فهرست مطالب a.a. shamsipour

Desertification is a serious ecological, environmental, and socio-economic threat to the world, and there is an urgent need to develop rational methods for its evaluation at different spatio-temporal scales. This study aimed to address the main directions of desertification changes in Semnan County, Iran. Monthly precipitation was used to calculate a 12-month SPI (Standardized Precipitation Index) and the normalized difference vegetation index (NDVI) obtained by LandsatThematicMapper (TM) sensor of April month were used for the three years, viz., 1987, 1998, and 2011. Five major categories were identified at level-I and they were subdivided into 11 categories including, 1. Residential areas, 2. Vegetation, 3. Bare and rocky areas, 4. Salt lands and 5. Sand areas. The results indicated that the reduction of the NDVI values was consistent with the changes in land use/land cover. This progress was taken place in some areas with the development of bare soil to salt land, and in some areas with the expansion of sand land, particularly from 1987 to 1998. The results indicated that the salt lands increased 348.24 and 721.57 square kilometers from 1987 to 1998 and from 1998 to 2011, respectively. The results revealed that desertification occurred at a rapid rate, especially towards the east and southeast directions in the study area. That was, towards the Dasht-e-Kavir and Damghan City. The results showed that besides using NDVI and SPI for drought monitoring, the meteorological variables such as temperature, sunshine hours and evaporation could improve the accuracy of interpretation of the results.

One of the most important inheritances of climate quaternary is glacier geomorphology evidence in Iran. Identifying and demarcation of glacial landforms in highlands are the best evidences to recognize morphoclimatic and morphodynamic territories. The study aimed to determine the morphoclimatic and morphodynamic zones in the last glacier period and current boundaries in the Jajroud basin, and compare results with previous theories. Hence, by using satellite imageries, topographic maps, GIS geology software and field observations, the locations of cirques were identified and then by using Peltier method morphoclimatic and morphodynamic boundaries in quaternary, were determined. Method and data used in this study were mainly obtained from topographic maps, geology, satellite images, climate data temperature and monthly precipitation. Results show that low level of glacier areas already existed at height of 5220 meter, and levels of solifluction, pluvial and pediment are at 4000 meter height, fluvial at, 3400 meter, and pediment at 1565 meter respectively. Also in the last glacier period, the lowest level of glacial was respectively at 3900 meter, Solifluction at 3000 meter, and fluvial at 2000 meter. The results show that morphodynamic and morphoclimatic levels were higher than former results attained by "Alborz Mountain researches".