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981.
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984.
华北平原有咸水区雨洪控制利用 总被引:2,自引:1,他引:2
华北平原有咸水区,水资源短缺,深层地下水严重超采,生态环境恶化。在这个地区开发利用咸水,腾出地下库容,能够减少潜水蒸发与雨洪径流,增大降雨入渗,把时空分布不均的天然降雨转化为可利用的水资源。该文总结了农村用微咸水灌溉,抗旱增产,调控地下水埋深,增大雨洪回灌,淡化地下水质的经验。提出了城区雨洪控制利用的建议。 相似文献
985.
A stochastic simulation model of daily rainfall in discrete time is proposed. The model simulates the sequence of rainfall occurrences using the method of transition probability matrices. Synthetic daily rainfall depths are then generated using sampling methods plus a two step power transformation scheme (TSPT). Rainfall data from four meteorological stations from the islands Rhodes and Chios (Aegean Sea) were used for model validation. The proposed model was also compared to a widely used TPG model. Results showed that the proposed model performed more satisfactorilly than the TPG model preserving the statistical characteristics and the total number of rainfall occurrences of the historical samples. 相似文献
986.
在宁夏中部干旱带年平均降雨量350 mm的限额灌溉区,以滴灌玉米种植为对象,集成覆膜微集雨、土壤保水、抑制蒸腾等技术,开展降水资源就地高效利用试验研究,通过对试验区玉米在不同模式下产量及水分生产效率的对比分析,从而提出深翻20~40 cm+半覆膜膜侧种植+保水剂(秦威加力7.5 kg/hm2)+喷施抗蒸腾剂(万代红1.05 L/hm2)为宁夏中部干旱带限额灌溉区适宜的玉米降水资源高效利用模式,产量达到13 785 kg/hm2,水分利用效率达到4.22 kg/m3。 相似文献
987.
考虑降雨空间变化的流域产流模型 总被引:7,自引:1,他引:7
本文从确定性与随机性相结合的途径出发,将超渗产流模型与降雨空间变化的频率特性有机结合,引入流域降雨产流计算中,经在黄土地区四个流域的初步应用,表明模型具有模型具有物理概念明确,弹性大的特点,对不同面积大小的流域均具有良好的适用性。 相似文献
988.
Pedro Garcia‐del‐Pino Ana Benarroch Jose M. Riera 《International Journal of Satellite Communications and Networking》2015,33(1):43-56
Modern and future satellite systems working in the Ka and Q/V bands often require the application of site diversity to mitigate the degradations caused by rain. Satellite systems operating in these bands may make use of multi‐beam techniques to provide high‐capacity services. To achieve an efficient performance in both techniques, precise information is necessary on the occurrence of simultaneous rain fades in various links under a given satellite coverage. This is attained through the knowledge of the spatial characteristics of rainfall rate over the area of interest. The availability of a large database of rain gauge data from about 50 sites in Spain has allowed the undertaking of a study on the large‐scale spatial distribution of rainfall rate. Joint distributions and correlation parameters have been investigated for pairs of sites, and experimental results have been compared with predictions based on the ITU‐R site diversity model, obtaining the best results when stratiform rainfall is dominant in both sites. Some statistical dependence has been found even for distances above 700 km. The values obtained from the statistical analysis have been represented taking a given site as reference in maps of contour lines using standard mapping procedures. Correlation parameters are expected to decrease with distance; however, the contour maps reveal a significant influence of climatic and geographic factors such as weather fronts, orography or the proximity to the sea. The statistics and maps obtained are useful to optimise both power sharing in multi‐beam satellite systems and the application of site diversity. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
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990.
LIU Ge ZHAO Ping & ZHOU XiuJi Chinese Academy of Meteorological Sciences Beijing China National Meteorological Information Centre 《中国科学:技术科学(英文版)》2011,(5)
Using observational data,the East Asian-North Indian Ocean index(IEANI),which reflects a tropospheric thermal contrast,is found to correlate well with the East Asian summer monsoon(EASM) and associated rainfall over eastern China.Corresponding to a higher(lower) IEANI,the EASM at mid-latitudes is stronger(weaker),and there is more(less) rainfall in North China and less(more) rainfall near the Yangtze River valley.To investigate long-term variation in the EASM,we reconstructed the BC 665-AD 1985 IEANI based ... 相似文献