral expansion of upstream irrigation, as the latter will reduce hydropower generation and relocate, rather than increase, food production.     

滏阳河流域的水资源问题

根据对华北地区水资源短缺最严重的滏阳河流域的实证研究表明,随着部门和上下游用水者之间用水竞争程度的加剧,流域从开放向闭合的转变,地下水位的逐年下降及引致的环境问题,节水的空间也变得十分有限。解决未来水资源短缺的问题很大程度上将依赖于如何运用政策、制度和经济措施实现水资源的优化配置和综合管理,提高灌区的运行绩效和实现有效的产权制度创新。     

Climate change and water resources management in Tuwei river basin of Northwest China

Water resources are an integral part of the socio-economic-environmental system. Water resources have dynamic interactions with related social, economic and environmental elements, as well as regulatory factors that are characterized by non-linear and multi-loop feedbacks. In this paper, a complex System Dynamic (SD) model is used to study the relationship among population growth, economic development, climate change, management strategies and water resources, and identify the best management strategy to adapt with the changing environment in the Tuwei river basin of Northwest China. Three management alternatives viz. business as usual, water supply management and water demand management are studied under different climate change scenarios. Results indicate that water shortage rate in Tuwei river basin may increase up to 80 % by the year 2030 if current management practices are continued or the supply based management strategy is adopted. On the other hand, water demand management can keep the water shortage rate within a tolerable limit and therefore can be considered as the sustainable strategy for water resources management to maintain the economic growth and ecological status of the Tuwei river basin.     

Estimating the non-market benefits of climate change adaptation of river ecosystem services: A choice experiment application in the Aoos basin,Greece

Mountains are important global reservoirs of water resources. However they are highly vulnerable to climate change as limited alterations in temperature and precipitation may cause harmful effects to water systems. Southern Europe and especially Greece are expected to undergo a drought trend over the next decades, resulting in less recharge for the aquifers and water services reduction. Thus, climate change may distort both natural and socioeconomic characteristics of freshwater ecosystem services deteriorating the general social welfare related to them. This paper examines the economic impacts of climate change on river uses of the Aoos basin in Greece. In this regard, a choice experiment is conducted to estimate the value changes in different ecological and economic services in a mountain community. The econometric simulations using conditional logit, random parameters logit and latent class models reveal that despite existing preference heterogeneity, respondents on average derive positive and significant welfare effects from climate change adaptation measures. The findings of the survey may assist in adaptation planning for the Aoos River basin, with possible extensions to other river systems enduring similar climate change indications.     

Global evaluation of the effects of agriculture and water management adaptations on the water-stressed population

Fresh water is one of the most important resources required for human existence, and ensuring its stable supply is a critical issue for sustainable development. The effects of a general set of agriculture and water management adaptations on the size of the world’s water-stressed population were assessed for a specific but consistent scenario on socio-economic development and climate change during the 21st century. To maintain consistency with agricultural land use change, we developed a grid-based water supply–demand model integrated with an agro-land use model and evaluated the water-stressed population using a water withdrawals-to-availability ratio for river basins. Our evaluation shows that, if no adaptation options are implemented, the world’s water-stressed population will increase from 1.8 billion in 2000 to about 3.3 billion in 2050, and then remain fairly constant. The population and economic growth rather than climate change will be dominant factors of this increase. Significant increase in the water-stressed population will occur in regions such as North Africa and the Middle East, India, Other South Asia, China and Southeast Asia. The key adaptation options differ by region, depending on dominant crops, increase in crop demand and so on. For instance, ‘improvement of irrigation efficiency’ and ‘enhancement of reclamation water’ seem to be one of important options to reduce the water stress in Southeast Asia, and North Africa and the Middle East, respectively. The worldwide implementation of adaptation options could decrease the water-stressed population by about 5 % and 7–17 %, relative to the scenario without adaptations, in 2050 and 2100, respectively.     

The impact of climate change mitigation on water demand for energy and food: An integrated analysis based on the Shared Socioeconomic Pathways

Climate change mitigation, in the context of growing population and ever increasing economic activity, will require a transformation of energy and agricultural systems, posing significant challenges to global water resources. We use an integrated modelling framework of the water-energy-land-climate systems to assess how changes in electricity and land use, induced by climate change mitigation, impact on water demand under alternative socioeconomic (Shared Socioeconomic Pathways) and water policy assumptions (irrigation of bioenergy crops, cooling technologies for electricity generation). The impacts of climate change mitigation on cumulated global water demand across the century are highly uncertain, and depending on socioeconomic and water policy conditions, they range from a reduction of 15,000 km³ to an increase of more than 160,000 km³. The impact of irrigation of bioenergy crops is the most prominent factor, leading to significantly higher water requirements under climate change mitigation if bioenergy crops are irrigated. Differences in socioeconomic drivers and fossil fuel availability result in significant differences in electricity and bioenergy demands, in the associated electricity and primary energy mixes, and consequently in water demand. Economic affluence and abundance of fossil fuels aggravate pressures on water resources due to higher energy demand and greater deployment of water intensive technologies such as bioenergy and nuclear power. The evolution of future cooling systems is also identified as an important determinant of electricity water demand. Climate policy can result in a reduction of water demand if combined with policies on irrigation of bioenergy, and the deployment of non-water-intensive electricity sources and cooling types.     

Impacts of climatic change on water and natural hazards in the Alps: Can current water governance cope with future challenges? Examples from the European “ACQWA” project

This paper reviews the possible future situation of the Rhone River in the Swiss part of its catchment. Physical processes in the Alps govern the behaviour of the Rhone from its source (Rhone Glacier) to the Lake of Geneva, and substantial changes are expected to occur in the amount and seasonality of precipitation, and in the response of snow and glaciers to a warming climate. As a result, discharge in the alpine part of the Rhone River is likely to undergo an increase in winter and early spring, but strongly decreases from late spring to late autumn. These changes in water regimes will certainly be accompanied by more frequent geomorphic hazards, related to increases in heavy precipitation events and the melting of permanently frozen grounds. The direct and indirect impacts of a warming climate will affect key economic sectors such as tourism, hydropower, and agriculture, while shifts in extreme events will have an impact on the vulnerability of infrastructure and a range of economic sectors and services. Projections of the future course of events can help in advance planning and decision making in order to alleviate some of the more negative consequences of climate and hydrological impacts on key economic sectors in the region. This paper will thus discuss issues related to current and future water governance in the region, whether water-related policies are sufficiently robust today to cope with what may be rapid changes in water availability and water use in coming decades, and to resolve possible rivalries between economic sectors that may be increasingly confronted with problems of water availability at critical times of the year.     

Changes in terrestrial water stress and contributions of major factors under temperature rise constraint scenarios

The Paris agreement adopted at the 21st Conference of Parties of the United Nations Framework Convention on Climate Change stipulates 2 and 1.5 °C targets, but their consistency with sustainable development is poorly understood. This study focuses on water stress defined by annual water consumption-to-availability ratio (CAR) and analyzes the CAR changes for 32 global regions during this century for scenarios of the 2 and 1.5 °C targets. It also estimates contributions of major factors behind such change for addressing the adaptation planning. The results show that the CARs in many (i.e., 25) regions remain very small (less than 0.1) regardless of the future temperature level. For the other seven regions, the CARs undergo significant changes, while the changes and contributing factors to them are different by region and the future temperature level. Possible adaptation strategies are given for regions of significantly increasing CARs. For instance, in Afghanistan and Pakistan and South Africa, the CARs increase mainly due to increases in irrigation water associated with socioeconomic development (i.e., food demand growth). Decreases in water availability and increases in irrigation water due to climate change also contribute to the CAR increases after 2030. The contributions of other factors (i.e., demand changes in municipal water, water for electricity generation, other industrial water, and water for livestock) are small. In these regions, securing water resources as well as irrigation water conservation are important to avoid worsening of the CAR. Adaptation strategy recommendations for other regions are also presented.     

基于SWAT-WEAP联合模型的西辽河支流水资源脆弱性研究

气候变化与人类活动对水循环及水资源安全的影响是近代水科学面临的主要科学问题。以西辽河支流老哈河流域为研究区,探索了一种水文模型耦合方法(SWAT-WEAP),以水短缺量为指标,同等考虑水资源供给端与需求端,对气候变化与不同人类利用情景下水资源系统脆弱性进行定量分析,结果表明:①暖干化气候情景比暖湿化气候情景明显加剧了老哈河流域水资源系统的脆弱性,降水减少10%导致的水短缺量比降水导致10%所缓解的短缺量要多31.17%;②气候变化对流域农业灌溉用水影响最大,对城乡生活用水和工业用水影响相对很小;③老哈河流域水资源系统脆弱性的主要驱动力之一源自农业不合理灌溉,发展畜牧业、 改变种植结构与高效节水灌溉是缓解水短缺、 降低水资源系统脆弱性最为有效的措施,也是应对气候变化最为有效的方式;④基于供水端的措施(如水库)在暖干化气候时由于水资源供给来源受限,其缓解作用有所减弱。     

中国气候变化影响研究概况

介绍了目前我国在未来气候变化影响研究方面的概况，气候影响研究采用的方法多为政府间气候变化专业委员会（ＩＰＣＣ） 第二工作组提出的气候变化影响评价方法。未来气候变化影响研究是在大气中ＣＯ２ 浓度加倍，或气温、降水变化的情景下，进行未来农业、林业、水资源、生态环境以及海平面上升等方面的潜在影响研究，其中有模型研究、实验室研究、宏观研究和适应对策研究等。这些研究采用的未来气候情景多为ＧＣＭ 模型预测的气候情景     

Impact of Climate Change on Maize Yield in Central and Northern Greece: A Simulation Study with Ceres-Maize

The potential impacts of climate change on the phenology and yield of two maize varieties in Greece were studied. Three sites representing the central and northern agricultural regions were selected: Karditsa, Naoussa and Xanthi. The CERES-Maize model, embedded in the Decision Support System for Agrotechnology Transfer (DSSAT 3.0), was used for the crop simulations, with current and possible future management practices. Equilibrium doubled CO₂ climate change scenarios were derived from the GISS, GFDL, and UKMO general circulation models (GCMs); a transient scenario was developed from the GISS GCM transient run A. These scenarios predict consistent increases in air temperature, small increases in solar radiation and precipitation changes that vary considerably over the study regions in Greece. Physiological effects of CO₂ on crop growth and yield were simulated. Under present management practices, the climate change scenarios generally resulted in decreases in maize yield due to reduced duration of the growing period at all sites. Adaptation analyses showed that mitigation of climate change effects may be achieved through earlier sowing dates and the use of new maize varieties. Varieties with higher kernel-filling rates, currently restricted to the central regions, could be extended to the northern regions of Greece. In the central regions, new maize varieties with longer grain-filling periods might be needed.     

Economic feasibility of adapting crop enterprises to future climate change: a case study of flexible scheduling and irrigation for representative farms in Flathead Valley,Montana, USA

Future climate change directly impacts crop agriculture by altering temperature and precipitation regimes, crop yields, crop enterprise net returns, and net farm income. Most previous studies assess the potential impacts of agricultural adaptation to climate change on crop yields. This study attempts to evaluate the potential impacts of crop producers’ adaptation to future climate change on crop yield, crop enterprise net returns, and net farm income in Flathead Valley, Montana, USA. Crop enterprises refer to the combinations of inputs (e.g., land, labor, and capital) and field operations used to produce a crop. Two crop enterprise adaptations are evaluated: flexible scheduling of field operations; and crop irrigation. All crop yields are simulated using the Environmental Policy Integrated Climate (EPIC) model. Net farm income is assessed for small and large representative farms and two soils in the study area. Results show that average crop yields in the future period (2006–2050) without adaptation are between 7% and 48% lower than in the historical period (1960–2005). Flexible scheduling of the operations used in crop enterprises does not appear to be an economically efficient form of crop enterprise adaptation because it does not improve crop yields and crop enterprise net returns in the future period. With irrigation, crop yields are generally higher for all crop enterprises and crop enterprise net returns increase for the canola and alfalfa enterprises but decrease for all other assessed crop enterprises relative to no adaptation. Overall, average crop enterprise net return in the future period is 45% lower with than without irrigation. Net farm income decreases for both the large and small representative farms with both flexible scheduling and irrigation. Results indicate that flexible scheduling and irrigation adaptation are unlikely to reduce the potential adverse economic impacts of climate change on crop producers in Montana’s Flathead Valley.