山区暴雨泥石流预报数学模型的研究

采用有限体积方法,研究了计算区域网格自动划分、GIS图形数据采集、单元中心和节点的混合式地形插值、河网单元通道概化,提出了河道型、坡面型、陡坡型水流计算的处理模式,给出了不同重现期的面雨量暴雨过程,建立了山区暴雨泥石流预报数学模型.结合桂林地区地质、气象、地形等特点,对地质条件、地形条件、水动力条件和泥石流起动影响条件进行单元域化、数字化处理,提出了桂林地区在暴雨作用下不同区域泥石流发生可能性的判定条件,取得了不同重现期暴雨过程条件下桂林地区泥石流发生危险程度的计算成果,并与桂林地区地质灾害分布图比较,危险区域范围基本吻合.     

2006年“7．2”陕北南部暴雨过程分析

2006年7月2日出现在陕北南部的区域性暴雨是副热带高压影响下的一次暴雨过程。前期的高温高湿对暴雨产生积累了大量的不稳定能量，高原东侧的西南暖湿气流为暴雨的发生提供了充足的水汽输送，高低空急流的耦合为暴雨的维持和加强提供了有利条件，中尺度对流系统对暴雨的产生和维持有重要影响，冷空气的侵入是暴雨产生的触发条件。     

设计暴雨雨型对高植被覆盖流域径流形成影响的数值模拟

为分析设计暴雨雨型对山区小流域山洪灾害的影响，应用时空变源混合产流模型，以四川省关口、汉王场为研究区域，分析高植被覆盖流域对不同重现期以及不同设计暴雨雨型条件下降水的响应规律，并对不同雨型及重现期条件下流域的洪峰流量、峰现时间、洪峰滞后时间等量值进行对比分析。结果表明：时空变源混合产流模型在高植被覆盖流域洪水模拟应用过程中能够取得较好的模拟精度，具有一定的适用性；关口、汉王场流域同一重现期条件下偏后型雨型相对于偏前和居中型条件下形成的洪峰流量更多，但偏前型雨型相对于居中型和偏后型雨型而言形成的洪水总量更大；在不同雨型条件下，随着重现期的增加，关口、汉王场流域的洪峰流量均是呈现增加的趋势；林草植被覆盖率为汉王场>关口流域，关口流域在不同重现期设计暴雨雨型条件下的峰现时间均是提前于汉王场流域，林草植被覆盖对于洪水的径流过程具有一定的调节作用；关口流域和汉王场流域洪峰出现时间相较于暴雨雨峰出现时间的滞后时间均为偏前型>居中型>偏后型；揭示西南山区高植被覆盖流域对于不同重现期设计暴雨雨型条件下的量化规律，在分析西南山区高植被覆盖流域暴雨洪水的形成过程、提高流域洪水预报精度与防...     

埭溪流域毛竹林地磷素流失特征研究

磷肥过量施用导致磷在土壤中累积,在暴雨条件下,农田磷素向水体的迁移加快了磷素敏感地区水体的富营养化.为此,采用野外人工模拟降雨试验和定点监测相结合的方法,研究了湖州市埭溪流域典型毛竹林地在降雨条件下坡面径流中总磷和有效磷流失过程的特征;讨论了毛竹林地磷的径流流失规律,为控制埭溪流域水体富营养化状态提供了可用的数据.     

江苏里下河平原农田涝灾的情景模拟分析——以高邮灌区典型圩垸为例

为了分析环境改变后江苏里下河平原农田涝灾的变化特点,以高邮灌区某典型圩垸为例,利用构建的农田涝灾分布式模型模拟了不同暴雨强度、斗沟规模、外排条件、抽排能力和泵站调度规则等环境因子改变条件下的涝灾减产分布.结果表明:现状条件下,在遭遇5%暴雨时受涝面积比为10.47%,最大减产率为4.07%;遭遇2%和1%暴雨时,受涝面积比增至56.54%和86.87%,最大减产率增至10.32%和13.37%.若将斗沟深度由现状的1.3 m挖深至2.0 m,则可以使5%, 2%和1%暴雨条件的受灾面积分别减少14.73%,16.11%和3.91%,最大减产率分别降低5.16%,4.75%和3.81%.若将外河水位预降0.5 m,则可以使5%,2%和1%暴雨条件的受灾面积分别减少86.87%,13.62%和8.52%,最大减产率分别降低66.59%,40.60%和28.12%.若将泵站外排能力由现状的9 m³/s提高到14 m³/s,在遭遇5%暴雨时,受灾情况无变化;2%和1%暴雨条件下的受灾面积分别减少31.68%和11.52%,最大减产率分别降低31.10%和11.44%.单纯降低泵站启排水位而不同时降低外河闸的关闸警戒水位,对涝灾减轻效果几乎没有影响.     

一次区域性暴雨过程的多普勒回波分析

应用榆林新一代天气雷达回波资料对陕西榆林市区域性暴雨进行分析,发现本次暴雨过程是层状云上的中小尺度扰动所致,具有覆盖范围广、持续时间长等特点.组合反射率因子图较好地反映了中小尺度雨团活动全过程;径向速度图较好地反映了大范围降水形势下低空急流的位置及各层气流辐合辐散的特征;风廓线资料较好地反映了各层风向风速的大小和演变;风暴总降水产品反映了本次暴雨过程总降水量的平均值.     

平原河网区排涝计算研究

行洪排涝是平原河网区汛期的重要任务。利用MIKE11模型中的HD模块,以江苏省泗洪县城区水系为实例,建立了一维水动力学模型,并利用产汇流计算确定了模型的边界条件,对20年一遇暴雨条件下的城区河网水量进行了模拟计算。结果表明,在现有的排涝设施条件下,泗洪县城区河网能够满足设计暴雨下的排涝要求。     

广州市移民新村内涝控制方案研究

遭受暴雨与内涝的侵袭和困扰,是我国城镇在经济发展过程中遇到的普遍问题,在广州地区表现尤为突出。基于暴雨强度公式,应用芝加哥降雨过程线对广州市在不同重现期暴雨进行时程分配,得到1~50a5种典型暴雨重现期的设计降雨过程。采用SWMM模型,选取广州市一典型移民新村作为研究对象,将其排水系统进行概化,模拟在实际暴雨情景下入水口流量、节点积水和管渠满载情况,并与实际监测数据对比,以验证模拟的准确性。模拟不同重现期设计暴雨过程研究区内涝情景,考察不同暴雨强度下内涝点数量、积水程度和管网负荷,以探寻研究区域内涝的限制性因素,并基于此提出内涝控制措施。     

脉冲电气浮过程中非均匀流场模拟及分析

针对浮选过程中传统电气浮存在大范围剧烈环流,造成泡絮混合物生长和浮上的干扰较大,导致能量利用率低的问题,提出了采用方形脉冲通电的脉冲电气浮的方式,产生非均匀流场,以减轻环流对泡絮混合物的影响,提高能量利用效率.采用Ansys13.0中的Fluent模块对脉冲电气浮气液两相流场进行了模拟.研究结果表明,与常规电气浮相比,脉冲电气浮非均匀湍流场的能量分布更为合理,微气泡上浮过程中产生的环流程度较小,有利于泡絮混合物的形成和浮选过程.在相同电流密度的前提下,脉冲电气浮的耗电量仅为传统电气浮1/4～1/3,且能达到与传统电气浮近似相同的浮选效果,能量利用效率较高.     

暴雨衰减指数在中小流域雨型设计中的运用探讨

求得设计雨量后,还需拟定设计暴雨时程分配过程,简称“雨型”设计,现今通常采用典型暴雨过程同频率放大而得.鉴于实测典型雨型偶然性较大,通过引入暴雨衰减指数(np)这个量化指标来进行雨型设计.并根据浙江省中小流域特点,分析时段为1h、3h、6h的暴雨衰减指数、区间暴雨衰减指数来提高雨型设计的计算精度,并应用于工程实际.     

饮料中柠檬黄含量测定的不确定度分析

对饮料中的柠檬黄含量进行了测定和不确定度分析,通过对各影响因素的不确定度评定,试验重复性对饮料中合成着色剂的测量结果不确定度的影响最大,其次是样品处理回收率和标准曲线拟合引入的不确定度对试验结果也有较大的影响。结果表明:饮料中柠檬黄的含量为（103.5?3.5）mgkg,k＝2。      

Role of farmers' attitudes in adoption of irrigation in Saskatchewan

Adoption of a new technology, such as irrigation, is a complex phenomenon. Several factors of economic and social nature contribute to the farm-level decisions affecting adoption. In this study, the role played by attitudes of potential adopters towards irrigation and its subsequent adoption on their farm unit was estimated. Two models were estimated, one incorporating only adopters' socio-economic characteristics, and the other, only their attitudes towards irrigation. Results suggest that adopters' attitude, particularly with respect to economic and environmental effects of irrigation, were significant determinants of their decision to proceed with adoption of irrigation, and have a role to play in adoption of irrigation over and above that explained by socio-economic characteristics. In particular, these results suggest that negative perceptions with respect to economics of irrigation and those related to its detrimental impacts on environmental quality, particularly through soil salinity, may be significant deterrents for adoption of irrigation. The study suggests that planning of large scale water development projects, particularly those involving irrigation, must be cognizant of attitudes of potential adopters. Furthermore, during the planning stages, more attention should be paid to the development of proper educational programs, as well as extension packages, to ensure that potential adopters formulate correct attitudes towards the new technology.     

技工院校数学教学中培养学生应用能力的对策分析

数学作为一门基础性学科，在学生的各个学习阶段都起到了不可替代的作用，在工科院校中数学教学的重要性更是升到了一个新的高度。通过数学的学习，可以培养学生的应用能力和探究思维，通过对数学知识的学习和灵活运用，学生的综合能力会得到系统性的提高。对于数学的教学工作，应当做到有针对性、有目标，在教学工作中，充分做到对症下药、有的放矢，让学生通过对数学的学习，提高自身的综合能力，更好地为社会建设贡献力量。     

沼气在冬季温室生产中的应用

本试验通过沼气燃烧,提高冬季温室温度,促进西红柿生长发育.试验结果表明:增温可有效提高冬季温室温度,为西红柿越冬生产提供良好条件,有利于西红柿植株茎粗增加及果实膨大速率提高;可使西红柿坐果期提前10天左右,采收期延长20天左右,并提早上市.同时,增温可显著提高西红柿产量,亩增产800kg.     

四川简阳地区砂岩层中水分利用研究

分析了四川简阳地区砂岩和土壤中的水分运动特性和砂岩中储存的水分对土壤水分补给量的多少。对当地的砂岩和土壤进行了水分特征曲线的测定试验、入渗试验和蒸发试验,并采用研究中常用模型对试验结果进行了拟合,通过对拟合结果的分析,得出了当地土壤和砂岩的水分特性,总结出了该地区表面土层在缺水时水分很容易被下部砂岩层补给,砂岩中的水分是作物利用的重要水资源的结论。这对于充分利用当地水资源,合理确定类似地质条件地区灌溉定额,解决无灌溉条件丘陵区作物缺水问题,实现农业节水灌溉有一定的参考价值。     

Advances in application of climate prediction in agriculture

Agricultural ecosystems and their associated business and government systems are diverse and varied. They range from farms, to input supply businesses, to marketing and government policy systems, among others. These systems are dynamic and responsive to fluctuations in climate. Skill in climate prediction offers considerable opportunities to managers via its potential to realise system improvements (i.e. increased food production and profit and/or reduced risks). Realising these opportunities, however, is not straightforward as the forecasting skill is imperfect and approaches to applying the existing skill to management issues have not been developed and tested extensively. While there has been much written about impacts of climate variability, there has been relatively little done in relation to applying knowledge of climate predictions to modify actions ahead of likely impacts. However, a considerable body of effort in various parts of the world is now being focused on this issue of applying climate predictions to improve agricultural systems.

In this paper, we outline the basis for climate prediction, with emphasis on the El Niño-Southern Oscillation phenomenon, and catalogue experiences at field, national and global scales in applying climate predictions to agriculture. These diverse experiences are synthesised to derive general lessons about approaches to applying climate prediction in agriculture. The case studies have been selected to represent a diversity of agricultural systems and scales of operation. They also represent the on-going activities of some of the key research and development groups in this field around the world. The case studies include applications at field/farm scale to dryland cropping systems in Australia, Zimbabwe, and Argentina. This spectrum covers resource-rich and resource-poor farming with motivations ranging from profit to food security. At national and global scale we consider possible applications of climate prediction in commodity forecasting (wheat in Australia) and examine implications on global wheat trade and price associated with global consequences of climate prediction.

In cataloguing these experiences we note some general lessons. Foremost is the value of an interdisciplinary systems approach in connecting disciplinary knowledge in a manner most suited to decision-makers. This approach often includes scenario analysis based on simulation with credible models as a key aspect of the learning process. Interaction among researchers, analysts and decision-makers is vital in the development of effective applications — all of the players learn. Issues associated with balance between information demand and supply as well as appreciation of awareness limitations of decision-makers, analysts, and scientists are highlighted. It is argued that understanding and communicating decision risks is one of the keys to successful applications of climate prediction.

We consider that advances of the future will be made by better connecting agricultural scientists and practitioners with the science of climate prediction. Professions involved in decision making must take a proactive role in the development of climate forecasts if the design and use of climate predictions are to reach their full potential.     

Fate and transport of atrazine in a sandy soil in the presence of antibiotics in poultry manures

Pesticides degrade principally through biodegradation processes, whereas antibiotics kill microorganisms or inhibit their growth in soils and thus may affect the fate of pesticides. In this study, the impact of antibiotics on the degradation of atrazine in a sandy soil is investigated in lysimeters over a ninety-day period. Four treatments, monensin, narasin, salinomycin and non-antibiotic, were assigned in triplicate to twelve PVC lysimeters. Both soil and leachate samples were collected and analyzed at predetermined time intervals. In all treatments, atrazine was found to leach down through the soil profiles with the concentration level decreasing with depth, and only trace amounts of atrazine were found in the leachate. However, the statistical analysis of the results showed that all the three antibiotic treatments yielded a significantly slower dissipation of the atrazine level as compared to the non-antibiotic treatment; the mass balance analysis indicated an increased half-life of atrazine in the presence of antibiotics.     

北京典型灌区土壤和农产品多氯联苯污染风险评估

为明确北京东南郊灌区表层土壤和农作物多氯联苯(PCBs)含量和污染水平以及人体健康风险,2015年在该灌区采集了20个土壤样品和28个作物样品,利用气相色谱-质谱联用仪分析了样品中7大类PCBs含量。研究结果表明,灌区表层土壤PCBs质量比为ND(低于检出限)到0.711 776μg/kg,均值为0.43μg/kg,总体上土壤PCBs含量随污灌历史年限增加而增加。本研究区表层土壤PCBs含量处于较低水平,土壤未受到PCBs污染且其生态风险概率均小于10%。灌区采集的冬小麦籽粒、大葱、茄子、梨、白薯、芥蓝PCBs含量均低于实验检出限,未检出;夏玉米籽粒、菜心和油菜PCBs总量分别为0.17~0.47μg/kg、1.63μg/kg和5.91μg/kg。不同污灌历史年限并未显著影响夏玉米籽粒PCBs含量。本研究区农产品PCBs含量处于较低水平,均低于美国卫生及公共服务部建议限量。采集的土壤和农产品样品仅四氯联苯含量高于实验检出限,能检测出;一氯联苯到三氯联苯和五氯联苯到七氯联苯均低于实验检出限,未检出。本研究中成人和儿童PCBs致癌风险分别为8.49×10-7和4.66×10-7,非致癌风险分别为1.41×10-1和3.88×10-1,均低于US EPA规定限值,说明PCBs未对人群产生明显的健康危害。致癌危害和非致癌危害均以口-作物(玉米和蔬菜)为主,其对人体健康所造成的风险占总个人年风险的比例分别为99.79%~99.95%和99.81%~99.94%。