| 1. |
- Fazel, Nasim, et al.
(författare)
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Regionalization and spatial analysis of precipitation of the Urmia Lake Basin, Iran
- 2015
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Ingår i: World Environmental and Water Resources Congress 2015 : Floods, Droughts, and Ecosystems - Proceedings of the 2015 World Environmental and Water Resources Congress - Floods, Droughts, and Ecosystems - Proceedings of the 2015 World Environmental and Water Resources Congress. - Reston, VA : American Society of Civil Engineers. - 9780784479162 ; , s. 1101-1107
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Konferensbidrag (refereegranskat)abstract
- The spatial patterns of precipitation regarding physiography and atmospheric circulations in the Lake Urmia Basin have been investigated. Daily rainfall time series for the 50 most reliable precipitation stations for the period 1980-2010 were analyzed to detect the regional precipitation pattern. To identify rainfall homogeneous regions, principal component analysis was applied to the precipitation dataset. Agglomerative hierarchical clustering analysis using the Ward and Euclidean distance methods revealed three distinctive precipitation regions in the basin influenced by topography and lake. The first region (G1) covers the north and northeastern part of the Lake Urmia. G2 includes stations located in south and southeastern part of the basin, while G3 covers the western part of the lake basin. The results from this study can be used to better plan agricultural land use, cropping patterns and water management in the delineated homogeneous rainfall regions.
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| 2. |
- Fazel, Nasim, et al.
(författare)
-
Regionalization of precipitation characteristics in Iran's Lake Urmia basin
- 2018
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Ingår i: Journal of Theoretical and Applied Climatology. - : Springer Science and Business Media LLC. - 0177-798X .- 1434-4483. ; 132:1-2, s. 363-373
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Tidskriftsartikel (refereegranskat)abstract
- Lake Urmia in northwest Iran, once one of the largest hypersaline lakes in the world, has shrunk by almost 90% in area and 80% in volume during the last four decades. To improve the understanding of regional differences in water availability throughout the region and to refine the existing information on precipitation variability, this study investigated the spatial pattern of precipitation for the Lake Urmia basin. Daily rainfall time series from 122 precipitation stations with different record lengths were used to extract 15 statistical descriptors comprising 25th percentile, 75th percentile, and coefficient of variation for annual and seasonal total precipitation. Principal component analysis in association with cluster analysis identified three main homogeneous precipitation groups in the lake basin. The first sub-region (group 1) includes stations located in the center and southeast; the second sub-region (group 2) covers mostly northern and northeastern part of the basin, and the third sub-region (group 3) covers the western and southern edges of the basin. Results of principal component (PC) and clustering analyses showed that seasonal precipitation variation is the most important feature controlling the spatial pattern of precipitation in the lake basin. The 25th and 75th percentiles of winter and autumn are the most important variables controlling the spatial pattern of the first rotated principal component explaining about 32% of the total variance. Summer and spring precipitation variations are the most important variables in the second and third rotated principal components, respectively. Seasonal variation in precipitation amount and seasonality are explained by topography and influenced by the lake and westerly winds that are related to the strength of the North Atlantic Oscillation. Despite using incomplete time series with different lengths, the identified sub-regions are physically meaningful.
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