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2004-2009年黄河口近岸海域低盐区面积的变化趋势研究 总被引:1,自引:0,他引:1
近年来黄河人海淡水量显著降低,而且年内分布极其不均匀,河口区的盐度场发生了重大变化.准确了解河口近岸海域的低盐区面积及其变化趋势,对于河口生态系统的研究极为重要.本文通过对2004-2009年丰、枯水期黄河口近岸海域低盐区面积大小的分析,建立了低盐区面积与黄河径流量的关系.结果表明,2004-2009年丰、枯水期低盐区面积与月径流量均呈现较好的线性关系,增加单位平方千米盐度小于27的低盐区面积需要增加的月径流量约为0.046亿m3;若要维持紧邻河口的3号方区海域的平均盐度小于27,月径流量应保持在50亿m3以上.此外,年内黄河口近岸海域低盐区面积的较大值主要集中在6~11月份,均高于370km2,而4、5月份的低盐区面积却不足200 km2,春季生态补水刻不容缓. 相似文献
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地下水动态预测的径向基函数法 总被引:12,自引:0,他引:12
地下水系统是一个复杂的随机系统,根据地下水位与其影响因素之间存在的映射关系,建立了一个RBF人工神经网络模型,并将其用于地下水位的动态预测,实例表明,该方法预测精度较高,具有一定的推广价值。 相似文献
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中国西北干旱区水资源可持续利用对策研究 总被引:7,自引:1,他引:7
近50年来,随着水土资源开发利用规模的不断扩大,西北干旱区的工农业与经济得到了快速发展,但同时也引发了一系列的环境问题,如河流下游水量锐减,甚至断流,泉水资源衰减;地下水超采,地下水位持续下降;水质恶化;土地次生盐渍化,沙漠化严重等。文章在详细分析中国西北干旱区水资源的特征以及水资源不合理开发利用所引发的环境问题的基础上,认为实行流域水资源统一规划与管理,发展新绿洲,建立高效节水型农业是实现我国西北干旱区水资源可持续利用的根本途径。 相似文献
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Present granite landform characteristics and distribution are the integrated result of climate, tectonics and lithology. Various
types of granite landforms in China signify climate zonality and differential vertical movement of earth surface, while published
research results on Chinese granite landforms are very rare, especially in international journals. Based on the process analysis
of chemical weathering and physical disintegration, four granite landform regions in China are classified according to the
present climate regime. On the Tibetan Plateau, the cold and freezing climate induced periglacial landscapes; the northeast
region is characterized by physical disintegration and low round mounds are widespread; in the northwest region controlled
by arid climate, wind-carved minor landscapes are extremely prominent. The most spectacular granite landscapes in China are
presented in southeast as a result of longtime chemical weathering under humid and warm conditions, as well as the differential
uplift after Neogene. Correlating the weathering crust in southern China, Tibetan Plateau and India, a possible unified planation
surface in Neogene is proposed. With corestones as indicators of original weathering front, the differential uplift extent
of dissected planation surfaces can be estimated. At least three landforms implying uplift can be identified in southeastern
China, with elevations of 300–400 m, 2000 m and 3600 m above the sea level respectively. 相似文献
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赤潮预测的人工神经网络方法初步研究 总被引:13,自引:0,他引:13
赤潮是一种由多因素综合作用引发的生态异常现象,具有突发性及非线性等特点。对其进行预测预报一直是海洋科学研究的热点。探讨了应用人工神经网络原理进行赤潮预测的方法,简要介绍了BP和RBF算法的基本原理,用2种算法对不同海域赤潮生物与环境因子之间非线性和不确定性的复杂关系进行学习训练和预测检验,并与传统的统计方法进行了比较。结果表明:人工神经网络方法在模拟和预测方面优于传统的统计回归模型,具有较强的模拟预测能力及实用性,值得进一步探索。 相似文献
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环境质量评价属于多因子识别和排序问题。在实际应用中评价因子的基准往往难以确定 ,从而影响评价结果。针对此问题 ,提出了多目标模糊优选模型 ,它是分析多目标环境系统的一个较新的方法 ,在介绍该理论的基础上 ,建立了环境质量评价模型 ,并在吉林西部进行了应用 ,通过与其它评价方法的比较表明 ,该方法用于环境质量评价具有通用性、合理性和实用性 相似文献
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基于AMBI和M-AMBI指数的黄河口及邻近海域底栖生境质量评价 总被引:4,自引:3,他引:1
The protection of the biological diversity and the maintenance of the regional ecological integrity for the Huanghe (Yellow River) Estuary and its adjacent areas are practically significant and valuable. However, frequent human activities and natural climate changes have caused vigorous disturbances on the ecosystem in these sea areas. An objective assessment on the benthic habitat quality (BHQ) of the Huanghe Estuary and its adjacent areas is conducted, using AZTI's Marine Biotic Index (AMBI) and multivariate AMBI (M-AMBI) based on the data of macrobenthos in May and August 2011. The results show that both the indices do not correlate significantly, and their assessment results are greatly different. All of the samples assessed using the AMBI were "high" or "good", because the ecological group I (EGI) and the ecological group II (EGII) were dominant macrobenthic ecological groups in the research area. Owing to a low species' richness and a high individual abundance in some samples, the BHQ levels using the M-AMBI were worse than those of the AMBI. Significant correlations are observed between the M-AMBI, water depth, bottom water salinity and dissolved inorganic nitrogen, thus the M-AMBI could sensitively respond to environmental changes and distinguish influences from uninfluenced stations, but the AMBI could not. The consistent results between the AMBI and the M-AMBI mainly appeared in the uninfluenced (undisturbed or slightly disturbed) sta- tions. Therefore, the M-AMBI is more effective than the AMBI in assessing the benthic habitat quality in the Huanghe Estuary and its adjacent areas. Using the M-AMBI to assess the BHQ of the Huanghe Estuary and its adjacent areas, the results show that 3% of the stations are undisturbed and the BHQs are "high", and 61% of the stations are slightly disturbed and those of the BHQ are "good", and the rest are meanly disturbed and those of the BHQ are "moderate". 相似文献
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关于点苍山“大理冰期” 总被引:1,自引:0,他引:1
云南点苍山是大理冰期的命名地, 通过文献查询明确了大理冰期这一概念提出的过程. 基于多次的实地考察, 对云南点苍山冰川地貌进行了系统研究, 建立了该地区第四纪以来冰川活动可靠的年代序列, 明确了冰川发育的规模. 研究结果表明, 点苍山最早的冰川活动发生于30~ 40 ka BP, 之后经历了末次冰期晚阶段、晚冰期、新冰期等各次冰川前进, 直至1.2~1.5 cal ka BP 前后冰川最后消失. 空间上, 该地区的冰川活动仅局限于海拔3600 m以上的主体部分, 低海拔及其周边山体上没有冰川发育. 相似文献