参考作物蒸发蒸腾量计算方法的应用比较

应用国家"863"节水农业重大专项子课题示范现场的气象资料,对4种分属于不同类型的参考作物蒸发蒸腾量ET0计算公式进行了日ET0值的验证计算。结果显示,在时间序列上,随气象因素变化各方法计算的日ET0值呈相同的变化趋势,但计算值有较大的差异;选取FAO56Penman-Monteith公式计算结果为标准,Priestley-Taylor(1972)方法结果与之最为接近,其余依次是Irmark-Allen拟合法和Hargreaves-Samani(1985)法;不同天气类型条件下,Priestley-Taylor(1972)结果与FAO56Penman-Monteith有较高的一致性,而其他2种方法随n/N的减小,误差急剧增加,尤其是Hargreaves-Samani(1985)方法。     

参考作物腾发量计算方法的适用性研究

选用5种方法,利用陕西6站的气象资料,计算了各站逐日ET0。并以FAO56 Penman-Monteith(P-M)法为标准,对其它方法进行评价。结果表明,在陕西6地区,5种方法计算的ET0变化趋势基本相同,但数值上有一定差异,所有的差异随ET0的增大而增大。Hargreaves法计算结果差异性较小,适用性较好;1948Penman和Priestley-Taylor二方法估值较FAO24 Penman法更接近P-M法的计算结果;缺气象资料时,Priestley-Taylor法可获得较好估值,且更适用于湿润地区;FAO24 Penman法也能获得较好结果,但其估值精度低于Priestley-Taylor法,一般不宜采用。同时分析了P-M法计算的ET0值和水面蒸发量之间的关系,为利用水面蒸发资料估算陕西6地区ET0值提供参考。     

气象资料缺测条件下武汉地区计算ET0方法适用性分析

运用Priestley-Taylor公式, Hargreaves公式和Penman-Monteith公式,对武汉市各典型水文年参考作物腾发量进行了计算,以Penman-Monteith公式的计算结果为标准,对Priestley-Taylor公式和Hargreaves公式的计算结果进行分析。结果表明：各典型年Hargreaves公式计算的ET0值与Penman-Monteith公式计算结果无显著性差异,在气象资料缺测的条件下可直接代替Penman-Monteith公式在该地区使用;而Priestley-Taylor公式与Penman-Monteith公式计算结果有很大差异,使用前须进行修正。     

中国不同气候区参考作物蒸散量计算模型适用性评价

参考作物蒸散量(ET0)的准确计算是制定作物灌溉制度和区域灌溉用水量计划的基本依据.为提高中国不同气候区域ET0计算精度,以FAO56 Penman-Monteith(PM)模型为标准,对28个基于温度和辐射的ET0经验模型在中国温带季风区(TMZ)、温带大陆区(TCZ)、高原山丘区(MPZ)和亚热带季风区(SMZ)的...     

关中地区夏玉米和冬小麦不同蒸发蒸腾量估算方法的研究

参考作物蒸发蒸腾量(ET0)是精准估算作物需水量、提高农田水分利用效率的重要依据。基于2013-2017年的田间试验数据以及相关气象观测资料,采用5种计算ET0的方法计算关中地区日平均ET0和年平均ET0,采用Origin对ET0及环境因子进行相关分析,使用标准误差估计(SSE)和决定系数r2,在FAO-56 PM和其他4种简单替代方法之间进行比较。结果表明:对ET0和气象因子的标准分数的分析表明,ET测量值和5种方法的估计值均高度依赖于太阳辐射和温度,但与相对湿度和风速的关系较小。对5种ET0估算方法,即:FAO-56 Penman-Monteith(FAO-56 PM)、Penman-Monteith(PM)、Priestly-Taylor(PT)、Mankink(MK)和Hargreaves(HG)进行了评估。统计分析表明PM可代替FAO-56 PM方法来预测该地区的ET_0值。这与作物蒸发蒸腾量(ETC)的准确估计直接相关,这也取决于作物生理特征和发育阶段、天气参数、环境条件和管理实践。     

黄河三角洲参考作物腾发量计算方法适宜性研究

准确估算各地区的参考作物腾发量(ET0)是农业灌溉设计和节水规划中必不可少的内容。利用黄河三角洲地区4个典型气候区的气象资料,选用5种计算方法(P-M,FAO-79Penman、Priestley-Taylor,FAO-24Penman和Hargreaves-Samani)计算了ET0,并以P-M方法作为标准,对其他方法进行了评价。结果表明,在黄河三角洲各气候区FAO-Penman法估算的ET0较Priestley-Taylor方法更接近于P-M法的计算结果,并且计算精度较高,误差在3%~10%之间。在缺少资料的湿润区,用Priestley-Taylor方法可以得到与P-M法估值相近的结果。     

3种ET_0计算方法在海南省的适用性比较

为了探究不同参考作物需水量(ET0)计算方法在海南省的适用性,收集了海南省7个站点2000-2014年的气象数据,以Penman-Montieth公式的ET0计算结果为基准,选取了Priestley-Taylor公式、Irmak-Allen公式和Hargreaves-Samani公式3种计算方法,比较ET0计算值逐日变化规律,并进行误差分析和相关性分析。结果表明,Priestley-Taylor公式的ET0计算结果精度最高,其平均绝对误差和平均相对误差分别为0.760 mm/d和24.190%,其次为Hargreaves-Samani公式的ET0计算结果,Irmak-Allen公式的ET0计算结果精度较差。相关性分析中,Priestley-Taylor公式和Irmak-Allen公式表现较好,两个公式计算结果的相关系数均大于0.9,回归方程斜率分别为1.203和0.883。由研究可知,Priestley-Taylor公式在海南省具有较好的适用性。     

西藏高原灌区参考作物蒸散量模型的适用性研究

为明确参考作物蒸散量(ET_0)计算模型在西藏高原灌区的适用性,推荐适宜于气象资料短缺条件下的ET_0计算模型,本研究基于满拉、墨达、江北3个灌区的气象站的长系列数据,以FAO推荐的Penman-Monteith(FAO 56 PM)模型计算的ET_0为标准,对ET_0的5种常用计算模型的适用性进行评价。结果表明:Makkink、Irmark-Allen、FAO 17Penman、Hargreaves-Samani和Priestley-Taylor 5种模型模拟的日尺度ET_0变化趋势与FAO 56 PM模型一致,在年际间均呈先增后减的变化规律,且峰值出现在6～7月份,但各模型适用性存在显著差异。Makkink模型的日尺度MAE、RMSE、NSE值分别为0.37 mm/d、0.45 mm/d和0.84,模拟精度及可信度最高;Irmark-Allen模型次之,MAE、RMSE、NSE分别为0.65 mm/d、0.71 mm/d、0.62;Priestley-Taylor模型最差,MAE值最大达4.91 mm/d且NSE值小于0。年尺度下,各模型较FAO 56 PM均存在高估现象,其中FAO 17Penman、Hargreaves-Samani、Priestley-Taylor模型的NSE值介于-3 571.76～-118.00之间,模拟结果不可信;Makkink模型的NSE值最接近于0,模拟结果可信,但模拟过程的误差较大。综合评定,推荐Makkink为西藏高原灌区气象资料短缺条件下的ET_0简化模型。     

泸州市参考作物腾发量计算方法比较与修正

为实现参考作物腾发量（ET0）在气象资料缺失地区的准确计算,探究ET0简便方法在泸州市的适用性,以Penman-Monteith（PM）法作为标准方法,对Hargreaves（Har）法、FAO24 Blaney-Criddle（FAO24 BC）法、Makkink（Mak）法、Priestley-Taylor（PT）法计算的ET0进行适用性分析,并采用线性关系和贝叶斯公式对各方法进行修正。通过误差分析得出,Har、PT法在研究区的适用性较好,RMSE在0.5~1.1 mm/d、PE在10%~15%,误差相对较小,且利用线性关系修正比贝叶斯公式好,线性修正后的Har法、PT法误差分别下降50%、80%左右,可以看出PT法的修正效果比Har法更理想。采用线性关系修正后的PT法更适合代替PM法计算气象资料缺失时的ET0,可为估算作物需水量提供理论依据和数据支持。      

基于知识流的作物蒸散量数据挖掘方法研究

随着信息技术的发展,采集、存储和管理数据的手段日益完善,数据挖掘学科应运而生。针对作物蒸散量(ET0)计算中参数多、噪声复杂和非线性的特点,研究一种数据挖掘方法——随机森林,在数据挖掘建模过程中引入知识流的概念,通过知识流模型的分层,实现从不同角度、不同层次观察模型知识流的分布和流动情况,抓住建模关键环节,为更加准确、高效地建立模型提供支持。将其应用于作物蒸散量计算中,以西安的气象数据为输入参数,以FAO56Penman-Monteith公式计算的结果作为预测对比值,进行了建模与验证。结果表明,采用知识流建立的数据挖掘模型预测精度较高、稳定性好、泛化能力强,能够有效预测作物蒸散量。相比其他模型效率高,性能更优,尤其适用于大样本的作物蒸散量预测分析中,对于确定作物需水量有一定的参考价值。     

Overland water and salt flows in a set of rice paddies

Cultivation of paddy rice in semiarid areas of the world faces problems related to water scarcity. This paper aims at characterizing water use in a set of paddies located in the central Ebro basin of Spain using experimentation and computer simulation. A commercial field with six interconnected paddies, with a total area of 5.31 ha, was instrumented to measure discharge and water quality at the inflow and at the runoff outlet. The soil was classified as a Typic Calcixerept, and was characterized by a mild salinity (2.5 dS m⁻¹) and an infiltration rate of 5.8 mm day⁻¹. The evolution of flow depth at all paddies was recorded. Data from the 2002 rice-growing season was elaborated using a mass balance approach to estimate the infiltration rate and the evolution of discharge between paddies. Seasonal crop evapotranspiration, estimated with the surface renewal method, was 731 mm (5.1 mm day⁻¹), very similar to that of other summer cereals grown in the area, like corn. The irrigation input was 1874 mm, deep percolation was 830 mm and surface runoff was 372 mm. Irrigation efficiency was estimated as 41%. The quality of surface runoff water was slightly degraded due to evapoconcentration and to the contact with the soil. During the period 2001–2003, the electrical conductivity of surface runoff water was 54% higher than that of irrigation water. However, the runoff water was suitable for irrigation. A mechanistic mass balance model of inter-paddy water flow permitted to conclude that improvements in irrigation efficiency cannot be easily obtained in the experimental conditions. Since deep percolation losses more than double surface runoff losses, a reduction in irrigation discharge would not have much room for efficiency improvement. Simulations also showed that rice irrigation performance was not negatively affected by the fluctuating inflow hydrograph. These hydrographs are typical of turnouts located at the tail end of tertiary irrigation ditches. In fact, these are the sites where rice has been historically cultivated in the study area, since local soils are often saline-sodic and can only grow paddy rice taking advantage of the low salinity of the irrigation water. The low infiltration rate characteristic of these saline-sodic soils (an experimental value of 3.2 mm day⁻¹ was obtained) combined with a reduced irrigation discharge resulted in a simulated irrigation efficiency of 60%. Paddy rice irrigation efficiency can attain reasonable values in the local saline-sodic soils, where the infiltration rate is clearly smaller than the average daily rice evapotranspiration.     

瓦房店市水果生产标准化发展研究

瓦房店市是我国重要的水果生产基地,在国内水果生产领域占有重要地位。随着水果市场化的不断深入,如何满足和适应国内外市场需求成为瓦房店市水果生产的关键问题。从瓦房店市水果生产实际出发,阐述了实施水果生产标准化的必要性,提出了发展水果生产标准化的具体措施。     

金谷子耐旱TG118引种试种及推广应用

对引进的谷子新品种金谷子耐旱TG118进行品种比较试验和多点试种。结果表明：该品种抗旱、耐瘠、适应性强,稳产、高产、抗病抗风抗倒伏强,品质优良,粮草兼用,种植简单,省工易管;一般产量在6000kg/hm2以上,比当地主栽品种增产20%以上。最高产量达9450kg/hm2,适于在辽西北地区推广应用。     

对《种子法》存在问题的探讨

《种子法》是我国种植业第一部法律。自实施以来,为依法加强种子管理提供了有力的法律支撑,促进我国种子产业发生翻天覆地的变化。但随着依法管理工作的深入和种子产业的快速发展,《种子法》及配套规章的一些问题逐步显现出来。对《种子法》及配套规章存在的问题进行深入分析,对需要进一步补充的章节以及需要调整的内容进行深入探讨,以求更加完善和明确。     

Review of the Egyptian experience in implementing land drainage projects

About 30 years have passed since the Government of Egypt embarked on implementing a series of large scale drainage projects. At present, about 3.8 million acres have been provided with drainage systems on the basis of systematic pre-drainage investigations and designs. The target is to provide drains in approximately 6.4 million acres in the Nile Valley and Delta.The implementation of the subsurface drainage system is carried out by the public sector and private contractors under direct supervision of governmental regional departments. The implementation process depends on many factors related to the drainage material, machinery, manpower, site requirements, farmers and organizations involved. Problems and constraints are sometimes challenging, however, the annual rate of implementation has gradually increased to 170,000 acre/year.This paper discusses the different aspects involved in the implementation process of drainage systems. The development in materials, machinery and construction technologies will be reviewed. Institutional and management factors are going to be also considered.     

和谐社会理论建设的几点哲学思考

在新世纪,面对机遇和挑战,党的十六大把“社会更加和谐”作为全面建设更高水平的小康社会的一个重要目标。中国人素有社会和谐的理想;西方人自古也向往社会和谐;借鉴东西方两种和谐社会思想的经验、教训,构建社会主义和谐社会理论。     

A European irrigation map for spatially distributed agricultural modelling

We present a pan-European irrigation map based on regional European statistics, a European land use map and a global irrigation map. The map provides spatial information on the distribution of irrigated areas per crop type which allows determining irrigated areas at the level of spatial modelling units. The map is a requirement for a European scale assessment of the impacts of irrigated agriculture on water resources based on spatially distributed modelling of crop growth and water balance. The irrigation map was compiled in a two step procedure. First, irrigated areas were distributed to potentially irrigated crops at a regional level (European statistical regions NUTS3), combining Farm Structure Survey (FSS) data on irrigated area, crop-specific irrigated area for crops whenever available, and total crop area. Second, crop-specific irrigated area was distributed within each statistical region based on the crop distribution given in our land use map. A global map of irrigated areas with a 5′ resolution was used to further constrain the distribution within each NUTS3 based on the density of irrigated areas. The constrained distribution of irrigated areas as taken from statistics to a high resolution dataset enables us to estimate irrigated areas for various spatial entities, including administrative, natural and artificial units, providing a reasonable input scenario for large-scale distributed modelling applications. The dataset bridges a gap between global datasets and detailed regional data on the distribution of irrigated areas and provides information for various assessments and modelling applications.     

粉质仪和拉伸仪在面粉生产中的应用

在介绍粉质仪和拉伸仪结构和原理的基础上,探讨了粉质曲线中吸水率、形成时间、稳定时间、弱化度和评价值等指标与面粉品质的关系,以及如何根据拉伸曲线中面团最大拉伸阻力、延伸度和拉伸曲线面积等指标来评价面团品质,并结合生产实际,概述了粉质仪和拉伸仪在面粉生产中的作用。     

农村信息化服务的现状及建设措施

分析当前我国农村信息化服务的现状,提出加强农村信息化服务的新举措。     

车辆ABS控制算法的研究及探讨

对现代汽车的ABS控制算法作了一些简单的介绍,同时指出了它们的一些缺陷,相应地提出了几种对ABS的其它控制方法并加以探讨,其中着重论述了ABS门限值控制算法中参考车速的确定方法和基于附着系数的控制算法。