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Abu Muhammad Shajaat Ali 《地球科学进展》2006,21(2):183-191
在实地采访、地块土地利用/覆盖调查和1 260个土样的收集和实验室分析等野外工作的基础上,对比分析了1984—1985年和2003—2004年265个家户的人口、农业系统、土地利用和土壤质量数据,研究了孟加拉国6个村庄农业诱导强度增强对土地和土壤质量的影响。1984—2004年家户和土质数据的百分比变化用来构建诱导强度增强模型和土地退化模型中的统计变量和土地退化指标。结果表明:研究区种植强度和土地生产力的增加主要是由于低压泵灌溉的普及,化肥和杀虫剂的使用以及水稻、蔬菜和虾生产的多元化高产。诱导强度增强模型可以解释研究区81%的种植强度增量和73%的土地生产力增量。人口压力和市场驱动也诱发了农业利用强度的增加;环境约束起到了一定制约作用;低压泵灌溉等应对干旱的技术也对农业增产有一定贡献。然而动力耕作机、低压泵灌溉和化学物质的持续利用再加上除草性水稻、蔬菜和虾的频繁耕作和养殖已经导致土壤结构、质地和化学属性的退化,生产力也有所降低。利用强度越大的土地退化现象越严重,生产力下降得也更多。土地的不断退化将有可能会引发孟加拉国的马尔萨斯危机。 相似文献
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孟加拉国位于南亚次大陆东北部,是传统的农业国,耕地面积占全国面积的54.86%,林地占10.05%,水域占9.6%,城市面积占0.1%。孟加拉国土地所有权形式高度不平衡,占有面积大于3公顷的5%的农户拥有26%的土地,占有面积小于1.5公顷的70%的农户只占有29%的土地。孟加拉国管理土地的政府部门是土地部。任何单位或政府机构要得到土地必须通过土地部的批准。自1950年以来,土地部在不同的时期采用了不同的名称。土地部的目标和目的就是管理和处理国家拥有的土地、沙石地、土地财产和废弃的土地财产。征收土地开发税、土地测量与记录保存和更新土地记录是该部的另一项重要任务。土地征用同样也是该部的重要任务。因此,该部是孟加拉国负责土地管理和开发的政府机构。 相似文献
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There are several well-established methods for obtaining beach profiles, and more accurate and precise high-tech methods are emerging. Traditional low-cost methods requiring minimal user skill or training are still popular among professionals, scientists, and coastal zone management practitioners. Simple methods are being developed with a primary focus on sand and gravel beaches. This paper describes a simple, low-cost, manual field method for measuring profiles of beaches, which is particularly suitable for muddy shores. The equipment is a type of flexible U-tube manometer that uses liquid columns in vertical tubes to measure differences in elevation; the supporting frame is constructed from wooden poles with base disks, which hold measuring scales and a PVC tube. The structure was trialed on a mudflat characterized by a 20~0-cm-thick surface layer of silt and clay, located at the Kutubdia Island, Bangladesh. The study results are discussed with notes on the method's applicability, advantages and limitations, and several optional modifications for different scenarios for routine profiling of muddy shores. The equipment can be used by one person or two people, and the accuracy of the method is comparable to those in other methods. The equipment can also be used on sandy or gravel beaches. 相似文献
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The Kushiyara and Monu rivers are two of the major river systems in the northeast region of Bangladesh. Analyzing satellite images of the Kushiyara and Monu rivers between 1990 and 1997, it was found that significant changes occurred at five distinct locations; i.e., Ahmadpur, Monumukh, Raysrr, Kaprangibari and Telibil. The amount of change was measured as 168.34 ha by using a plani-meter. Transportation of sediment was the major contributing factor of morphological change. The total average sediment concentration of Kushiyara and Monu rivers was found to be 16889.6 ppm per year during the study period by applying the Engelund and Hansen equation approach. Protection work has been suggested at the vulnerable locations. 相似文献
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达卡,是孟加拉国首都,达卡专区首府,坐落于恒河三角洲布里甘加河北岸,是孟加拉国最大的城市,也是南亚主要城市之一,其都会区有1200多万人口。达卡,旧称贾罕吉尔纳加尔,1608年由莫卧儿帝国孟加拉地区总督苏贝达·伊斯兰汗建立。在17世纪,达卡是世界性的穆斯林贸易中心。然而,达卡的现代城市建设主要始于19世纪英国殖民时期,并迅速成为仅次于加尔各答的孟加拉第二大城市。 相似文献
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