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Daily precipitation data for 1957-2009 from 53 stations in the Xinjiang, China, are analyzed, based on the Standardized Precipitation Index (SPI) with the aim to investigate spatio-temporal patterns of droughts. The Mann-Kendall trend test is used to detect the trends in the SPI values of monthly drought series, drought severity and drought duration. The frequencies of moderate, severe and extreme droughts are higher in the North Xinjiang, while mild droughts occur more often in the South Xinjiang. A decreasing frequency of droughts in the North Xinjiang is found in winter, but a drying tendency is detected in the western parts of the North Xinjiang during spring, summer and autumn, which may be harmful for agriculture. The South Xinjiang seems to be getting wetter in summer, while the south parts of the South Xinjiang seem to be getting drier in spring. The middle of the East Xinjiang is identified to be in a slightly dry tendency. The drought severity is decreasing and drought duration is getting shorter in the North Xinjiang, while both of them increase in the southern parts of the South Xinjiang. In addition, droughts in the middle parts of the East Xinjiang are intensifying. [ABSTRACT FROM AUTHOR]

Using daily precipitation data spanning 1960-2005 from 51 meteorological stations in Xinjiang province, China, spatial and temporal changes in consecutive maximum wet days in the year, summer, and winter were investigated. Fifteen precipitation extreme indices, which reflect the attributes of consecutive maximum wet days, were defined, and the modified Mann-Kendall test was applied to detect the tendencies, and changes in the indices were evaluated through linear regression with the F test. Results showed that: (1) two consecutive wet days occurred most frequently in the year and summer, and the fractional contributions and precipitation intensities decreased as the duration increased; in winter, one wet day had the maximum possibility, fractional contributions decreased and intensities increased as the duration increased. (2) The possibility of consecutive wet days which had short durations reduced, while those of long durations increased; annual fractional contributions of short durations decreased, while those of long durations increased; summer and winter fractional contribution of all durations decreased first and then increased; the intensities of all durations increased. (3) The wet tendency was identified in Xinjiang; the wet trend in Southern Xinjiang was more significant than Northern Xinjiang in summer, while in winter the wet tendency in Northern Xinjiang was more pronounced. [ABSTRACT FROM AUTHOR]

Summary: The characteristics of hydro-climatic changes in the Tarim River Basin were analysed based on data collected at 39 weather stations and 29hydrological stations for the period 1961–2008 and 1952–2008, respectively. A non-parametric trend test on basin scale for annual data shows an increasing trend of precipitation, relative humidity, vapour pressure, and the aridity index since 1986. Surface temperature started increasing in 1996. A decreasing trend of sunshine started in 1990. The potential evapotranspiration (ET) is calculated by the Penman–Monteith equation, and points out decreasing trend of potential evapotranspiration since 1985. This negative trend can also be detected for wind speed in both the same time scale and spatial extent. The stations with significant increasing trends in annual streamflow are mainly distributed at the southern slope of Tianshan Mountain, which can only be explained by climatic changes. The detected negative runoff trend of the main stream of the Tarim River can be explained by anthropogenic activities (such as irrigation and domestic water use) and climatic changes. A quantitative assessment reveals that local human activities since the 1970s led to a decrease of the water volume diverted into the main stream of the Tarim River Basin, which has been aggravated in the 2000s. [ABSTRACT FROM AUTHOR]

• The CSM-CROPGRO-Cotton model was modified for drip irrigation under plastic film mulch. • The calculation of potential evapotranspiration, extinction coefficients and soil evaporation were improved. • The genetic coefficients of cotton were determined using data from different irrigation treatments. • The modified model well simulated cotton growth and soil water content under film-mulched drip irrigation. Cotton is one of the major cash crops in Xinjiang, an arid region in northwestern China. Most cotton fields in this region are drip irrigated with plastic film mulch. However, few studies have tested the performance of the DSSAT (Decision Support System for Agrotechnology Transfer) model on cotton under film-mulched drip irrigation. The objective of this study is to evaluate the performance of the modified CSM-CROPGRO-Cotton model and determine the genetic coefficients of cotton using data from different irrigation treatments conducted at the irrigation experiment station in Bayingol Mongolian Autonomous Prefecture, Korla, China. Based on the selected genetic coefficients, the model was calibrated using field experiment datasets in 2016 and validated using datasets in 2015. The simulation results of soil water content, leaf area index, phenological period and cotton yield were compared with their corresponding measurements. Absolute relative error (ARE) of seeding emergence date, flowing date, maturity date and cotton yield simulated by the original model were 5.8%, 7.3%, 5.0% and 70.6%, respectively, while those of the modified model were 1.7%, 1.1%, 1.1% and 0.1%, respectively. Simulated leaf area index agreed well with the field observations with the coefficient of determination (R2) > 0.739, the index of agreement (d) > 0.910 and the root mean square error (RMSE) < 0.965. Simulated soil water content in the 20–40 cm soil layer were generally consistent with the measured values with R2 = 0.724, d = 0.639 and RMSE = 0.087 cm3/cm3, while the simulated soil water content in the 40–60 cm was slightly worse than the observations with R2 = 0.708, d = 0.519 and RMSE = 0.109 cm3/cm3. Overall, the modified CSM-CROPGRO-Cotton model can be used as a practical tool to simulate the cotton growth under film-mulched drip irrigation in this region. Potential opportunities for the model improvement in cotton growth include the influence of various scenarios such as soil types, climates and irrigation strategies. [ABSTRACT FROM AUTHOR]

Summary: This study aims to study joint probabilities and changing characteristics of precipitation extremes, as well as the implications of these changes in Xinjiang. Daily rainfall data from 53 stations across Xinjiang, China, covering a period of 1957–2009 were collected. Using eight precipitation indices, probabilistic characteristics of precipitation extremes were analyzed based on Copulas. The K–S method was employed to select appropriate marginal probability distributions for determining quantiles, and the Akaike Information Criterion (AIC) was used to select copulas. Results indicate the following: (1) North Xinjiang is wetter than south Xinjiang; (2) More concurrent strong and weak precipitation extremes are observed in the areas along Tianshan Mountains, and in eastern parts of the Xinjiang than those in western parts of the Xinjiang; (3) After 1980, the Xinjiang region is exhibiting a wetting tendency, and the heavy precipitation extremes tend to occur more severely and frequently; and also the possibilities of concurrent strong and weak precipitation extremes altered in a distinct pattern; (4) Tianshan Mountains can be taken as the demarcation for the occurrences of floods and droughts and the risk of droughts and floods across the Xinjiang region is expected to increase. [Copyright &y& Elsevier]

Biochar application has been a promising approach to improve soil quality but their optimal amount in improving physical and hydraulic properties remains contradictory and inconclusive. The objective of this study was to examine and propose an optimal biochar application amount in saline alkali soil considering their impact on soil physical and hydraulic properties. A three-year field experiment was conducted in the saline-alkali soils under plastic film-mulched drip irrigation in Xinjiang, China. The studied physical and hydraulic properties included bulk density, soil porosity, saturated soil water content (θ s ), permanent wilting point (PWP), field capacity (FC), plant available water (PAW), spatial distribution of soil water content, planar soil water storage (PSWS), and soil evaporation. The treatments included biochar application amounts of 0 (CK), 10 (B10), 50 (B50), and 100 t ha -1 (B100) in 2018. Additional two treatments with 25 t ha -1 (B25) and 30 t ha -1 (B30) were added in 2019 and 2020, respectively. A four-parameter Gaussian function was fitted to the single-peak curves of the studied hydraulic properties vs. biochar application amounts to determine the most optimal biochar application amount. The results indicated that: (1) All of the biochar treatments significantly decreased bulk density and increased soil porosity over CK; (2) B10 and B25 treatments significantly increased θ s , FC, PAW, PWP, and PSWS of root zones in the film-mulched zones over CK, but reverse results were observed in the B50 and B100 treatments; (3) Daily and cumulative soil evaporation were increased in no mulch zones of all biochar treatments over CK; (4) A dose of 21.9 t ha -1 was recommended as the most optimal biochar application amount for improving physical and hydraulic properties of saline-alkali soil. This research provided useful information on biochar application amounts for improving physical and hydraulic properties in saline-alkali soil., Competing Interests: Declaration of competing interest We declare that we do not have any commercial or associative interest that represents a conflict of interest in connection with the work submitted., (Copyright © 2021 Elsevier B.V. All rights reserved.)