应用官司河分布式水文模型模拟流域降雨-径流过程

由于地理要素（地形、气候、土壤、植被等）的空间异质性,森林的生态服务功能,尤其是涵养水源和保持水土的功能,也存在着空间分异。本文根据森林水文过程和森林水文生态功能的形成机理,建立了通用性较强的官司河分布式水文模型。官司河模型根据流域内部地理要素的空间异质性把流域分成一系列的单元和作用层,以单元和作用层为基本单位,连续计算每个单元和作用层的水文过程和水文要素变化,包括降雨输入、冠层截留、枯落物层吸水、入渗、蒸散、壤中流、地表径流等,进而得到流域水文的时空变化。用此模型模拟了四川绵阳官司河流域的降雨－径流过程,计算结果与观测结果基本吻合。     

林冠降水截留效应国内研究进展

林冠对降雨截留再分配过程的影响,涉及到森林生态、森林水文、森林气象及水土保持等诸多方面,是森林涵养水源、减少地表径流的重要生态水文过程,对林地水分平衡和养分循环具有重要意义。近年我国对林冠截留、穿透雨、树干流的降水截留效应研究有较多报道,本文对近几十年来我国林冠对降水截留效应研究进展和现状进行简要整理     

长沙市郊枫香人工林水文生态效应的研究

为了科学评价城市景观公益林的生态效益,采用森林水文定位观测、样品采集和实验分析相结合的方法,从森林林冠层、林下枯落物层、土壤层3个生态作用层对长沙市郊枫香人工林水文生态效应进行研究并以荒地作为对照。结果表明:观测期内林冠截留量占平均总降雨量的22.37%,穿透雨、树干茎流与林外降雨存在线性关系,林冠截留量与降雨量具有显著的幂函数关系;林下枯落物贮量为4.56 t.hm-2,枯落物最大持水量为6.79t.hm-2;林地土壤容重小于荒地,非毛管孔隙度是荒地的2倍,林地0～45 cm层土壤最大持水量为197.80 mm;枫香人工林能够改善土壤结构,相对于荒地具有明显的水土保持作用。     

氢氧稳定同位素在淡水湿地森林水文过程研究中的应用

湿地森林在蓄洪防旱、净化水质等方面对区域水文过程起着重要的调控作用。以往对于淡水湿地森林水文的研究多集中在运用传统水文学方法研究单一水文过程,很少将各水文过程作为一个整体来研究,且各个过程对降水截留效应的影响程度也未全部量化。而利用水分子中天然存在的氢氧稳定同位素作为示踪剂可综合反映并量化植被和土壤对降水的截留能力。文中综述湿地森林对水文过程调控作用的国内外研究概况,探讨氢氧稳定同位素技术在湿地森林水文研究中的进展,包括大气降水、林冠穿透水、降雨径流、土壤水、地下水、蒸发水、植物水的水分来源及各水体的转化关系等。在全球变化背景下,运用氢氧同位素技术系统定量地分析降水在生态系统水文过程的分配比例对于揭示湿地森林植被结构对水文过程的调控机制等具有重要意义,同时也可为建立淡水湿地森林植被恢复模式和制定保护策略提供参考。     

森林乔木冠层雨水再分配特征及机制研究综述

森林乔木冠层对降雨的再分配具有重要的水文生态意义,有助于定量评价不同区域、尺度、类型的森林冠层雨水利用效率,可为深入研究森林冠层变化对区域水分循环的调节作用提供科学依据。文中从森林冠层雨水截留、林内穿透雨、树干茎流和林下凋落物截留4个方面评述了近20年来国内外对森林乔木冠层影响雨水再分配的研究最新进展。研究认为,由于森林冠层雨水再分配的生态机理仍未明晰,因此建立精确度高的截留模型仍将作为此类研究的重难点之一;引入激光雷达技术获得森林冠层三维结构,以及多角度、多通道的多种传感器观测垂直空间多层次的森林冠层雨水再利用规律将会成为未来的研究方向之一;目前林冠雨水截留研究缺乏其与区域水文变化之间的关联性研究,将林冠雨水再分配研究的成果转化为区域水文问题的解决方案也将会是未来研究的趋势之一。     

沙棘林水文效应分析与利用

各地的试验研究资料从树冠截留降雨、残落物持水、林地透水性和坡面减流方面,证明了沙棘林显著的涵养水源、减缓暴雨径流等水文效应,从而加深了对沙棘林水土保持功能等生态效益的理解.     

广西龙桥林区不同植被类型水文效益的研究

1985～1987年,在广西龙桥林区,对杉木、马尾松人工纯林和柠檬桉与马尾松人工混交林,以及天然灌木草本群落4种不同植被类型对降水的截留、地表径流及调蓄功能等水文效益进行测定,结果表明,对降水的截留效果以马尾松林为最好,混交林次之,杉木林较差,在同一植被类型的不同层次,以乔木层的截留量占绝对优势;对减少地表径流和延缓洪峰的效果,以层次结构较为复杂的混交林最佳。在同一植被类型内部结构特征的诸因子中,活地被物层的总盖度和草本层的生物量,是影响地表径流的主导因子:植被土壤对降水的调蓄功能,以混交林为最好。其他3种植被类型差异不大。说明在山地防护林建设中,营造针阔叶混交林,使其形成复层林,并保护好灌木草本层和死地被物层,对增强森林的调蓄能力具有重要的意义。     

滇中高原区主要森林类型森林植物的降雨截留功能

通过调查实测,研究了１０个乔木树种和２３个灌木树种树冠对降雨的截留作用,对３２个森林类型乔木层、灌木层、草本层的降雨截留能力和再分配作用进行了分析研究。以此对不同林分类型的总体截留功能作评价。     

湖南省张家界马尾松林冠生态水文效应及其影响因素分析

对马尾松林的穿透雨、林冠截留和树干流的水文效应进行监测,并对其影响因素进行初步分析.结果表明:降雨主要集中在5-8月,期间穿透雨量、林冠截留量和树干流量分别占全年分配量的一半以上.穿透雨量、树干流量和林冠截留量与降雨量显著正相关,而穿透雨率和树干流率随着降雨强度的增加而升高,但截留率逐渐降低.马尾松林穿透雨量最大值出现在最大雨量级(≥90.0 mm)和3.0～4.0 mm·h-1雨强范围内; 但是截留率最大值出现在最小的雨量级(＜10.0 mm)和＜1.0 mm·h-1雨强范围内; 树干流率最大值出现在中等雨量(60.0～70.0 mm)和2.0～3.0 mm·h-1雨强范围内,显然降雨特征是影响马尾松林内雨的关键因子.林下穿透雨率存在明显的空间异质性,靠近树干的林冠内部穿透雨率高于林冠外部,而且空间异质性随着降雨量的增加而降低.马尾松树干流与胸径及冠层面积呈极显著正相关.     

太行山低质低效林改造后的水文效益

在示范林内选取了几种有代表性的森林植被类型,即分别代表太行山的主要乡土树种油松、辽东栎,及经改造形成的主要混交林类型松栎混交林和油落桦混交林。用标准木法和样方法分别测定了林分单位面积各森林植被层的生物量及总生物量,用浸水法测定了各森林植被层的日最大持水量。观测了油松示范林林冠截留降雨能力。     

阔叶树截留降雨试验与模型——以色木槭为例

通过实验室模拟试验,得到不同雨强和叶面积指数组合下的色木槭截留降雨过程,并考虑树冠湿润度的影响.结果表明:单位叶面积次降雨最大截留量随雨强增大而减小,枝叶截留速率随树冠湿润度变化而变化.构建色木槭截留降雨随雨强和叶面积指数变化的模型,对模型模拟验证,模拟精度为92.7%.     

Rainfall interception and drop size-development and calibration of the two-layer stochastic interception model

This paper reviews the development of the stochastic interception model from the original, single-layer, drop-size-dependent model to the two-layer model that recognizes that vegetation canopies are wetted through both the primary impact of raindrops to the top layer of the canopy and secondary impacts from drops falling from the vegetation to lower layers of the canopy. It is shown that drop volumes of primary raindrops can be calculated from the Marshall-Palmer distribution and drop volumes of secondary drops can be estimated from disdrometer measurements of the characteristic volume appropriate to the particular vegetation species. It is recognized that, in addition to the volume-dependent stochastic wetting effect, there is also another drop-size-dependent wetting effect that is related to the kinetic energy of the raindrops, which reduces the maximum storage that can be achieved on the canopy. The predicted wetting functions for canopies of different density are described and compared with observations made with the use of a rainfall simulator. It is also shown that the species-dependent model parameters can be determined from measurements made with the rainfall simulator. The improved performance of the model compared with conventional interception models is demonstrated for a tropical forest in Sri Lanka. Application of the two-layer model may explain why interception losses from coniferous, fine-leaved forests in the temperate, low-intensity rainfall climate of the uplands of the U.K. are among the highest in the world, whereas interception losses from tropical broad leaved forest in high-intensity rainfall climates of the tropics are among the lowest.     

Predicted models for potential canopy rainfall interception capacity of landscape trees in Shanghai,China

This study aimed to build urban green space with environmental functions (e.g., canopy interception of rainfall) and adjust hydrographic balance to some extent for forecasting the potential canopy rainfall interception capacity of landscape trees and the effects on rainfall distribution. The effects of urban green space on interception and runoff reduction have been conceptualized, but not quantified. Therefore, the leaf area index and the water storage abilities of 17 kinds of landscape trees in common use were measured, at Shanghai, and canopy rainfall interception capacity was calculated using the interception formula. The predicted rainfall interception capacity models were established choosing tree morphological characteristics (diameter at the breast height, height, and crown width) as variables. The model test showed that the errors of 12 models were less than 5% between the predicted and the measured data and the errors of four models were within 5 and 10%, with the error for only one model being between 10 and 11%. Also, the study indicated that conifer trees were able to hold more rainfall compared with broad-leaved trees per unit area (k). The results showed that these models could effectively predict the potential capacity of canopy rainfall interception for landscape trees in Shanghai area and were beneficial for species selection in constructing plant communities, aiming to improve the rainfall interception capacity of urban green space.     

冀北山地华北落叶松人工林对降水截留效应的初步研究

在冀北山地华北落叶松集中分布的地区,利用对降水在林分中的样地进行定位观测的方法,研究了该地区主要造林树种华北落叶松对降水的截留效应。据2002-2005年的连续观测,结果表明:华北落叶松林冠平均截留率为23.6%,树干茎流率占大气降水量的3.7%,枯枝落叶层的截留率为10.2%。说明华北落叶松在冀北山地发挥了巨大的水文生态作用。     

鄂西山地马尾松林水文效应研究

为了定量评价马尾松林的综合水文功能,对鄂西山地区内的马尾松林林冠截留、枯落物截留和林地土壤蓄流等关键水文效应进行了观测研究。结果表明：林冠截留率为19.14%,树干茎流率为0.48%;林冠截留量与降雨量呈幂函数关系,林内透雨、树干茎流分别与降雨量呈线性关系;枯落物最大持水率为224.23%,土壤贮水力为291.63t/...     

Relationship between annual rainfall and interception ratio for forests across Japan

Several previous studies in Japan have examined differences in rainfall interception amounts induced by differences in forest properties by comparing the annual rainfall interception ratios (annual rainfall interception divided by annual rainfall) from various sites without considering variations in meteorological conditions between sites. Rainfall interception actually depends on meteorological conditions as well as forest properties. This study examined variations in the annual interception ratio relating to the variation in annual rainfall, which would be the primary factor relating to the interception ratio, across Japan with the use of a rainfall interception model assuming the same forest properties (i.e., the canopy storage capacity, canopy closure, leaf area index (LAI), and the bulk coefficient for sensible heat transfer). The ratio ranged between 0.12 and 0.24 across Japan and was highly correlated to annual rainfall. This indicates that considering the variation in annual rainfall is critical for assessing the difference in rainfall interception amounts induced by forest properties. We reconsidered the results of previous studies in Japan that compared annual interception ratios between sites with different forest properties: (i) there is no clear difference in interception amounts between broadleaf and coniferous forests and (ii) there is a positive correlation in stem density and interception amounts for coniferous forests. These results still held when considering differences in annual rainfall between sites.     

三峡库区典型森林植被类型对坡面产流影响

在一定地形地貌基础上,植被与降水是决定坡面产流、产沙量的主要因素.2005～2006年对重庆缙云山4个天然林地径流场和农地径流场进行定位观测,结果表明:①森林植被在一定范围内对坡面径流量有削减作用,前期降雨对坡面径流有影响;②坡面径流峰值与暴雨峰值呈一一对应关系,马尾松和常绿阔叶林的变化幅度较小,楠竹林和常绿阔叶灌丛变化较大;③地下径流深与降雨量呈一一对应关系,地下径流深与降雨量关系反映出前期降雨对地下径流量的影响;④马尾松阔叶混交林、常绿阔叶林和常绿阔叶冠丛地下径流峰值的总体趋势是随降雨强度的增加而增加;楠竹林和农地随降雨强度的增加而呈下降趋势.     

Spatial variability of throughfall in a Chinese pine (Pinus tabulaeformis) plantation in northern China

The interception of rainfall by vegetation and the subsequent evaporation of intercepted water from the canopy surface play an important role in hydrological processes, and the water and energy balance of forest ecosystems. Spatial variability of interception has different effects on water yield from watersheds located in different climatic and biome regions. In order to explain the spatial patterns of interception, we adopted grid-sampling method to install rain-gauges to measure throughfall. Results show that the coefficient of variation (Cv) of throughfall tends to decline as rain intensity increases. After the canopy is saturated, Cv of throughfall remained at a constant value, which is close to the Cv of the canopy leaf area index (LAI) value 0.18. Thus, the Cv of LAI is regarded as the extremum of that of throughfall. Because of the special characteristic of Chinese pine (Pinus tabulaeformis), and the lower droopy branches, negative values for interception account for only 13% of the total samples. Furthermore, the max is above 70% of gross rainfall. __________ Translated from Science of Soil and Water Conservation, 2006, 4(3): 26–30 [译自: 中国水土保持科学]     

径流泥沙影响因子及其尺度分析研究

径流和泥沙研究一直是国内外水文学界研究的重点。文章分析了降雨、森林植被、地形因素、人类活动、地质和土壤因素对径流和泥沙的影响。阐述了水文学中的尺度分析和尺度转换，提出了不同尺度下影响径流泥沙的主导影响因子。