塔里木盆地风沙灾害强度和频次的时空分布特征

Sandstorm is a common meteorological disaster that causes serious damage to agricultural production and animal husbandry in the Tarim Basin, Xinjiang, China. Based on the disaster data acquired from the 1028 wind-sand disasters that occurred in 42 counties (cities) in the Tarim Basin from 1990 to 2019, six factors were selected as major disaster elements, namely, death toll, number of collapsed houses, collapsed shed circles, damaged sheds, livestock deaths, and affected areas. The disaster damage index could be integrated to express the intensity of disaster events using the method of ratio scale weighting and the dimensionless approach of linear combination. The intensity of disaster events was quantitatively divided into four levels using the percentile method: general (level 1), heavy (level 2), large (level 3), and extremely large (level 4). The temporal and spatial distribution characteristics of wind-sand disasters in the basin were analyzed in terms of the frequency of occurrence and the disaster damage index. Results showed that the wind-sand disaster hit the basin with the highest frequency and intensity in spring, especially in April and May. The frequency and intensity in the north Tarim Basin were obviously higher than those in other areas in the basin, making it the most frequently and hardest hit area of wind-sand disasters. During 1990-2019, the annual frequency of occurrence of wind-sand disasters in the basin considerably increased linearly, but the intensity fluctuated around the climatic average. The annual occurrence and intensity of wind- sand disaster in level 1 also showed a considerable linear increase, whereas level 2- 4 varied around the climatic average. The established Loulan index, which is defined as the pressure difference between the east and west parts of the basin, could explain the dynamic mechanism of long-term changes in the frequency of occurrence of wind-sand disasters in the basin based on dynamic climatology. As this index increased during 1990-2019, the occurrence of an average wind speed of more than 6.0 m·s⁻¹ per hour in the basin from April to May increased per year. The scale of the basin oasis gradually expanded, resulting in the yearly increasing occurrence of wind-sand disaster in the basin. Thus, this study could provide a scientific basis for the prevention of wind-sand disasters in the Tarim Basin.