Abstract:

Changes in meteorological elements have a highly important impact to the ecological environment of the mining area, especially in the cold and arid region of the Qinghai-Tibet Plateau, China. A comprehensive and systematic understanding of characteristics of historical meteorological changes plays a guiding role in the ecological environment protection for alpine mining areas. In this study, trends of precipitation, air temperature, and evaporation were comprehensively analyzed by linear tendency estimation, the ensemble empirical mode decomposition (EEMD), and Morlet wavelet analysis using monthly data from 1956 to 2022 in the Da Qaidam mining area of the Qinghai-Tibet Plateau. The normalized difference vegetation index (INDV) was extracted from three phases of Landsat satellite images with a spatial resolution of 30 m. Results showed that the climate in the study area developed towards warming and humidification with a slightly increasing trend of precipitation, a significantly trend of temperature, and a markedly decreasing trend of evaporation. No abrupt changes points were detected for precipitation and temperature, but a sudden change in evaporation existed in 1979. Evaporation increased slowly from 1956 to 1979, and decreased slowly from 1979 to 2022. Precipitation had a significant 12-month oscillation period from 2000 to 2016, while temperature and evaporation had a 12-month oscillation period throughout the entire study period. INDV data indicated that vegetation was mostly concentrated near the water bodies, and the coverage expanded and the growth activity enhanced over time in the entire study area. It is predicted that precipitation and temperature would continuously increase and annual evaporation would be in a relatively small period. The vegetation growth activity would be strengthened for next few years in the Da Qaidam mining area.

Key words: high-cold mining area, meteorological elements, EEMD, Morlet wavelet function, precipitation, air temperature, evaporation