黑河上游高寒山区降雨-径流形成过程的同位素示踪

为揭示中、低纬度高寒山区降雨-径流的形成过程,指导水资源的合理开发利用,选择黑河上游红泥沟小流域为研究区,基于河道径流量及雨水和河水稳定同位素的观测数据,构建二元混合模型,计算了2013年7月23日及8月21日两次典型降雨-径流事件中事件水（降雨）和事件前水（流域前期储水）对河道径流的贡献及其动态变化.结果显示:两次降雨事件中事件前水的贡献比例分别为68.69%和54.46%;事件前水的贡献比例在涨水阶段减小,在退水阶段增大.结合河水电导率的观测结果,进一步分析了降雨-径流的形成过程:河道径流的形成主要受饱和区蓄满产流、河岸带地下径流和山坡地下径流3种产流机制控制;事件水主要源于蓄满产流,事件前水主要源于河岸带和山坡地下径流;事件初期和末期以河岸带地下水补给为主,涨水阶段后期和退水阶段前期转为以蓄满产流和山坡地下水补给为主,洪峰期间蓄满产流的贡献达到最大.两次事件的对比表明,事件前的湿度条件和降雨强度对降雨-径流的形成过程有着重要影响:前期越湿润,流域储水能力越弱,导水能力越强,事件水的贡献越大,河道径流对降雨的响应越迅速;降雨强度越大,蓄满产流及其中的事件水比例越高,河道径流中事件水的比例也越高.      

考虑风场影响的城市建筑区产流计算方法

风场作用下城市建筑物的遮挡作用直接影响区域产流过程,为提高城市雨洪模拟精度,需揭示风场作用下建筑区的独特产流机理并构建相应的计算方法。将建筑区的产流面划分为水平面和竖直面,基于计算流体力学理论求解降雨倾角,结合几何关系确定降雨在水平面和竖直面上的分布,通过产流理论分别计算2类产流面的产流,提出建筑区的产流计算方法,并将其耦合入SWMM模型在试验流域进行了验证。结果表明：(1)改动模型所模拟的径流的纳什效率系数整体高于原始SWMM模型,且洪峰模拟效果更好;(2)改动模型的土壤饱和导水率等关键参数取值更为合理;(3)改动模型对不同气象条件下建筑区产流模拟的稳定性更好。该方法可提高建筑区产流模拟精度。     

一个网格型松散结构分布式水文模型的构建

根据流域降雨径流的基本过程,以蓄满产流理论为基础,建立了一个网格型松散结构的分布式流域水文模型。模型将流域离散为包含河道与不包含河道两种类型的单元格,以协克里金方法插值得到空间离散的降雨输入,考虑的产汇流物理过程包括降雨、植被截留及蒸散发、单元格产流、单元格汇流及河网汇流。模型结构简单,参数较少,在充分利用植被覆盖类型图及土地利用类型图的基础上,能够获得大部分参数的选用值。通过在长江三峡区间沿渡河流域的实际应用,模型计算成果令人满意。     

1990—2019年黑河流域植被覆盖度动态变化及气温对其影响

植被覆盖度的变化特征是流域生态监测的重要内容,能为流域综合管理决策提供基础信息。黑河流域是中国西北干旱-半干旱地区第二大的内陆河流域。为研究我国西北干旱-半干旱地区的生态状况,以黑河流域为研究区,根据1990—2019年Landsat NDVI数据,综合应用像元二分模型和一元线性回归方法,分析黑河流域植被覆盖度的动态变化并探讨气温对其影响。结果表明: 黑河流域植被覆盖度呈现由南向北递减的空间分布特征; 近30 a来,植被覆盖面积总体呈上升趋势,中高植被覆盖度增长速度最快; 流域大部分地区植被覆盖度保持不变,植被覆盖度增加的区域多于退化区域; 受全球变暖影响,整个流域气温呈升高趋势,中游气温上升最快,上游最慢,流域上游和中游气温的升高对植被覆盖度起到促进作用,下游气温的升高则抑制了植被生长。     

黑河上游红泥沟小流域基于溶解硅的降雨径流路径示踪

为揭示高寒山区冻土对降雨-径流过程的影响,对黑河上游红泥沟小流域典型降雨事件全过程出口断面的径流量进行了观测,采集降雨和河水样品,测定其中溶解硅的质量浓度,进而分析径流量和溶解硅质量浓度的动态变化规律,并以溶解硅为示踪剂将小流域出口径流分割为地面径流(腐殖层中流和坡面流)和地下径流(矿质层中流)。结果表明,洪峰上升期,地面径流对河道径流的贡献率为47%,地下径流贡献率为53%;洪峰降落期,地面径流贡献率为29%,地下径流贡献率为71%。整个观测过程中地面径流对河道径流的贡献率为30.7%,地下径流的贡献率为69.3%,说明洪峰期间河道径流以地下径流为主。分析认为冻土分布地区夏季降雨-径流过程中,由于土壤逐渐解冻,降雨入渗驱替冻土层上水排入河网,流域产流仍以地下径流为主。     

坡地径流入渗机制对水文模拟的影响分析

建立了适用于栅格单元系统的基于运动波理论的降尺度新安江模型(KWXAJ)。在栅格单元中采用新安江模型计算产流,运动波模型进行坡面汇流演算。模型中,为考虑上游坡地单元入流的径流入渗(run-on)效应,在进行坡地产流计算时,降雨及上游坡面流及壤中出流被同时作为来水输入新安江模型。在运动波模型中,糙率系数依据土地利用方式及洪水量级确定。选取淮河史灌河流域黄泥庄以上集水区域,作为研究区域。用流域历史上的13次洪水过程来率定和验证此模型。研究表明,run-on机制对流域产汇流预测有重要影响,其显著影响流域内土壤蓄水量时空分布,进而改变产汇流机制。数据分析还显示,不考虑run-on机制将导致模拟洪峰滞后。     

嫩江流域径流时空演化规律分析

以流域时空分布理论框架为基础,分析嫩江流域径流时空演化规律,并着重从地形地貌影响因素方面进行归因分析。采用1955-2003年49 a的降水资料和1955-1973年19 a的径流资料,通过对代表性水文站自上游至下游（空间上）径流、地表径流和地下径流的年内与年际（时间上）演变规律进行分析。结果表明：1）嫩江流域降水年内变化及年际变化过程基本一致,可以忽略降水时空分布对径流时空演化规律的影响。2）从径流年内演化规律上可以判定上下游水源组合的差异性：上游以地表径流为主,在春季来源于融雪,汛期来源于大气降水,枯水季节来源于地下水补给;下游全年以地下径流为主。3）由于坡度和水文地质条件作用,上游更容易产流,下游受下垫面调蓄作用更强,不易产流;因此,从径流年际演化规律上可以判定径流产量自上游至下游逐渐减小。     

喀斯特流域分布式水文模型及植被生态水文效应

根据喀斯特流域多孔介质与裂隙水流特征,建立了达西流、裂隙渗流与槽蓄汇流演算相结合的混合汇流演算模式,实现了对分布式水文-植被-土壤模型(DHSVM)的改进。利用贵州普定喀斯特生态水文试验站陈旗小流域观测资料,对模型计算的流量过程及植被截流、蒸散发及土壤含水率时空分布进行验证。结果表明,模型能较好地模拟喀斯特流域陡涨、陡落的流量过程。同时,模型能模拟出土壤含水率、实际蒸散发与降雨、下垫面岩溶裂隙、植被覆盖的响应关系,对分析中国南方喀斯特地区下垫面变化条件下的生态水文效应具有重要意义。     

山区小流域洪水分布模式模拟与危险性评估

流域暴雨山洪过程时空异质性强,准确评估雨洪变化特性和洪水危险性对山洪灾害防治具有重要意义。以7个降雨特征指标和6个洪水特征指标刻画流域场次雨洪特性,采用中国山洪水文模型和洪水频率指标相结合,模拟和评估口前流域洪水过程及其危险性。结果表明：场次洪水洪峰模数、洪峰时间偏度、高脉冲历时占比、涨落洪速率与降雨总量、平均雨量、最大雨强、雨峰位置系数、基尼系数等降雨特征指标显著相关,三场致灾洪水过程的降雨均呈现量级大、强度大、历时短、暴雨中心偏中下游的特点;率定期和验证期的平均径流深相对误差均在9%以内,平均洪峰流量相对误差均在11%以内,平均峰现时间误差均在1.7 h以内,平均Nash-Sutcliffe系数为0.80和0.76;各场次洪水有0.0%～93.3%的河段流量达到一般危险及以上等级,三场致灾洪水过程的危险性等级最高,分别有80.0%、35.0%和1.7%的小流域河段流量达到高危险及以上等级。研究可为山区小流域暴雨洪水危险性评估、灾害响应和复盘等提供技术支撑。     

黄河数字流域模型的建立和应用

黄河数字流域模型是“数字黄河”的重要组成部分,在数字流域模型框架下,以坡面为基本单元,建立了包括植被截留、融雪、地表蓄滞、表层土蓄滞、中层土蓄滞和深层土蓄滞共6层的产流模型.模型在垂向上考虑3层出流:地表超渗产流、表层土侧向渗流和中层土侧向渗流,既反映当前的降水过程,又体现前期降水过程和土壤前期含水量的影响,比较适合黄河流域的产流特点.在坡面产流的基础上,还给出了坡面单元侵蚀产沙公式,用于建立流域产沙数学模型.应用建立的模型,给出了3个计算实例:黄河全流域水量计算、小花区间汛期洪水模拟和多沙粗沙区产沙计算.实践表明:建立的模型基本具备了在黄河全流域进行降雨-径流模拟、侵蚀产沙计算的功能,辅以降雨预报模块则可进行洪水预报.     

基于太湖流域模型的城市内涝过程高效模拟

城市内涝的高效模拟对于降低内涝灾害影响、制定防灾减灾措施具有极其重要的意义。本文提出了基于雨篦子耦合地表与管网的城市降雨-产汇流-内涝全过程高效模拟方法, 结合常州市双桥浜城市产汇流与内涝试验基地监测数据, 分别构建了基于高效模拟算法和二维水动力算法的城市内涝模型。根据监测数据对所构建的模型进行了率定与验证, 并分析对比了2种算法在不同降雨事件中的精度与可靠性。结果表明: 太湖流域模型中基于雨篦子的城市水文特征单元高效模拟方法能够较为真实地反映城市内涝的具体特征, 且在模型参数一致的前提下, 其计算效率约为二维水动力算法的780~1 275倍, 能够对城市内涝情况进行快速模拟。     

Study on rain-runoff process in the peripheral mountainous area of the Sichuan Basin

Studies on rain-runoff process in the peripheral mountainous area of the Sichuan Basin, which is regarded as a key ecological shelter, will contribute to flood control and environmental protection for the Upper Yangtze River Basin. In two typical catchments--the Fujiang River Catchment and the Wujiang River Catchment, rainfall simulations have been conducted to study the rain-runoff processes of yellow soil and limestone soil in three types of land use--forestland, farmland and grassland. Results showed that （1） within the same rainfall process, overland flow occurs first on farmland, then on grassland, and finally on forestland; （2） soil surface coverage has a great impact on the occurrence and amount of overland flow. The runoff amount can increase 2-4 times after the coverage is removed; （3） the infiltration before the occurrence of overland flow will decrease because of higher gravel contents of soil, but it takes no effect on infiltration once overland flow becomes stable; （4） the runoff coefficient of the limestone soil forestland is greater than that of the yellow soil forest land, but less than that of the farmland; （5） three empirical infiltration models, including Horton＇ model, Kostiakov＇ model, and modified Kostiakov＇ model, were compared by using the observed results under rainfall simulation. The results showed that the Kostiakov＇ model performed better than both the Horton＇ model and modified Kostiakov model. According to the results of this research, the Kostiakov＇s model can be used to simulate rainfall infiltration when water erosion is modeled in the peripheral mountainous area of the Sichuan Basin.     

Study on rain-runoff process in the peripheral mountainous area of tne Sichuan Basin

Studies on rain.runoff process in the peripheral mountainous area of the Sichuan Basin,which is re-garded as a key ecological shelter,will contribute to flood control and environmental protection for the Upper Yang-tze River Basin.In two typical catchments--the Fujiang River Catchment and the Wujiang River Catchment,rainfall simulations have been conducted to study the rain-runoff processes of yellow soil and limestone soil in three types of land use-forestland.farmland and grassland.Results showed that(1)within the same rainfall process,overland flow occurs first on farmland,then on grassland,and finally on forestland;(2)soil surface coverage has a great im-pact on the occurrence and amount of overland flow.The runoff amount Can increase 2-4 times after the coverage iS removed;(3)the infiltration before the occurrence of overland flow will decrease because of higher gravel contents of soil.but it takes no effect on infiltration once,overland flow becomes stable;(4)the runoff coefficient of the lime-stone soil forestland iS greater than that of the yellow soil forest land,but less than that of the farmland;(5)threeempirical infiltration models,including Horton'model,Kostiakov'model,and modified Kostiakov'model,were compared by using the observed results under rainfall simulation.The results showed that the Kostiakov'model per-formed better than both the Horton'model and modified Kostiakov model.According to the results of this research,the Kostiakov's model Can be used to simulate rainfall infiltration when water erosion is modeled in the peripheral mountainous area of the Sichuan Basin.     

流域植被对径流调节作用的实验研究

根据河北省邢台市西部山区两个小流域实验站的水文监测资料,研究了不同流域内的不同植被对径流的影响。分析了流域植被对径流的年内分配、径流系数、削减洪峰以及枯季径流量等的影响。结果表明,流域植被对涵养水源、调节径流量、增大枯季径流量起到重要作用。     

Distribution of stable isotopes in arid storms

 Temporal distributions of the isotopic composition in arid rain storms and in the associated runoff were investigated in a small arid rocky basin in Israel. Customized rain and runoff samplers provided sequential water samples hermetically sealed in high-density PVC bags. In several storms where the runoff was isotopically depleted, compared with the rainfall, the difference could not be explained by fractionation effects occurring during overland flow. A water-balance study relating the runoff discharge to rainfall over a rocky watershed showed that the entire discharge is produced by a very small segment (1–2 mm) of the rain storm. The major objective, therefore, was to provide quantitative relations between segments of rainfall (rain showers and rain spells) and runoff. The time distribution of the composition of stable isotopes (oxygen and hydrogen) was used to quantify the correlation between the rain spell's amount and the consequent runoff. The aim of this work was to (a) utilize the dynamic variations in the isotopic composition in rainfall and runoff and model the magnitude of surface-storage capacity associated with runoff processes of overland flow, and (b) characterize the isotopic composition of the percolating water with respect to the isotopic distribution in rainfall and runoff events. The conceptual model postulates an isotopic mixing of overland flow with water within the depression storage. A transport model was then formulated in order to estimate the physical watershed parameters that control the development of overland flow from a certain rainfall period. Part I (this paper) presents the results and the assessment of the relative depression storage obtained from oxygen-18 and deuterium analyses that lead to the physical and mathematical formulation of a double-component model of kinematic-wave flow and transport, which is presented in Part II (accompanying paper). Received, February 1997 · Revised, September 1997 · Accepted, September 1997     

Assessing flash flood hazard in an arid mountainous region

Although flash floods are one of the major natural disasters that may hamper human development in arid areas, aspects of the process leading to their initiation remain uncertain and poorly understood. In the present study, wadi El-Alam Basin, one of the major basins in the Eastern Desert of Egypt that is frequently subjected to severe flash flood damage, is selected for investigation. Here, a hydrological modeling approach was used to predict flash flood hazard within the basin. Earlier work conducted for the same basin showed that such approach is successful and was able to accurately highlight the locations of historical flood damage. However, such work was based on one set of arbitrary model parameters. The present study has taking into account the rainfall as the excitation factor in the adopted hydrological modeling. The study aims to build on the earlier study by investigating impacts of variation of rainfall depth, areal coverage, and location on flash flood generation. Results demonstrate that the basin under study requires a rainstorm intensity of at least 40 mm in order to initiate surface runoff with a noticeable flood peak at its main outlet. The location of rainstorm has a major effect on the shape of the basin final hydrograph. Furthermore, in the study basin, the upstream flood appears to be of a magnitude and a peak flow that is much higher than those for downstream ones, which believes to be strongly attributed to the surface steepness and impermeability of the former. The used approach shows to be useful in the rapid assessing of flash flood hazard in mountainous desert and could be adopted, with appropriate modifications, elsewhere in arid regions.     

淤泥质海岸入海河口闸下港道河相关系

以江苏沿海北部的射阳河闸下港道为原型,建立二维水动力及泥沙输运概化数学模型,模拟了淤泥质海岸闸下港道淤积过程。分别在不考虑径流年内分配变化和考虑径流年内分配变化的情况下,研究了入海径流对港道内水沙动力和冲淤演变的影响。参考前人研究成果,结合量纲和谐准则,根据模型的计算结果,建立了淤泥质海岸闸下港道年均平衡流量与汛期排水比例、河床断面积、外海潮差、潮波变形、港道长度等因素间的河相关系式,对在实际情况中达到动态冲淤平衡的某条特定港道,可简化为港道年均流量与河床断面积间关系式的简化形式,并通过分析实测资料,对公式的简化形式加以佐证。     

Impact assessment of land cover changes on the runoff changes on the extreme flood events in the Kelantan River basin

In the current years, changing the land cover/land use had serious hydrological impacts affecting the flood events in the Kelantan River basin. The flood events at the east coast of the peninsular Malaysia got highly affected in the recent decades due to several factors like urbanisation, rapid changes in the utilisation of land and lack of meteorological (i.e. change in climate) and developmental monitoring and planning. The Kelantan River basin has been highly influenced due to a rapid change in land use during 1984 to 2013, which occurred in the form of transformation of agricultural area and deforestation (logging activities). In order to evaluate the influence of the modifications in land cover on the flood events, two hydrological regional models of rainfall-induced runoff event, the Hydrologic Engineering Center (HEC)-Hydrologic Modeling System (HMS) model and improved transient rainfall infiltration and grid-based regional model (Improved TRIGRS), were employed in this study. The responses of land cover changes on the peak flow and runoff volume were investigated using 10 days of hourly rainfall events from 20 December to the end of December 2014 at the study area. The usage of two hydrological models defined that the changes in land use/land cover caused momentous changes in hydrological response towards water flow. The outcomes also revealed that the increase of severe water flow at the study area is a function of urbanisation and deforestation, particularly in the conversion of the forest area to the less canopy coverage, for example, oil palm, mixed agriculture and rubber. The monsoon season floods and runoff escalate in the cleared land or low-density vegetation area, while the normal flow gets the contribution from interflow generated from secondary jungle and forested areas.