Assessment of hydrological regime alteration in the Naoli River since the 1950s

The temporal variability of daily runoff from 1956 to 2005 in Baoqing station, which is located in the upper reaches of Naoli River, had been analyzed in the present study. The Mann-Kendall statistical test was applied to assess the changes of the hydrological features in the station and the jump of trends was 1966. Therefore, the runoff records of Baoqing station was divided into two stages namely the period of more natural or less altered flow conditions (1956-1966) and the period of more altered conditions (1967-2005). Then, the Rang of Variability Approach (RVA) proposed by Richer was used to analyze the hydrological situation changes in the upper watershed of Naoli River. The results showed that the human events have tremendously changed the hydrological regime of the upstream of Naoli River and the ecological environment has been destructed to a certain extent. In the future, the mankind´s activities in the watershed should be decreased opportunely.