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Scientific understanding of regional wind speed variation characteristics and driving mechanisms is of great practical significance to the management and rational utilization of wind energy resources, ecological protection and governance, and sustainable development of agriculture. Taking the Shiyang River Basin in inland river basin of monsoon marginal zone as the study area, this paper analyzed wind speed changes and influencing factors at different time and space scales. The results showed that, first of all, the annual average wind speed showed a downward trend as a whole in Shiyang River Basin, and the change of spring wind speed and the decreasing frequency of daily max-wind speed above Grade 5 were the main contributors. The turning point of annual average wind speed was consistent with that in spring and autumn (1981) and earlier than that in winter and summer (1982). Secondly, as far as the wind speed change tendency rate is concerned, before the turning point, Yongchang area had the largest decline rate with obvious “2000 m effect”, while after the turning point, Wuwei Basin had the largest rise rate with obvious “basin effect”. Focusing on the downstream desert oasis region, the sand-driving wind speed showed a decreasing trend as a whole, and showed a “cliff-like” decline after 1988. The rising trend of sand-driving wind speed after 2014 will pose greater challenges to ecological governance. Finally, under the background of unbalanced global warming, the wind speed changes in different periods were driven by the circulation system changes. In 1970–1981, the decline of the wind speed was the result of the combined action of Arctic Oscillation and Asia Polar Vortex. However, after 1981, it was affected by North Atlantic Oscillation, Asian Meridional Circulation, Tibet Plateau Circulation, India-Burma Trough, Western Pacific Subtropical High and Northern Hemisphere Subtropical High.

Adjusting the agricultural planting structure is one of the important means to realize agricultural water-saving, especially in inland river basin with droughts and water shortages. In this paper, taking Shiyang River Basin in Northwest arid inland river basin as an example, on the basis of determining the crop water production function, a multi-objective optimization model was constructed, which comprehensively considered the maximization of economic benefits, the green water utilization rate and ecological benefits. The optimized planting structure was obtained by using GAMS (General Algebraic Modeling System) model solver. The results showed that: after optimization, the sown areas of wheat, tubers, vegetables and cotton all increased, of which the sown area of tubers increased the most by 8.81×104ha. The sown areas of corn, oil-bearing crops and fruits all decreased, of which the sown area of corn decreased the most by 8.03×104ha. The optimization results of planting structure were different in different counties and districts. The average contribution rate of planting structure adjustment to total water saving was 75.24%, indicating that planting structure adjustment was the key to water-saving. The water consumption of the same crop was different in different counties. Oil-bearing crops and vegetables were more suitable for planting in the lower reaches, while corn and tubers were more suitable for planting in the middle reaches.

The increase in the frequency and intensity of extreme weather events around the world has led to the frequent occurrence of global disasters, which have had serious impacts on the society, economic and ecological environment, especially fragile arid areas. Based on the daily maximum temperature and daily minimum temperature data of four meteorological stations in Shiyang River Basin (SRB) from 1960 to 2015, the spatio-temporal variation characteristics of extreme temperature indices were analyzed by means of univariate linear regression analysis, Mann&ndash, Kendall test and correlation analysis. The results showed that the extreme temperatures warming indices and the minimum of daily maximum temperature (TXn) and the minimum of daily minimum temperature (TNn) of cold indices showed an increasing trend from 1960 to 2016, especially since the 1990s, where the growth rate was fast and the response to global warming was sensitive. Except TXn and TNn, other cold indices showed a decreasing trend, especially Diurnal temperature (DTR) range, which decreased rapidly, indicating that the increasing speed of daily min-temperature were greater than of daily max-temperature in SRB. In space, the change tendency rate of the warm index basically showed an obvious altitude gradient effect that decreased with the altitude, which was consistent with Frost day (FD0) and Cool nights (TN10p) in the cold index, while Ice days (ID0) and Cool days (TX10p) are opposite. The mutation of the cold indices occurred earlier than the warm indices, illustrating that the cold indices in SRB were more sensitive to global warming. The change in extreme temperatures that would have a significant impact on the vegetation and glacier permafrost in the basin was the result of the combined function of different atmospheric circulation systems, which included the Arctic polar vortex, Western Pacific subtropical high and Qinghai-tibet Plateau circulation.