The Long-Period Variation Characteristics of Water Discharge with Estuarine Sluice and Climate Change in a Small Watershed:A Case Study in Yancheng Coast

Discharge fluxes into the ocean are an important component of material and energy cycle in estuarine and coastal areas. They are also the primary controlling factor of morphological and environmental evolution. Based on statistical analysis of rainfall and runoff of tidal rivers with sluices at Yancheng coast from 1957 to 2012, the authors studied features of multi-scale changes in runoff affected by tidal sluices using M-K trend test and wavelet analysis, etc. Results of the present study have great implications for estuarine and coastal management under the influence of climate change and sea level rise. It is found that runoff into the ocean decreases at a rate of 3×10⁶ m³ (10 a)^-1, seasonal and decadal variability in runoff are obvious, and statistical characteristics of runoff differ greatly before and after 1965. Runoff variation displays a multi-scale feature, and the primary period is 23.38 a. Runoff and rainfall demonstrate alternating "high-low" and "wet-dry" conditions respectively at different scales. In addition, ENSO events and sluices at estuaries could affect the inter-annual, inter-decadal and seasonal variability of runoff. Runoff estimation and evaluation of runoff changes should be conducted in the future with consideration of climate and land surface changes.