气候变化对灌区农业需水量的影响研究

气候变暖不仅影响水资源量及其时空分布的变化,而且也会使农作物蒸发蒸腾量增加,从而加剧农业水资源供需矛盾。因此,研究气候变化对农业需水量的影响对保障农业用水安全具有重要的意义。本文利用陕西省宝鸡峡灌区11个气象站28 a的气象资料,分析了灌区气候变化特征;计算了主要作物需水量和农田灌溉需水量;利用单因素敏感性分析法研究了气候变化对农业需水量的影响。研究结果表明:灌区年平均气温显著上升,降水量持续下降,蒸发量明显增大,大部分地区相对湿度和风速显著下降,而日照时数有所增加;冬小麦、玉米、棉花和油菜生育期需水量明显增加;各气候因素对农田灌溉需水量影响顺序为:降水量>相对湿度>最高气温>日照时数>平均气温>风速,气温的上升、相对湿度的下降、降水量的减少以及日照时数的增大使作物需水量明显增大,而灌溉面积减小使农业需水量有减少的趋势。     

Climate change does not explain historical changes in the pelagic ecosystem of Lake Kariba (Zambia–Zimbabwe)

Recent studies on the pelagic ecosystem of Lake Kariba identified a number of changes in its thermal regime, planktonic communities and fishery production, concluding they were the result of climate change, particularly warming. This study re‐examines these conclusions and suggests alternative explanations for these changes. Historical data suggest there was no warming of the lake until at least the 1990s. Furthermore, lack of recent data makes it difficult to conclude that the lake’s temperature has increased by 2 °C. It is also not clear that the pattern of thermal stratification has changed, or that the thermocline has risen and become more stable. Although one of the suggested effects of climate change was a decreased number of larger zooplankton, this change occurred in the 1970s, when there had been no change in the lake temperature. Rather, there is strong evidence that the zooplankton composition changed as a result of selective predation by the introduced clupeid, Limnothrissa miodon. Furthermore, the loss of large grazing zooplankton species could have affected the composition of the phytoplankton, although this phenomenon also has been attributed to climate change. Although the phytoplankton communities in the lake are not as well documented as the zooplankton communities, it is clear that many changes in the lake actually began in the 1970s. Finally, the decline in the pelagic fishery for Limnothrissa was also linked to temperature changes. However, because the fisheries on the Zambian and Zimbabwean sides exhibited very different behaviours, there is little evidence to support this conclusion. It is concluded that the impacts of climate change on Lake Kariba are likely to be complex and that possible over‐simplification in identifying these impacts will not facilitate our understanding of these complexities.     

Effects of land‐use change and climate variability on streamflow in the Woken River basin in Northeast China

In this study, the soil and water assessment tool, which is a widely used hydrological model, is applied to study the response of streamflow to land‐use changes and climate variability in the Woken River basin in northeastern China. This model is calibrated and verified based on sensitivity analysis to simulate the effects of land‐use change, climate variability, and extreme land‐use scenarios on streamflow. Simulations are performed to construct different scenarios for quantitative analysis. Compared with the base period, the land‐use change reduced the annual average streamflow and had little effect on the monthly streamflow. Climate variability increased the average annual streamflow and had a substantial effect on monthly streamflow. The effect of climate variability on streamflow was much greater than that of land‐use changes. Under the extreme land‐use scenarios, the annual average streamflow under the forestland scenario decreased, and the average annual streamflow under the grassland and agricultural land scenarios increased. Both the forestland and grassland scenarios exhibited lower monthly streamflow from March to August with especially large influences in June–August, which was when floods were more likely to occur. The agricultural land scenario exhibited the opposite trend. These results indicate that climate variability will obviously change streamflow and that natural disasters related to both high and heavy precipitation must be emphasised. Relevant departments can optimize the land‐use structure and spatial layout to mitigate the negative effects of climate variability.     

Large wood debris recruitment on differing riparian landforms along a Gulf Coastal Plain (USA) stream: a comparison of large floods and average flows

In southeastern Coastal Plain streams, wood debris can be very abundant and is recruited from extensive forested floodplains. Despite importance of wood debris, there have been few opportunities to examine recruitment and redistribution of wood in an undisturbed setting, particularly in the southeastern Coastal Plain. Following extensive flooding in 1994, measurements of individual downed trees (species, dbh, orientation, distance from base‐flow channel and condition) were made across replicated riparian landforms in a Gulf Coastal Plain 5th‐order stream. Annually, the fate of these trees was determined and newly recruited trees were noted. More than 300 downed trees have been recorded. Recruitment varied across landforms with more constrained reaches having greatest mortality. Total tree mortality varied substantially across years. Generally, tree recruitment was greatest in years with substantial floods (1994 and 1998). For each riparian landform type, tree mortality was correlated with the maximum daily flow during the period preceding annual debris surveys. This relationship was particularly strong for sand ridges (r² = 0.942) and low terraces (r² = 0.915), but was significant for floodplains (r² = 0.413). Greatest rates of debris recruitment per maximum daily flow were observed for sand ridges followed by low terraces. Flood characteristics also influenced debris recruitment. The 1994 flood was caused by a tropical storm and resulted in a rapid rise in streamflow. Much of the debris recruited during this flood was from toppled trees and was oriented parallel to the stream channel. In contrast, the 1998 flood was preceded by a wetter than average winter with more gradually rising flows and there was no relationship between riparian landform and debris characteristics. These results indicate that wood recruitment dynamics in Coastal Plain streams are complex. Wood recruitment rates are controlled by cyclical variations in climate interacting with riparian geomorphology. Infrequent high flows appear critical in the maintenance of the instream debris pool. Copyright © 2007 John Wiley & Sons, Ltd.     

变化环境对华北平原地下水可持续利用的影响研究

针对华北平原地下水利用中存在的问题,采用分布式水文MIKE SHE模型,考虑人类活动(农业节水措施和南水北调工程)和气候变化等变化环境的影响,通过设定4大类情景(每类情景中均设定了3类气候变化子情景)模拟了2019-2028年华北平原地下水的利用状况.结果 表明:农业节水措施和南水北调工程等人类活动对华北平原地下水水位...     

气候变化及人类活动对灞河源流区径流的影响

灞河是西安市主要水源地之一,对于改善城市生态环境和维持快速发展具有重要作用.近年来,气候变化和不断加强的水资源开发利用活动,已经引起生态环境问题.根据灞河流域1966-1975及1991-2000年6个观测站的降雨、径流资料,并结合ARCGIS流域地形及水系提取结果,定量分析了气候变化、人类活动对流域径流的影响.结果表明:灞河上游水资源开发利用强度不大,径流变化受人类活动影响比例54.6％,气候变化因素影响45.4％;气候变化对降水空间分布、年内变化影响较大,降雨分配年内和空间分布更加集中.     

饱和水汽压计算公式的比较研究

目前计算饱和水汽压的公式比较多，并且各单位使用的没有统一。本文对经常使用的三个公式进行了比较，讨论了它们各自的优缺点。     

Thermal performance of different planting substrates and irrigation frequencies in extensive tropical rooftop greeneries

The need for the better use of scarce planetary resources has never been more evident than it is today. However, this need is poorly reflected in human housing. In recent years, there has been a growing realization of the importance of constructing human shelters that better conserve energy and water through appropriate insulation and architectural designs. Among the important advancements in these areas is the use of rooftop greeneries for both energy and water conservation. This paper performs an investigation into this topic within the specific climatic context of tropical regions. Long-term experimental results are provided from a four-floor building in Kaohsiung in the southern part of Taiwan. The study involves a fully monitored extensive rooftop greenery and examines four different plant substrates, three different irrigation regimes, and different types of drought-enduring plants to find the most efficient combination of all three in providing maximum heat insulation and water usage efficiency. The attenuation of solar radiation through the vegetation layer is evaluated, as well as the thermal insulation performance of the rooftop greenery structure. Among the substrates, burned sludge has the best thermal reduction percentage of heat amplitude under the roof slab surface (up to 84.4%). Irrigation twice a week has the best thermal reduction percentage of heat amplitude (91.6%). Among the plant types, Sansevieria trifasciata cv. Laurentii Compacta and Rhoeo spathaceo cv. Compacta are found to be suitable for extensive rooftop greeneries because they have the best coverage ratio and are most drought enduring.     

基于CAN总线的集成式气候传感器的研究

针对智能建筑室内环境控制系统对室外环境参数的检测要求,开发了一种集照度检测、风速检测和雨量检测功能于一体的集成式气候传感器．并构建基于CAN总线控制器SJA1000,收发器PCA82C250的通信接口．实现集成式气候传感器与上位机的数据传输。