College of Tourism and Urban-Rural Planning, Chengdu University of Technology, Chengdu 610059, China.
College of Earth Sciences, Chengdu University of Technology, Chengdu 610059, China.
Int J Environ Res Public Health. 2022 Jun 28;19(13):7909. doi: 10.3390/ijerph19137909.
The Qinghai-Tibet Plateau (QTP) is a sensor of global climate change and regional human activities, and drought monitoring will help to achieve its ecological protection and sustainable development. In order to effectively control the geospatial scale effect, we divided the study area into eight geomorphological sub-regions, and calculated the Temperature-Vegetation Drought Index (TVDI) of each geomorphological sub-region based on MODIS Normalized Difference Vegetation Index (NDVI) and Land Surface Temperature (LST) data, and synthesized the TVDI of the whole region. We employed partial and multiple correlation analyses to identify the relationship between TVDI and temperature and precipitation. The random forest model was further used to study the driving mechanism of TVDI in each geomorphological division. The results of the study were as follows: (1) From 2000 to 2019, the QTP showed a drought trend, with the most significant drought trend in the central region. The spatial pattern of TVDI changes of QTP was consistent with the gradient changes of precipitation and temperature, both showing a gradual trend from southeast to northwest. (2) There was a risk of drought in the four seasons of the QTP, and the seasonal variation of TVDI was significant, which was characterized by being relatively dry in spring and summer and relatively humid in autumn and winter. (3) Drought in the QTP was mainly driven by natural factors, supplemented by human factors. The driving effect of temperature and precipitation factors on TVDI was stable and significant, which mainly determined the spatial distribution and variation of TVDI of the QTP. Geomorphological factors led to regional intensification and local differentiation effects of drought, especially in high mountains, flat slopes, sunny slopes and other places, which had a more significant impact on TVDI. Human activities had local point-like and linear impacts, and grass-land and cultivated land that were closely related to the relatively high impacts on TVDI of human grazing and farming activities. In view of the spatial-temporal patterns of change in TVDI in the study area, it is important to strengthen the monitoring and early warning of changes in natural factors, optimize the spatial distribution of human activities, and scientifically promote ecological protection and restoration.
青藏高原（QTP）是全球气候变化和区域人类活动的传感器，干旱监测将有助于实现其生态保护和可持续发展。为了有效控制地理空间尺度效应，我们将研究区域分为八个地貌分区，根据 MODIS 归一化植被指数（NDVI）和地表温度（LST）数据计算每个地貌分区的温度-植被干旱指数（TVDI），并综合整个区域的 TVDI。我们采用偏相关和多元相关分析来确定 TVDI 与温度和降水的关系。进一步利用随机森林模型研究各地貌分区 TVDI 的驱动机制。研究结果如下：（1）2000-2019 年，青藏高原呈干旱趋势，其中中部地区干旱趋势最为显著。青藏高原 TVDI 变化的空间格局与降水和温度的梯度变化一致，均表现为自东南向西北逐渐变化。（2）青藏高原四季均存在干旱风险，TVDI 季节性变化显著，春夏季相对干燥，秋冬季相对湿润。（3）青藏高原的干旱主要受自然因素驱动，辅以人为因素。温度和降水因素对 TVDI 的驱动作用稳定且显著，主要决定了青藏高原 TVDI 的空间分布和变化。地貌因素导致干旱的区域强化和局部分化效应，特别是在高山、平坦山坡、向阳山坡等地方，对 TVDI 的影响更为显著。人为活动具有局部点状和线状影响，与人类放牧和农耕活动相对较高影响密切相关的草地和耕地对 TVDI 的影响较大。鉴于研究区域内 TVDI 的时空变化模式，加强对自然因素变化的监测和预警、优化人类活动的空间分布、科学推进生态保护和恢复至关重要。
