Combined use of GIS and experimental functions for the morphometric study of glacial cirques, Zardkuh Mountain, Iran

Morphometric analysis using DEM (with 10 m spatial resolution) is performed on the main cirque-like features in the Zardkuh Mountain (central Zagros Mountain Range, IRAN) to study the evolution patterns of these features. For this purpose, the cirque like-features were delimitated manually and their headwall and floor boundaries were modified based on the slope map (10 m spatial resolution) classified based on the definition of cirque. The power law functions were fitted to 58 longitudinal cross-sections of the cirque-like features and their parameters were analyzed. The analysis showed that high values of b coefficient have good correlation with the cirque-like features which their morphometric characteristics are generally coincide with the definitions of cirques and location of the small glaciers. All the cirque-like features were classified based on results of the power function model and comparison of longitudinal profiles of the cirque like-features with the Vilborg and Evans classification system. At least 9 cirques with the classical characteristics were distinguished in the altitudes above 3650 m a.s.l. of Zardkuh Mountain (mean values of b coefficient (b¯) is equal to 2.1). In addition, 19 cirques were classified as “Well-defined” (10 cirques with b¯ ≥ 2.0) and “Definite cirques” (9 cirques with b¯ ≥ 1.7). The other cirque-like features (30 cirques with b¯ ≥ 1.4) were considered as “Poor” and “Marginal” cirques. In addition, the morphometric parameters of 28 cirques (with most glacial characteristics) and their allometric behaviors were analyzed. The allometric coefficients of length and width are above 1.0 and for depth is significantly below 1.0 (or vertical development of the cirques increases slower than that of length and width) in accordance with similar research.