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鹤地水库浮游植物时空分布特征研究 总被引:1,自引:0,他引:1
在探讨鹤地水库浮游植物群落结构及种群数量变化规律的基础上,对库区不同水文与营养状态下浮游植物的时空分布特征进行了研究。研究结果表明,库内以硅藻门小环藻、直链藻以及蓝藻门微囊藻和假鱼腥藻为优势种的浮游植物,其丰度受库区降雨、水位调节、营养盐水平和气温等因素共同影响,从入水口开始往下游方向存在明显纵向梯度分布,且呈现夏、秋季节高和冬、春季节低的特征。 相似文献
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采用主分量分析(EOF)、旋转主分量分析(REOF)、小波分析方法,对广东省1954—2007年春季(2—5月)降水标准化距平场进行分区,并对春季降水的空间分布特征、时间变化规律进行分析。结果表明,广东省春季平均降水量和标准差变化较大;春季降水的主要空间分布型表现为全省一致偏旱(涝)型;降水区域大致可划分为4个区,即粤东区、粤北区、粤中区、粤西区。除了粤东以外,其余区域都存显著周期性变化。 相似文献
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广东省降水的趋势变化和时空分布特性分析 总被引:6,自引:0,他引:6
降水作为重要的水文要素之一,是水资源的总补给源,更是分析水资源状况时计算本地来水的直接依据.选用资料系列较长、资料质量好的雨量代表站点442个,通过计算其不同系列年的统计参数特征值,分析了广东省降水的时空分布特性. 相似文献
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Predicting Shallow Water Table Depth at Regional Scale: Optimizing Monitoring Network in Space and Time 总被引:1,自引:0,他引:1
Emanuele Barca Maria Costanza Calzolari Giuseppe Passarella Fabrizio Ungaro 《Water Resources Management》2013,27(15):5171-5190
Shallow water table levels can be predicted using several approaches, either based on climatic records, on field evidences based on soil morphology, or on the outputs of physically based models. In this study, data from a monitoring network in a relevant agricultural area of Northern Italy (ca. 12,000 Km2) were used to develop a data driven model for predicting water table depth in space and time from meteorological data and long-term water table characteristics and to optimize sampling density in space and time. Evolutionary Polynomial Regressions (EPR) were used to calibrate a predictive tool based on climatic data and on the records from 48 selected sites (N?=?5,611). The model was validated against the water table depths observed in 15 independent sites (N?=?1,739), resulting in a mean absolute error of 30.8 cm (R 2?=?0.61). The model was applied to the whole study area, using the geostatistical estimates of the average water table depth as input, to provide spatio-temporal maps of the water table depth. The impact of the degradation of data input in the temporal and spatial domain was then assessed following two approaches. In the first case, three different EPR models were calibrated based on 25 %, 50 % and 75 % of the available data, and the error indexes compared. In the second case, an increasing number of monitoring sites were removed from the initial data set, and the associated increased kriging standard deviation was assessed. Reducing the average sampling frequency from 1.5 per month to 1 every 40 days did not impact significantly on the prediction capability of the proposed model. Reducing the sampling frequency to 1 every 4 months resulted in a loss of accuracy <3 %, while removing more than half locations from the network, resulted in a global loss of information <15 %. 相似文献
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本文引入浑沌理论中分形几何的思想并结合灰色系统理论关联分析及灰域预测原理,提出了多维时序因子灰色模式识别预测方法。并以珠江流域某河流的长期水文预测报为实例。 相似文献
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应用季节性肯达尔检验方法及概率法对邕江三个水质监测站的系列监测资料进行水质时空趋势分析,得出邕江水质呈有机污染型的逐年下降趋势,上游的南宁站水质优于下游的豹子头、蒲庙两站,为Ⅱ-Ⅲ类水,豹子头、蒲庙由于受上游南宁市区五大排污口影响,水质较劣,分别为Ⅴ、Ⅳ类的结论. 相似文献
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以土壤墒情的时空变化规律为试验对象,将一种可双向钻土式自升降喷灌装置在延庆生态试验基地露天植物种植区内进行实际应用,并对该装置应用前后的土壤进行分层取样以及含水量监测分析,结果表明:①该装置能够将土壤体积含水量、质量含水量、相对含水量3个指标分别由装置实施前的均不足15%、11%、50%提高到31%、22%、103%以上,有效解决了作物生长阶段经常出现的土壤水分供应不足问题;②该装置显著提高了浅层土壤的含水量,能够最大限度满足作物生长对水分的需求;③该装置具有显著的节水效果,灌溉用水量从3 150 m~3/hm~2减少到2 800 m~3/hm~2。 相似文献