Investigating the Trends and Fluctations of Precipitation in the Golpayegan Saline Wetland

Changes and fluctuations of precipitation are one of the most important climate change outcomes in the world. The changes in surface water flow and hydrological cycle are directly affected. Therefore, recognition of fluctuations behavior and its governing patterns in a catchment area plays a very important role in optimal management of catchment areas. Therefore, in this research, we have tried to identify the trends of fluctuations patterns of rainfall and also the type of precipitation trend in the Golpayegan catchment area. For this purpose, daily rainfall data of precipitation stations near the Golpayegan saline wetland were used. For trend analysis, linear regression and Mann-Kendall method were used and for identify the rainfall prevailing cycles, Spectrum analysis technique was used. The results of trend analysis showed that in all studied stations, rainfall had a significant decrease. The highest trend is a significant decrease of 23 mm for the Golpayegan station. The results of spectral analysis also indicate that the short-term cycles of 2 to 5 years are in most of the studied stations. Most scientists have attributed this cycle as a result of El Niño - Southern Oscillation (ENSO) and Quasi-biennial oscillation (QBO).