青藏高原东南缘复杂地形条件下降水特征分析

针对青藏高原东南缘泥石流灾害活动频繁,但形成区缺乏较为准确的降水资料的现实需求,按照水系的分水岭将研究区分为6个区域,并利用区内60个气象观测站点1981~2010年年均降水量、海拔高度、坡向、坡度资料,结合GIS和统计分析,建立了各分区的降水垂直分布关系式,并以金沙江流域的拉哇沟、大渡河流域的江咀沟对该统计模型进行了初步验证。结果显示:针对不同的流域,该降水垂直分布关系式能够获取缺气象观测站点的山区降水数据,大体上适用于青藏高原东南缘降水测算,能为泥石流等山地灾害形成区的汇流计算提供参考。     

具有层次结构的正交变化模型的研究

目前的正交变化模型存在对变化点和变体的定义不准确、无法描述复杂的层次结构关系以及无法自动地辨识领域中的共性和可变性的缺点.针对这些不足进行研究,通过从时间和空间的角度去重新明确地定义变化点和变体之间的关系,提出一种具有层次结构的正交变化模型.该模型具有良好的层次结构扩展能力,能够应对复杂的变化性描述,并且通过该模型可以明确地辨识出领域中具有共性和可变性的部分,使自动计算成为可能.具有层次结构的正交变化模型为领域中相关计算提供了基础,与以往的正交变化模型比较,更接近变化性描述具有复杂性这一实际情况,因此具有更实际的使用价值.     

基于复用的软件产品线工程关键技术研究

软件复用技术在软件工程领域具有重要作用并且被广泛应用,尤其是在软件产品线工程领域,系统化的软件复用技术为软件产品线的设计和实现提供了基础。论文首先详细阐述了具有代表性的系统化软件复用支撑技术,随后在一个通用的软件产品线参考架构的基础上,探讨了复用技术在软件产品线工程领域的主要应用形式,最后针对可变性定义及其管理问题,引人并着重探讨了三种可变性管理模型及技术。     

管理导向的软件产品族变化性建模方法研究

控制和管理软件产品族变化性对提高软件复用性、满足用户多变需求具有重要意义.提出一种管理导向的软件产品族变化性建模(Management-oriented variability modeling,MOVM)方法,该方法以变化性管理为指导,贯穿于整个软件产品族变化性生命周期以及反馈演化过程,对各阶段设计相应的策略以支持变...     

Human and climate impacts on Columbia River hydrology and salmonids

The Columbia River had until recently the world's largest Chinook salmon runs. Restoration of the system's severely decimated runs requires understanding changes in the hydrologic variables (e.g. flow and sediment transport) important to salmonids. We describe here methods to distinguish the human and climate‐induced contributions to Columbia River hydrologic processes relevant to the crucial seaward spring migration of juveniles through the tidal river and estuary. Flow regulation has caused most of the decrease in peak flow and sediment transport; it has contributed to changes in spring freshet timing. Climate change has reduced peak and average flows and sediment transport, changing spring‐freshet timing by several weeks. Irrigation diversion has reduced the annual average flow as much as climate change. A better understanding of historical changes in hydrologic processes entailed in this paper tells us how management and climate have changed the Columbia River system over time. The separation of the climate and anthropogenic influences used here may assist in policy analyses and strategies aimed at restoration of the Columbia River endangered salmonids, and in management of other systems. Copyright © 2010 John Wiley & Sons, Ltd.     

River impoundment and sunfish growth

Impoundment of rivers by dams is widespread and one of the most devastating anthropogenic impacts to freshwater environments. Linking theoretical and applied research on river impoundment requires an improved capacity for predicting how varying degrees of impoundment affects a range of species. Here, growth of 14 North American sunfish species resilient to river impoundment was compared in rivers versus impoundments. Growth response to river impoundment varied widely, but consistently among taxa: five species (shadow bass, rock bass, flier, redbreast sunfish and green sunfish) showed significantly higher growth in riverine ecosystems, four species (largemouth bass, smallmouth bass, spotted bass and longear sunfish) showed significantly higher growth in impounded ecosystems, and five species (bluegill, black crappie, white crappie, redear sunfish and warmouth) displayed no difference in growth between rivers and impoundments. Furthermore, significant linear models were developed for predicting growth of two species (largemouth bass, R² = 0.75 and warmouth, R² = 0.44) based on a physiographically specific index of reservoir retention time. For another species (white crappie), growth could not be predicted by the retention time index in Central Lowlands rivers (R² = 0.001), but was strongly predicted by this factor in southeastern Coastal Plain rivers (R² = 0.76) showing how impacts of impoundment, and prediction of its consequences, can vary across river landscape types. Further analysis of fish growth in response to river impoundment, regulation and fragmentation could greatly enhance conservation biology, restoration ecology and basic land use decisions in riverine landscapes. Copyright © 2010 John Wiley & Sons, Ltd.     

河北省永定河流域水文循环及时空分布规律

受人类活动和自然因素共同作用的影响,近几十年来,河北省永定河流域的水文循环过程产生了较为显著的变化。对1962年-2001年的降水-径流过程进行了分析,结果表明,降水量呈先增加后减少的趋势,而径流量却呈逐年递减的趋势。降水量与径流量均主要分布在汛期,冬季为分布最少时段。从空间分布上来说,流域降水量在空间上分布不均,总体呈现北部降雨量大于南部,东部降雨量大于西部的分布特征;径流量最主要分布在桑干河,其次是洋河,两者年径流量占流域年径流量的90%左右。流域水文循环过程改变原因除气候变化、水资源量短缺、时空分布不均等自然因素外,人类活动对水循环的影响也是重要原因。在对降水和径流进行时空分布及变化特征分析的基础上,对影响流域水文循环因素进行了分析,以期为流域制定水资源开发利用规划提供参考依据,使水资源在持续保护的基础上得到更高效利用。     

南水西调——保护青藏高原气候及生态环境的利器

在全球变暖背景下,青藏高原也正以三倍的速度加速变暖,使原本生态环境极其脆弱的青藏高原环境问题日趋恶劣。本文分析了青藏高原变暖原因,提出了青藏高原目前主要存在着三大污染作用,即棕黄色污染、黑色污染、热污染。指出南水西调战略在减缓塔里木沙尘暴和减缓青藏高原黑炭、热污染的机理和作用,提出了保护青藏高原气候、生态环境的战略对策。     

环境变化对汉江上游径流影响的定量分析

气候和土地利用等环境变化的水文响应研究对流域水资源利用具有重要价值。以汉江石泉水文站上游为研究区,采用7种基于Budyko理论的弹性系数法和SWAT模型定量分析了气候变化和人类活动对径流变化的贡献率,设置多种气候变化和土地利用变化情景,分析其对径流的影响。结果表明,石泉水文站年径流呈减少趋势,气候变化对径流减少的贡献率为65.3% ~ 68.1%,人类活动的贡献率为31.9% ~ 34.7%,气候变化是近56年径流减少的主要原因。气候变化情景的模拟显示径流变化主要由降水变化主导。土地利用自然增长情景和极端草地情景使石泉水文站年径流量增加,而退耕还林、极端耕地和极端林地情景使年径流量减少。