基于MODIS数据的中亚地区旱情监测及影响因素分析

    Monitoring drought situation and analyzing influencing factors in Central Asia using MODIS data

    • 摘要: 在全球变暖的背景下,及时准确地进行干旱监测对保障区域生态安全、对"新丝绸之路经济带"沿线各国的经济发展以及农业生产具有重要的指导意义。近年来,世界各地自然灾害频繁发生,中亚地区的干旱问题已成为全球生态环境变化中最显著的问题之一,阻碍了中亚及周边国家社会经济的长期、稳定发展。该研究基于2001-2020年的MODIS地表温度(Land Surface Temperature,LST)和归一化植被指数(Normalized Difference Vegetation Index,NDVI)数据建立了温度植被干旱指数(Temperature Vegetation Dryness Index,TVDI)模型,利用趋势分析、MK趋势检验、地理探测器等方法揭示了中亚地区近20 a的干旱时空变化及特征、干旱演变规律并探讨了不同因素(气温、年均降雨量、土地利用类型、人口密度、高程、坡度、坡向)对TVDI的影响。结果表明:1)中亚干旱区TVDI空间分布具有明显的区域特征,呈现出自西南向东北递减趋势,其中66%面积呈干旱显著加剧趋势(P<0.05),34%的面积呈干旱显著减弱趋势(P<0.05),呈现"北部变干、南部变湿"空间变化趋势。其中,哈萨克斯坦的西北部一带旱情加剧显著;2)从旱情年际变化趋势可知,近20 a中亚地区生长季干旱程度略呈加剧趋势,2012年为干旱最严重的年份。TVDI空间分布差异显著,整体呈季节性变化,其干旱等级表现为:夏季>春季>秋季;3)单因子探测结果显示,气温和高程是驱动研究区干旱化形成的主要影响因素,多因子交互作用下,气温和高程、气温和坡度、气温和土地利用、气温与降雨量这4对组合贡献最大。随着全球气候变化、人类活动(植被破环、城市化建设、开垦耕地、过度放牧、工业污染等)持续加剧,近20 a来中亚地区气温逐渐上升,降雨量的减少,导致植被退化,进而导致生态环境恶化、干旱化趋势加剧。该研究可为当地政府及相关部门的旱灾防控提供参考和提升中国应对中亚生态风险及地缘安全影响的能力具有重要意义。

       

      Abstract: Abstract: Drought has become a global concern, and timely and accurate drought monitoring has an important guiding significance for the regional ecological security, economic development, and agricultural production of countries along the "New Silk Road Economic Belt" in the context of global warming. Since natural disasters have occurred frequently around the world in recent years, the drought has also posed a great threat to the global ecological environment, particularly to the long-term social and economic development of Central Asia and the surrounding countries. In this study, a Temperature Vegetation Dryness Index (TVDI) model was established using the MODIS Land Surface Temperature (LST) and Normalized Difference Vegetation Index (NDVI) in Central Asia from 2001 to 2020. Based on trend analysis, MK test, and geographic detectors, the spatial and temporal variations, of drought and drought changing patterns in Central Asia in the last 20 years, the drought evolution pattern and the influence of different factors (temperature, mean annual precipitation, land use type, population density, DEM, slope, aspect) on TVDI were also investigated. The results show that: 1) There was an obvious regional pattern in the spatial distribution of TVDI in the study area, which were mainly characterized by regional and local droughts. The frequency and degree of droughts in the southwestern part of Central Asia are than those in the northeastern part, with a decreasing trend from the southwest to the northeast. For all the study area, 66% of the area showed a significantly increasing trend of drought (P<0.05), whereas, 34% of the area showed a significant decreasing trend of drought (P<0.05), indicating a pattern of "dry in the north and wet in the south". Overall, Central Asia shows an increasing trend of aridity, with the most severest drought in the northwestern part of Kazakhstan. 2) The degree annual of drought slightly increased over the past 20 years, with the severest drought occurred in 2012. There was a significantly different spatial distribution of TVDI, which with a clear seasonal change. The drought degree was ranked as follows: summer>spring>autumn. 3) The single-factor detection results showed that the contribution of the influencing factors to drought was ranked as follows: temperature > DEM > slope > precipitation > land use type, with the controlling factors of temperature and DEM for the drought (all q values were greater than 0.45). The multi-factor analysis showed the two-factor enhancement and non-linear enhancement, with t major contribution from the four combinations, e.g., - temperature and DEM, temperature and slope, temperature and land use, and temperature and precipitation. Under the background of global climate warming and increasing human activities (vegetation deterioration, urbanization and construction, cultivation, overgrazing, industrial pollution, etc.), the air temperature gradually increased and the precipitation decreased in Central Asia over the past 20 years. These changes led to vegetation degradation, which in turn resulted in ecological degradation and increased drought degrees. This finding can provide a scientific reference for the decision-making on the drought prevention and control, particularly for the ecological risks and geo-security impacts.

       

    /

    返回文章
    返回