“玉米带”改种多年生草类后对农田排水的水文效应模拟

该文针对美国密西西比河上游明尼苏达州农田排水氮素流失严重,近年来又大力发展生物燃料产业的现状,采用田间水文模型——DRAINMOD模拟分析了玉米-大豆轮作区改种多年生草类后对农田排水的水文效应。结果表明改种多年生草后,植物耗水量的增加使得农田排水量明显减少;较深的草根系,尤其是在干旱年份消耗了大量的深层土壤水,降低了地下水位。种草后的生物排水量远远大于其他工程措施（如增加排水间距或潜埋排水管等）,可显著减少农田排水氮素流失对水环境的影响。     

三峡库区端坊溪小流域的森林水文效益

 三峡库区的森林水文作用,对于长江三峡水利枢纽工程的安全运行和效益发挥具有重要意义,对于改善和维持三峡库区的生态环境具有重要作用。根据1992— 2000年实测降雨、径流等观测资料,分析了三峡库区端坊溪小流域森林的林冠截留作用、林地枯落物的水文作用及森林覆盖率与土壤容重、土壤孔隙和小流域径流的关系。结果表明:三峡库区端坊溪小流域不同树种枝条基部直径与枝叶质量呈线性正相关,不同树种枝叶容水量与枝叶质量呈线性正相关,不同森林类型在场降雨中,林冠截留量为0.38～8.78mm,截留率为10.27%～49.48%,林冠截留量与降雨量呈幂函数关系;随着森林覆盖率的增加,林地的土壤容重减少,总孔隙度增加;主要森林类型中,针阔混交林林地枯落物的饱和持水量最大,端坊溪小流域枯落物层截留量可达到降水量的2.8%～6.3%;小流域径流量与同期降水量呈线性正相关。端坊溪小流域森林覆盖率每增加1%,小流域汛期径流深减少6.95mm。     

基于分布式水文模型的水土保持水文水资源效应研究

 以往水土保持水文水资源效应研究所采取的方法均为水文法和水保法。由于这2种方法都不能系统地揭示水土保持对水循环影响的物理机制,并且采用的水资源评价口径只是单一的狭义水资源,使得研究成果不能真实反映水土保持的水文水资源效应。以狭义水资源和广义水资源为评价口径的基于物理机制的分布式水文模型则能克服水文法和水保法的严重弊端。评述分布式水文模型的研究进展;应用基于物理机制的分布式水文模型(WEP-L模型),以黄河流域的重点水土流失治理区——河口镇至龙门区间为例,对水土保持的水文水资源效应进行定量研究。结果表明:水土保持使广义水资源量增加72．6亿m3,增幅27．1％;使狭义水资源量减少9．0亿m3,减幅14．4％;使狭义水资源的构成发生了变化,即地表水资源量减小、不重复量和地下水资源量增加。     

Recovery of saturated hydraulic conductivity under secondary succession on former pasture in the humid tropics

Landscapes in the humid tropics are undergoing a continuous change in land use. Deforestation is still taking its toll on forested areas, but at the same time more and more secondary forests emerge where formerly agricultural lands and pastures are being abandoned. Regarding soil hydrology, the extent to which secondary succession can recover soil hydrological properties disturbed by antecedent deforestation and pasture use is yet poorly understood. We investigated the effect of secondary succession on saturated hydraulic conductivity (Ks) at two soil depths (0-6 and 6-12 cm) using a space-for-time approach in a landscape mosaic in central Panama. The following four land-use classes were studied: pasture (P), secondary forest of 5-8 years of age (SF5), secondary forest of 12-15 years of age (SF12) and secondary forest of more than 100 years of age (SF100), each replicated altogether four times in different micro-catchments across the study region. The hydrological implications of differences in Ks in response to land-use change with land use, especially regarding overland flow generation, were assessed via comparisons with rainfall intensities.Recovery of Ks could be detected in the 0-6 cm depth after 12 years of secondary succession: P and SF5 held similar Ks values, but differed significantly (α = 0.05) from SF12 and SF100 which in turn were indistinguishable. Variability within the land cover classes was large but, due to sufficient replication in the study, Ks recovery could be detected nonetheless. Ks in the 6-12 cm depth did not show any differences between the land cover classes; only Ks of the uppermost soil layer was affected by land-use changes. Overland flow - as inferred from comparisons of Ks with rainfall intensities - is more likely on P and SF5 sites compared to SF12 and SF100 for the upper sample depth; however, generally low values at the 6-12 cm depth are likely to impede vertical percolation during high rainfall intensities regardless of land use.We conclude that Ks can recover from pasture use under secondary succession up to pre-pasture levels, but the process may take more than 8 years. In order to gain comprehensive understanding of Ks change with land use and its hydrological implications, more studies with detailed land-use histories and combined measurements of Ks, overland flow, precipitation and throughfall are essential.     

辽宁东部山区几种主要森林植被类型林冠层对降雨的再分配作用

用固定标准地方法对辽东山区5种主要森林植被类型生长季林冠的降雨再分配特点进行了研究。结果表明，生长季时期降雨林冠再分配特点因林型而异。林冠截留率23.1%-29.3%，平均值为25.3%，针叶林的截留率大于阔叶林。辽东山区林内雨率68.9%-76.3%，平均值为73.4%，阔叶林大于针叶林。各林型的茎流率都很低，不超过1%；5种林型生长季场降雨的截留量都表现出随降雨量的增大而增大。截留率随降雨量的增大而减少，在降雨初期下降梯度最大，以后趋于平稳，达到饱和，各林型的理论饱和截留率为16.4%-29.7%。林内雨量在低雨量级时增加缓慢，随降雨量增大，增加梯度明显加大。林内雨率在低雨量时增加梯度大，而到高雨量级时，逐渐趋于稳定。从平均角度看，阔叶林的林内雨率要高于针叶林。茎流量在降雨超过一定量时发生，在低雨量级时增加缓慢，以后随雨量级增大而大致呈直线上升，茎流率不超过1%，茎流量不超过0.2mm。     

用DRAINMOD模型预测不同气候条件下排水及来水量对湿地水文的影响

水量减少是目前威胁湿地生存的一个重要原因.本文采用原美国农业部水土保持局(现美 国自然资源保护局,US-NRCS)所推荐的水管理模型DRAINMOD,根据该局1991年所 建议的湿地水文识别准则,利用不同气候条件下的降水资料,对湿润地区由于排水而引起湿 地水文情势的变化,以及干旱地区湿地形成过程中所需要的基本水量进行了预测分析.模拟结果表明对于年降水量大于1 000 mm的温暖湿润地区,在没有人工排水的情况下,湿地特征十分明显;当排水间距大于150 m时,仍可在50%的年份内满足湿地判别准则的湿润条件.而 对于年降水量小于250 mm的干旱模拟区,形成满足生长期内湿润时段的最小来水量在初春( 3月)时为173 mm,在生长期末(11月)为155 mm,分别是同期月平均降雨量的22倍和16倍 .     

Hydrological properties of a Mediterranean soil burned with different fire intensities

The influence of vegetation cover on soil hydrological properties and its response to the impact of different fire intensities, in a Mediterranean forest environment, has been evaluated. The study was carried out in the Permanent Experimental Field Station of La Concordia (Llíria–Valencia, Spain), on a set of nine erosion plots (4 × 20 m²). The Station is located on a calcareous hillside S–SE oriented, with soils of Rendzic Leptosol type and supporting Mediterranean shrubland vegetation. All runoff generated and sediment produced in every rain event was collected from each plot. The set up includes a system of sensors for the continuous monitoring of climatic parameters (air temperature and humidity, rain volume, intensity, etc.).In June 1995, a set of experimental fires was carried out to the Station. Three of the plots were burned with high intensity fire, three with moderate intensity and the remaining were left unaltered. Soil water content and water retention capacity (WRC) were measured in the different plots and in two different vegetation covers: under canopy (UC) and in bare soil (BS). The pF curves were also obtained for each fire treatment.A year after the fires (June 1995–June 1996), great differences, reaching 77.15%, in runoff generation between fire treatments and the control plots were observed.No significant differences were detected on water retention capacity between soils UC and BS in the burned plots. However, these differences appeared in the control plots, giving UC and BS values of 13% and 18%, respectively. Plots corresponding to the high intensity fire treatment showed values of WRC significantly higher than those of the moderate intensity and of the control treatments.The pF curves show that the values of water volume, at the different pressure points studied, were slightly greater on UC soil. Values obtained for BS samples are higher in the fire treatments, showing significant differences in respect to the control plots at pF 1 and 2. These differences were also observed for UC soil, but in this case at pF 2, 2.5 and 4.2.     

A GIS based approach to modelling the effects of land-use change on soil erosion in New Zealand

Abstract. The problem of soil erosion is particularly evident in New Zealand, given the combination of coarse-textured soils, steep relief, high rainfall, and intensification of agriculture. A study was undertaken to assess the effects of land use change on soil erosion and sediment transport for the Ngongotaha catchment in New Zealand's North Island, using a GIS based decision support and modelling system. Model simulations considered the effect of increased catchment area under deer farming and forestry on the amount of sediment delivered to the catchment outlet, averaged over a period of six years. The simulations predicted that sediment loss from land under deer farming was considerably greater than from land under other livestock or forestry. Further model simulations testing best management practices demonstrated that sediment yield could be halved if deer farming was restricted to slopes under 20%.     

树干茎流研究方法及其述评

树干茎流研究是国内外森林水文学研究中的重要内容,对国内外树干茎流的研究方法及研究成果进行综述,并将树干茎流研究方法分为野外实测法和数学模型估测法,分别进行了系统分类和简要述评。树干茎流的野外实测法有观测标准株的选取与树干茎流水的收集两个关键技术环节。树干茎流的数学模型分为3种类型,即经验模型、概念模型、理论模型。经验模型反映的是树干茎流量(或茎流流率)与降雨量的定量关系,概念模型描述的是茎流量与降雨特征及林分特征因子的数量关系,理论模型刻画了树干茎流形成的机理和动态变化过程(树干茎流随降雨的时空变化规律),分别给出了各类模型主要的数学表达式,并分析了各类模型主要的优点和缺点。