Mann-Kendall检验不需要样本遵循一定的分布，也不受少数异常值的干扰，用来分析降水、径流、气温和水质等要素时间序列趋势变化(The Mann-Kendall test does not require samples to follow a certain distribution and is not disturbed by a small number of outliers. It can be used to analyze the trend of time series of elements such as precipitation, runoff, temperature and water quality)