降雨条件下坡积土边坡暂态饱和区形成机理及分布规律

降雨是引起坡积土边坡失稳的最常见外部因素之一。雨水的入渗在引起土体抗剪强度参数降低的同时，还将导致土体重度的增加、基质吸力的降低，最终造成边坡的失稳。开展雨水在边坡内部的渗流过程研究已成为分析边坡在降雨条件下稳定性的前提。基于有限元数值模拟方法，进行了雨水在土体中渗流过程的模拟，着眼于降雨条件下边坡暂态饱和区的形成、分布及消散特征，描述了该过程中边坡内部含水率、基质吸力、水力梯度的变化规律。结果表明：暂态饱和区形成的主要原因是土体中向湿润锋下方渗出的雨水量小于降雨入渗补给量，从而使得土体中的含水率累积升高；暂态饱和区的形成与降雨强度、降雨时间具有十分密切的关系，暂态饱和区形成时间、雨水入渗深度、土体表面体积含水率大小分别与降雨强度存在函数关系；清晰描述了暂态饱和区形成发展消散地下水位升高的全过程，从该过程看，边坡排水措施的设计值得思考。     

辽西北沙地流动沙丘土壤水分时空变化特征研究

以辽西北沙地流动沙丘为对象,研究了土壤水分运动的时空变化特征。结果表明：流动沙丘土壤含水率的时间变化与降雨有密切关系,春季土壤含水率较低,为0.1%~3.1%;夏季土壤含水率较高,为2.5%~5.1%;秋季土壤含水率略高于春季,为2.2%~3.6%。土壤含水率垂直变化位为：0~10cm土壤含水率变异程度较大,受降雨和蒸发影响强烈;10cm~80cm变异程度相对小些;80cm~120cm土壤含水率比较稳定。流动沙丘不同部位的土壤含水率受干沙层厚度频繁变化和降雨量影响显著,阴坡底含水率＞阳坡底＞阳坡中＞丘顶＞阴中。     

杏鲍菇微波干燥研究与参数优化

以干燥时间、色差为指标,微波强度、初始含水率、切片厚度为试验因素进行正交试验,研究杏鲍菇微波干燥的失水规律。研究发现,杏鲍菇微波干燥失水分为受热升温、快速失水2个阶段。优选杏鲍菇微波干燥的工艺参数为初始含水率60%,微波强度32 k W/kg,切片厚度3 mm。     

砂田降雨入渗过程的模拟实验研究

砂田是一种具有综合效能的旱作技术,在干旱半干旱地区得到了不同程度的应用。为了研究砂石覆盖下降雨入渗的规律,笔者进行了室内模拟实验,对土壤水分的动态变化过程进行了研究。结果表明：在模拟降雨过程中,砂石覆盖下土壤的累计产流量一直低于裸土,说明砂石覆盖有利于减少土表降雨产流。砂石覆盖的土壤的各个深度土壤含水率均比裸土对照组要高,表明砂石覆盖有降雨入渗到土壤中。在经过一定时间的降雨后,砂石覆盖土柱中不同深度的土壤含水率变化会趋于稳定,且数值接近,表明砂石覆盖的土壤比裸土更快地进入稳渗阶段。     

Influence of indoor temperature on equivalent thermal resistance of green roof

绿化屋顶在节能设计中以附加当量热阻增大屋顶总热阻值,有效减少由屋顶进入室内的热量,降低室内空气温度。但根据已有的实验研究,绿化屋顶隔热特性与室内气温是耦合关系,随室内气温的变化,绿化屋顶会呈现出不同的隔热特性。用实验测试与数值模拟相结合的方法,分析在不同室内气温下绿化屋顶、参照屋顶与等效保温屋顶内表面温度与热流的变化。结果表明：室内气温会显著改变绿化屋顶的隔热性能,其当量热阻为与室内温度正相关的变量。在被动式建筑中,绿化屋顶更能充分发挥隔热功效,且具有不向室内传热的特性。     

不同耗水强度下节水灌溉稻田土壤含水率与非饱和土层厚度关系研究

为了探索基于土壤非饱和层厚度指导水稻节水灌溉的可能性,研究节水灌溉稻田土壤含水率与非饱和土层厚度的关系非常必要。本文通过设计盆栽试验,针对不同耗水强度开展连续观测,根据实时观测的土壤含水率与非饱和土层厚度,建立起两者之间的定量关系。结果表明：稻田日耗水强度越大,其非饱和土层厚度随时间增加的速率越大,达到最大值所需的时间越短。非饱和土层随时间增加时对应的土壤含水率则随时间下降,两者之间成负相关关系。通过建立土壤含水率与非饱和土层厚度的二次抛物线关系,结果显示将非饱和土层厚度作为水分控制指标指导灌溉精度高、切实可行。最后,将土壤含水率与非饱和土层厚度关系曲线运用到水稻控制灌溉的实践中,推算出土壤含水量下限对应的非饱和土层厚度值,确定以非饱和土层厚度为指标的控制灌溉方法,为黑龙江地区水稻节水灌溉管理技术提供参考,为下一步的水分运动模型率定及模拟更多土质和更多耗水情形下的土壤水分提供依据。     

北京地区轻型屋顶绿化植被毯多植物配植模式初探

屋顶绿化是构建海绵城市的重要措施之一,轻型屋顶绿化植被毯有着建坪速度快、绿化效果好,便于快速推广等优势,但北京地区目前屋顶绿化植被毯存在植物种类单一、景观效果差等问题。以筛选出的适合屋顶绿化的蒙古百里香(Thymus mongolicus)、垂盆草(Sedum sarmentorsum)、‘胭脂’红景天(Sedum spurium‘Coccineum’)、反曲景天(Sedum reflexum)和白花点地梅(Androsace incana)5 种植物材料,运用对比试验法,以椰丝垫作为基底材料,进行多种植物配植的植被毯试验,通过2、4 cm 2 种基质厚度对比试验,发现4 cm厚基质的5种植物组合大约在施工后47天左右成坪,57天左右成毯。     

覆盖生态木屑对城市公园土壤温湿度的影响

为实现绿化垃圾的循环利用,量化评估覆盖生态木屑对土壤表层温湿度的影响。利用土壤温湿度计定期测定土壤表层温湿度持续1年。结果表明,冬季铺设生态木屑具有良好的保温保湿效果,不铺设木屑土壤含水率迅速下降到10%以下,铺设生态木屑15~20 cm后整个冬季土壤含水率都保持在16%以上,后者土壤温度比前者土壤温度高2℃以上。夏季铺设生态木屑5~10 cm的样树,含水率低于不铺生态木屑的对照组和其他试验组,但对温度的影响并不明显。冬季覆盖生态木屑对土壤表层具有明显的保温保湿效果,且覆盖生态木屑越厚保温保湿效果越显著;而夏季覆盖生态木屑的最佳厚度为5~10 cm,覆盖此厚度的生态木屑既可以起到海绵体吸收多余水分的作用,又不会因为覆盖生态木屑后树冠与根系间的温差增大导致的植物生理性缺水。因此,建议城市公园铺设生态木屑的厚度为5~10 cm。     

异位发酵床垫料的直剪切及压缩试验研究

为研究不同含水率的条件下异位发酵床垫料：抗剪强度、黏聚力、内摩擦系数、压缩载荷的变化规律。本研究采用土壤力学试验方法,测定垫料五种不同含水率的相关参数。结果表明：当垫料含水率为29.22%~36.13%时,抗剪强度、内摩擦角系数会随着含水率的增大而增大;当含水率为45.55%~61.11%时,抗剪强度、内摩擦角系数会随着含水率的增大而减小。黏聚力不会因含水率的改变而出现明显变化;垫料的压缩载荷随加载时间增大而增大,递增幅度逐渐增大。     

饱和渗透系数空间变异性对边坡稳定性的影响

研究了降雨雨型、雨强和持时对边坡孔隙水压力分布的影响以及降雨入渗条件下饱和渗透系数的空间变异性对孔隙水压力、含水率、抗剪强度参数、局部安全系数等参数空间分布的影响。研究结果表明，降雨特性对边坡孔隙水压力的影响较大；受渗流主方向影响，降雨条件下饱和渗透系数的水平波动尺度对孔隙水压力及含水率的变异性影响小于竖向波动尺度，降雨致滑坡的临界滑面基本与坡面平行且深度较浅；随着饱和渗透系数水平波动尺度的增加，滑坡深度随之增大，从总体上坡体上部局部安全系数随饱和渗透系数竖向波动尺度的增加而减小。     

Towards Development of Eco-Agriculture of Rainwater-Harvesting for Supplemental Irrigation in the Semi-Arid Loess Plateau of China

The semi-arid Loess Plateau is a central zone of Chinese rain-fed farming. Drought and soil erosion are the two major obstacles to restrict economic development in this semi-arid Loess Plateau. The traditional conservation agriculture and runoff agriculture have been developed for several decades, which have reduced water and soil loss and improved rainwater utilization efficiency to a certain extent. However, its regulative role in rainwater is very much limited, and problems of agriculture production, such as severe seasonal drought and water shortage, low agriculture productivity, fragile ecological environment, and low yield-invest ratio, are still going on. Supplemental irrigation of harvested rainwater is an important form of rainfall regulation and utilization on the basis of sophisticated technologies and theories of conservation agriculture and runoff agriculture, which not only promotes fulfilling rainfall harvesting in spatial location like the conservation agriculture and runoff agriculture measure but also gets at true rainfall harvesting in time distribution by principle of superposition and also decreases invalid evaporation for rainfall runoff. Agriculture productivity will be highly increased by using rainwater harvesting for supplemental irrigation. It not only brings about the integration of ecological reconstruction with economic development, but also provides a new approach to the agriculture sustainable development and overcomes two of the biggest obstacles (drought and soil erosion). It is suggested that this technology will become a strategic measure and comprehensive development model in semi-arid Loess Plateau of China.     

Effect of antecedent soil water content and rainfall regime on microrelief changes

Surface microrelief substantially affects surface sealing, runoff, and soil erosion processes on bare soils. Yet, the stability of microrelief for different antecedent soil water contents and rainstorms is not well understood. This study investigates the effect of surface microrelief and antecedent water content on the decay of microrelief under different rainstorm regimes. Two different rainstorm regimes were studied in laboratory experiments: continuous rainfall for a total amount of 60 mm applied at 30 mm/h intensity, and intermittent rainfall consisting of five successive rainstorms of 12 mm each, again with an intensity of 30 mm/h and separated by one week drying cycles. Rough, medium, and fine microrelief surface conditions representing different degrees of seedbed preparation were studied for three soils at antecedent soil water contents of 2–4% and 14–20%. Before and after rainfall, digital elevation models determining the surface microrelief were developed using a laser scanner with 2 mm grid spacing. The specific surface area calculated from microrelief data was used as an index to characterize microrelief. Microrelief stability increased with increasing initial roughness and was much higher for the antecedent wet soils than for the dry soils. Microrelief stability for the continuous rainstorm regime was higher than for intermittent rainfall. Differences in microrelief stability were mostly attributed to different aggregate stabilities. Additionally, the higher stability for the rougher microrelief surfaces was attributed to the lower drop impact density and splash density on the surfaces with larger specific surface area. Aggregate slaking due to air escape and rapid wetting was found to be responsible for the low microrelief stability at initially dry conditions.     

花生复合系统土壤水分动态与平衡特征研究

花生复合系统是促进低丘红壤区农业水分资源综合利用的重要耕作方式,其在不同时段水分动态、水分平衡和利用过程差异值得进一步探索。土壤表层采用15 bar的先进负压计监测,结合定位法于2001—2003年监测收集了花生生长季花生复合系统、花生单作田间土壤水分、地表径流、降雨资料,分析了花生复合系统对土壤水分动态、降雨影响和水分平衡各要素的影响。分析表明,土壤10 cm与 60 cm水分单作花生地与复合系统在雨季无明显差异,但受降雨过程影响。旱季单作花生10 cm水势降到最低值-344.0 kPa,复合系统水势最低值为-50.6 kPa,60 cm单作花生地水势数值也低于复合系统花生地,旱季复合系统能减少土壤表层的蒸发。3年土壤水分周期动态可分为3个阶段,即水分盈余期、水分消耗期、水分稳定期。花生复合系统旱季表现出较强的耗水作用,2001年7月贮水量减少108.8 mm,2002年8月贮水量减少111.7 mm,2003年7月贮水量减少105.5 mm。花生复合系统平均渗漏量低于花生单作62.2 mm,平均贮水量变化低于花生单作41.8 mm。桔树与花生作物在旱季水分利用方面没有明显的竞争作用,花生复合系统系统的表土水分保持作用和生态效应明显。     

Cropping system effects of maize on infiltration,runoff and erosion on loess soils in South-Limbourg (The Netherlands): A comparison of two rainfall events

Two natural rainfall events are compared to evaluate the effects of three cropping systems of silage maize on soil moisture content, infiltration, runoff and erosion. Both rainfall events took place in early summer. One was a low intensity event with 27.6 mm of rain in 9 hours, and the other a high intensity event with 33.4 mm in 42 minutes. Cropping systems were:

• 1.(I) a spring tilled system (conventional),
• 2.(II) an autumn and spring tilled system with summer barley as spring cover crop, and
• 3.(III) an autumn tilled system with winter rye as winter cover crop and direct drilling of silage maize.

During the low intensity event, soil moisture content of the top 5 cm rose to field capacity on all three cropping systems. No runoff was generated. During the high intensity event, soil moisture content rose to field capacity on the two spring tilled cropping systems but was only slightly raised in the direct drill system, in spite of 17.7 mm of infiltrated rain. Runoff coefficients of the high intensity event were 41.7% (conventional system), 14.9% (autumn and spring tilled system) and 47.0% (direct drill system). The direct drill system showed a severely slaked soil surface in early summer, caused by winter rain.The response to rainfall of soil moisture content is ascribed to:

• 1.(I) a predominance of matrix infiltration on all cropping systems during the low intensity event and on the spring tilled systems during the high intensity event, and
• 2.(II) a predominance of infiltration via continuous macropores, open to the surface (of biologic origin), by-passing the soil matrix, on the direct drill system during the high intensity event.

The presence of continuous, vertical macropores on the direct drill system explains its surprisingly high infiltration capacity, considering its strongly slaked appearance. The smooth soil surface of the direct drill cropping system may have delayed infiltration during the flooded stage of the high intensity event by not providing vent points for the escape of soil air. Soil loss from the direct drill system during the high intensity event was only 15.6% of that from the conventional system. This is ascribed to low detachment rates of soil material by drop impact and/or overland flow, due to the presence of winter rye remains and, especially, the relatively high soil surface shear strength of the direct drill cropping system in early summer.     

西藏河谷农区灌水和中后期降雨对高产青稞耗水量与产量的影响

利用盆栽试验研究人工灌水及雨水对西藏河谷农区高产青稞耗水特性及产量的影响。试验材料为西藏青稞品种 ‘藏青 25’ , 水分处理 8个： 全生育期正常水分、 轻度水分胁迫、 中度水分胁迫和重度水分胁迫理, 以及灌浆前正常水分、 轻度水分胁迫、 中度水分胁迫和重度水分胁迫处理后灌浆期以后雨水灌溉。试验结果表明, 土壤含水量越大, 青稞耗水量越大, 拔节期及灌浆期是青稞耗水量最大的时期。全生育期土壤水分胁迫会降低青稞的生物量及产量, 轻度水分胁迫、 中度水分胁迫、 重度水分胁迫与正常水分处理相比生物量下降了 29.9%、 41.7%、 47.6%, 单株产量下降了 15.8%、 43.7%、 57.2%。但前期水分胁迫灌浆期后雨水灌溉对青稞的生长受到促进, 生物量和产量增大, 与长期水分胁迫相比生物量增长了 13%、 75.8%、 128.1%、 157.8%, 产量增长了 42.8%、 84%、 201.6%和 269.5%。雨水灌溉在后期对青稞进行了补偿生长, 水分利用率也相应提高。因此, 在适当的水分胁迫 （50%~65%土壤田间持水量） 下, 利用雨水补充灌溉, 可以提高西藏高产青稞 ‘藏青25’ 的水分利用率, 增加产量。     

高速公路边坡不同乡土灌木建植模式的产流·产沙特征研究(英文)

[Objective] Indigenous plants with favorable water and soil conservation effects were screened for the shrub planting.[Method] Suining-Ziyang-Meishan Highway in the hilly areas of central Sichuan Province was taken for example,through sorting out plant species investigated in the route planning,3 indigenous shrub species(Neosinocalamus affinis,Vitex negundo and Coriaria nepalensis) and 3 indigenous herbaceous species(Setaria viridis,Miscanthus floridulus,Artemisia argyi) were selected.Rainfall simulation experiment was adopted to compare runoff and sediment yields of different combination modes and ratios under constant rainfall intensity(20 mm/min).[Result] Different combination modes under constant rainfall intensity all showed better water and soil conservation effects than that of control group did.For example,runoff appeared 1'-4'05"later,sediment yield reduced by 6.56-33.86 g respectively.Among all combination modes,runoff and sediment yield showed great difference after 20 min of constant rainfall,V.negundo+S.viridis had the lowest runoff(1,700 ml) and sediment yield(60.71 g);C nepalensis+A. argyi had the highest runoff(1,920 ml) and sediment yield(84.02 g).[Conclusion] Given the same planting conditions such as side slope and seeding quantity,and also the same planting techniques,in the hilly areas of central Sichuan Province,the combination of V.negundo and S.viridis can greatly improve the water and soil conservation capacity of highway.     

滇池流域农田土壤氮污染负荷影响因素研究

采取模拟试验的方法,研究了在人工降雨和自然降雨条件下,坡度、土壤质地、地表覆盖状况以及施肥方式对坡地农田径流中氮素污染负荷的影响。结果表明：随着坡度的增加,农田土壤径流中氮的浓度和氮的输出量都增加;在人工模拟降雨和自然降雨条件下,土壤径流中氮的浓度变化趋势相同,都随着质地的变粗而减少;和裸地相比,种植小麦能明显减少土壤径流中氮的浓度和输出量,氮的流失量减少范围在11.80~238.46kg/hm2之间;相同施肥量条件下,面施氮肥时土壤径流中氮的浓度和输出量比穴施时明显增加。     

云南磷石膏堆存对区域水环境的影响研究

伴随着磷肥产量增加,磷石膏产排量对环境污染等问题愈加突出。为解决磷石膏堆放对环境造成的威胁和磷石膏的资源化利用,本研究通过对云南省磷矿资源主要集中地磷石膏堆场的实地调查、采样并结合模拟试验、建立预测模型等方法,明确磷石膏对区域水体环境介质存在的影响。结论如下：（1）不同堆存点磷石膏均呈酸性。滇池流域的磷石膏含磷量较高、抚仙湖流域的磷石膏含氟量较高。（2）通过地表径流试验,地表水总磷和氟化物的含量基本呈现随迁移距离增加而不断下降的趋势。并建立地表水污染物沿程迁移变化回归模型。地表径流中总磷和氟化物分别迁移至距堆场186.45 m和167.30 m外,可达到地表Ⅲ类水标准。（3）通过土柱淋溶试验,淋出液中总磷含量随淋溶次数的增加整体呈下降的趋势。不同土柱淋出液中氟含量呈现正相关的变化趋势,除个别土柱淋出液外,其他深度的淋出液氟含量在0.15~0.45 mg/L范围之内,可达到地下水的Ⅰ类至Ⅲ类标准。本研究为解决磷矿区乃至流域内磷石膏对水环境等造成的污染负荷问题,提供定量化的理论基础。     

岩溶森林区地下河流域水文地球化学特征研究-以贵州荔波板寨地下河为例

通过对板寨地下河流域内岩溶泉、地表水体和地下河水各测站的水化学资料的分析,讨论了流域内各点的水化学类型、空间分布及成因。由于森林植被覆盖,计算得岩溶泉水的PCO2很高,实测得拉桥泉域内土层20cm深处CO2浓度高,达38000ppm,是退耕田地中土壤CO2浓度的30倍;森林中地表覆被形成林中滞留水含水层,它与岩溶含水岩层组形成多层水文地质含水空间结构,增加了调蓄量,延缓了水的释放,这极大改善了区内因降雨分布不均匀而引起的干旱面貌。虽然茂兰处在原始森林区,但是土壤较少,根据实验结果,森林区岩溶作用强度并不比非森林岩溶区强。自然保护区缓冲区有少量村民居住,农业活动,如施肥和生活污水排放等,造成了地下水污染。岩溶表层带泉,受地表环境、降雨量影响大,水化学动态变化较大。地下河水的水化学变化特征明显受降雨的稀释作用影响。