A digital elevation analysis: a spatially distributed flow apportioning algorithm     

Sanghyun Kim  Haksu Lee 《水文研究》2004,18(10):1777-1794

An integrated flow determination algorithm is proposed to calculate the spatial distribution of the topographic index to the channel network. The advantages of a single flow direction algorithm and other multiple flow direction schemes are selectively considered in order to address the drawbacks of existing algorithms. A spatially varying flow apportioning factor is introduced to distribute the contributing area from upslope cells to downslope cells. The channel initiation threshold concept is expanded and integrated into a spatially distributed flow apportioning algorithm to delineate a realistic channel network. The functional relationships between the flow apportioning factors and the expanded channel initiation threshold (ECIT) are developed to address the spatially varied flow distribution patterns considering the permanent channel locations. A genetic algorithm (GA) is integrated into the spatially distributed flow apportioning algorithm (SDFAA) with the objective function of river cell evaluation. An application of a field example suggests that the spatially distributed flow apportioning scheme provides several advantages over the existing approaches; the advantages include the relaxation of overdissipation problems near channel cells, the connectivity feature of river cells and the robustness of the parameter determination procedure over existing algorithms. Copyright © 2004 John Wiley & Sons, Ltd.  相似文献   

Refined conceptualization of TOPMODEL for shallow subsurface flows     

M. Todd Walter  Tammo S. Steenhuis  Vishal K. Mehta  Dominique Thongs  Mark Zion  Elliot Schneiderman 《水文研究》2002,16(10):2041-2046

The TOPMODEL framework was used to derive expressions that account for saturated and unsaturated flow through shallow soil on a hillslope. The resulting equations were the basis for a shallow‐soil TOPMODEL (STOPMODEL). The common TOPMODEL theory implicitly assumes a water table below the entire watershed and this does not conceptually apply to systems hydrologically controlled by shallow interflow of perched groundwater. STOPMODEL provides an approach for extending TOPMODEL's conceptualization to apply to shallow, interflow‐driven watersheds by using soil moisture deficit instead of water table depth as the state variable. Deriving STOPMODEL by using a hydraulic conductivity function that changes exponentially with soil moisture content results in equations that look very similar to those commonly associated with TOPMODEL. This alternative way of conceptualizing TOPMODEL makes the modelling approach available to researchers, planners, and engineers who work in areas where TOPMODEL was previously believed to be unsuited, such as the New York City Watershed in the Catskills region of New York State. Copyright © 2002 John Wiley & Sons, Ltd.  相似文献   

Moments of inertia and the Chandlerian period for two-and three-layer models of the Galilean satellite Io     

V. N. Zharkov  A. L. Sobisevich 《Astronomy Letters》2005,31(3):205-212

We consider two-layer (Fe-FeS core+silicate mantle) and three-layer (Fe-FeS core+silicate mantle+crust) models of the Galilean satellite Io. Two parameters are known from observations for the equilibrium figure of the satellite, the mean density ρ₀ and the Love number k₂. Previously, the Radau-Darwin formula was used to determine the mean moment of inertia. Using formulas of the Figure Theory, we calculated the principal moments of inertia A, B, and C and the mean moment of inertia I for the two-and three-layer models of Io using ρ₀ and k₂ as the boundary conditions. We concluded that when modeling the internal structure of Io, it is better to use the observed value of k₂ than the moment of inertia I derived from k₂ using the Radau-Darwin formula. For the models under consideration, we calculated the Chandlerian wobble periods of Io. For the three-layer model, this period is approximately 460 days.  相似文献   

水文气象研究进展   总被引：5，自引：0，他引：5  

赵琳娜  包红军  田付友  梁莉  刘莹 《气象》2012,38(2):147-154

从面向流域的定量降水估测与预报、流域水文模型、水文气象耦合预报三个方面系统介绍水文气象研究进展。研究指出,融合天气雷达、卫星遥感及实况降水等多源信息是精细化定量降水估测产品的主要发展方向;采用多模式降水预报集成技术是提高定量降水预报精度的重要途径;分布式水文模型是流域水文模型的发展方向;引入定量降水预报的水文气象耦合预报模式可以延长洪水预报预见期,水文集合预报是水文预报方法的有效解决途径,而数值预报模式与水文模型的双向耦合模式是另一重要发展方向。  相似文献   

基于云团特征的短时临近强降水预报技术     

胡波  杜惠良  滕卫平  石蓉蓉 《气象》2009,35(9):104-111

通过分析2005-2008年影响浙江的梅汛期强降水云团特征,将云团分为偏北型、居中型和偏南型,研究这三种类型云团云顶亮温与地面1小时强降水极值和10mm/h以上降水覆盖面积关系,结果表明偏南型和偏北型云团有较多相似特征,而居中型云团较其他两种云团则有较多相反特征.通过分析1小时强降水相对于云团中心移动路径的落区,指出梅汛期云顶1小时变温和亮温梯度与地面1小时强降水落区无明显配对模型.随后利用天气形势场资料,分析强降水云团与环境要素场的关系,指出云顶亮温的宏观特征与中高层的垂直速度、水汽通量密切相关,最后尝试建立三种类型强降水云团成熟阶段云顶亮温和地面降水人工神经网络预报方程,给预报员提供参考.  相似文献   

雷达在水文预报应用中的研究进展     

胡彩虹  张青山  杨帆  李析男 《河南气象》2009,(1):75-81

雷达可随时跟踪雨区范围、暴雨走向和降雨量的变化,而降雨是水文预报最重要的输入信息,对于水文预报、水库蓄放及江河流域水量的短时洪水预报都是很重要的。本文在介绍雷达测雨及国内外雷达测雨业务系统的基础上,重点总结了国内雷达测雨在水文预报中的研究进展,并提出了雷达在水文预报中的应用思路,探讨了雷达测雨在我国水文应用中的前景及其发展方向。数字化雷达测雨、地理信息系统以及数字高程图等系列新信息,将进一步推动新一代分布式降雨—径流模型的开发,并将极大地拓宽水文预报研究的思路和方法,从而提高预报精度。  相似文献   

气候变暖条件下水文循环变化检测与归因研究的几点认识     

刘春蓁  夏军 《气候变化研究进展》2010,6(5):313-318

气候变化检测与归因的实践指南(GPGP)综合了4种检测归因方法,它囊括了目前研究这一因果链采用的不同途径。自1990年政府间气候变化专门委员会(IPCC)第一次评估报告以来,气候变化的检测与归因从气温升高和其他系统或变量变化趋势的研究开始,经历了从全球、半球、海洋与陆地、七大洲乃至区域尺度的细化进程。人为气候变化的指纹检测与归因方法已普遍用于全球大尺度水文循环要素——纬度带平均降水、强降水、径流、比湿、水汽含量等时空型态变化的研究,个别地也应用到流域尺度,如以冰雪融水补给为主的河流的天然流量、积雪和最低温度变化的研究。对于以降水为主,且受人类活动干扰较大的流域,观测的水文循环要素变化的检测与归因,大多数聚焦于观测的气候要素及非气候变量对其的影响,而不回答变化是自然的还是人为强迫引起的。这种方法要求高质量长系列的观测数据、先进的统计检验技术以及物理基础好的水文模型。对于水文循环要素对气候变化敏感的流域,若观测数据满足要求,则采用正规的检测与归因方法或最优指纹法识别外强迫及驱动因子的影响研究,将具有重要科学意义和发展前景。  相似文献   

Global and Regional Impacts of Vegetation on the Hydrological Cycle and Energy Budget as Represented by the Community Atmosphere Model （CAM3）          下载免费PDF全文

XU Zhongfeng  ZENG Gang  FU Congbin 《大气和海洋科学快报》2009,2(2):85-90

The effects of vegetation and its seasonal variation on energy and the hydrological cycle were examined using a state-of-the-art Community Atmosphere Model （CAM3）. Three 15-year numerical experiments were completed： the first with realistic vegetation characteristics varying monthly （VEG run）, the second without vegetation over land （NOVEG run）, and the third with the vegetation characteristics held at their annual mean values （VEGMEAN run）. In these models, the hydrological cycle and land surface energy budget were widely affected by vegetation. Globaland annual-mean evapotranspiration significantly increased compared with the NOVEG by 11.8% in the VEG run run, while runoff decreased by 13.2% when the realistic vegetation is incorporated. Vegetation plays different roles in different regions. In tropical Asia, vegetation-induced cooling of the land surface plays a crucial role in decreasing tropical precipitation. In middle latitudes and the Amazon region, however, the vegetation-induced increase of evapotranspiration plays a more important role in increasing precipitation. The seasonal variation of vegetation also shows clear influences on the hydrological cycle and energy budget. In the boreal mid-high latitudes where vegetation shows a strong seasonal cycle, evapotranspiration and precipitation are higher in the summer in the VEG run than in the VEGMEAN run.  相似文献   

分布式水文模型DHSVM对兰江流域径流变化的模拟试验   总被引：4，自引：0，他引：4  

康丽莉  王守荣  顾骏强 《热带气象学报》2008,24(2):176-182

介绍如何建立分布式水文模型DHSVM(The Distributed Hydrology Soil Vegetation Model).首先对模型输入和模型参数进行了详细描述,并给出了植被类型和土壤类型等模型参数的取值范围.再将水文模型DHSVM应用到浙江省的兰江流域,通过与实测的年、月径流量过程的对比分析发现,模型模拟的年、月径流量均与实测比较吻合,表明该模型具有一定的适用性,可用于中小流域径流变化的模拟研究.  相似文献   

Effects of pipe outlet blocking on hydrological functioning in a degraded blanket peatland     

Taco H. Regensburg  Pippa J. Chapman  Michael G. Pilkington  David M. Chandler  Martin G. Evans  Joseph Holden 《水文研究》2021,35(3):e14102

Peatland restoration practitioners are keen to understand the role of drainage via natural soil pipes, especially where erosion has released large quantities of fluvial carbon in stream waters. However, little is known about pipe-to-stream connectivity and whether blocking methods used to impede flow in open ditch networks and gullies also work on pipe networks. Two streams in a heavily degraded blanket bog (southern Pennines, UK) were used to assess whether impeding drainage from pipe networks alters the streamflow responses to storm events, and how such intervention affects the hydrological functioning of the pipe network and the surrounding peat. Pipeflow was impeded in half of the pipe outlets in one stream, either by inserting a plug-like structure in the pipe-end or by the insertion of a vertical screen at the pipe outlet perpendicular to the direction of the predicted pipe course. Statistical response variable η² showed the overall effects of pipe outlet blocking on stream responses were small with η² = 0.022 for total storm runoff, η² = 0.097 for peak discharge, η² = 0.014 for peak lag, and η² = 0.207 for response index. Both trialled blocking methods either led to new pipe outlets appearing or seepage occurring around blocks within 90 days of blocking. Discharge from four individual pipe outlets was monitored for 17 months before blocking and contributed 11.3% of streamflow. Pipe outlets on streambanks with headward retreat produced significantly larger peak flows and storm contributions to streamflow compared to pipe outlets that issued onto straight streambank sections. We found a distinctive distance-decay effect of the water table around pipe outlets, with deeper water tables around pipe outlets that issued onto straight streambanks sections. We suggest that impeding pipeflow at pipe outlets would exacerbate pipe development in the gully edge zone, and propose that future pipe blocking efforts in peatlands prioritize increasing the residence time of pipe water by forming surface storage higher up the pipe network.  相似文献