Regional accessibility of land traffic network in the Yangtze River Delta     

ZHANG Li  LU Yuqi 《地理学报》2007,17(3):351-364

In a given district, the accessibility of any point should be the synthetically evalua-tion of the internal and external accessibilities. Using MapX component and Delphi, the author presents an information system to calculate and analyze regional accessibility according to the shortest travel time, generating thus a mark diffusing figure. Based on land traffic network, this paper assesses the present and the future regional accessibilities of sixteen major cities in the Yangtze River Delta. The result shows that the regional accessibility of the Yangtze River Delta presents a fan with Shanghai as its core. The top two most accessible cities are Shanghai and Jiaxing, and the bottom two ones are Taizhou (Zhejiang province) and Nantong. With the construction of Sutong Bridge, Hangzhouwan Bridge and Zhoushan Bridge, the re-gional internal accessibility of all cities will be improved. Especially for Shaoxing, Ningbo and Taizhou (Jiangsu province), the regional internal accessibility will be decreased by one hour, and other cities will be shortened by about 25 minutes averagely. As the construction of Yangkou Harbor in Nantong, the regional external accessibility of the harbor cities in Jiangsu province will be speeded up by about one hour.  相似文献   

珠江三角洲丘陵赤红壤开发中的问题与可持续利用   总被引：1，自引：0，他引：1  

杨恬  朱照宇 《热带地理》2007,27(5):395-399,404

丘陵赤红壤是珠江三角洲社会经济发展的重要土壤资源,但是长期以来的人为干扰和不合理利用使土壤性能退化,生态环境恶化,严重影响了丘陵赤红壤的可持续利用。文中总结了丘陵赤红壤的基本特性及利用现状,探讨其生态环境重建及实现可持续利用的途径。认为丘陵赤红壤面临的主要问题有:水土流失、养分贫瘠、表土砂质化、土壤结构退化、土壤水分性能退化、酸雨和重金属造成的污染等。指出实现其可持续利用的途径主要有:加强水土流失的治理;培育土壤肥力,调节土壤水分;增加生物多样性,建立良好的生态结构;防治"三废"污染,使用清洁能源;发展绿色农业与观光农业。  相似文献   

The Western Pearl River Delta: Growth and Opportunities for Cooperative Development with Hong Kong by Y. M. Yeung,Shen Jianfa,and Zhang Li     

Mike Rudibaugh 《The Professional geographer》2007,59(3):397-398

  相似文献   

Determining the seasonality of groundwater recharge using water isotopes: a case study from the upper North Han River basin,Korea     

Kwang-Sik Lee  Yongje Kim 《Environmental Geology》2007,52(5):853-859

The stable isotopes of oxygen and hydrogen were used to determine the seasonal contributions of precipitation to groundwater recharge at a forested catchment area in the upper North Han River basin, Korea. A comparison of the stable isotopic signatures of groundwater and precipitation indicates that the precipitations which occurred during both the dry and rainy seasons are the important source of groundwater recharge in this region. A stable isotopic signature shown in the stream waters at the upstream reaches is similar to that of groundwaters, indicating that stream waters are mostly fed by groundwater discharge. Reservoir waters in the downstream flood control dams have lower deuterium excess values or d-values compared with those of the upstream waters, indicating a secondary evaporative enrichment. These results can provide a basis for the effective management of groundwater and stream water resources in the North Han River basin.  相似文献   

Limitations of real-time models for forecasting river flooding from monsoon rainfall   总被引：1，自引：0，他引：1  

Muthiah Perumal  Bhabagrahi Sahoo 《Natural Hazards》2007,42(2):415-422

Very intense rainfall during the southwest and northeast monsoons causes severe river flooding in India. Some traditional techniques used for real-time forecasting of flooding involve the relationship between effective rainfall and direct surface runoff, which simplifies the complex interactions between rainfall and runoff processes. There are, however, serious problems in deducing these variables in real time, so it is highly desirable to have a real-time flood forecasting model that would directly relate the observed discharge hydrograph to the observed rainfall. The storage routing model described by Baba and Hoshi (1997), Tanaka et al. (1997), and Baba et al. (2000), and a simplified version of this model, have been used to compute observed river discharge directly from observed hourly rainfall. This method has been used to study rainfall–runoff data of the Ajay River Basin in eastern India. Five intense rainfall events of this basin were studied. Our results showed that the Nash–Sutcliffe efficiency of discharge prediction for these five events was 98.6%, 94.3%, 86.9%, 85.6%, and 67%. The hindcast for the first two events is regarded as completely satisfactory whereas for the next two events it is deemed reasonable and for the fifth it is unsatisfactory. It seems the models will yield accurate hindcast if the rainfall is uniform over the drainage basin. When the rainfall is not uniform the performance of the model is unsatisfactory. In future this problem can, in principle, be corrected by using a weighted amount if rainfall is based upon multiple rain-gauge observations over the drainage basin. This would provide some measure of the dispersion in the rainfall. The model also seems unable to simulate flooding events with multiple peaks.  相似文献   

Early Paleozoic gabbro-granitoid associations in eastern segment of the Mongolian-Okhotsk foldbelt (Amur River basin): Age and tectonic position     

A. A. Sorokin  A. B. Kotov  E. B. Sal’nikova  N. M. Kudryashov  V. P. Kovach 《Stratigraphy and Geological Correlation》2007,15(3):241-257

Magmatic rocks of the Pikan and Un’ya massifs situated in eastern segment of the Mongolian-Okhotsk foldbelt are studied using isotopic-geochronological (U-Pb zircon dating) and geochemical methods. Two rock complexes different in age are recognized in the Pikan massif: the high-Al gabbro-tonalite association of the Middle Ordovician (468 ± Ma) and granodiorite-granite association of the Late Silurian-Early Devonian (415 ± 7 Ma). The Late Ordovician age (454 ± 5 Ma) is established for leucocratic granites of the Un’ya massif. As is suggested, the Pikan and Un’ya massifs are “allogenic blocks” detached from continental framework of the Mongolian-Okhotsk foldbelt and tectonically emplaced into the foldbelt structure at the last stage of its development.  相似文献   

闽江河口湿地资源动态变化的分形研究     

钟春棋  曾从盛  柳铮铮 《湿地科学与管理》2007,3(3):50-53

本研究以分形理论为基础,并借助GIS、RS技术,利用1986年和2002年两期TM遥感影像,提取获得了1986年和2002年闽江河口湿地资源的空间信息,根据分形理论中分形维数和稳定性指数的物理意义,揭示了闽江河口湿地资源动态变化情况。研究表明:闽江河口的湿地类型具有分形结构.并且由于受到较强的人类活动的干预,湿地斑块的形状较为复杂,且稳定性较差。  相似文献   

水盐梯度下黄河三角洲湿地植被空间分异规律的定量分析   总被引：11，自引：1，他引：11  

贺强  崔保山  赵欣胜  付华龄  熊雄  冯光海 《湿地科学》2007,5(3):208-214

三角洲湿地植被的形成和分布同时受水深、土壤含盐量两个环境因子的作用。采用模糊数学排序方法分析了黄河三角洲湿地植被在水深、土壤含盐量两个环境梯度下的空间分异规律。结果表明,由TWINSPAN划分而得到的8个植被类型在模糊数学排序图中有各自的分布范围,界线明显。以穗状狐尾藻(Myriophyllum spica-tum)等水生植物为优势种的群落分布在排序图的左上部,为黄河三角洲湿地高水深、低盐分地区;以柽柳(Tam-arix chinensis)、翅碱蓬(Suaeda heteroptera)等典型盐生植物为优势种的群落分布在排序图的右下部,为黄河三角洲的低水深、高盐分地区;其他以芦苇(Phragmites australis)、荻(Triarrhena sacchariflora)、旱柳(Salix matsudana)等为优势种的群落分布在排序图的中部。利用Gini-Simpson指数,在模糊数学排序图中分析了植物物种多样性随水深、土壤含盐量梯度的空间变化,结果表明,高水深、低盐分和低水深、高盐分地区植物物种多样性均较低,而二者过渡区域植物物种多样性较高。  相似文献   

经济合作区域的选择方法研究——以云南在泛珠三角中选择重点合作省区为例     

段七零 《云南地理环境研究》2007,19(5):12-16,20

从成功的区域合作经验看,区域间的差异性和联系性是选择经济合作区域必须考虑的两大核心因素.通过多种指标对两大因素进行测度和分析,最终正确选择合作区域.泛珠三角合作为云南经济发展提供难得机遇,云南如何立足自身优势,正确选择重点合作省区,关系到合作的最终成效.从云南与泛珠三角其他省区间的经济发展差异、产业结构差异、优劣势条件、综合距离系数以及历史联系等角度分析,提出了云南应把广东、广西、四川、香港作为重点合作省区.  相似文献   

泛珠江三角洲区域经济开放的趋势分析   总被引：1，自引：0，他引：1  

张杜鹃  陈忠暖 《热带地理》2007,27(1):35-39

通过分析泛珠江三角洲地域结构演变对区域经济开放的影响和九省区(除两个特别行政区)国际开放度、区际开放度的测算结果及排名对比,探讨了中国式区域经济开放模式及制度和转型经济下该区域经济开放的路径。即从目前测算结果来看,泛珠江三角洲区域经济二元化开放整体上依然是国际开放度大于区际开放度,然而从地缘结构演变、国际国内和区际环境以及地缘优势来看,该区域在今后长远发展趋势上将会呈现出区际开放大于国际开放的趋势。这一分析结果印证了泛珠江三角洲经济圈的建立,顺应了当今世界经济和中国经济发展之大势。  相似文献