珠江口盆地深部基底地层的地震时深转换研究

盆地深部基底的地震解释需要时深尺.而钻遇基底的探井通常很少且仅揭示基底顶部,致使常规VSP时深转换曲线难以达到基底研究所涉及的深度.为此本文提出深部下延段校正的VSP时深转换方法,即用深井和钻遇基底井VSP数据与深反射地震、双船折射地震和重磁数据在深部下延段选取控制点的时深数据,重新拟合时深转换的二次多项式,使其可用于深部地震解释.将珠江口盆地分为深水区(>300 m)和浅水区(<300 m)分别进行水深修正时深拟合.用克里金法对两区同一基准面的等深线进行插值,最终完成全区的时深转换,并藉此编制出全区基底顶面埋深图.     

On new species and records of Hydroidomedusae from the Changjiang River Estuary and its adjacent waters

1 IntroductionSamples of medusae collected from 37 stationsof the Changjiang River Estuary ( 28°0. 00′~32°19.60′N,121°6.52′~124°0.00′E) during14 ~16 June 2003,Altogether,164 qualitative andquantitative samples of the plankton are analyzed,and 49 s     

21世纪黄河下游防洪减灾对策

黄河是受人类活动强烈影响的河流,随着人类活动对流域环境的影响日趋增强,进入黄河下游的水沙条件发生了重大改变,防洪出现了许多新情况、新问题。黄河水资源进一步开发利用,下游牵断流及小水时间逐年延长,黄河将无有效输沙水量,如果来沙不能控制,现行河道的行洪能力和寿命将始终是中国的忧患。小浪底水库２００１年投入运用后,对黄河下游又将强烈堆积。２１世纪社会经济发展对黄河下游防洪减灾提出了更高要求,根据多年对黄     

祁连山区黑河流域季节冻土时空变化研究

季节冻土的时空变化对地—气水热交换、地表能量平衡、地表水文过程、生态系统及碳循环等有着非常重要的影响.利用黑河流域11个气象站40多年的气温数据和5 cm深度处的土壤温度数据,建立了月平均气温与土壤冻结天数之间的关系.同时应用月平均气温与冻结天数的相关关系和5 km网格化月平均气温及30 m分辨率的DEM数据,编制了黑河流域逐月季节冻土分布图,并按其空间分布特征,将逐月地表冻融状态划分为:完全冻结、不完全冻结和不冻结3种.系统研究了黑河流域2000-2009年逐月季节冻土分布及冻结概率的时空变化特征.在季节分配上,黑河流域完全冻结面积最大值出现在1月;不完全冻结面积最大值在11月;而不冻结面积最大值在6月和7月.在年际变化上,完全冻结状态的离差值在冷季变化大,暖季变化小;不完全冻结状态在一年的回暖期和降温初期,年际变化较大;不冻结状态分别在4月和10月变化较大.冻结概率在1月达到最大值,6月和7月降低到最小值.在空间分布上,黑河流域季节冻土的逐月分布与变化和冻结概率主要受海拔高度控制,纬度的影响次之.     

黄河三角洲地区地下淡水(微咸水)的形成与演化

黄河三角洲地区地下淡水(微咸水)资源贫乏,咸水广布.南部冲洪积平原受第二次海侵层位的影响形成大面积咸水,后又被逐渐淡化.近年来由于开采量加大,又使北部咸水南侵.海积冲积平原随着黄河河道的变迁,仅在黄河现行河道两侧和充水的黄河故道带分布有淡水(微咸水).近代、现代黄河三角洲古河道带和决口扇淡水体已被咸化.     

Multidecadal trend analysis of hydrological drought along River Niger using the Streamflow Drought Index

Droughts affect human well-being and the economy of countries across the world. Understanding the long-term evolution of droughts within a particular region will help in drought mitigation and adaptation plans, thereby reducing drought impact on the environment. This study examined the multidecadal trends in hydrological droughts at two stations along River Niger using 3-month, 6-month, and annual time scales. Hydrological drought events were identified using the streamflow drought index (SDI) between 1915 and 1990 based on the Theil-Sen slope and Mann-Kendall approaches. Across the timescales, extreme and severe droughts occurred in 1982/84 and 1983/84 with -2 ≤ S_d < -1.5. On an annual scale, the results from the annual SDI further showed that the 7th and 8th decades (1971−1990) recorded more drought events of varying degrees ranging from mild to extreme drought in both stations than in other decades. The last two decades (7th and 8th) further revealed the most extended hydrological drought duration from 1974/75 to 1988/89 for Baro and from 1979/80 to 1988/89 for Lokoja. The highest severity recorded at Baro was -15.56 and -14.26 at Lokoja. The prolonged duration of drought events across the stations and their associated yearly intensities suggests that more proactive measures are needed to ameliorate the hydrological drought impact in the study area.     

Navigating the evolution of marine policy in Panama: Current policies and community responses in the Pearl Islands and Bocas del Toro Archipelagos of Panama

Recent changes in marine policy in Panama are closely related to sustained expansion of the Panamanian economy in the past ten years. Important drivers of economic growth such as the Panama Canal expansion, tourism, and real estate development directly involve marine and coastal areas. Therefore, maintaining the quality of these environments, as well as the sustainability of the human communities that depend on them, calls for the implementation of adequate management and planning policies. In light of a complex history of marine and coastal policy in Panama, current institutional restructuring processes, and a growing recognition of the importance of marine and coastal geographies, the authors aim to document the current status of, and community response to, marine and coastal policy in Panama, analyzed in terms of three important cross-cutting sectors: tourism, fishing, and conservation. To do so, the authors introduce two case studies: one in the Pearl Islands Archipelago and one in Bocas del Toro, each with varying degrees of participation or involvement in each sector, to illustrate the range of adaptations to change occurring in coastal communities. Based on an in-depth policy analysis and the case studies, the authors suggest that there are important administrative and structural gaps in the legislation and institutions that enforce them, as well as a lack of integration across institutions. In particular, the authors highlight the lack of clear marine and coastal property regimes as an obstacle to the implementation of integrative marine policies in Panama.     

太原市饮用水源地水质评价研究

运用层次分析法对汾河流域静乐县断面、岚县断面及娄烦县断面的水体质量进行评价,并确定水质优劣顺序,为优先污染控制以及水环境决策提供科学依据。评价结果为岚县断面监测水质较好,娄烦县断面次之,静乐县断面监测水质较差。在水质较差的断面应加大环保投入,加强水质管理,从根本上改善流域水质现状。     

技术创新对黄河流域城市绿色发展的影响研究

创新是推动黄河流域高质量发展的重要途径之一。利用2006—2018年黄河流域79个地级以上城市的面板数据,首先构建指标体系对各城市技术创新及绿色发展水平进行分析,其次通过面板计量模型深入探究技术创新对城市绿色发展的作用机理。研究表明：① 2006—2018年,黄河流域城市技术创新与绿色发展水平均得到明显提升,但空间差异显著,总体呈“下游>中游>上游”阶梯式递减特征。② 黄河流域城市技术创新对绿色发展总体上没有显著影响,但在加入技术创新的二次项后,两者之间呈现显著的“U”型非线性关系,即技术创新先抑制后促进城市绿色发展,这也验证了技术的“回弹效应”假说;③ 技术创新对黄河流域城市绿色发展的影响可以通过直接效应和间接效应共同体现,但这两种效应正好相反,即一个城市技术创新能力的提升对该城市绿色发展存在显著的“U”型（先抑制后促进）关系,但对邻近城市的作用呈现倒“U”型相反的关系。根据研究结论,从技术创新对城市绿色发展的直接效应和间接效应2个方面提出了相应的政策建议。