【作者】 胡晓静；

【导师】 吴斌； 齐实；

【作者基本信息】 北京林业大学 ， 水土保持与荒漠化防治， 2007， 博士

【摘要】 森林植被究竟在多大程度上影响洪水是急待解决的科学问题。本文结合国家自然科学基金“三峡库区以流域为单元森林植被对洪水影响研究”，从主要森林植物群落对降水、径流、入渗等水文环节的影响作用研究着手，构建、拟合和验证适合三峡库区森林流域的分布式暴雨水文模型(PRMS Storm)。以四面山响水溪两个嵌套流域为例，通过模型拟合和参数率定，以检验模型模拟精度；在此基础上，总结归纳得到三峡库区森林流域模型主要水文参数数值，为该模型推广到不同尺度提供参数依据及支撑；利用该模型模拟不同情景下森林植被对洪水的影响作用，为进一步揭示三峡库区流域森林植被的生态水文过程提供研究基础。以MMS(模块化模型系统)为基础，应用ArcGIS等手段，结合定位观测和实验研究，构建了具有物理基础的流域分布式暴雨水文模型。通过野外调查、观测，计算得到四面山响水溪森林流域主要参数数值。对于土壤最大滞留贮水量(非毛管贮水量)，计算1m深度得到该值最大为尖杉、马尾松阔叶林混交林，最小为荒草地；土壤入渗主要参数水力传导度kpar在0.6～6.3mm/min之间，最大值为楠竹林，最小为马尾松阔叶混交林；林冠截留量与林外降雨量表现出明显的幂函数关系；典型林分枯落物持水率最大为柳杉林，最低为板栗林；林地糙率系数n值介于0.0182～0.2575之间；利用地理信息系统获取基本地形数据参数，将响水溪流域划分为16条河网，30个水文响应单元(HRU)。两个嵌套流域进行拟合验证后，得到：1号小流域Nash确定性系数为0.738，洪水预报合格率达80％；2号小流域Nash确定性系数为0.697，洪水预报合格率达83.3％，两个流域模拟均得到较高的精度。总结归纳获得三峡库区森林流域模型主要参数数值。库区土壤最大滞留贮水量最大值为黄棕壤土壤，最小值为南方水稻土；三峡库区5类主要森林土壤入渗kpar、psp、rgf三个参数数值差异较大，水力传导度kpar均值大小顺序为：黄棕壤＞紫色土＞石灰土＞水稻土＞黄壤，而psp和rgf两个参数值则均以黄壤最大；得到库区4种主要森林类型林冠截留估算方程，各方程相关系数在0.60～0.81之间；库区几种主要植被类型枯落物持水量最大为针阔混交林，最小为竹林；通过灰色关联分析得到，影响糙率系数各指标因子的关联度顺序为0～20cm土层容重(0.68)、土壤总孔隙度(0.66)、非毛管孔隙度(0.64)、＞2mm石砾含量(0.61)、坡度(0.48)及林下枯落物量(0.44)。在此基础上，模拟森林覆盖率变化及不同森林群落的情景下森林植被对洪水过程的影响得到：无植被及森林覆盖率在20％、40％、60％下，实测12场降雨产生洪峰的平均值分别为0.294mm/min、0.248mm/min、0.214mm/min和0.167mm/min；特大暴雨情景下，洪峰分别为1.160mm/min、1.002mm/min、0.849mm/min和0.659mm/min。同时可知在同一森林覆盖率下，森林的不同分布位置削减峰值的作用也不相同，即在流域内低海拔处造林，削减洪峰效果更明显；模拟实测的12场降雨得到无植被条件下的径流总量均值分别为20％、40％、60％以及现状情况下的1.13、1.26、1.45和2.47倍；而特大暴雨情景下产生的径流总量分别为森林覆盖率在20％、40％、60％以及现状情况下的1.09、1.17、1.29和1.61倍。根据三峡库区流域三种森林群落配置类型，即针阔混交林型、常绿阔叶林型和综合配置型(针阔混交林，常绿阔叶林和灌木林综合配置)，模拟各自的洪峰及径流量，可得出针阔混交林型和综合配置型的作用要好于阔叶混交林型，而针阔混交林型的削减洪峰和缓解洪水流量作用最佳。但由于综合配置型更符合营林实际情况，建议选用此配置类型。更多还原

【Abstract】 In which extent that forest vegetation affect flooding is a scientific problem still need to be solved. The study on storm event hydrological processes in the Three Gorges Reservoir watershed based on MMS (Modular Modeling System) sponsored by national natural science foundation program-The forest vegetation impacts on flooding in the watershed of the Three Gorges Reservoir- is been done from the hydrological processes such as the effect of forest vegetation on precipitation, runoff and infiltration etc.. A storm event distributed hydrological model (PRMS_ Storm) with physical mechanism is built and the model is calibrated and validated by the data of the Xiangshuixi forest watershed of Simian Mountain. According to the results of case study, the values of main parameters of the Three Gorges Reservoir Region are work out in order to do further study for the different scale. And the storm event process in the different vegetation cover scenarios is simulated and could be useful for discovering forest watershed eco-hydrological process in the Three Gorges Reservoir Region.First of all, the storm event distributed hydrological model (PRMS_Storm) with physical mechanism is built based on MMS (Modular Modeling System) with ArcGIS tools.Main model parameters of Xiangshuixi forest watershed in Simian Mountain are acquired by field investigation, plot observation and experiments. In which, the maximum value of soil non-capillary moisture capacity is in the mixed forest of Cephalotaxus fortunei Hook, with Pinus massoniana and broad-leaved trees and the minimum one is in the wild land; the amount of hydraulic conductivity varies from 0.6 to 6.3mm/min and the maximum is Phyllostachys pubescens, the minimum is in the mixed forest of Pinus massoniana and broad-leaved trees; the maximum of water holding capacity of litters is Cryptpomeria fortunei Hooibrenk forest, the minimum is in the Castanea mollissima forest stand; the surface roughness coefficient varies from 0.0182 to 0.2575 and results also show that there is typical power function relationship between interception and rainfall. 16 channel networks and 30 hydrologic response units in Xiang shuixi watershed are obtained by using the GIS tools.The model-fit efficiency is 0.738 and over 80% of result is qualified in the first watershed. And in the second watershed, the model-fit efficiency is 0.697 and over 83.3% of result is qualified. Accordingly, the simulation precisions of two nested watershed are high.Main model parameters in the Three Gorges Reservoir Areas are gained in terms of soil map, topographical map and land use map. In which, the maximum of soil non-capillary moisture capacity is in the yellow brown soil and the minimum is in the paddy soil. And in 5 main forest types of the Three Gorges Reservoir Area, the amounts of soil infiltration parameters of kpar, psp and rgf have great difference. The mean of kpar from high to low is as follows: yellow brown soil, purple soil, lime stone soil, paddy soil and yellow soil, but the maximum of psp and rgf are all in the yellow soil. Furthermore, the correlation coefficients of canopy interception equation of 4 main forests are between 0.60 and 0.81; the maximum of water holding capacity of litters is coniferous and broad-leaved mixed forest, the minimum is in the bamboo forest stand. At last, the amount of correlation degree affecting roughness by using the grey correlation analysis method is calculated, that is: soil density in 0～20cm (0.68), soil total porosity (0.66), soil non-capillary porosity (0.64), the gravel content greater than 2mm (0.61), slope (0.48) and litter (0.44).The storm event processes under the different forest coverage and forest community scenarios are simulated, the results show that: when forest coverage is 0, 20 percent, 40 percent and 60 percent, the corresponding average peak flow under 12 storm events are 0.294 mm/min, 0.248 mm/min, 0.214 mm/min and 0.167 mm/min, but under a 100-year storm recurrence scenario, the corresponding average peaks flood are 1.16 mm/min, 1.002 mm/min, 0.849mm/min and 0.659mm/min. The result also suggested that peak flow reduction in the different forest distribution is different even in the same forest coverage, and it means that effect on reducing peak flow is more obvious when forest vegetation is distributed in low elevation of the watershed. The amount of average runoff of 12 measuring storms under no vegetation condition is 1.13 times, 1.26 times, 1.45 times and 2.47 times of those forest coverage is 0, 20 percent, 40 percent and 60 percent and current condition, and runoff in 100-year recurrence storm event is 1.09 times, 1.17 times, 1.29 times and 1.61 times.The peak flow and runoff of three forest community spatial pattern scenarios which are mixed conifer-broadleaf forest type, broadleaf forest type, and synthetic arrange type (mixed conifer-broadleaf forest, broadleaf forest and shrub forest) in the Three Gorges Reservoir Areas are simulated, the results indicated that the reduction effect on peakflow of mixed conifer-broadleaf forest type and general arrange type are better than broadleaf forest type. At the same time, mixed conifer-broadleaf forest type is the best for reducing peakflow in the study region and the synthetic arrange type is selected considering forestation actual situation.更多还原