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Accueil du site → Doctorat → Iran → Study the Role of Geomorphologic Parameters in Distribution of Vegetation in Arsbaran Catchments (Case Study : Naposhtecay, Ilghinehcay and Mardanqumcay)

University of Mohaghegh Ardabili (2018)

Study the Role of Geomorphologic Parameters in Distribution of Vegetation in Arsbaran Catchments (Case Study : Naposhtecay, Ilghinehcay and Mardanqumcay)

Gharachorlu, Mortaza

Titre : Study the Role of Geomorphologic Parameters in Distribution of Vegetation in Arsbaran Catchments (Case Study : Naposhtecay, Ilghinehcay and Mardanqumcay)

بررسی نقش پارامترهای ژئومورفولوژی در پراکنش پوشش گیاهی حوضه های آبخیز ارسباران (مطالعه موردی : ناپشته چای، ایلگینه چای و مردانقم چای)

Auteur : Gharachorlu, Mortaza

Université de soutenance : University of Mohaghegh Ardabili

Grade : Doctor 2018

Résumé
The purpose of this study was to investigate the spatial relationship between geomorphologic parameters and vegetation cover in Arasbaran catchments (three catchments of Naposhtehchay, Ilginehchay and Mardanqumchay) located in the north of East Azarbaijan Province, Iran. Library references such as base maps and satellite (Landsat and SRTM) imageries formed bulk of the resources used. The present study was based on the pixel-wise geomorphometric approach and used multivariate spatial regression analysis to identify and explain the relationships between geomorphology and vegetation cover. Preliminary results of the regression analysis between 27 geomorphologic parameters (independent variables) and NDVI (dependent variable) showed that many of independent variables had significant relations with dependent variable and 8 parameters including valley depth, topography position index, elevation, slope, slope position, transformed aspect, earth surface convexity and general curvature played more important role in the spatial distribution of vegetation. The strongest and weakest regression models were observed in Mardanqumchay catchment with 0/32 R2 value and Naposhtehcay catchment with 0/11 R2 value, respectively. Results of the regression analysis at sub-catchment scale indicated that there were considerable differences among sub-catchments and between catchments and sub-catchments in terms of the strength of spatial relationships. Maximum coefficients of determination (R2) were equal to 0.42, 0.51 and 0.62, and the minima of them were equal to 0.08, 0.15 and 0.13 in sub-catchments of Naposhtehchay, Ilginehchay and Mardanqumchay, respectively, which showed these differences. Results of the second part of the research indicated good performance of logistic regression model for predicting the occurrence of forest cover loss in relation to geomorphic parameters. The modeling showed that the highest probability of forest cover loss was related to low altitudes, valleys and around of rivers, convex and divergent (of flow) surfaces, the south and west aspects, steep slopes and streams with low power. Results of the final section of the study indicated that there is a significant relationships between the geomorphic parameters and the vegetation cover in terms of spatial homogeneity, so that the strongest and weakest relations were observed in Ilginehchay catchment (R2 equal to 0.21) and Naposhtehchay catchment (R2equal to 0.16), respectively. The results of this study revealed the necessity to pay attention to geomorphometry parameters in order to spatial analysis and modeling of vegetation cover, especially in subcathment scale. Moreover, in view of the decline in forest cover, there is a need for a greater protection and support for forest cover in large valleys and downstream sections.

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Page publiée le 19 avril 2020