三种气象干旱指数在青海省东部农业区的适用性分析

发布时间：2018-11-13 16:03

【摘要】：干旱问题是一个全球性的问题,它是世界上影响范围广,持续时间长,造成危害大,出现频率高的对人类社会影响最严的自然灾害之一。干旱导致供水资源匮乏,危害作物生长,使作物产量减少,并且影响着居民生活,工业生产及其他社会活动。青海省地处内陆腹地,青藏高原北部,它是世界上面积最大、高度最高、地形最复杂的高原,暖湿气团不易入侵,大部分地区处于干旱、半干旱带,对农牧业影响很大。干旱指数的研究可以对干旱发生过程进行量化。而干旱指标种类繁多并且对不同的地区适应性也各不相同,故此本文选取降水距平百分率,标准化降水指数,综合气象干旱指数做青海省东部农业区的适应性分析,选出适宜西北干旱区的干旱指标对提高预警预报精度,为防灾减灾提供参考和科学规划的依据,提高水资源可持续利用和管理水平有重要意义。本文利用青海省东部农业区1960-2006年的气象资料,对降水量进行EOF分解、M-K趋势检验法,分析降水在研究区的年际和年内变化;计算选取的三种干旱指标,通过对比干旱特征,与实际干旱情况进行核对得出了适宜的干旱指数,并以此分析研究区干旱时空分布规律。得出以下结论:(1)研究区1960-2006年年降水量自1972年发生突变,呈现增长的态势,并一直持续的到2002年,但这种增长的趋势不明显,所以47年年降水总体趋势变化不明显。空间分布上,年降水EOF第一模态方差贡献率为70.57%,第一模态呈整体变化趋势一致,中部变化大,南北两部变化相对较小;年内降水主要集中在5-9月,占全年降水的84%,且年内5月与其他11个月份的降水变化趋势相反,降水变化大的月份有7月、8月以及9月。(2)在春季和夏季干旱过程中,季尺度的SPI和Pa变化趋势比较一致,季平均CInew在某些年份的变化趋势与其他两个指标不同,会出现一些小的波动。CInew指数可以对干旱进行逐日监测,能够探测到干旱的发生和发展,但是由于前期90d的降水和蒸散量的影响而在月尺度和日尺度下表现不是很好,存在误差,并且旱情偏重,需要在前期90d的降水和蒸散量的权重问题上重新考量。MI指数则在重旱能很好的表现,在其他旱情下表现一般。SPI则是在旱情轻的地方表现较好而在旱情严重表现一般。Pa指数能较好地表现旱情的情况和发展,并且在与实际旱情对比上,Pa指数稳定地保持着较高的准确率。(3)春夏两季干旱变化趋势越大的地方,旱灾发生越频繁;春季以重旱、轻旱为主要旱情,乐都、民和、循化、尖扎、黄南地区易发生严重干旱;夏季以轻旱为主要旱情,贵德、乐都、循化、黄南、大通易发生干旱。春季旱情呈持续好转,直到2001年旱情开始恶化,而夏季旱情则呈持续恶化的状况。
[Abstract]:Drought is a global problem. It is one of the most severe natural disasters which has the most severe impact on human society. Drought leads to a shortage of water resources, endangers crop growth, reduces crop yields, and affects people's lives, industrial production and other social activities. Qinghai Province is located in the inland hinterland and the northern part of the Qinghai-Tibet Plateau. It is the largest highland with the highest height and the most complicated topography in the world. The warm and wet air mass is not easy to invade and most areas are in arid and semi-arid zone which has great influence on agriculture and animal husbandry. The study of drought index can quantify the process of drought occurrence. There are many kinds of drought indexes and the adaptability to different regions is different. Therefore, this paper selects the percentage of precipitation anomaly, standardized precipitation index and comprehensive meteorological drought index to analyze the adaptability of the eastern agricultural region of Qinghai Province. The selection of drought indexes suitable for arid areas in northwest China is of great significance to improve the precision of early warning and forecast, to provide reference for disaster prevention and mitigation, and to improve the level of sustainable utilization and management of water resources. Based on the meteorological data from 1960 to 2006 in the eastern agricultural region of Qinghai Province, the precipitation was decomposed by EOF and M-K trend test method was used to analyze the interannual and annual variation of precipitation in the study area. By comparing the drought characteristics with the actual drought conditions, the suitable drought index is obtained, and the spatial and temporal distribution of drought in the study area is analyzed. The main conclusions are as follows: (1) the annual precipitation of 1960-2006 in the study area changed from 1972 to 2002, and continued to increase until 2002, but the trend of this increase is not obvious, so the general trend of precipitation in 47 years is not obvious. In the spatial distribution, the contribution rate of the first mode variance of the annual precipitation EOF is 70.57, the first mode is the same as the whole change trend, the change of the middle part is big, the change of the two parts of north and south is relatively small; The precipitation during the year was mainly concentrated in May and September, accounting for 84% of the total precipitation in the whole year, and the trend of precipitation variation in May of this year was opposite to that in the other 11 months. (2) during the drought in spring and summer, the variation trend of SPI and Pa in seasonal scale is the same, and the variation trend of seasonal average CInew in some years is different from that of other two indexes. There will be some small fluctuations. The CInew index can monitor the drought day by day, and can detect the occurrence and development of drought, but because of the effect of precipitation and evapotranspiration in the early 90 days, it is not very good at the monthly and daily scales. There are errors, and the drought is heavy, so we need to reconsider the weight of precipitation and evapotranspiration in the early 90 days. The MI index can perform well in severe drought. In other drought conditions, SPI is better in areas with mild drought and generally in severe drought. The Pa index can better show the situation and development of drought, and compare with actual drought. The Pa index keeps a high accuracy steadily. (3) the greater the trend of drought in spring and summer, the more frequent drought occurs; The main drought in spring is heavy drought, light drought, Ledu, Minhe, Xunhua, Jianzha, Huangnan area prone to severe drought; summer with light drought as the main drought situation, Guide, Ledu, Xunhua, Huangnan, Datong prone to drought. The drought in spring continued to improve until the drought began to deteriorate in 2001 and the drought in summer continued to deteriorate.
【学位授予单位】：西北农林科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：S423

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