جستجوی مقالات مرتبط با کلیدواژه « sealing degree » در نشریات گروه « آب و خاک »

Morphology of rivers constantly changes due to their dynamic features, and these changes can negatively affect the structures in riversides, agricultural lands, etc. Meanders are considered as important indicators of environmental change. This study examines the changes of the sealing degree and meander shapes of the Kashafroud river using 1966 aerial photography, 1987 Landsat TM sensing images, and 2013 Google Earth images. In this study, morphological parameters of 16 meanders in a range of 11 kilometers along the Kashafroud river was determined for each period. The results of the paired t mean comparison showed that changes in the sealing degree ranging from 1966 to 2013 have a significant difference at level of one percent. To determine the effects of changes in some meanders parameters on sealing degree, multivariate linear regression model was used. The results showed that in case of change in the sealing degree, meanders reduce along the river. In addition, Spearman correlation analysis showed that changes in the parameters of sealing level and meander shape are strongly interdependent, so that there is a significant correlation between changes in sealing degree and meander shape at level of one percent. With increasing degree of sealing, meander shapes convert into U and Ω shapes, and meanders tend to close. In meanders with reduced sealing degree, such as meanders number 2, 3, 11, and 12, the path will mainly change into a strait one, and a part of the river will be separated as bovine horn ponds.

The most important indicators of environmental changes are meanders. For the first times, this study was carried out investigation of sealing degree and morphology changes of meander in Karoon River using TM and ETM+ instruments images of Landsat satellite and remote sensing in 1989 and 1995. In this research, morphological parameters of 20 meanders were determined at 128 km of Karoon River in two mentioned years. The results of t student testshowed that sealing degrees have a significant difference at 1% level in years 1989 and 1995. The multiple linear regressions were used for the sealing degree changes and some meander parameters changes. The modeling results showed that the meander length (L) have reduces, if sealing degree changed. Also, the results of Spearman correlation showed that sealing degree and meander shape correlated strongly. Therefore, there are significant correlations between changes of sealing degree and meander shape in the level of 1 percent. By increasing the sealing degree, the meander shape changed to U and Ω shapes and meander tended to be closed.