广西山区夏凉气候资源的合理开发与利用     

庞庭颐 《气象研究与应用》2001,22(1):47-51

对广西山区夏凉气候资源的开发与利用进行了分析 ,提出发展喜凉蔬菜和建立猕猴桃产业 ,是发展山区经济的好路子  相似文献   

The world''s large lake basins as denudation-accumulation systems and implications for their lifetimes     

Matthias Hinderer  Gerhard Einsele 《Journal of Paleolimnology》2001,26(4):355-372

The mechanical denudation rates of 81 large lake basins (lake area > 500 km²) were determined from long-term river loads and erosion maps. Using the drainage area/lake area ratios the mean sedimentation rates of the lakes were calculated for a porosity of 0.3. The mean sedimentation rates of different lake types vary between 0.1 mm/a (glacial lakes, lowland) and 5.4 mm/a (mostly sag basin lakes). The calculated lifetimes of the lakes are based on the lake volumes and mean sedimentation rates, assuming steady-state conditions and solely clastic material. On average, glacial lakes in highlands and fault-related lakes show the shortest lifetimes (c. 70 ka), glacial lakes in lowlands and rift lakes have the longest lifetimes (c. 1 Ma). Some lakes remain unfilled for very long time spans due to rapid subsidence of their basin floors. The calculated lifetimes are compared with those derived from sediment core studies. Most core studies indicate lower mechanical sedimentation rates than the calculated ones because a major part of the incoming sediment is trapped in deltas. However, a number of lakes (e.g., the Great Lakes of North America) show the opposite tendency which is largely caused by extensive shoreline erosion and resuspension. The lifetimes of large glacial lakes often exceed the duration of interglacials. Hence, their lifetimes are restricted by glaciation and not by sediment infill. Rift lakes persist for long time periods which exceed the calculated lifetimes in some cases. Time-dependent subsidence, basin extension, as well as the impact of climate change are briefly described.  相似文献   

西南地区山地不同土地退化类型特征及调控途径   总被引：4，自引：7，他引：4  

张建平 《地理科学》2001,21(3):236-241

土地退化不仅是目前全还需性的重大环境问题之一，而且也是重大的社会和经济问题之一，西南地区的土地退化是以水力侵蚀为主要动力形成的，文中简述了西南地区的土地退化状况，选择了4个（楚雄市、遂宁市，毕节地区及元谋县）山地不同土地退化类型进行分析，讨论了土 退化过程，提出了土地退化调控途径。  相似文献   

梵净山区格林威尔期造山带与Rodinia超大陆   总被引：7，自引：6，他引：7  

王砚耕 《贵州地质》2001,18(4):211-216

贵州梵净山区有保存完好、发育齐全的中元古代的地质记录 ,是扬子陆块晚前寒武地质研究的理想场所和重要窗口。现有地质和同位素年代学等资料表明 ,该区存在格林威尔期造山带 ,其形成时间为ca 10 0 0Ma±。它同原始江南造山带一起成为华南Rodinia超大陆的组成部分 ;对其进行探讨 ,必将促进我国Rodinia超大陆聚合、裂解及其演化的研究 ,并具有重大的科学意义。  相似文献   

祁连山北坡流域冰川物质平衡波动及其对河西水资源的影响   总被引：16，自引：27，他引：16  

沈永平  刘时银  甄丽丽  王根绪  刘光 《冰川冻土》2001,23(3):244-250

祁连山北坡各流域发育有现代冰川 2 166条 ,总面积 13 0 8km2 ,冰储量 60km3,冰川融水补给河流约 8× 10 8m3·a-1,占河西地表总径流量的 11% .近 4 0a来 ,东段石羊河流域冰川物质平衡 (Bn)呈较大负平衡 ,Bn在 - 80～ - 12 0mm间 ;西段的讨勒河、疏勒河和党河流域冰川具正物质平衡 ,Bn在+ 5 0～ + 90mm ;黑河流域的冰川处于过渡区 ,其冰川物质平衡多年平均在 - 4 0～ + 4 0mm间 .冰川物质平衡的变化直接影响着河流径流的变化 ,洪水坝河、党河和昌马河的冰川融水补给率达 3 0～ 4 0 %以上 ,东大河、大渚马河、马营河和讨勒河的补给率在 12 %～ 14 %之间 ,而西营河和梨园河仅有 7%左右 .冰川物质平衡逐年变化显示 ,2 0世纪 5 0～ 70年代冰川以负物质平衡为主 ,80年代开始向正的平衡开始转化 ,90年代以正平衡为主 ,主要是冬季气温上升引起的降雪量增加的结果 .在全球气温变暖情景下 ,东段冰川物质平衡将呈增加的趋势 ,西段冰川物质平衡将呈下降的趋势 ,将使西段以冰川融水补给的河流径流增加 ,而东段石羊河流域径流下降明显 .  相似文献   

地表复杂地区煤田地震勘探方法及效果   总被引：2，自引：6，他引：2  

徐成明  王云 《物探与化探》2001,25(6):437-442

以宁夏、山东的煤矿地震勘探为例,介绍了复杂地表工区地震勘探的方法与地质效果。  相似文献   

长白山区热量资源立体分布模式及其应用   总被引：1，自引：0，他引：1  

马树庆  袁福香 《气象》1996,22(6):15-18

采用二次趋势势面函数模拟长白山区热量资料的地理分布，用地理细网格分析方法推算山区各地的热量资源状况，并以此为基本依据，分析山区主要农作物品种的合理布局，指出不同品种在各地的适宜种植高度带，该项分析了已长白山区气候及农业资源立体开发中的发挥作用。  相似文献   

近百年来山地冰川波动与气候变化   总被引：20，自引：16，他引：20  

王宁练  张祥松 《冰川冻土》1992,14(3):241-250

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Biomonitoring past salinity changes in an athalassic subarctic lake   总被引：1，自引：0，他引：1  

R. Pienitz  I. R. Walker  B. A. Zeeb  J. P. Smol  P. R. Leavitt 《International Journal of Salt Lake Research》1992,1(2):91-123

A short sediment core was taken from a small saline lake located on an intermontane plateau in the central Yukon Territory, Canada. In July 1990, chemical analyses indicated that, although the lake was shallow (Z_max=1.1 m), it was also chemically stratified, with hyposaline (9.9 to 10.0 g L⁻¹) surface waters and slightly mesosaline (22.0 g L⁻¹) deeper waters. The surface water was dominated by Na⁺ and HCO ₃ ⁻ . To our knowledge, this is the northernmost athalassic saline lake yet recorded. Quantification of algal (diatom, chrysophyte, and pigment) and invertebrate (chironomid, ceratopogonid, andChaoborus) fossils at four stratigraphic levels indicated that the lake sediments preserved numerous biological indicators that could be used to infer recent lake development. Many of the taxa are found in other athalassic salt lakes. The most striking stratigraphic change was a remarkable drop in the species richness of diatoms and invertebrates in the recent sediments, which parallels the elimination of species characteristic of less saline conditions. Halophilous taxa dominate the most recent sediments, indicating the development of more saline conditions. At the same time, a significant shift in chrysophyte cyst composition was observed. Fossil carotenoids and chlorophylls indicated a decrease in total algal abundance in recent sediments, as green and blue-green algae replaced diatoms and chrysophytes. Together, these paleolimnological data suggest a recent shift to drier conditions or increased evaporation in the central Yukon Territory.  相似文献   

新疆昆仑山、喀喇昆仑山中泥盆世及石炭纪一些四射珊瑚     

蔡土赐 《新疆地质》1992,(1)

昆仑山西段及喀喇昆仑山,部分四射珊瑚化石,经笔者研究计有:喀喇昆仑山楚隆帕斯坦中泥盆统落石沟组含Grypophyllum kelakunlunense(sp.nov.);昆仑山西段下石炭统他龙群产Diphyphyllum kunlunense(sp.nov.)喀喇昆仑山中石炭统含Protodurhamina kelakunlunensis(sp.nov.), Lithostrotionella sp.;昆仑山西段中、上石炭统库尔浪群含Protodurhamina kunlunensis (sp.nov.), Neokoninckophyllum sp., Kionophyllum kunlunense(sp. nov.), Paracarruthersella sp., Orygmophyllum convexum Fomitchev。  相似文献