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81.
用甘肃省春麦区31个县区1970~2000年的旬平均气温、旬日照时数、旬降水量、≥0℃积温、海拔高度等建立春小麦生态气候适宜度隶属函数和综合适宜度,结果表明:春小麦对海拔高度适宜度在0.15~0.85之间,最小出现在定西和古浪,最大值在金塔和敦煌。≥0℃的积温适宜度与海拔高度适宜度趋势基本一致。旬平均气温适宜度在0.35~0.56之间,说明气温对春小麦生产较适宜。用积分回归分析春小麦在不同气候类区不同生育时段生态气候条件的贡献系数,温和平川绿洲灌区光、温、水要素的平均贡献系数最高,温暖沿沙漠绿洲灌区次之,冷凉浅山半灌溉区、温凉半干旱旱作区最小。用生态气候适应性对春小麦的影响程度和依赖度及产量,确定生态气候区划综合指标体系将春小麦划分出5级适生种植区划,并提出利用和开发生态气候资源有效途径。 相似文献
82.
Jiazhong Qian Hongbin Zhan Yifeng Wu Fulin Li Jiaquan Wang 《Hydrogeology Journal》2006,14(7):1192-1205
Jinan Springs are an important historical heritage in China and have been well known for hundreds of years. Over-abstraction of groundwater in the Jinan area has seriously endangered the hydrological system of the springs, which have stopped flowing for significant periods of time in recent years. A three-dimensional finite-element model programmed primarily at the Hefei University of Technology has been developed to simulate groundwater level change in the large fractured-karst aquifer system in the Jinan Springs field. Various spring protection plans have been explored and their effects on the water table analyzed and compared. It was found that the present rate of groundwater withdrawal from the fractured-karst system in this area was inappropriate for spring protection. The simulated results suggest that decreasing the rate of groundwater pumping from 6.9×105 to 2.7×105 m3/day is needed to protect spring flows. Additional water resource requirements in that area may be met by use of surface water and recycled waste water. 相似文献
83.
利用中国西北五省(区)和内蒙古西部的共106个测站的1960~1990年3~5月的月、季总降水量和太平洋10°S~50°N,120°E~80°W范围内286个格点(5°×5°)的秋季(9~11月)的平均海表温度,通过EOF、REOF、SVD及交叉谱分析等方法,对秋季太平洋海温的异常特性及其与我国西北干旱半干旱地区后期春季降水之间的空间地域遥相关耦合特征进行了分析研究。结果表明,秋季太平洋海温差异常存在6个关键区域,其中赤道东太平洋地区是最敏感的异常信号区;西北干旱半干旱地区春季降水与前期秋季赤道东太平洋海温异常之间有着清晰的遥相关。当海温异常偏高,即有EL-Nino现象时,西北地区的降水普遍偏少,并以高原东侧青、甘、宁交界地区及渭水流域的偏少为主;La-Nina时的情况正好相反,内蒙西部的春季降水变化趋势与我国西北地区基本一致。 相似文献
84.
倒春寒的划分和预报服务探讨 总被引:3,自引:0,他引:3
本文利用预报区域1960~1995年春季逐日气象资料,分析得到了倒春寒天气的客观划分标准、气候特点、主要影响系统及其形势特征。采用较新特色的折扣回归模型,建立了三、四月份各旬倒春寒的集成预报方程;利用短期预报资料,研制出若干预报判据和消空指标,建立了短期预报回归方程,并编制出具有一定特色的预报服务系统。经1997年实际应用,倒春寒天气的预报准确率在经验预报的基础上提高20%左右。 相似文献
85.
An inventory of artesian springs emerging from fractures (fracture springs) was conducted in the Pinh?o River Basin and Morais
Massif, northern Portugal, comprising an area of approximately 650 km2. Over 1,500 springs were identified and associated with geological domains and fracture sets. Using cross-tabulation analysis,
spring distributions by fracture sets were compared among geological environments, and the deviations related to differences
in rock structure and, presumably, to differences in deformational histories. The relation between spring frequencies and
rock structures was further investigated by spectral determination, the model introduced in this study. Input data are the
spring frequencies and fracture lengths in each geological domain, in addition to the angles between fracture strikes and
present-day stress-field orientation (θ). The model's output includes the so-called intrinsic densities, a parameter indexing spring occurrence to factors such as
fracture type and associated deformational regime and age. The highest densities (12.2 springs/km of lineament) were associated
with young shear fractures produced by brittle deformation, and the lowest (0.1) with old tensional and ductile fractures.
Spectral determination also relates each orientation class to a dominant structural parameter: where spring occurrence is
controlled by θ, the class is parallel to the present-day stress-field orientation; where the control is attributed to the length of fractures,
the spring occurrence follows the strike of large-scale normal faults crossing the region.
Electronic Publication 相似文献
86.
辛安泉是山西省第二岩溶大泉,该岩溶泉水是长治市除漳泽水库外的主要供水水源。泉域为一完整的岩溶地下水系统,具有独立的补给、径流、排泄关系,为全排型岩溶大泉。通过对泉域岩溶地下水水文地质特征、岩溶水天然资源量、可开采资源量及开发利用现状的分析研究,为区域水资源的优化配置提供了科学依据。 相似文献
87.
Michael C. Ewers Ryan Dicce Jesse P.H. Poon Jeffery Chow Justin Gengler 《Urban geography》2018,39(1):3-25
Although primarily concentrated in countries with Muslim majorities, Islamic finance has become a global industry representing both a decentering of the global financial architecture and the emergence of an urban network that resides beyond the confines of traditional world city literature. While geographers have identified the “Mecca’s” of the Islamic finance industry – one of which is Bahrain – there remains a need to identify the factors necessary to create and sustain centers of Islamic finance. This paper examines these factors through a firm-level survey of foreign and local Islamic financial institutions in Bahrain, in conjunction with key informant interviews with representatives of these firms. We find that while Bahrain’s entrenched institutional advantages have preserved its role as a center in the Islamic financial landscape, ongoing political instability and the increasing attractiveness of new and emerging centers are threatening this role. As the country navigates the current social and political unrest, questions are raised as to what it takes to be an Islamic financial center. 相似文献
88.
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90.
滇黔准静止锋诱发贵州春季暴雨的锋生机制分析 总被引:3,自引:0,他引:3
利用卫星云图、常规地面观测资料和逐6 h的1°×1°NCEP再分析资料,对2003-2006年春季滇黔准静止锋背景下,出现的5次贵州暴雨天气过程进行了诊断分析和总结。结果表明:在准静止锋背景下,贵州春季暴雨是由高低空急流、高空槽、冷空气与准静止锋的共同作用产生的。低空急流将大量的水汽从孟加拉湾和北部湾输送到贵州,不断积累对流有效位能;高空急流的加速增强了"高层辐散、低层辐合"的大尺度上升运动,并通过急流下侧的正环流圈带动冷空气南下,使得准静止锋活跃锋生,是暴雨天气过程的触发机制。锋生现象分析表明,高空急流加速导致对流层中高层极锋锋区内锋生和对流层中层正环流圈的形成,加强了准静止锋附近的水平变形和垂直运动,进而促使锋生加强。水平变形和垂直运动对暴雨的产生也有直接影响:水平变形项范围越大则降雨强度越强,与垂直运动相关的倾斜项移动与在准静止锋附近生成的强对流云团的移动方向一致。准静止锋与贵州春季的暴雨过程关系密切,暴雨落区集中分布在准静止锋南侧1个纬距带内。高空急流加速度、冷锋附近的水汽辐合强度以及对流有效位能的高能舌区范围对暴雨范围和强度有指示作用。基于以上锋生机制,提炼了滇黔准静止锋诱发贵州春季暴雨的物理模型。 相似文献