Three geomorphological rainfall–runoff models based on the linear reservoir concept

Three geomorphological models, based on linear reservoirs cascade, are developed; two of the models are unit hydrograph (UH) models and one contains a non-linear routing approach. In the first UH model, each sub-basin is represented as a cascade of equal linear reservoirs (Nash's model) which directly discharges to the watershed outlet through a linear channel. In the second UH model each sub-basin is represented as a linear reservoir arranged in a sequence based on the drainage network. For both unit hydrograph models, parameters are explicitly derived, which make the models simple and applicable for real world problems. In the third model, output hydrographs of the sub-basins are calculated by the Nash model but with consideration of geomorphological properties of the sub-basins. Then, the obtained hydrographs are routed through the main channel using a non-linear kinematic wave model. Combination of the kinematic wave routing model (a non-linear routing model) and the Nash model (a linear lumped model) makes this third model more appropriate for runoff modeling.Two important properties of these three models are that they consider the effect of watershed geomorphology and include only one parameter which can be estimated using observed rainfall–runoff data. GIS tools are used for determining the watershed geomorphological parameters. The results of these models are compared with the Nash's black box and the geomorphological SCS models for the Amameh watershed, Iran. Although the results show that the proposed models yield good efficiency in rainfall–runoff modeling, the semi-distributed routing ability in the second and third models produces better results.     

基于地理信息的SCS模型及其在黄土高原小流域降雨-径流关系中的应用

基于土地利用、土壤类型等信息数据和流域水文、气象资料，应用美国农业部水土保持局研制的小流域设计洪水模型-SCS模型对王东沟流域径流过程进行了模拟。按照集水区自然分水线划分流域子单元，并提出了适合该流域产流计算的CN值表。结果表明，模型所模拟的径流过程与实测径流过程具有较好的一致性，模拟精度在75%以上，说明模型在参数的确定上较为合理，可以应用于黄土高原典型流域，为建立分布式水文模型对流域进行生态水文综合评价提供了科学方法。     

Comparing Different Infiltration Methods of the HEC‐HMS Model: The Case Study of the Mésima Torrent (Southern Italy)

The Hydrologic Engineering Center – Hydrologic Modelling System (HEC‐HMS) model has been widely applied for estimating hydrological variables at event scale. The choice of the most suitable infiltration method simplifies model's applicability under different environmental conditions. A proper case study for evaluating the runoff prediction capability of HEC‐HMS by the available infiltration methods is the semi‐arid torrents typical of Southern Italy as they are small and intermittent water courses, often subject to high‐magnitude flash floods and erosive events. HEC‐HMS performance of the ‘SCS‐CN’, ‘Green‐Ampt’ and ‘Initial and Constant’ infiltration methods in predicting runoff volume and peak flow was evaluated at the outlet of the Mésima torrent, Calabria, Southern Italy. Fourteen rainfall–runoff events were simulated by HEC‐HMS and compared with the corresponding observations by a quantitative approach. A good accuracy in predicting runoff volume was achieved using the ‘SCS‐CN’ method after calibration of the initial curve numbers. Peak flow was better estimated using the ‘Initial and Constant’ method, also thanks to calibration of the ‘constant rate’ parameter. The calibrated hydrographs were very similar to the observations for both ‘SCS‐CN’ and ‘Initial and Constant’ methods. Adopting the ‘Green‐Ampt’ equations, however, showed low reliability. The evaluation of the time to flood peak was in some cases inadequate. Copyright © 2016 John Wiley & Sons, Ltd.     

Application of a unit hydrograph based on subwatershed division and comparison with Nash's instantaneous unit hydrograph

The Unit Hydrograph (UH) technique is widely used for runoff estimation, especially for determining peak discharges. In this paper, a geomorphologically based UH has been applied. Its most remarkable characteristic is that it includes the watershed structure in its formulation. This is defined from the drainage network, each subwatershed being considered as a linear reservoir. In this method, the fact of considering this reservoir sequence according to the drainage network leads to the formulation of the model only depending on a single parameter. The Geomorphological Unit Hydrograph of Reservoirs (GUHR), proposed in this paper, is compared with Nash's Instantaneous Unit Hydrograph (Nash's IUH), by applying the two methods to the Aixola watershed. This 4.7-km² watershed is located in Gipuzkoa (Northern Spain). It is characteristic of the headwaters watersheds of the area. Most of them are forested and have steep slopes. Annual rainfall is over 1500 mm and many intense rainfall events are observed, among which 18 were selected for this study. Both UH techniques were applied to the rainstorms. The resulting hydrographs were plotted against registered data and the best fits were determined. According to these results, the GUHR model behaved similarly to Nash's IUH. However, the GUHR method seemed able to reproduce a wider range of rainstorms than Nash's IUH. While analyzing the UHs calculated, seasonal behavior was observed in runoff generation, and different average UHs were proposed for two different periods. This variability was also observed in values adopted by the GUHR model parameter, providing some information about the watershed time response. The dynamic character of the only uncertain parameter, and the model formulation, in which the watershed morphology is reflected, together with the model's simplicity, leads us to consider GUHR as being a promising UH model.     

基于动水法的流量过程线推移法在渠道渗漏计算中的应用

动水法观测渠道渗漏较静水法便捷,但由于动水法观测条件苛刻,通常使得动水法定义下的计算结果可靠性较差。该文通过对动水法观测问题及特点分析,建立了流量过程线推移法,通过数据平行检验,绘制有效数据的流量过程线,并对流量过程线进行顺流推移和逆流推移,从而获得某观测时段内上、下游观测断面的流量过程线差,进而算得损失流量。该文以石津灌区四干三分干南四支梯形混凝土衬砌渠道为例进行了分析,对该段渠道上6种衬砌形式进行静水法和流量过程线推移法观测。静水法分析得6种衬砌形式的渗漏量与渠道水深之间均表现为幂函数形式。流量过程线推移法通过平行检验得到19组数据,计算得到渗漏量,将其与静水法得到结果进行比较,得到有12组数据绝对误差小于10 m3/(km·h)。两种方法的渗漏量与水深相关分析呈现相同的变化趋势,即渗漏量随水深的增加而增加。该研究初步验证了流量过程线推移法在渗漏量计算上的可行性。     

Evaluation of runoff,peak flow and sediment yield for events simulated by the AnnAGNPS model in a belgian agricultural watershed

The AnnAGNPS model, widely utilized as a practical tool for addressing erosion problems and land use planning, was implemented in a small agricultural watershed located in central Belgium, to assess its prediction capacity of runoff, peak flow and sediment yield in humid temperate conditions. Model performance was evaluated at the event scale by using a database reporting hydrological, geomorphologic and land use data collected during a 2‐year period. Seventeen events were modelled and compared with the corresponding observations at the watershed outlet. The model performed well in predicting the largest runoff volumes, as shown by the high values achieved for the coefficients of efficiency (E = 0·89) and determination (r² = 0·92). However, some events resulted in zero runoff simulation. The prediction capability for peak flow and sediment yield was poor (E = 0·35 and 0·16, respectively). This inaccuracy can have several causes: the internal model deficiencies may be due to the incomplete representation of watershed complex processes, while external problems may be related to the conditions within the modelled watershed and the quality of recorded data. On the whole the AnnAGNPS model may be considered as being suitable to simulate the significant runoff events in the experimental watershed. However, the model may be seen as better suited for comparative assessments of alternative management and policy scenarios and for gross estimation of nutrient loads rather than the precise prediction of a single event, consequently helping in the prediction of land degradation problems in the experimented conditions. Copyright © 2010 John Wiley & Sons, Ltd.     

基于能量转换的地貌单位线计算方法及应用

该研究基于能量转换原理构建汇流模型,针对中小河流汇流参数确定困难、汇流计算准确度低的问题,分析流域内水质点能量的空间分布,采用将重力势能转化为动能的方式估计地表水流速度,计算空间流速场并提取地貌单位线。采用分辨率30 m×30 m的数字高程模型（Digital Elevation Model,DEM）数据,将湖南省竹溪坡流域划分为57个计算单元,分别采用能量转换法和坡度雨强法提取了地貌单位线。构建了研究区的分布式模型,其中产流计算采用新安江模型,坡面汇流采用地貌单位线模型,河网汇流采用马斯京根法,对竹溪坡流域36场降雨径流过程进行模拟。采用统计方法分析汇流参数,对参数的取值范围进行了评估。结果表明,与坡度雨强法相比,基于能量转换方式的洪水模拟结果中,峰现时间误差不超过1 h的场次比例由30.5%提高到83.3%,确定性系数不低于0.9的场次由9场提升至17场,平均确定性系数达到0.89,显著提高了模拟精度。通过对断面流速进行统计分析,评估竹溪坡流域汇流参数取值范围为[0.008, 0.014],当参数在此区间浮动时,确定性系数不低于0.9的场次比例为44%～50%,与率定得到的结果接近。该方法物理意义明确,参数可以通过率定或者测量方式确定,为无资料地区汇流规律研究提供了一种可靠思路。     

基于原型观测与DEM的强风化花岗岩小流域水文过程模拟

为了解华南花岗岩小流域特殊的产流机制,以土壤为砂壤土、基岩为强风化花岗岩的中山大学珠海校区滨海小流域作为研究对象,观测了2个分别代表森林、灌丛覆盖的5 m×10 m的径流试验场的产流过程和土壤含水率变化过程。观测结果表明超渗产流、优先流是试验场的重要产流方式,壤中流（尤其是在土壤-基岩界面上产生的壤中流）对试验场的总产流量也有较大贡献。在径流试验场原型观测基础上,建立了一个基于数字高程模型（DEM）的、包括地表径流、壤中流和基岩裂隙出流的三水源小流域水文模型。利用9次降雨径流过程对模型参数进行率定,利用4次降雨径流过程进行验证,模型的率定、验证均取得了良好的拟合效果。根据模型的模拟结果,在径流的起涨阶段地表产流贡献最大,而基岩裂隙出流对退水过程贡献明显。综合试验场原型观测结果与模型模拟结果得出结论：明显的壤中流和基岩裂隙出流是华南花岗岩小流域显著的产流特点。     

SCS模型在泥石流多发区降雨—径流模拟中的应用——以云南省蒋家沟流域为例

基于云南省蒋家沟流域的DEM,根据流域地貌,利用地理信息系统软件划分流域子单元,在此基础上利用蒋家沟土地利用类型、土壤类型等地理信息数据和流域水文、气象资料,根据SCS模型CN值标准表,提出适合各子流域产流计算的CN值,绘制出了蒋家沟流域次降雨的CN值分布图,进而应用SCS产流模型和等流时线法对云南省蒋家沟流域的降雨一径流过程进行了模拟.模拟结果表明,与有限的实测资料相比较,模型的模拟精度在90%以上,模拟结果较为满意,说明基于CN值的SCS模型可以应用于蒋家沟流域,同时模拟的径流过程可以弥补实测资料的不足,为蒋家沟流域分布式水文模型的建立提供理论依据和研究方法.     

基于垂向混合产流模型的北京山区山洪预警模型构建

[目的]构建基于垂向混合产流模型的北京山区山洪预警模型,为临界雨量的计算提供理论基础。[方法]结合北京市的气候条件,选用垂向混合产流模型进行产流模拟,用单位线法和线性水库法进行坡面汇流模拟,用马斯京根法进行河道汇流模拟。安全流量则用淹没出流量代表。北京山区山洪预警模型中的参数可通过外业实验测定和历史数据率定获得。[结果]通过对降雨和流量历史资料的验证,确定性系数、洪峰流量、峰现时间、时效等级均符合洪水预报的要求和规定,是否发生山洪的预测结果也与实际情况一致,证明了该模型的准确性。[结论]该模型可以应用于北京山区的山洪预警,降低由山洪导致的人员伤亡与财产损失的可能性。同时,该模型还可为北京山区山洪灾害临界雨量的推求奠定基础。     

Hydrosedimentology of nested subtropical watersheds with native and eucalyptus forests

Purpose

Information on the effects of eucalyptus forests on hydrosedimentological processes is scarce, particularly at the catchment scale. Monitoring and mathematical modeling are efficient scientific tools used to address the lack of information for natural resource management and the representation and prediction of those processes. This study evaluates the effects of eucalyptus cultivation on hydrosedimentological processes in watersheds and to use the Limburg soil erosion model (LISEM) to represent and predict hydrological processes.

Material and methods

The study was conducted in two forested watersheds: the main watershed (94.46 ha) and a nested sub-watershed (38.86 ha), both cultivated with eucalyptus and residual riparian native forest, located in southern Brazil. Hydrosedimentalogical monitoring was conducted from 16th February 2011 to 31st December 2012, and LISEM model calibrations were performed on the bases of six storms events.

Results and discussion

The sediment yield for 2011 was 41.6 Mg km^?2 and 38.5 Mg km^?2 for the watershed and sub-watershed, respectively. An extreme event in 2012 provided greater sediment yield for the sub-watershed (99.8 Mg km^?2) than that for the watershed (51.7 Mg km^?2). Rainfall events with a greater maximum intensity generated rapid discharge and suspended sediment concentration responses in the sub-watershed due to the smaller drainage area and steeper landscape. In the main watershed, the accumulation of flood waves occurred for most events, with less steep hydrographs, and a later occurrence of the discharge peak after that of the sub-watershed. The LISEM adequately reproduced the peak discharge and runoff for the calibrated events; however, the peak time and the shape of the hydrograph were not adequately represented.

Conclusions

The hydrosedimentological patterns of the watershed and sub-watershed, both cultivated with eucalyptus, was characterized by sedimentographs preceding hydrographs during rainfall–runoff events where scale effects occur, with maximum discharge and specific sediment yield greater in the watershed than that in the sub-watershed. Empirical models based on hydrologic variables may be used for estimating the suspended sediment concentration and sediment yield. Therefore, LISEM may be used for the prediction of hydrological variables in these forested watersheds.     

The influence of rainfall distribution and morphological factors on runoff delivery from dryland catchments in SE Spain

A simplified theoretical model of storm runoff has been combined with analysis of rainfall records to improve understanding of dryland runoff processes in the Guadalentin catchment of SE Spain, and in particular the decrease in runoff fraction with increasing slope length or catchment area.Estimates of storm runoff volumes can be made using a simple runoff threshold, SCS Curve Numbers, or infiltration equations. A modified Green–Ampt equation is applied here to give storm runoff estimates for conditions of constant effective rainfall intensity. This can be seen as both an improvement on estimates made using the simple runoff threshold, although with no additional parameters, and a good approximation to the SCS Curve Number family of rainfall–runoff relationships, providing an improved theoretical basis for the Curve Number approach and an explicit means of linking it to existing soils data on infiltration and surface properties. The frequency distribution of intensities is examined to determine an appropriate effective intensity in relation to slope length, with a duration long enough to allow overland flow to reach the slope base. Hydrologically Similar Surfaces (HYSS) are defined by local runoff characteristics, and the linkage to infiltration allows an explicit comparison with routing over land areas of different area, shape and topography. This provides the basis for up-scaling from at-a-point runoff to runoff from larger areas which are mapped as belonging to the same HYSS class, explicitly allowing for their different topography and size, providing an essential step in up-scaling data on fine-scale surface characteristics to the response of catchment areas. Here we focus on the ways in which catchment area or slope length influence runoff production within a given HYSS class.Characteristics which drive catchment response include (1) variations in intensity over time through a storm (2) areal variations in storm volume. For measured rainfall in the upper Guadalentin catchment, SE Spain, the first of these factors is seen to be the most important for catchments of up to 500 km², and a procedure is suggested for deriving effective rainfalls from recorded intensity data. The rainfall data can then be combined with a HYSS analysis of the soil/land use response, and analyses of catchment network morphology and connectivity to forecast the heterogeneous distribution of ephemeral stream runoff.     

Dissolved and Particulate Metals in the Mero River (NW Spain): Factors affecting Concentrations and Load during Runoff Events

This article examines the metal [aluminum (Al), iron (Fe), manganese (Mn), copper (Cu), and zinc (Zn)] runoff dynamics in the Mero River (northwestern Spain). At the catchment outlet, metal concentrations, suspended solids, dissolved organic carbon, pH, and discharge were determined during three runoff events. The river drains an agroforestry catchment of 65 km² with relatively high livestock density. Dissolved and particulate metal concentrations increased during the events with respect to pre-event concentrations, but the increase of the dissolved fraction is relatively small compared to that of the particulate fraction. The dissolved metal concentration peaks appeared after the hydrograph peak, suggesting transport associated with subsurface flow. For particulate metals, peaks usually occurred during the falling limb of hydrograph, implying distant-river source of metals. Particulate forms represented more than 90% of total Al, Fe, and Mn load, whereas for Cu and Zn its contributions were 52–76% and 31–56%, respectively. The high positive correlations of all particulate metals, except Zn, with suspended solid concentrations indicate that these constituents play a major role in transport of metals. Soil erosion is the main process responsible for causing elevated Al, Fe, and Mn concentrations in the river during rainfall–runoff events while Zn and Cu come mainly from the addition of slurries and manures to farmland.     

不同土壤物理属性空间分布对水文过程模拟的影响

基于不同空间分辨率的土壤物理属性数据(土壤田间持水量、孔隙度和饱和水力传导度),运用WATLAC分布式水文模型模拟了西苕溪流域2005-2010年的水文过程。对比评价了土壤物理属性空间分布对地下水补给、土壤蒸发、径流量及其组分的影响。结果显示,利用不同空间分辨率土壤物理属性数据模拟的流量过程与实测值都匹配的很好,模拟精度相当,更详尽的土壤属性空间分布信息未能明显提高模型模拟的精度;而对于地下水补给量,高分辨率的土壤属性空间分布会使其模拟结果大幅减小,但对土壤蒸发量则影响较小,两种数据模拟的结果及其空间分布都很接近;同时,虽然土壤物理属性空间分布的分辨率对模拟的径流总量影响甚微,但对基流与地表径流的分割却产生了较大影响。     

黄丘一区小流域洪水输沙特性研究

<正> 长期的土壤侵蚀,把黄丘一区地表切割成千沟万壑的形态,坡陡流急,干沟沟底比降1％～3％,支毛沟比降更大。一遇暴雨洪水,当汇集坡面来水来沙后,沟岸侧蚀、沟底下切、沟头前进严重,形成沟道网络的高含沙水流,其含沙量500～1000kg/m~3,最高可达1700kg/m~3。由于含沙量大,水流容重和粘滞性增加,紊动减弱,成为非牛顿二相流,具有流变性质。本文根据绥德水保站及有关站(所)的实测资料和研究成果,对黄丘一区小流域洪水输沙特性作一分析。     

曲线数值法(SCS模型)在北京温榆河流域降雨－径流关系中的应用研究

为研究北京城市化进程中降雨-径流关系变化,在温榆河流域应用SCS模型,对该流域部分实测次降雨-径流过程及不同频率年降雨-径流进行模拟,得出SCS模型在温榆河流域预测径流是可行的,无论哪种前期土壤湿润条件,不同频率降雨的年径流量随着时间的推移有增大的趋势,相同前期土壤湿润情况下年径流量绝对增量顺序为,丰水年＞平水年＞枯水年,而相对增量是枯水年＞平水年＞丰水年.相同前期土壤湿润程度及相同频率降雨条件下,城市化水平越高,径流量越大.     

Suitability of Watershed Models to Predict Distributed Hydrologic Response in the Awramba Watershed in Lake Tana Basin

Planning effective landscape interventions is an important tool to fight against land degradation and requires knowledge on spatial distribution of runoff. The objective of this paper was to test models that predict temporal and spatial distribution of runoff. The selected models were parameter‐efficient semi‐distributed watershed model (PED‐WM), Hydrologiska Byrans Vattenbalansavdelning integrated hydrological modeling system (HBV‐IHMS), and Soil and Water Assessment Tool (SWAT). We choose 7‐km² Awramba watershed in the Lake Tana basin with detailed hydrological information for testing these models. Discharge at the outlet, rainfall, and distributed information on infiltration rates, water table, and extent of the saturated area were collected from 2013 to 2015. The maximum saturated area was 6·5% of the watershed. Infiltration rates exceeded rainfall intensities 91% of the time. Hence, saturation excess runoff was the main runoff mechanism. Models were calibrated for the rainy seasons in 2013 and 2014 and validated for 2015. For daily flow validation, the PED‐WM model (Nash–Sutcliff efficiency, NSE = 0·61) outperformed HBV‐IHMS (NSE = 0·51) and SWAT (NSE = 0·48). Performance on monthly time step was similar. Difference in model behavior depended on runoff mechanism. In PED‐WM, saturation excess is the main direct runoff process and could predict the maximum extent of the saturated area closely at 6·9%. HBV‐IHMS model runoff simulation depended on soil moisture status and evapotranspiration, and hence was able to simulate saturation excess flow but not the extent of the saturated area. SWAT, where infiltration excess is the main runoff mechanism, could only predict the monthly discharges well. This study shows that prevailing runoff mechanisms and distribution of runoff source areas should be used for proper model selection. Copyright © 2016 John Wiley & Sons, Ltd.     

递推关系概化前期产流条件改进SCS模型

降雨径流的精准模拟和预测是开展水资源管理和水土环境质量评价的重要依据之一,但现有SCS模型不能有效表征前期降雨蓄存和消耗对产流的影响,进而限制了其径流预测精度。该文基于潜在初损和有效降雨影响系数形成日有效影响雨量的递推关系,将前期产流条件概化成前期日降雨量对降雨初损的影响函数,从而构建了改进SCS模型。其中潜在初损量明确了产流前流域的最大降雨蓄存潜力和日降雨量的有效影响阈值,而前期有效降雨影响系数则表示了在蒸发蒸腾或渗漏过程作用下前期有效日降雨量的动态消耗。在小区、田间、流域3种排水面积下的模型应用结果表明,改进SCS模型能更准确地预报产流的变化,验证期的确定系数R2和纳什系数NSE比SCS原模型分别提高了27.0%~30.9%和1.0%~78.3%。前期有效降雨影响系数的稳定性较好,两模型的曲线数的拟合值比较一致。该改进SCS模型为更准确预测蒸发蒸腾或渗漏较为剧烈地区的径流提供参考。     

HEC-HMS水文模型系统在汉江褒河流域的应用研究

基于地理信息系统和遥感技术的水文模型集成系统将成为未来水文循环过程研究的发展趋势。基于HEC-HMS水文模型系统,采用多种方案对位于汉江上游的褒河流域进行了降雨径流模拟。研究结果表明:基于DEM、遥感影像和土壤资料,并结合GIS技术推求反映流域下垫面特征的关键水文参数的方法可以与HEC-HMS水文模型系统很好地耦合。该模型对于我国湿润、半湿润山区的次洪模拟具有较好的适用性。     

嘉陵江流域非点源溶解态氮污染负荷模拟研究

嘉陵江流域是乏峡水库最大的支流,为研究嘉陵江流域非点源溶解态氮污染负荷的年际变化规律及其来源的空间分布情况,以流域土地利用类型为研究单元,通过引入具有物理机制的半分布式水文模型——sLuRP水文模型,并推导溶解态氮的流域输移损失系数,建立了流域非点源溶解态氮污染年负荷模型。借助GIS技术,应用所建模型,对嘉陵江流域各土地利用类型L的年地表径流量和溶解态氮污染负荷进行了模拟。模拟结果表明,以旱地和水田为主的涪江流域的溶解态氮流失情况最为严重,其次是渠江下游流域和西汉水流域,1990---2005年嘉陵江流域各土地利用类型上产生的非点源溶解态氮年均负荷为35726t·a^-1,约占流域出口总氮负荷的32％。