地表水空间分布与土壤类别多样性关联分析

为探索水土资源在空间分布上的内在联系,选取河南省不同生态环境和社会发展条件下5个典型样区,将多样性理论与研究方法应用于地表水资源的空间分布离散性评价中.计算了各样区及样区分区域内1 km×1 km网格尺度下的地表水体空间分布多样性和土壤类别构成组分多样性,并探索了两者之间的内在联系.研究表明:多样性理论与研究方法适用于水土资源分布的评价研究并具有广阔应用前景;水体总面积和其空间分布离散性之间存在线性正相关关系,大尺度样区下相关系数值高达0.70,小尺度分区下减小为约0.45;水体空间分布离散性与土壤分类单元数目之间存在一定程度的负相关变化趋势,该趋势随研究区面积的增大和人类活动干扰的减弱而增强;水体分布对土壤类别的空间构成产生重要影响.     

地表水体空间分布多样性的实用性与科学性验证

选择传统的水体周长、水体总面积和河流密度以及最新的水体空间分布多样性4类地表水体分布特征评价参数,对河南省中部典型样区的地表水体信息进行深入分析。研究表明,当研究区内水体以河流等线状水体类型为主时,4者均能较好地描述区域地表水体的分布特征,且两两之间具有明显的一元线性正相关关系,判定系数平均达到0.89左右;当研究区由河流、湖泊、水库等复杂水体类型构成时,选择最新的水体空间分布多样性评价参数能够更好地描述区域地表水体的空间分布特征。     

基于点扩散函数的条件植被温度指数降尺度转换方法

以陕西省关中平原为研究区域,基于MODIS数据反演的条件植被温度指数(VTCI)的定量化干旱监测结果(MODIS-VTCI)和基于Landsat数据反演的VTCI相对干湿监测结果(Landsat-VTCI),应用点扩散函数(PSF)将930 m空间分辨率的MODIS-VTCI降尺度转换至30 m,并对降尺度转换的VTCI进行定量化验证。结果表明,降尺度转换的VTCI与Landsat-VTCI间的相关系数和结构相似度均较大,降尺度转换的VTCI与累计降水量间的相关性和MODISVTCI与累计降水间的相关性相近,且均高于Landsat-VTCI与累计降水量间的相关性,说明降尺度转换的VTCI既考虑了Landsat-VTCI的空间变异,又保持了MODIS-VTCI较为准确的定量化干旱监测特性。     

应用中值融合模型的条件植被温度指数降尺度转换研究

为获得基于Landsat卫星遥感数据更为精确的定量化干旱监测结果,以陕西省关中平原为研究区域,基于Aqua MODIS数据反演的1 km空间分辨率的条件植被温度指数(VTCI)的定量化干旱监测结果(MODIS-VTCI)和Landsat OLI/TIRS数据反演的30 m空间分辨率的VTCI相对干湿监测结果(Landsat-VTCI),应用降尺度的中值融合模型(MFM)将基于MODIS数据反演的VTCI降尺度至30 m空间分辨率的VTCI定量化干旱监测,并对其结果进行验证。结果表明,应用降尺度的中值融合模型转换的VTCI定量化干旱监测结果(MFM-VTCI)与Landsat-VTCI的空间分布及纹理特征相似,两者间的相关系数和结构相似度均较大,均方根误差、差值影像及差值频数分布图所呈现的结果与定量化干旱监测结果和相对干湿监测结果间的系统误差相符,表明Landsat-VTCI与MFM-VTCI间的可比性较强。MFM-VTCI与累计降水间的相关性和MODIS-VTCI与累计降水间的相关性相近,均大于Landsat-VTCI与累计降水间的相关性,表明MFM-VTCI是定量化的干旱监测结果。     

黄河流域农业系统水资源价值及其空间分布研究

【目的】分析黄河流域农业系统水资源空间分布特征。【方法】以黄河流域为研究对象,通过能值理论与方法、空间自相关分析法及空间滞后回归模型,研究了农业系统水资源价值空间分布特征及其主要影响因素。【结果】①农业系统水资源价值介于4.01～6.10元/m~3,流域中下游价值较高;②农业系统水资源价值全局莫兰(Moran)指数为0.277 2,呈空间正向自相关特征;主要以高值集聚型(H-H)聚集在流域中下游;③农业系统水资源价值空间变化的主要影响因素为GDP、海拔、用水量。【结论】以价值引导水资源分配,增加流域中下游农业用水有助于提高流域整体水资源农业生产效益。     

基于遥感蒸散发模型的净灌溉水量测算空间尺度研究

【目的】农业用水总量和灌溉水有效利用系数是最严格水资源管理考核总量红线和效率红线控制的重要指标。目前遥感蒸散发模型在珠江片区域蒸散发量估算和净灌溉水量评估的应用度不高,对其空间适用尺度缺乏研究。【方法】以广西区为例,通过试验观测-遥感解译等技术计算不同空间尺度遥感蒸散发量,并与相应尺度直接量测的净灌溉水量建立线性相关关系,根据相关系数,得出误差最小的空间尺度,从而建立一套更准确、快速、有效的最优空间尺度下,根据遥感蒸散发量进行区域净灌溉水量估算的方法。【结果】在较大的广西区、片区尺度,净灌溉用水量和遥感蒸散发量之间存在明显的线性相关关系,相关系数在0.8以上;对比广西区和桂中片区净灌溉用水量实测结果与遥感估算结果,误差均在0.5%以内。【结论】在片区和广西区等较大尺度,遥感测算结果的可信度较高,遥感蒸散发模型适用性较强,其估算结果可为最严格水资源管理考核和农业水资源科学管理提供科学支撑。     

基于SMOS降尺度数据的土壤水分时空变化分析研究

把握土壤水分时空格局变化特征,对生态环境综合治理、防止水土流失具有重要参考价值与现实意义。提出一种基于DEM校正TVDI的SMOS土壤水分数据降尺度方法,对25 km空间分辨率的SMOS L3土壤水分产品空间尺度降至1 km,并对降尺度结果进行了验证。然后利用土壤水分变化的空间均方根误差(RMSEδs)和时间均方根误差(RMSEδt)对2017年研究区的土壤水分时空格局变化进行了分析,分析结果表明研究区土壤水分时空分布呈现不均一性,总体上南部和东部地区土壤水分含量较高,北部和西部地区含量较低。土壤水分随时间变化有所波动,6-8月份雨季时期土壤水分值普遍较高。此外,TRMM 3B43降水数据和土壤水分降尺度结果相关性分析表明,不同降雨条件会对土壤水分和降雨之间的相关系数产生显著的差异性影响。     

灌溉水利用效率的空间分布特征及等值线图研究

基于全国各行政区的现状灌溉水利用效率数据,采用地质统计学及空间自相关分析方法对灌溉水利用效率的空间分布特性进行分析。结果表明:空间自相关法得到现状灌溉水利用效率在1500 km范围内各方向上存在着较明显的自相关关系,总体上没有较显著的方向性,但在ES-WN方向上的自相关性起主要作用。灌溉水利用效率各向同性条件下变异函数可用指数模型描述,在1900 km空间范围内存在着显著的相关性,除ES-WN方向外,并未体现明显的各向异性,与空间自相关分析结论基本一致。理论变异参数的分析结果表明,灌溉水利用效率的空间变异主要是结构性因素起决定作用,结构性变异达到91%左右。对比灌溉水利用效率及代表影响指标的空间分布格局可知,ET0均值、年均降水量对于灌溉水利用效率的影响是间接的,灌溉水利用效率与节水灌溉工程面积比存在显著正相关关系。     

南方农田土壤容重空间变异性及其尺度效应

以南方典型农田作物生长地为试验区,利用经典统计与地统计学方法,分析研究了选定区域不同深度土层(0~10,10~20 cm)土壤容重的空间异质性及其尺度效应,并对试验区农田土壤容重进行空间插值估算.结果表明农田土壤容重变异系数较小,为弱变异.半方差函数分析表明土壤容重的块基比小于10%,田间土壤容重由空间自相关部分引起的异质性程度很大.在尺度效应研究中,随着采样幅度增大,变异系数呈先减小后增大趋势;通过调整采样点位置"再采样"发现,当采样间距增大时,土壤容重变异系数变化幅度很小(6.32%~7.92%),而相关距离却减小.说明当采样幅度一定时,采样间距对土壤容重变异系数的影响很小.通过空间插值估算,绘制等值线图发现两层土壤容重也具有相关联的空间分布规律,且呈显著正相关关系,相关系数为0.76.此外,土壤容重空间变异受人为活动影响程度大.     

水资源系统对鄱阳湖流域城镇化的响应关系研究

为了探究城镇化发展与水资源利用的内在响应机制及响应程度,以便优化配置水资源,协调城镇发展速度与水资源开发利用程度.以水资源时空分布为基石,构建响应度模型,由熵权法确定权重,相关分析法分析城镇化与水资源利用的相关关系.结果表明:鄱阳湖流域城镇化发展水平和水资源利用程度同步增长.城镇化系统中社会、人口和空间城镇化的上升趋势...     

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。