共查询到20条相似文献，搜索用时 31 毫秒
1.
《Global Environmental Change》2000,10(2):109-120
This paper identifies challenges inherent in addressing multi-scale environmental problems, and outlines tentative guidelines for addressing such challenges and linking science and policy across scales. The study and practice of environmental assessment and management increasingly recognize the importance of scale and cross-scale dynamics in understanding and addressing global environmental change. These ongoing efforts, however, lack a systematic way of thinking about and addressing the challenges involved in integrating science and policy across multiple scales, for example, in the design of policy-relevant, scientific assessments of problems such as climate change. These challenges include matching scales of biogeophysical systems with scales of management systems, avoiding scale discordance (matching the scale of the assessment with the scale of management), and accounting for cross-scale dynamics. In this paper we propose tentative guidelines for meeting such challenges for both assessors and decision-makers: (1) utilize boundary organizations — institutions which serve to mediate between scientists and decision-makers, and between these actors at different scales; (2) utilize scale-dependent comparative advantages — coordinating the allocation of resources, technical expertise, and decision-making authority to best capitalize on scale-specific capabilities; and (3) employ adaptive assessment and management strategies — constructing long-term, iterative, experiment-based processes of integrated assessment and management. 相似文献
2.
Is irrigated agriculture in the Murray Darling Basin well prepared to deal with reductions in water availability? 总被引：1，自引：0，他引：1
Yongping WeiJohn Langford Ian R. WillettSnow Barlow Clive Lyle 《Global Environmental Change》2011,21(3):906-916
The “Big Dry”, a prolonged dry period in Australia from 1997 to 2009, dried out much of the Murray-Darling Basin (MDB) and resulted in large agricultural losses and degraded river ecosystems. Climate projections are that dry conditions in the MDB are likely to be more regular and severe than ever before, and recent policy initiatives are likely to reduce consumptive water use and redirect water to ecosystem management. This paper aims to develop an understanding of the interactions between water policy and irrigation practices by deriving lessons from drought management in irrigated agriculture of the MDB during the Big Dry, and furthermore, to draw out lessons to enhance the preparedness of irrigated agriculture for a future drier climate and reduced water availability. Reviews of irrigation farmers’ practices, attitudes and capacity to manage during prolonged droughts in the MDB, and the evolution of agricultural water policy in Australia since 1990 were made. It is clear that farmers could be better prepared to deal with a drier climate if their water management practices, e.g. irrigation methods and soil moisture measuring tools are improved, if the impediments to the uncertainty of water allocation and low water availability could be overcome, and if well-targeted research and extension could assist farmers to use water more wisely. It is also clear that Australian water policy could be better prepared in terms of assisting irrigated agriculture to deal with a drier climate. Key areas are reduction of barriers and distortions to water trading, optimizing the environmental water allocation, and seeking mutual benefits between environmental water allocation and irrigated agriculture, improvement of the cost-effectiveness of investments in water supply infrastructure, facilitating carryover and capacity sharing at larger scales, and provision of accurate, accessible and useful water information at different scales. An approach to irrigation practice and water policy is proposed based on past experience and potential opportunities. The approach is a set of linked strategies for more robust agricultural production and a more sustainable environment under a drier climate and reduced water availability. 相似文献
3.
针对两系杂交稻制种易遇夏季低温危害制种纯度的技术瓶颈,为正确采用以水调温预防技术,本文依据热量平衡原理,建立了制种稻田的水热传输多层模型。经实测资料检验,模型稳定、可靠。对模型输入不同灌水参数的计算结果表明:20 cm气温(不育系敏感期的幼穗高度)随着净辐射通量、灌水深度、进水及出水口水温的升高而增加,增温幅度受这些因子的综合影响。要合理的利用水资源必须考虑多种因子的相互作用。对育性的实测表明,以水调温对防御夏季低温,提高制种纯度效果良好。 相似文献
4.
5.
Improving the adaptive capacity of small-scale irrigation systems to the impacts of climate change is crucial for food security in Asia. This study analyzes the capacity of small-scale irrigation systems dependent on the Asian monsoon to adapt to variability in river discharge caused by climate change. Our study is motivated by the Pumpa irrigation system, a small-scale irrigation system located in Nepal that is a model for this type of system. We developed an agent-based model in which we simulated the decisions farmers make about the irrigation strategy to use according to available water flow. Given the uncertainty associated with how climate change may affect the Asian monsoon, we simulated the performance of the system under different projections of climate change in the region (increase and decrease in rainfall, reduction and expansion of the monsoon season, and changes in the timing of the onset of the monsoon). Accordingly to our simulations, farmers might need to adapt to rainfall intensification and a late onset in the monsoon season. The demands for collective action among farmers (e.g. infrastructure repair, meetings, decisions, etc.) might increase considerably due to climate change. Although our model suggests that investment in new infrastructure might increase the performance of the system under some climate change scenarios, the high inequality among farmers when water availability is reduced might hinder the efficiency of these measures due to a reduction of farmers’ willingness to cooperate. Our modeling exercise helps to hypothesize about the most sensitive climate change scenarios for smallscale irrigation farming in Nepal and helps to frame a discussion of some possible solutions and fundamental trade-offs in the process of adaptation to improve for food and water security under climate change. 相似文献
6.
Pricing China's irrigation water 总被引：1，自引：0，他引：1
Many development agencies and other actors are advocating that China adopt a system of water markets or of high water prices in order to resolve the inefficiencies of irrigation agriculture and to supply sufficient water for growing urban and industrial uses. We argue that this proposal rests on a series of propositions: that the price of water is too low to encourage farmers to be efficient; that farmers are not charged volumetric prices and so are not encouraged to conserve water; that water is scarce largely because farmers are profligate in their use of water; and that proper pricing of water will not affect equity. None of these contentions is true. Farmers have to pay not only the official charges for water but also the much higher costs of pumping it onto their fields. Once pumping is included, farmers are paying prices that are volumetric. Furthermore, the inefficiency of farmers arises in large part from the manner in which water is delivered to them: the system offers no rewards for care in the use of water and instead rewards greed. And, finally, although it might be true that higher prices do not affect equity within a village, in fact they would have substantial effects on inter-sectoral equity, with farmers becoming worse off in comparison to urban dwellers. The paper concludes by sketching a more appropriate scheme for raising the efficiency of use of irrigation water. 相似文献
7.
Researchers who do not take into account farm heterogeneity in implementing specific climate change adaptation options might significantly bias their findings. To prove this point, this paper focusses on irrigation as an adaptation option to climate change and highlights the fact that there is no such thing as “irrigation.” Instead, different farms consider water management options across a spectrum that ranges from purely rainfed farms to purely irrigated farms with in between the extreme practices such as supplemental irrigation, water conservation practices, and different irrigation techniques. Accounting for such differences is necessary, yet difficult due to a lack of farm-specific data on water management and irrigation. This paper uses unique Farm Accountancy Data Network data of Western European farmers on the proportion of farmland that each farm irrigates. Unlike previous work, this allows taking into account some within-irrigation heterogeneity instead of simply categorizing farms as being “irrigated.” We estimate and compare climate response models based on the Ricardian cross-sectional method for a large range of irrigation categories. The results give insights into how the farm irrigation climate response can be significantly different depending on how irrigation is defined. This proves that ignoring within-adaptation differences when comparing non-adaptation with adaptation (in this case, rainfed versus irrigated agriculture) might lead to biased conclusions with regard to effectiveness of adaptation strategies. We therefore argue that it might be more relevant to understand at which point and under which circumstances irrigated agriculture is more or less beneficial than rainfed agriculture. 相似文献
8.
通过 1 997～ 1 999年在河北省衡水半干旱地区对冬小麦进行耕作、覆盖、底墒和补水灌溉等综合应变防御技术田间试验研究 ,在拔节期以有限水分胁迫效益指标 ( 55% )为依据 ,制定出脯氨酸含量大于 0 .30 g/ 1 0 0 g为小麦受旱的生化指标 ;选取土壤水分、叶面积系数、生物量、补水量、水分利用效率等小麦受旱程度的特征量进行综合分析 ,得出了平均每实施一项抗旱技术 ,可使小麦增产 4.3% ,以深松 覆盖 足墒综合配套技术增产效果最明显 ,可增产 2 7.0 % ,水分利用效率达到 2 0 .1 kg/ ( mm· hm2 ) ,其次是深松 覆盖 欠墒综合配套技术 相似文献
9.
王志成 《沙漠与绿洲气象(新疆气象)》2018,12(3):33-39
阿克苏河灌区是中纬度干旱区典型的绿洲灌溉系统,同时也是新疆第二大灌区,了解灌区作物需水量可为灌区种植结构调整、水资源优化配置提供科学依据。本研究基于联合国粮农组织(FAO)的Penman-Monteith蒸散发模型,结合作物系数法估算了阿克苏灌区作物需水量的时空变化及其对气候因子和作物种植结构的敏感性。结果表明,1960—2015年阿克苏灌区多年平均作物需水量为586 mm,且呈显著上升趋势,上升速率为38.43 mm/10 a。随着气候变化和作物种植结构的改变,1990—2015年间作物需水量急剧增加,增加速率高达99.37 mm/10 a。对于不同作物类型,果林的需水量最大,高达829.8 mm,其次是棉花、水稻和玉米,小麦需水量最低。阿克苏灌区的作物需水量对日最高气温和日照时数较为敏感,而对最低气温、风速和水汽压的敏感度较低。当日最高气温升高2℃时,作物需水量增加4%,当日照时数增加10%时,作物需水量将增加3.2%。另外,作物需水量对作物种植结构非常敏感,当果林的种植面积比例增加10%时,作物需水量增加了12.1%。 相似文献
10.
Accurate global irrigation information is essential for managing water scarcity and improving food security. However, the mapping of high-resolution irrigation at the global scale is challenging due to the wide range of climate conditions, crop types and phenology, ambiguous and heterogeneous spectral features, and farming practices. Here, a robust method is proposed using irrigation performance under drought stress as a proxy for crop productivity stabilization and crop water consumption. For each irrigation mapping zone (IMZ), dry months in the 2017–2019 period and the driest months in the 2010–2019 period were identified over the growing season. The thresholds of the normalized difference vegetation index (NDVI) in the dry months from 2017 to 2019 and the NDVI deviation (NDVIdev) in the driest month were identified to separate irrigated and rainfed cropland with samples. The final threshold from either the NDVI or the NDVIdev of the IMZ was determined with a higher overall accuracy in separating irrigated and non-irrigated areas. The results show that the global maximum irrigation extent (GMIE) at a 30-m resolution was 23.38% of global cropland in 2010–2019, with an overall accuracy of 83.6% globally and significant regional differences in irrigation proportions ranging from 1.1% in western Africa to 100% in Old World deserts among the 110 IMZs and from 0.4% in Belarus to 80.2% in Pakistan and 100% in Egypt among 45 countries. The study quantitatively distinguished annually and intermittently irrigated regions, which had values of 42% and 58% of global cropland, respectively, by applying indicators. This method, using the NDVI and NDVIdev thresholds, is simple, concrete and reproducible and better for zones with homogeneous weather conditions. The study offers independent, consistent and comparable information for defining the baseline, tracking changes in irrigation infrastructure, and leading future changes in how stakeholders plan and design irrigation systems. 相似文献
11.
Water stored as part of the land surface is lost to evapotranspiration and runoff on different time scales,and the partitioning between these time scales is important for modeling soil water in a climate model.Different time scales are imposed on evapotranspiration primarily because it is derived from different reservoirs with different storage capacities, from the very rapid evaporation of canopy stores to the slow removal by transpiration of rooting zone soil moisture. Runoff likewise ranges in time scale from rapid surface terms to the slower base-flow. The longest time scale losses of water determine the slow variation of soil moisture and hence the longer time scale effects of soil moisture on precipitation. This paper shows with a simple analysis how shifting the partitioning of evapotranspiration between the different reservoirs affects the variability of soil moisture and precipitation. In particular, it is concluded that a shift to shorter time scale reservoirs shifts the variance of precipitation from that which is potentially predictable to unpredictable. 相似文献
12.
水储量变化可视为气候变化对水文系统影响的指示器。基于GRACE数据,结合气候数据和冰川积雪数据,分析了近10 a年来阿克苏河流域的水储量变化。研究结果表明:(1)过去10 a间阿克苏河流域的水储量呈递减趋势,减少速率为-0.12±0.85 cm/a,且春季表现为正距平,而秋季表现为负距平;(2)山区冰川退缩和积雪消融是该流域山区水储量减少的主要原因,近半个世纪以来冰川物质平衡为负平衡,同时近十年来积雪面积递减速率为-24 km~2/a;(3)阿克苏河流域的耕地面积的迅速增加导致了地下水过度超采,是绿洲区水储量减少的主要驱动因子。 相似文献
13.
A situated and socially engaged science of loss arising from climate change takes people’s lived experiences with risk and harm as its fundamental starting point. It foregrounds what losses occur, where and how, which of these losses matter most to people and why, and whether or not such losses are considered acceptable and potentially reversible. However, obtaining such insight is difficult if the many things people value, across space and time, are intangible, i.e. they cannot and perhaps should not be quantified, and hence are often overlooked and omitted. This is the case, for instance, for the symbolic and affective dimensions of culture and place, such as sense of belonging, personal and collective notions of identity, and ways of knowing and making sense of the world, all of which are already undermined by climate change. Here, we perform the first systematic comparative analysis of people-centered and place-specific experiences with climate-related harm to people’s values that are largely intangible and non-commensurable. We draw upon >100 published case studies from around the world to make visible and concrete what matters most to people and what is at stake in the context of climate-related hazards and impacts. We show that the same threats can produce vastly different outcomes, ranging from reversible damages to irreversible losses and anticipated future risks, across numerous value dimensions, for indigenous and non-indigenous families, communities, and countries at all levels of development. Through this analysis, we also empirically validate dimensions of harm that have been produced and reproduced in the literature, albeit often devoid of distinct substance, lived experiences, and intrinsic significance. We end by discussing ethical implications of the ‘one thousand ways’ to encounter harm and offer recommendations to overcome methodological challenges in advancing a science of loss grounded in place. 相似文献
14.
Cynthia Rosenzweig Kenneth M. Strzepek David C. Major Ana Iglesias David N. Yates Alyssa McCluskey Daniel Hillel 《Global Environmental Change》2004,14(4):823
This integrated study examines the implications of changes in crop water demand and water availability for the reliability of irrigation, taking into account changes in competing municipal and industrial demands, and explores the effectiveness of adaptation options in maintaining reliability. It reports on methods of linking climate change scenarios with hydrologic, agricultural, and planning models to study water availability for agriculture under changing climate conditions, to estimate changes in ecosystem services, and to evaluate adaptation strategies for the water resources and agriculture sectors. The models are applied to major agricultural regions in Argentina, Brazil, China, Hungary, Romania, and the US, using projections of climate change, agricultural production, population, technology, and GDP growth.For most of the relatively water-rich areas studied, there appears to be sufficient water for agriculture given the climate change scenarios tested. Northeastern China suffers from the greatest lack of water availability for agriculture and ecosystem services both in the present and in the climate change projections. Projected runoff in the Danube Basin does not change substantially, although climate change causes shifts in environmental stresses within the region. Northern Argentina's occasional problems in water supply for agriculture under the current climate may be exacerbated and may require investments to relieve future tributary stress. In Southeastern Brazil, future water supply for agriculture appears to be plentiful. Water supply in most of the US Cornbelt is projected to increase in most climate change scenarios, but there is concern for tractability in the spring and water-logging in the summer.Adaptation tests imply that only the Brazil case study area can readily accommodate an expansion of irrigated land under climate change, while the other three areas would suffer decreases in system reliability if irrigation areas were to be expanded. Cultivars are available for agricultural adaptation to the projected changes, but their demand for water may be higher than currently adapted varieties. Thus, even in these relatively water-rich areas, changes in water demand due to climate change effects on agriculture and increased demand from urban growth will require timely improvements in crop cultivars, irrigation and drainage technology, and water management. 相似文献
15.
Understanding the linkages between social and ecological systems is key to developing sustainable natural resource management (NRM) institutions. Frequently, however, insufficient attention is paid to the historical development of NRM institutions. Instead, discussion largely focuses on models of economic efficiency at the expense of the cultural, historical, and ecological contexts within which institutions develop. Here we use the research program of historical ecology to explore the development, maintenance, and change of two contemporary fire management institutions in northern Australia and Colorado, USA, to demonstrate how social institutions and ecological systems change and resist change over time and how institutions interact across scales to negotiate contrasting goals and motivations. We argue that these NRM institutions are not strictly speaking evolutionary or adaptive, and that historical context is critical when evaluating how and why particular institutions and institutional relationships develop. As with ecosystems, the present characteristics of the NRM institutions are dependent on what has happened before and their efficacy can only be evaluated retrospectively. Therefore, an understanding of history is essential to questions of the desirability and feasibility of institutional change where such shifts are required from an ecological, social, or economic perspective. We further propose that institutional conflict arises from the differing goals and motives of resource management institutions at different scales. Our cases reveal that larger-scale institutions can be successful at achieving narrowly defined goals but often fall short of achieving socially desirable sustainable outcomes. Our findings support the use of narratives of community history, place, and being in considering the resilience and sustainability of social-ecological systems. We offer that historical ecology is complementary with institutional and economic approaches to the analysis of NRM institutions, and possesses a particular strength in linking ecology to the values and norms of small social groups. 相似文献
16.
Long-lasting community-based resource management systems have offered scholars important lessons in the study of human-environment relations. The examination of such systems has suffered from a sampling bias, however, in that it has focused disproportionately on successful systems. There are fewer studies that have explored the deterioration of such systems, particularly with an interdisciplinary approach. This shortfall is problematic given the increasing social and biophysical disturbances that communities are facing as they become more integrated into, and affected by, larger-scale processes.This study addresses this gap by analyzing the modern condition of a long-lasting community-based irrigation system known as the acequias in northern New Mexico. Using a mix of interview, survey, remote sensing, and census data, I examine the extent to which important indicators for the acequias have shifted in the last several decades and explore reasons for these changes. A mix of statistical and qualitative comparative techniques is used to conduct the analysis.By examining longitudinal data we find that the acequias are producing less than they have in the past and have mostly lost their common-property-based livestock pasturing system. While some of these changes can be attributed to similar declines in water availability, much of the change results from social drivers including demographic changes, regional-to-global market forces, and public policies. Overall the shift of the acequias to their current state is a result of their integration into a much larger-scale set of social and economic forces than they have experienced in the past. This shift will be very difficult to reverse, meaning the acequia farmers must adapt to the current condition. It is likely that these themes are common across many community-based resource management systems in many locations. In the future, further progress should be made in synthetically comparing such cases in ways that have already been done for long-lasting successful systems. 相似文献
17.
There is increasing interest in the water–food nexus, especially the restrictive effect of water on food production in hot spots where irrigation stress is growing. However, little is known about the larger-scale implications of future irrigation shortfalls for global trade and economic welfare, as well as of the potential buffering impacts of international trade on the local impacts of irrigation shortage. In this paper, we utilize a recently developed model, GTAP-BIO-W, to study the economic effects of changes in irrigation outlook for 126 river basins, globally by 2030. Projected irrigation availability is obtained from the IMPACT-WATER model, and imposed upon the present-day economy. Irrigation availability in 2030 is expected to drop by 30–60% in several key rivers basins, including: Hai He, Indus, Luni, and the Eastern Mediterranean basin, leading to significant output declines in China, South Asia, and the Middle East. We find that the regional production impacts of future irrigation water shortages are quite heterogeneous, depending on the size of the shortfall, the irrigation intensity of crop production, the possibility of expanding rainfed areas, as well as the crop mix. These changes in regional output significantly alter the geography of international trade. To compensate for the loss of productivity caused by the irrigation constraint, an estimated 7.6 million hectares of cropland expansion is needed to meet the demand for food. In spite of the remarkable reduction of irrigation in some basins, the resulting welfare impact is relatively modest as a result of the buffering capacity of global markets. The global welfare loss amounts to $3.7 billion (2001 prices) and results from a combination of the reduction in irrigation availability as well as the interplay with agricultural support policies. 相似文献
18.
Consuelo Varela-Ortega Irene Blanco-Gutiérrez Christopher H. Swartz Thomas E. Downing 《Global Environmental Change》2011,21(2):604-619
In arid countries worldwide, social conflicts between irrigation-based human development and the conservation of aquatic ecosystems are widespread and attract many public debates. This research focuses on the analysis of water and agricultural policies aimed at conserving groundwater resources and maintaining rural livelihoods in a basin in Spain's central arid region. Intensive groundwater mining for irrigation has caused overexploitation of the basin's large aquifer, the degradation of reputed wetlands and has given rise to notable social conflicts over the years. With the aim of tackling the multifaceted socio-ecological interactions of complex water systems, the methodology used in this study consists in a novel integration into a common platform of an economic optimization model and a hydrology model WEAP (Water Evaluation And Planning system). This robust tool is used to analyze the spatial and temporal effects of different water and agricultural policies under different climate scenarios. It permits the prediction of different climate and policy outcomes across farm types (water stress impacts and adaptation), at basin's level (aquifer recovery), and along the policies’ implementation horizon (short and long run). Results show that the region's current quota-based water policies may contribute to reduce water consumption in the farms but will not be able to recover the aquifer and will inflict income losses to the rural communities. This situation would worsen in case of drought. Economies of scale and technology are evidenced as larger farms with cropping diversification and those equipped with modern irrigation will better adapt to water stress conditions. However, the long-term sustainability of the aquifer and the maintenance of rural livelihoods will be attained only if additional policy measures are put in place such as the control of illegal abstractions and the establishing of a water bank. Within the policy domain, the research contributes to the new sustainable development strategy of the EU by concluding that, in water-scarce regions, effective integration of water and agricultural policies is essential for achieving the water protection objectives of the EU policies. Therefore, the design and enforcement of well-balanced region-specific polices is a major task faced by policy makers for achieving successful water management that will ensure nature protection and human development at tolerable social costs. From a methodological perspective, this research initiative contributes to better address hydrological questions as well as economic and social issues in complex water and human systems. Its integrated vision provides a valuable illustration to inform water policy and management decisions within contexts of water-related conflicts worldwide. 相似文献
19.
Methane Production, Emission and Possible Control Measures in the Rice Agriculture 总被引：19，自引：0，他引：19
Wang Mingxing Shangguan Xingjian Shen Renxing Wassmann Reiner Seiler Wolfgang 《大气科学进展》1993,10(3):307-314
In the rice field methane is produced in the soil layer with depths of 2-25 cm. The vertical profile of methane production rate in the paddy soil during the water covering period differs from that in the paddy soil in dry phase. Only a small part, about 30%. of the produced methane is emitted to the atmosphere through rice plant, air bubbles, and molecular diffusion. Therefore, the methane emission rate from the rice field depends not only on the methane production rate in the soil, but also on the transport efficiency of the rice plant, air bubble formation that in turn depends on the production rate, and molecular diffusion.Field measurements show that methane emission rates from a particular rice field have very large diurnal, seasonal and interannual variations, which are related to soil characteristics, water regime, farming procedure, local climate, and rice growing activities. The relationship between the methane emission rate and the above mentioned factors is very complicated. The emission rate 相似文献
20.
首次采用区域数值预报模式与农业气象模型结合的技术途径, 构成一个气候模式-土壤水分模式-灌溉模式的系统模型。模型的数值天气预报部分采用大气过程与陆面过程耦合的区域气候模式; 农业气象模型采用适用于冬小麦区的土壤水分和灌溉管理预报模型。研究表明, 本模型较农业气象模型中一般用气候平均作为环境背景场的方法其预测能力有显著提高, 并提供覆盖整个小麦生长期的区域土壤水分定量预报和灌溉管理服务, 具有很好的使用和推广前景。 相似文献