Detecting Abrupt Change of Streamflow Atlintong Station of Wei River

According to abrupt diagnosis of runoff, two methods, that is, moving approximate entropy and moving permutation entropy, areused to analyse the abrupt year of the daily river runoff from 1961 to 2006 at Lintong station of Wei River in Loess Plateau. Therunoff series are divided into 4 stages.With the analysis of hydrological characters of different stages, we find that there are abruptchanges at the three years 1972, 1983, and 2002.Theresult shows thatmoving approximate entropy and moving permutation entropymethods are useful tools for abrupt diagnosis of runoff.The attribution of abrupt change at the Lintong runoff series is primarilydue to the reduced precipitation, increased water conservancy project, increased water consumption of industry and agriculture,significantly decreased groundwater table, and increased evaporation.