面向地表过程模拟的降雨径流模型开发与应用

降雨径流是流域地表过程的主要驱动力,是众多地表模型的基础。该文在充分考虑流域气象及下垫面等要素空间异质性的基础上,提出了一个面向地表过程模拟的、基于DEM的分布式次降雨径流模型。模型将流域离散为栅格计算单元,并按水流特性将栅格划分为坡面单元和河网单元;模型考虑了降雨、植被截流和入渗等产流过程,利用运动波分级汇流的方式进行汇流演算。模型在江西躁口水流域进行了检验和应用。结果表明：该模型模拟的流量过程精度较高;模拟的径流深度及径流搬运力的空间分布符合水文规律。模型结构简洁、参数较少,具有较好的实用价值;为土壤侵蚀及非点源污染等以流路为基础的复杂地表过程研究奠定了基础。     

黄土区土质道路人工降雨及放水试验条件下产流产沙特征

为了研究土质路面草本植被降低水土流失的作用,采用室内人工降雨及放水试验的方法比较了裸露路和植物路的产流产沙过程及径流水动力学特征,结果表明：相对于裸露路,不同覆盖度植物路总径流量降低幅度为3.94%～ 25.10%,总泥沙量降低幅度为9.65%～45.69%;在大致相同放水量条件下,植物路的土壤侵蚀速率、径流流速和过水断面单位能量均低于裸露路;植物路的Darcy-weisbach阻力系数和曼宁糙率系数分别是裸露路的2.62～9.00倍和1.74～ 3.53倍;植物路通过降低径流流速、减小过水断面单位能量和增大路面粗糙度及径流阻力起到减轻道路侵蚀的作用。该文为广大土质山坡道路侵蚀防治和植物路铺设提供理论支持。     

云南省日极端降水概率特征及时空变化研究

不同重现期的暴雨设计值是推求设计洪水的基础。选取云南省29个气象站1960―2014年日降水资料,采用极大值法和超门限峰值法2种选样方法构成研究数据序列,通过K-S检验、L-矩法和日极端降水等值线图等方法分析了云南省日极端降水的概率特征及时空变化。结果表明,Wakeby分布函数较好地拟合了云南日极端降水序列;不同重现期下,云南省日极端降水量高值区位于滇南江城、勐腊一带,低值区位于滇西北德钦、中甸一带,极端降水量从南向西北呈阶梯状递减。分别计算不同重现期下的日降水量,时段极大值法设计值均大于以日极端降水资料95th分位数作为阈值的超门限峰法设计值。多数气象站基于Wakeby分布计算出的日极端降水设计值大于PⅢ分布函数设计值。     

水稻适雨灌溉对稻田CH_4和N_2O排放的影响

采用静态暗箱-气相色谱法,观测分析了水稻适雨灌溉和常规灌溉2种模式下稻田CH_4和N_2O的季节排放情况,评估了水稻适雨灌溉对稻田CH_4和N_2O排放的影响。结果表明,适雨灌溉稻田CH_4、N_2O排放峰值分别出现在分蘖期和拔节孕穗期,整个生育期CH_4、N_2O平均排放通量分别为16.77 mg/(m~2·h)、6.64μg/(m~2·h),适雨灌溉稻田CH_4、N_2O排放量较常规灌溉显著下降(p0.05),分别下降了74.47%和67.06%。水稻适雨灌溉通过合理利用雨水资源,减少灌溉次数及灌水量,显著降低了稻田CH_4和N_2O的排放。     

青海东部年降雨量变化与粮油作物病害发生的相关性研究

基于1999-2007年青海东部农业区病害发生情况,分析年降雨量的变化与小麦、油菜病害发生的相关性。结果显示,随年降雨量的不同,小麦和油菜病害的发生率也有差别。小麦病害发生率与年降雨量间的相关系数为0.350,满足方程y=-0.015 194x+6.538 82;油菜病害发生率与年降雨量间的相关系数为0.784,满足方程y=0.002 020x-0.569 56。表明小麦、油菜病害发生与年降雨量之间分别存在低度和中度正相关关系,即年降雨量越多,小麦病害和油菜病害发生越严重。     

An evaluation of furrows for managing soil and water loss from a shallow Alfisol under simulated rainfall

Furrows are widely used in rainfed areas of semi-arid India for soil and water conservation. The orientation of furrows, either down or across slope, and their spacing influence the effectiveness of furrows as soil and water conservation measures. We evaluated treatments with furrows aligned down and across 3% sloping land at spacings of 90, 60 and 30 cm under simulated rainfall intensities of 80 and 100 mm/h on a shallow Alfisol. A bare plot without any furrows was considered as a control. A large (24 m × 3 m) rainfall simulator developed at the Central Research Institute for Dryland Agriculture (CRIDA), Hyderabad, was used for this controlled study. Run-off was measured by a calibrated tipping bucket run-off recorder. The effects of the treatments on peak flow rate (L/s), sediment loss with run-off water (kg/ha/mm), peak sediment concentration (g/L), run-off (per cent rainfall) and time to peak (min) were investigated. When compared with the control (no furrows), across slope furrowing with 60- and 30-cm spacing reduced sediment yields by 19.9 and 21.3 kg/ha/mm of run-off, respectively, under a rainfall intensity of 80 mm/h and 24 and 25.3 kg/ha/mm of run-off, respectively, under a rainfall intensity of 100 mm/h. For the control, sediment loss was 50.72 kg/ha/mm run-off and 56.68 kg/ha/mm run-off for rainfall intensities of 80 and 100 mm/h, respectively. Similar trends were recorded from observations of peak flow, time to peak and peak sediment concentration. Run-off hydrographs demonstrated the conservation value of across slope furrowing by delaying run-off initiation, reducing run-off and slowly releasing the run-off after the cessation of rainfall. The results show that furrow orientation has major effects on reducing run-off, whereas furrow spacing has insignificant effects.     

坡度对东北黑土流失影响的研究

通过室外人工模拟降雨的方法，得出了在不同坡度、降雨量和降雨强度时，不同植被覆盖度的流失泥沙颗粒组成、黑土地表的径流量以及土壤含水量的相应变化。     

江西鹰潭地区降雨侵蚀力及简易算法初探

根据江西鹰潭市红壤生态站自建气象站1999￣2003年度观测资料,对该站自然降雨侵蚀力(R)及其特征进行了研究和分析。结果表明,1999￣2003年度红壤生态站具有侵蚀力的自然降雨次数共有180次,降雨过程主要发生在4￣6月。根据R值的“EI30”方法,计算出各年的降雨侵蚀力依次为:3722.3,6864.2,4520.5,6299.1和5580.9MJ·mm/(hm2·h·y)。利用各次有侵蚀力的降雨过程,初步总结了鹰潭地区降雨侵蚀力的简易算法。     

Simulation Study of the Impact of Permanent Groundcover on Soil and Water Changes in Jujube Orchards on Sloping Ground

Land degradation is recognized as a major environmental problem in rainfed fruit orchards on the Chinese Loess Plateau. Six treatments were used to investigate surface runoff and soil moisture by means of simulated rainfall experiments: (i) a control (clean cultivation) (CC); (ii) strip cock's foot (Dactylis glomerata L.) cover (SCF); (iii) strip crown vetch (Coronilla varia L.) cover (SCV); (iv) strip bird's foot trefoil (Lotus corniculatus L.) cover (SBF); (v) strip white clover (Trifolium repens L.) cover (SWC); and (vi) complete white clover cover (WCC). The time to runoff was significantly longer under WCC than under other treatments (p < 0·05). The total runoff volume and sediment yield were significantly greater under CC than under the vegetation cover treatments (p < 0·05). The mean infiltration rate under WCC and CC was the largest and lowest and differed significantly from that under other treatments (p < 0·05). The change of soil water storage was the largest under WCC and the least under CC. The soil moisture was significantly greater under SCF than under other treatments (p < 0·05). Treatment SCF seemed to be the best groundcover for rainfed sloping jujube orchards on the Chinese Loess Plateau. Copyright © 2014 John Wiley & Sons, Ltd.     

植被恢复演替初期对模拟降雨产流特征的影响

利用模拟降雨装置,研究了演替恢复初期不同植被覆盖以及不同处理下坡面降雨的产流过程和人渗率。实验研究结果表明,植被演替开始之初,由于地表土壤的土质比较疏松,土壤的人渗率比较大。随着植被演替的进行,土壤中有机质等物质的逐渐累积,土壤的理化性质发生了变化,土壤的人渗特征也随之降低。剪草降雨小区的实验研究结果说明,在降雨的初期,土壤的人渗性能相对较低,随着实验的进行,在雨滴的打击下,部分结皮被破坏,土壤的人渗率也随之增大。说明地表生物结皮的存在,降低了土壤的人渗性能。采取适当的措施破坏地表生物结皮,有利于提高土壤的人渗性能,增加干旱半干旱地区对降雨的利用程度。