Effects of Runoff and Sediment from Upland Catchment on Mangrove Forests Area (Case Study: Gabric-Hormozgan)

The aim of this research is exploring the impact of changes in runoff and sediment of the upstream catchment on the changes in the area and amount of canopy in Gabric-Jask mangrove. Hence, hydro-climatological parameters including amount of precipitation, discharge, and sediment in Gabric catchment during the statistical period of 1993 to 2010 were selected and the annual standardized index related to each parameter respectively including SRI, SPI, and SSI were calculated. Also, satellite images of Landsat of TM and ETM+ sensors were used in order to explore the changes in the canopy by the use of NDVI and the area was prepared and its calculations were done. Cross correlation function and moving average of 3, 5, and 7 years were used to explore the relation between hydro-climatologic factors and the area and canopy of mangrove. Based on the results related to the canopy changes there was two increasing periods and one decreasing period and the area changes had an increasing trend during the study statistical period. Results of exploring the relation between incoming precipitation, discharge, and sediment to the mangrove forests show that NDVI changes and the area of mangrove forests have a significant relationship with three years moving average of SPI, SRI, and SSI indices with the correlation coefficients of 0.6, 0.8, and 0.56, respectively. Finally, results showed an increase in the rate of NDVI index with an amount of 0.33 and an increase in the area of Gabric-Jask mangrove forests with an amount of 0.22 ha/year.