宁夏地区2000-2014年土地荒漠化遥感监测及驱动因子分析

发布时间：2018-08-26 09:55

【摘要】：土地荒漠化主要发生在生态脆弱的干旱半干旱地区,宁夏自治区是荒漠化较为严重的区域,近年来由于自然环境的改善、国家政策的实施,宁夏荒漠的面积逐渐减小,但荒漠化的状况依然严重。本研究利用遥感技术从像元尺度上对宁夏生长季植被覆盖和植被降水利用率(RUE)的变化特征和驱动因子进行系统分析,详细阐述了宁夏荒漠化的发生过程和原因,并针对荒漠化发生的驱动因子对宁夏荒漠化治理提出合理的建议,对宁夏生态环境的修复具有一定的参考价值。本研究利用了MOD13Q1数据、DEM数据和土地利用分类图等空间数据,以及气象数据和社会统计数据等非空间数据,在Matlab和ArcGIS等软件的支持下,通过空间趋势分析、重心迁移模型以及灰色关联度分析等方法开展了土地荒漠化现状评价。文章监测了2000-2014年植被覆盖退化的情况,尝试利用植被降水利用率作为荒漠化监测的主要指标,分析了宁夏近15年荒漠化的状况,并在此基础上定量分析了地形因素、植被类型、气象因素和社会经济因素对荒漠化的影响。主要研究成果如下:(1)根据宁夏1980-2014年的气象数据,分析了宁夏近35年气候变化特征,近35年宁夏气温主要呈上升趋势;降水量南部减小、中部平稳、北部增加;日照时数呈减小的趋势;相对湿度除中部上升外,南北部有减小的趋势。而2000-2014年平均气温上升的区域主要分布在宁夏北部,占总面积63.4%;降水量在中部和南部呈上升趋势;而日照时数全区均有下降趋势,且在南部地区尤为显著;平均相对湿度南增北减。从突变时间看,宁夏不同分区不同气象因子的突变时间存在很大的差异,南部的突变时间普遍落后于北部。(2)基于生长季累积归一化植被指数(NDVI)的值,分析了宁夏2000-2014年植被覆盖的动态变化,宁夏南部地区和引黄灌溉区的植被覆盖较高,中部沙化严重,植被覆盖较低。近15年宁夏植被覆盖主要呈改善的趋势,该区域占宁夏总面积的91.45%,植被退化的面积仅占5.79%,主要分布在灌溉区中心和贺兰山。通过对NDVI的持续性进行分析,表明植被覆盖未来将持续改善。植被覆盖的重心迁移路线表明,低植被覆盖逐渐向宁夏北部迁移,较高植被覆盖有向中部扩张的趋势。(3)根据生长季累积NDVI和降水量,计算得到植被降水利用率,通过分析RUE的变化趋势,对宁夏2000-2014年土地荒漠化的动态进行评价。以2000年为基准数据,2000-2014年发生荒漠化的区域占总面积的7.79%,主要位于贺兰山、六盘山、银川中部、青铜峡以及中宁县部分地区,其中部分地区植被也发生了退化。2005、2010和2014年发生荒漠化的区域分别占总面积的15.82%、11.61%和7.79%,因此宁夏荒漠化的比例正在逐渐减小,且荒漠化的重心有向北部迁移的趋势。宁夏荒漠化受高程和坡度的影响明显,均表现为随高程和坡度的增加,荒漠化发生比例先减小后增大的规律。(4)通过对宁夏植被动态与荒漠化的驱动因子进行分析,发现植被NDVI、植被降水利用率与各影响因子的相关性存在较大的差异性,尤其体现在降水量和相对湿度两个气象因子上,植被NDVI与降水量和相对湿度主要呈正相关,而植被降水利用率与降水量和相对湿度主要呈负相关。根据灰色关联度综合分析结果,发现植被覆盖的变化主要受气象因子的影响,且平均相对湿度、日照时数和平均气温是植被退化的主导因素;植被降水利用率的变化同时受气象因子和人为因子的影响,日照时数、平均气温、相对湿度、人口数以及畜牧业均是荒漠化发生的主要影响因素。
[Abstract]:Land desertification mainly occurs in arid and semi-arid areas with fragile ecology. Ningxia Autonomous Region is a serious area of desertification. In recent years, due to the improvement of natural environment and the implementation of national policies, the area of desertification in Ningxia has gradually decreased, but the situation of desertification is still serious. The change characteristics and driving factors of vegetation cover and vegetation precipitation use efficiency (RUE) in growing season were systematically analyzed. The occurrence process and causes of desertification in Ningxia were elaborated in detail. The reasonable suggestions for desertification control in Ningxia were put forward according to the driving factors of desertification occurrence, which had certain reference value for the restoration of ecological environment in Ningxia. In this study, MOD13Q1 data, DEM data, land use classification map and other spatial data, as well as meteorological data and social statistical data and other non-spatial data were used. With the support of MATlab and ArcGIS software, land desertification status was evaluated by spatial trend analysis, gravity center transfer model and grey relational analysis. In this paper, the degradation of vegetation cover from 2000 to 2014 is monitored, and the utilization rate of vegetation precipitation is used as the main index of desertification monitoring. The desertification situation in Ningxia in recent 15 years is analyzed. On this basis, the influence of topographic factors, vegetation types, meteorological factors and socio-economic factors on desertification is quantitatively analyzed. The following: (1) According to the meteorological data of Ningxia from 1980 to 2014, the climate change characteristics of Ningxia in the past 35 years were analyzed. The temperature of Ningxia in the past 35 years showed an upward trend; the precipitation in the South decreased, the central region was stable, and the northern region increased; the sunshine hours decreased; the relative humidity in the north and South decreased except the central region. The rising area mainly distributes in the north of Ningxia, accounting for 63.4% of the total area; the precipitation shows an upward trend in the middle and south of Ningxia; the sunshine hours all have a downward trend, especially in the south; the average relative humidity increases in the South and decreases in the north. (2) Based on the cumulative normalized vegetation index (NDVI) of the growing season, the dynamic changes of vegetation cover in Ningxia from 2000 to 2014 were analyzed. The vegetation cover in southern Ningxia and irrigation area of diversion from the Yellow River were higher, the desertification in central Ningxia was serious, and the vegetation cover was lower. The analysis of NDVI shows that the vegetation coverage will continue to improve in the future. The gravity migration route of vegetation coverage shows that the low vegetation coverage gradually migrates to the north of Ningxia, and the higher vegetation coverage has a direction. (3) According to the cumulative NDVI and precipitation in the growing season, the utilization rate of vegetation precipitation was calculated, and the dynamic of land desertification in Ningxia from 2000 to 2014 was evaluated by analyzing the changing trend of RUE. Based on the data of 2000, the area of desertification occurred in 2000-2014 accounted for 7.79% of the total area, mainly located in Helan Mountain and Liupan Mountain. In 2005, 2010 and 2014, desertification areas accounted for 15.82%, 11.61% and 7.79% of the total area, respectively. Therefore, the proportion of desertification in Ningxia is gradually decreasing, and the center of desertification tends to move northward. The influence of elevation and slope is obvious, which shows that the proportion of desertification decreases first and then increases with the increase of elevation and slope. (4) Through the analysis of the driving factors of vegetation dynamics and desertification in Ningxia, it is found that the correlation between vegetation NDVI, vegetation precipitation utilization rate and various influencing factors is quite different, especially in the aspects of vegetation dynamics and desertification. On the two meteorological factors of precipitation and relative humidity, NDVI of vegetation was positively correlated with precipitation and relative humidity, while the utilization ratio of vegetation precipitation was negatively correlated with precipitation and relative humidity. Hours and average temperature are the dominant factors of vegetation degradation, and the change of vegetation precipitation utilization rate is affected by both meteorological and human factors. Sunshine hours, average temperature, relative humidity, population and animal husbandry are the main factors of desertification.
【学位授予单位】：江苏师范大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：P237;P941.73

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