Statistical tests for monotonic trend in seasonal (eg monthly) hydrologic time series are commonly confounded by some of the following problems: nonnormal data, missing values, seasonality, censoring and serial dependence. An extension of the Mann-Kendall test for trend (designed for such data) is presented here. Because the test is based entirely on tanks, it is robust against nonnormality and censoring.-from Authors
Additional publication details
A nonparametric trend test for seasonal data with serial dependence.