多年变化 meaning in English
secular variation
Examples
- From the change of the analysis target of the water and the sediments in these years , we can see that these measures that take place in these years only make a little improvement on the degradation problem . these measures cannot change the trend of wetland ecosystem degradation
根据对玄武湖水体和沉积物的监测指标的多年变化分析发现，玄武湖近年来所采取的整治措施对于湿地的污染退化问题只起了短暂的改善作用，无法扭转整个湿地生态系统退化的趋势。 - The precipitation frequencies is analysed according to 1956 ~ 2000 years of rainfall record series in baoding area . the features of distribution of rainfall are detailed evaluated . firstly , the distribution of monthly precipitation is not even . for instance . the annual rainfall amount is about 548mm in whole year , about 80 % of them in summer season . secondly , yearly variation of rainfall is greater . thirdly , the abundant years usually are followed by short years , but the important changes have taken place in the last decades . before 70 ' s the abundant years took the dominant position , from the 70 ' s to the middle of 80 ' s the short years took place more frequently than ever . after the later of 80 ' s , the short years hold the main position . the above knowledge is instructive for guiding the rainwater resources effective utilization
本文利用1956 2000年保定市的长系列降雨资料，对保定市降水量进行了频率分析、年内变化分析和多年变化分析，明确了保定市降水量年内、年际间的变化情况：保定市降水量年内分配不均，汛期( 6 - 9月)占年降水量的81 。保定市降水量年际间变化大，丰水年和枯水年交替发生， 70年代以前以丰水年段为主； 70年代到80年代前期降水量丰枯交替频繁，总的接近于枯水年段； 80年代后期至今以枯水年段为主。这种降水分布规律对农业生产雨水资源的高效利用具有重要的指导意义。 - Through measuring slope forms on the spot , serried sampling , physical and chemical analyzing , and measuring soil erosion from natural and artificial rainfalls , the project researched in the approaches and behaviors of soil erosion affecting contents of soil carbon and nutrient , and the law of soil carbon and nutrient distributing in micro - topographty under influences of soil erosion . in the same time , supported by geographic information system , models of soil carbon and nutrient changing with soil erosion have been built , and spatial processes of soil erosion affecting soil carbon and nutrient have been simulated , and annual and long - term changing of soil carbon and nutrient under impact of soil erosion have been estimated and forecasted , and synchronously , a elementary assessment for different soil erosion management has b een performed by using the models built in the study
本研究以三峡库区秭归县水田坝乡王家桥小流域四个径流试验区二十个标准小区为研究对象，通过坡形实地测量、坡面密集采样的颗粒分析和养分含量分析以及人工模拟降雨实验，研究了土壤侵蚀对土壤碳和养分的影响途径和表现，侵蚀作用影响下土壤碳和养分在微地形空间的分布规律；同时，在地理信息系统的支持下，建立了侵蚀条件下的土壤碳和养分变化模型，模拟了侵蚀对土壤碳和养分影响的空间过程，预测了侵蚀影响下土壤碳和养分的年变化及多年变化，并通过研究建立的模型对不同侵蚀控制措施进行了初步的效益评价。 - Thirdly , present status of effect of erosion on soil carbon and nutrient has been illustrated in spatial scale of the watershed . based on geographic information system , actuality and process of soil erosion in and between land units were simulated , and actuality and process of annual and long term changing of soil carbon and nutrient in each land unit under erosion were sufficiently calculated and illustrated . results of simulation and illustration showed that , the relative area in which soil carbon , nitrogen , phosphorus and potassium is deceased is 44 . 1 % , 55 . 8 % , 39 . 2 % and 75 . 7 % respectively
三、在流域空间范围内描述了侵蚀影响土壤碳和养分的现状：在地理信息系统的支持下，模拟了流域各地块的侵蚀过程、现状，充分描述了各个地块在侵蚀影响下土壤碳和养分的年变化现状、过程及多年变化过程，得到在现有侵蚀及耕作管理条件下，全流域中土壤碳、全氮、全磷、全钾下降的地块面积分别占流域总面积的44 . 1 、 55 . 8 、 39 . 2 、 75 . 7 ，以及各个地块的碳和养分含量变化趋势，弥补了前人研究在地域华中农业大学2001届硕士研究生学位论文空间联系上的不足。