Determining the Distribution Pattern of Spatial Correlation of Flood Occurrence in Ardabil Province Using Moran's Index in GIS
Amirhosein Ghorbani
1
(
MSc. Student of Survey Engineering- Geographic Information Systems, Lamei Gorgani Institute of Higher Education, Gorgan, Iran
)
Mohsen Zabihi
2
(
Ph.D., Department of Watershed Management Engineering, Faculty of Natural Resources, Tarbiat Modares University, Tehran, Iran
)
Raoof Mostafazadeh
3
(
Associate Professor, Department of Watershed Management and Member of Water Management Research Institute, University of Mohaghegh Ardabili, Ardabil, Iran
)
Keywords: Clustering, Flood intensity, Moran', s statistic, Spatial distribution pattern, Spatial information system,
Abstract :
Mapping the patterns of spatial distribution and determining the trend of spatial changes in environmental data is very important. In this regard, the current research is planned with the aim of determining the spatial correlation and occurrence pattern of the instantaneous maximum discharge data in Ardabil province in different return periods using Moran's index. The flood discharge values were calculated using CumFreq software at different river gauge stations in 5, 10, 25 and 50 years return periods. Spatial correlation was calculated through the Global Moran's I index, and then the cluster occurrence pattern of floods was determined using Anselin Local Moran I index. Based on the results, the values of Global Moran's I index have been calculated as 0.168, 0.201, 0.268, 0.115 in 5, 10, 25, and 50 years return periods, respectively. The least spatial correlation was observed in the 50-year return period and the highest spatial correlation was observed in the 25-year return period. A high-high (HH) cluster pattern was observed in Gilandeh and Pol-Almas stations. On the other hand, some river gauge stations of the Sablan mountain range and the northeastern area of Ardabil province had not significant z-statistic values, which means there is no cluster pattern in the data of the mentioned stations with the neighboring stations. As a concluding remark, it can be said that the difference in the clustering pattern of instantaneous maximum discharge is related to different climatic conditions, topography and the difference in the causes of flooding in the watersheds.