Investigation and Analysis of 50-Year Trends of Rainfall Changes in Kashkan Poldokhtar basin during the Years 1969 to 2019
Elham kianisalmi
1
(
PhD student in watershed management, Faculty of Natural Resources, Lorestan University
)
Hossein Zeinivand
2
(
دانشیار گروه مهندسی آبخیزداری دانشگاه لرستان
)
Keywords: Change Trend, Seasonal Precipitation, Rainfall Station, Confidence Level, Basin,
Abstract :
Precipitation is one of the most important meteorological variables which can impact on the occurrence of flooding. Analysis of precipitation provides useful information for planning water resources in the region. In this research, an investigation of the rainfall, in Kashkan Poldokhtar basin, has been carried out using a homogeneous daily rainfall dataset of 11 rainfall stations with 50 years of observation. The linear regression analysis,, 5-year moving average, anomaly, and Mann-Kendall (MK) trend detection were used to assess the variability and trends in rainfall. The results showed no significant trend was observed in the annual rainfall amounts over the basin, but increasing trends were observed in the seasonal rainfall amounts in some stations. The seasonal rainfall trends based on MK test showed significant changes at 5% confidence level at 3 stations in the autumn, 5 stations in the spring, and 6 stations in the summer and basin in the spring and summer seasons. The mean annual rainfall of 7 stations exhibited a well linear trend. The results showed that a significant decreasing trend was observed in the Kohdasht, Khorramabad-Chamanjir, Kashkan-Poldokhtar, and Sorkhab-Keshvar (outside basin) stations. The UF(k) and UB(k) curves in all stations had intersections which indicated that the rainfall has seen an abrupt. The analysis of sudden changes in rainfall is a suitable guide for water resources management, flood control and drought investigation in Kashkan-Poldokhtar basin.