CLIMATIC CHANGE AND U.S. WATER RESOURCES: FROM MODELED WATERSHED IMPACTS TO NATIONAL ESTIMATES1

ABSTRACT: Water is potentially one of the most affected resources as climate changes. Though knowledge and understanding has steadily evolved about the nature and extent of many of the physical effects of possible climate change on water resources, much less is known about the economic responses and impacts that may emerge. Methods and results are presented that examine and quantify many of the important economic consequences of possible climate change on U.S. water resources. At the core of the assessment is the simulation of multiple climate change scenarios in economic models of four watersheds. These Water Allocation and Impact Models (Water‐AIM) simulate the effects of modeled runoff changes under various climate change scenarios on the spatial and temporal dimensions of water use, supply, and storage and on the magnitude and distribution of economic consequences. One of the key aspects and contributions of this approach is the capability of capturing economic response and adaptation behavior of water users to changes in water scarcity. By reflecting changes in the relative scarcity (and value) of water, users respond by changing their patterns of water use, intertemporal storage in reservoirs, and changes in the pricing of water. The estimates of economic welfare change that emerge from the Water‐AIM models are considered lower‐bound estimates owing to the conservative nature of the model formulation and key assumptions. The results from the Water‐AIM models form the basis for extrapolating impacts to the national level. Differences in the impacts across the regional models are carried through to the national assessment by matching the modeled basins with basins with similar geographical, climatic, and water use characteristics that have not been modeled and by using hydro‐logic data across all U.S. water resources regions. The results from the national analysis show that impacts are borne to a great extent by nonconsumptive users that depend on river flows, which rise and fall with precipitation, and by agricultural users, primarily in the western United States, that use a large share of available water in relatively low‐valued uses. Water used for municipal and industrial purposes is largely spared from reduced availability because of its relatively high marginal value. In some cases water quality concerns rise, and additional investments may be required to continue to meet established guidelines.     

三峡库区1980～2005年农业用地氮平衡时空变化研究

利用三峡库区分区县农业统计资料,对OECD土壤表观氮平衡模型进行适当改进,计算分析三峡库区1980~2005年农业用地氮平衡时空变化格局及驱动机制.结果表明,1980~2005年库区氮总输入和总盈余量呈显著增长趋势,分别从23.4万t和14.4万t增长到45.6万t和30万t;氮总输出量1980~1995年呈增加趋势,从9.0万t到16.7万t,1995年后基本保持稳定趋势;单位面积氮盈余量1980~1998年总体呈持续增加趋势,从133.4 kg/hm2增长到310.3 kg/hm2,1998年后逐步趋向稳定,但空间分布区域差异性增强,主要集中在库中和库首区县,与库区移民数量空间分布具有一定的相似性;氮输入贡献主要来源于化肥、牲畜粪便、人粪尿和生物固氮,累计占总输入90%以上;1995年前库区氮平衡变化主要受国内大量使用化肥宏观环境影响,1995年后受水库淹没和移民影响较大,但其具体影响程度有待进一步分析;建议考虑适当发展副业、改变农业种植结构或进行生态移民等措施减少氮排放量.     

1954—2000年渤海湾典型海岸带(天津段)景观空间格局动态变化分析

基于GIS技术和景观生态学方法,以渤海湾典型海岸带(天津段)为研究区,分析了该区域1954,1970,1981,1990和2000年的土地利用和覆盖变化特征,并在空间上反映出各时期的重点退化区域. 结果表明:1954—2000年研究区内高功能景观面积减少51.98%,主要是草地、沼泽和滩涂退化成农田、盐田、港口和养殖塘等经济价值较高的类型,其中以1954—1970年为高功能景观退化的最快时期,平均每年退化3 684.50 hm2,以沼泽和草地退化最为明显. 人口增长、滩涂利用和围海造地以及近岸环境污染是其重要的驱动力.      

广西土地利用变化及对粮食生产的影响

在统计软件SPSS支持下,深入分析了广西土地利用现状及1996—2001年土地利用结构变化的原因,在此基础上探讨了土地利用变化对粮食生产的影响,并提出了一些保障粮食安全的对策及建议。     

Linking gender,climate change and security in the Pacific Islands Region: A systematic review

This systematic review aims to address gaps in understanding how concepts of gender, climate change and security are given meaning and linked in empirical scholarship within the Pacific Islands Region. The review assesses the 53 articles returned through Web of Science, SCOPUS and ProQuest databases that are derived from empirical research and refer to gender, climate change and security. The findings indicate that this is an emerging topic in a region that is one of the most vulnerable to climate change across the globe. Most frequently gender analysis is given superficial treatment; there is limited literature that connects gendered vulnerabilities to historical legacies and structural inequalities; and women’s critical roles that create security are often overlooked and devalued. The review indicates that greater work is needed to question perceived threats to security and to reveal how climate change, gendered institutions, systems and spaces, historical legacies and politics interact to construct security in the Pacific Islands Region.     

Microeconomic adaptation to severe climate disturbances on Australian coral reefs

Coral reefs are increasingly affected by climate-induced disturbances that are magnified by increasing ocean temperatures. Loss of coral reefs strongly affects people whose livelihoods and wellbeing depend on the ecosystem services reefs provide. Yet the effects of coral loss and the capacity of people and businesses to adapt to it are poorly understood, particularly in the private sector. To address this gap, we surveyed about half (57 of 109) of Australian reef tourism operators to understand how they were affected by and responded to severe impacts from bleaching and cyclones. Reef restoration and spatial diversification were the primary responses to severe bleaching impacts, while for cyclone-impacts coping measures and product diversification were more important. Restoration responses were strongly linked to the severity of impacts. Our findings provide empirical support for the importance of response diversity, spatial heterogeneity, and learning for social-ecological resilience.Supplementary InformationThe online version contains supplementary material available at 10.1007/s13280-022-01798-w.     

清淤底泥脱水干化研究Ⅰ：相变式真空预压技术

针对底泥如何快速脱水干化问题,提出了一种相变式真空预压技术,实现了原位、高效和纯物理特点的快速脱水干化。通过室内模拟实验、现场实验和工程示范,先后开展了真空负压下纯水、水砂混合物和疏浚底泥的激烈相变点模拟研究,确定了温度和真空负压之间的变化规律,以及不同介质激烈相变点的确定方法,并探究了温度对底泥脱水干化效果的影响及温压耦合加载模式。结果表明：水的激烈相变点在相同介质下,随着真空负压增加而降低,不同介质中水的激烈相变点有所差异,纯水最低,水砂混合物次之,淤泥最高;通过累计出水量、出水速率和孔隙水压力的变化规律与温度之间关系确定了底泥的激烈相变点温度为68.7 ℃,脱水干化后的含水率为16.1 %,较常规真空预压降低了34.2 %,较电渗式真空预压降低了26.5 %,体积压缩率达到60.5 %,固结度97.2 %;确定了温压耦合加载模式,工程应用中初始真空负压为20~30 kPa,持续时间为3 d,其次为50~60 kPa,持续时间为5 d,然后真空满载 (80 kPa以上) ,真空满载后开始持续加载温度至底泥激烈相变点附近,并采用温控电箱进行间歇式加载,保证底泥温度一直处于激烈相变点附近,脱水速率最大化,节约能耗。该研究成果为底泥快速脱水干化提供一种新技术,并为此类工程的实施提供技术指导。     

人工湿地氮转化对水位变化响应的研究进展

人工湿地氮转化途径主要包括微生物的硝化反硝化作用、植物的吸收和湿地基质的吸附等。水位变化作为水文机制的重要方面,直接或间接的影响人工湿地环境各种形态氮质和量的变化。阐述了人工湿地氮转化机理和影响因子,并从湿地环境植物形态特征及生长发育、理化性质（DO、pH、Eh）和微生物的硝化反硝化强度三方面对水位变化响应的角度总结了国内外的相关研究进展,并提出研究中存在的问题和相关的建议：加强不同水位变化模式（水位变动幅度、水位变动周期）对人工湿地各种形态氮转化影响的研究,通过水位调控改善植物生长策略、提高微生物硝化反硝化强度,实现增强人工湿地脱氮功效的目的。     

我国突发环境事件演变态势、应对经验及防控建议

依据2006—2020年突发环境事件数据,运用统计和个案分析方法,分析了近年来我国突发环境事件的演变规律、总体情况及特点,基于典型案例,探讨了突发环境事件应对的有效模式及成功经验。结果表明：2006—2020年全国共发生突发环境事件6 569起,总体呈下降趋势;2016—2020年发生的重大及以上突发环境事件较2011—2015年下降了69%,趋势明显,说明我国突发环境事件总体上得到了有效防控。然而,事件多发频发的高风险态势并没有根本改变,近年来还呈现出情况复杂、类型多、诱因复杂、公众关注度高等一些新的发展态势。基层环境应急准备扎实、应急指挥体系高效顺畅、预警防控体系健全、科技支撑和物资储运保障有力、信息公开机制健全是妥善应对突发环境事件的成功经验。未来应注重重大环境风险的识别防范,重大及敏感突发环境事件的应急准备和应对、环境应急管理人员能力的培养、环境应急管理体制机制的创新。     

南海市耕地数量变化驱动力的定量分析

分析了南海市耕地数量变化的特点，并用定性与定量相结合的方法进一步探讨了耕地数量变化的驱动力。结果表明，南海市耕地数量的变化与珠江三角洲耕地数量变化的时间基本一致且与经济发展同步。经济发展、人口增长、基础设施建设及农业结构调整是耕地数量变化的主要驱动力。