基于流路坡度的分布式单位线应用研究

为了分析分布式或半分布式水文模型计算单元的单位线,提出了一种基于流路平均坡度的分布式单位线分析方法,该方法考虑了坡度对汇流的影响并且避免了零坡度网格的处理,可以直接应用于无资料中小流域和分布、半分布式流域水文模型中.将分析的单位线用于干江河流域HEC-HMS模型,模拟结果较好.     

论变动等流时线

本文提出了变动等流时线法,它集中了单位线与等流时线两类方法的主要优点,同时考虑雨洪汇流的非线性问题和空间分布问题.此法多年来在山区河流应用,效果良好. 变动等流时线与移滞河道汇流模型有机地结合,显著改进了变动等流时线法的河网调蓄作用,扩大了应用范围,提高了实用效果.     

单元嵌套网格产汇流理论

凭借"大数据"可以精细刻画降雨空间分布和下垫面空间变异性的优势,提出了"大数据"背景下考虑降雨空间分布和下垫面空间变异性对流域产汇流影响的计算方法,即单元嵌套网格剖分流域的方法。通过引入"网格水滴"的概念揭示了流域瞬时单位线的物理本质,对由RodriguezIturbe和Valdes所提出R-V地貌瞬时单位线理论进行补充,分析了等流时线法和单位线法的局限性,提出的单元嵌套网格产汇理论既克服了等流时线法和单位线法的缺点,也吸取了它们的优点,为在"大数据"支撑下统一等流时线和单位线法提供了可行性。     

分布式单位线在新安江模型中的应用

将基于空间分布流速场的分布式单位线计算方法应用于新安江模型单元流域,并将其用于大坡岭流域。结果表明:在1971—2003年的37场洪水中,洪峰流量相对误差小于20%的有36场,峰现时间误差小于2 h的有35场,确定性系数大于0.7的有36场;洪峰流量相对误差平均值为6.85%,峰现时间误差平均值为0.63 h,确定性系数平均值为0.93。将分布式单位线分析方法用于新安江模型不但是可行的,而且模拟效果非常理想。     

基于Nash 瞬时单位线法的渗透坡面汇流模拟

基于Nash瞬时单位线法,结合Horton土壤入渗经验模型,并考虑植被对降雨的截流作用,建立了渗透坡面汇流计算的数学模型。以矩形坡面为研究对象,基于其汇流时间-面积特性,结合等流时线法,推导建立了Nash瞬时单位线参数n、K的确定方法。其中,参数n的值为1.0,K的值与坡面汇流时间相等,相当于单一线性水库。应用本文建立的模型,对林地渗透坡面降雨径流进行计算,并与实测值进行比较。结果表明,计算值与实测值的变化趋势基本吻合,初步验证了本文方法的合理性。     

基于目标规划法的时段单位线多目标优化估计

时段单位线被广泛应用于模拟流域中的地面径流过程.用传统方法(如最小二乘法)推求时段单位线,容易产生锯齿形现象;目标规划法是一种多目标优化法.对两种方法的推算效果进行了比较,结果显示目标规划法成功地抑制了时段单位线锯齿形现象的产生,并且用两种方法计算得到的地面径流与观测值之间的吻合度是近似的.     

使用GIS技术支持下的地貌瞬时单位过程线估算设计洪水

在印度甘比希里河流域，应用GIS技术水陆两用全能信息系统软件建立数字高程模型进而建立1h间隔的流域等流时线图，估算出模型参数，并将每组设计暴雨数据、地貌特征、初始参数代入地貌瞬时单位线模型中，分别考虑单峰、双峰、三峡、四峰共4种情况计算出设计洪水过程线，并与其他方法进行比较。可以看到应用GIS技术较之手工方法更容易且更精确。     

基于流量-面积比值的小流域设计洪水计算方法对比研究

为确定分布式模型法、地区瞬时单位线法及推理公式法在估算山区小流域设计洪水过程中的适用性,基于洪峰流量-流域面积比值,以重庆市綦江区蒲河水系为研究对象,采用3种方法分别进行设计洪水计算,并与重庆市实测100 a一遇洪峰流量进行对比。结果表明:①当流域面积＜10 km²时,采用推理公式法更合理可靠;此时河道坡度较大,流域的产、汇流条件符合推理公式法假定条件,计算结果符合实际。②当流域面积为10~100 km²时,分布式模型法与地区瞬时单位线法均可合理计算设计洪水,但前者计算结果比后者更接近实测值。此类流域河道长、坡度平缓,流域的水动力在空间中可视为均匀的扩散;计算格栅单元间连续性强,各栅格向流域出口演算能合理反映真实的设计洪水过程。③当流域面积＞100 km²时,3种方法计算结果与实测值均有不同程度的偏离,但分布式模型法偏离程度最低,可作为设计洪水计算的首选方法。研究结果将有助于合理选择设计洪水计算方法,为类似山区小流域设计洪水计算提供参考。     

基于流量-面积比值的小流域设计洪水计算方法对比研究

为了对小流域洪水设计过程中常用的推理公式法、分布式模型法和地区瞬时单位线法的适用性进行探讨,本文以浙江省宁波市甬江地区水系为研究对象,利用洪峰流量-流域面积比值参数,对设计洪水分别采用3种方法进行计算,然后将各计算结果分别与宁波市洪峰流量100年一遇实测值进行对比分析。研究表明:推理公式法适用于面积小于10km2的流域,其假定条件均与流域的产、汇流条件相符,计算结果更加真实可靠;对于面积大于100km~2的流域,采用不同方法的计算结果与实测结果表现出不同程度的偏差,而分布式模型法的计算准确性相对较高;对于面积为10~100km~2的流域,其坡度较为平缓、河道较长,水动力在空间上可视为均匀分布态,采用地区瞬时单位线法和分布式模型法进行洪水设计较为合理,而后者的计算精确性更好。本文的研究成果有利于提高洪水设计计算法的适用性和准确性,并可为洪水设计方法的选择提供一定的数据支撑和决策依据。     

瞬时脉冲函数转换为时段单位线的计算

Nash瞬时单位线、迟滞瞬时单位线(滞后演算法)和线性扩散渡模拟法的公式均为瞬时脉冲函数的入流,应用这些方法需通过s电线将其转换为时段入流的单位线(汇流曲线).文中通过不完全г函数的多项式近似计算公式直接计算s曲线,进行单位线的时段转换,结果令人满意.     

Synthetic Unit Hydrograph for Al Fara'a Catchment in the West Bank

Abstract

Synthetic unit hydrographs are frequently used to estimate hydrograph characteristics when observed data are not available. A number of synthetic unit hydrograph approaches are available, but the ones that found widespread use are those based on models of Snyder, Clark, and the U.S. Soil Conservation Services (SCS). The major goal of the study is to develop a synthetic unit hydrograph for Wadi Al Fara'a Catchment, which is un-gauged and considered one of the West Bank's most important catchments. Unfortunately, none of the wadis in the West Bank are gauged and flow records are not available; therefore, it is hoped that this method will be applied successfully for Wadi Al Fara'a catchment and the results can hopefully to be applied to all West Bank catchments, which will facilitate estimation of potential runoff in the whole West Bank.     

分布式单位线在河北雨洪模型中的应用

因河北雨洪模型的汇流计算方法难以用于无资料流域,其汇流参数难以获得且不宜移用,为此,将基于数字高程模型的分布式单位线用于河北雨洪模型,并对峪门口流域4场较大洪水过程进行了模拟。结果表明:4场洪水洪峰流量相对误差均<5%,峰现时间误差均<2 h,确定性系数均>0.85,模拟效果令人满意。河北雨洪模型与基于流域地形地貌特征的分布式单位线相结合,可解决无资料流域,特别是山丘地区中小流域的洪灾预警预报等问题。     

流域汇流单位线时段转换应用分析

当流域汛期雨情报讯时段在特殊情况下出现变化时,流域汇流单位线必须事先进行时段转换后才能用于实际洪水预报。以实测水文原始数据为依据,根据示例流域在水文预报工作中的特殊需要,采用s曲线法对流域汇流单位线进行了实例转换和应用分析。分析成果符合相关行业规范精度标准,提出了分析成果的具体使用条件和应用范围,成果能够作为备选方法用于实际工作之中。     

Estimation of the Velocity Parameter of the Geomorphologic Instantaneous Unit Hydrograph

The problem of estimation of the velocity parameter in the exponential distribution geomorphological instantaneous unit hydrograph (ED-GIUH) is investigated in this study. The main difficulty in applying the ED-GIUH model is the estimation of this parameter. In the present study, the ED-GIUH model is applied to six watersheds in Indiana, U.S.A. The relationships between the velocity parameter and climatic as well as basin geomorphologic parameters are investigated. The results of the study indicate that the velocity parameter is related to effective rainfall depth, total basin area and cumulative slope; it does not depend on runoff characteristics. Therefore, the ED-GIUH model can be used for estimating discharge hydrographs from ungauged watersheds.     

Sensitivity Analysis of the GIUH based Clark Model for a Catchment

For estimation of runoff response of an ungauged catchment resulting from a rainfall event, geomorphologicalinstantaneous unit hydrograph (GIUH) approach is getting popularbecause of its direct application to an ungauged catchment. Itavoids adoption of tedious methods of regionalization of unithydrograph; wherein, the historical rainfall-runoff data of anumber of gauged catchments are required to be analyzed. In thisstudy, the GIUH derived from geomorphological characteristics ofa catchment has been related to the parameters of Clark IUH modelfor deriving its complete shape. The DSRO hydrographs estimatedby the GIUH based Clark model have been compared with the DSROhydrographs computed by the Clark IUH model option of the HEC-1package and the Nash IUH model by employing some of the commonlyused error functions. Sensitivity analysis of the GIUH basedClark model has been conducted with the objective to identify thegeomorphological and other model parameters which are moresensitive in estimation of peak of unit hydrographs computed bythe GIUH based Clark model. So that these parameters may beevaluated with more precision for accurate estimation of floodhydrographs for the ungauged catchments.     

Evaluation of three unit hydrograph models to predict the surface runoff from a Canadian watershed

The predictability of unit hydrograph (UH) models that are based on the concepts of land morphology and isochrones to generate direct runoff hydrograph (DRH) were evaluated in this paper. The intention of this study was to evaluate the models for accurate runoff prediction from ungauged watershed using the ArcGIS^® tool. Three models such as exponential distributed geomorphologic instantaneous unit hydrograph (ED-GIUH) model, GIUH based Clark model, and spatially distributed unit hydrograph (SDUH) model, were used to generate the DRHs for the St. Esprit watershed, Quebec, Canada. Predictability of these models was evaluated by comparing the generated DRHs versus the observed DRH at the watershed outlet. The model input data, including natural drainage network and Horton's morphological parameters (e.g. isochrone and instantaneous unit hydrograph), were prepared using a watershed morphological estimation tool (WMET) on ArcGIS^® platform. The isochrone feature class was generated in ArcGIS^® using the time of concentration concepts for overland and channel flow and the instantaneous unit hydrograph was generated using the Clark's reservoir routing and S-hydrograph methods. An accounting procedure was used to estimate UH and DRHs from rainfall events of the watershed. The variable slope method and phi-index method were used for base flow separation and rainfall excess estimation, respectively. It was revealed that the ED-GIUH models performed better for prediction of DRHs for short duration (≤6 h) storm events more accurately (prediction error as low as 4.6–22.8%) for the study watershed, than the GIUH and SDUH models. Thus, facilitated by using ArcGIS^®, the ED-GIUH model could be used as a potential tool to predict DRHs for ungauged watersheds that have similar geomorphology as that of the St. Esprit watershed.     

江垭水库洪水单位过程线的推求方法

以江垭水库某次洪水过程为例,探讨了洪水单位过程线的推求。由实际降雨量和流量过程线进行分析,并做了基本假定;所选的降雨洪水过程超过三个时段,且有一个最大值,故采用试错法进行推求,给出了推求过程及方法。将推求成果与降雨径流相关图配合使用,可对洪水过程进行预报。     

Derivation of Unit Hydrograph from GIUH Analysis for a Himalayan River

Unit Hydrograph (UH) is the most popular and widely used method for predicting flood hydrograph resulting from a known storm in a basin area. However, the non-availability of UH due to poor network of raingauge stations in flood prone Indian river basins is a major concern. The computation of Horton's ratios and their application in generating the Geomorphological Instantaneous Unit Hydrograph (GIUH) can provide a solution for ungauged rivers. A detailed drainage network analysis was carried out for a 5th order flood- prone Himalayan river system in order to highlight its significance in flood management program. The equations for GIUH of 5th order stream were derived through Markov Chain analysis. The GIUH model for the 5th order stream was used to derive the first ever analytical UH of the river. Further, it was applied to determine the 50-yr return period flood. The 50-yr return period flood matches with the result of flood frequency analysis based on observed peak discharge data. This drainage network analysis and application of GIUH can provide a significant contribution towards flood management program.     

瞬时单位线汇流参数m1非线性改进方法探讨

针对瞬时单位线计算设计洪水过程中,对单位线汇流参数m1进行非线性改进的运用条件和改进公式中采用的临界雨强等参数的取值等进行探讨.     

一个特殊的设计洪水流量过程线放制方法介绍

为满足水利水电工程的防洪要求，需进行设计洪水的计算，其中选择典型洪水过程线，由于条件所限，一般常用的典型洪水过程线放制方法所得过程线，不能真正代表工程所在流域的洪水特性，本文探讨某些特殊情况下，对典型线进行修改的必要性和修改方法。