فصلنامه پژوهش های فرسایش محیطی
سال پنجم شماره 4 (پیاپی 20، زمستان 1394)

Today, soil erosion is considered as one of main subjects of watershed management at national and global levels. Assessment of decreasing risk of soil and it spatial distribution are one of key factors for successful evaluation of soil erosion. The objectives of research were calculation and modeling of rain erosivity factor in Ilam province using data of number of 28 pluviometry stations during of 23 years period. After that, rain erosivity factor was calculated, map of rain erosivity factor was provided using geostatistical algorithms. Spatial correlation between data of rain erosivity was drawn using Variogram. In order to, studying of erosivity index were used (IDW), (GPI), (RBF), (LPI) and kriging. The best algorithm was selected using statistical indices of Root Mean Square Error (RMSE) and MAE. Results showed that, GPI was the best algorithm with RMSE and MAE equal to 28.93 and 20.95, respectively.

The first step to controlling soil loss, is estimating of soil erosion amount. Universal soil loss Equation is One of the ways is widely used to estimate erosion, in which the absence of long term data. Effective force in the development of various forms of erosion is the power erosivity of runoff and rainfall and are expressed in erosivity index. This study aimed to evaluate the erosivity Index of soil loss equation and its versions that storm-scale. Run-off and sediment from 20 Storm in experimental plots occurred in three consecutive years (length 20 m, width 2 m and pasture) Sanganeh soil conservation site in semi-arid regions of Khorasan Mashhad as reagents for analysis of was used erosivity index values were calculated using. The results indicate that erosion index of USLEM model with correlation 0.608 for the prediction of storm-scale erosion is most suitable index. The two characteristics of runoff coefficient (r =0.691 and p

Change in land use pattern influenced hydrological processes in basin and disrupt the normal balance of water flow. In the present research, hydrological parameters change of Babul Rod watershed basin has been that investigated concluded of land use changes in 1988 and 2009. To determine land use changes of Babul Rod watershed basin we has recruited TM satellite images 1988(1367) year and ETM 2009(1388) year with factor of spatial resolution of 30 meters that using stratified classification classified into four types: urban, land of combined(urban, garden and garden spaces), agriculture-horticulture and bare land. According to the classification, forest and combined lands(agriculture, garden) of Babul Rod basin have encountered with area reduce and pasture and urban lands use have encountered with increase area. The HEC-HMS model is used for investigating the impact of land use changes of Babul Rod on hydrology cycle and factors quantify of hydrology Balance of the investigating watershed basin and analyzing relationship. The results of this model has shown clearly: reducing the precipitation losses, increasing elevation and runoff coefficient, increasing maximum rate of flow and increasing medium rate of flow, the impact of Babul Rod river morphologic changes and land use of its territory on flood factors.

In arid and semiarid region, dust happened frequently. Including, result of adverse effects the occurrence of dust is on agricultural production, soil and water pollution, diseases of the respiratory and environmental issues, social challenges, a sharp reduction in horizontal visibility and traffic accidents resulting from its. In this research, changes in the number dust occurrence on the moon, season and years studied (2004-2010) were analyzed. After calculating the number of dust per year, dust zoning done with using kriging in software ArcGIS. The results indicate that Sarakhs and Ghochan respectively had maximum and minimum dust occurrence in year. Also may and spring maximum number occurrence dust in over months and seasons of the year. The result of zoning showed that we move from center and north to the borders of the number of dust is added. The results also indicate those years of 2008 and 2005 respectively highest and lowest number of dust were in the province.

The Imam Khomeini sugarcane agro-industry is one of ten sugarcane agro-industry plantations in Khuzestan province. As regard as the drains has been installed in this plantation many years ago so there is water and salt balance in this land that is one of the condition for implementation controlled drainage. This research was designed to investigate the possibility of using a controlled drainage system and its effect on soil salinity, sodium absorption ratio, pH and Cl- ions in three farms by three treatments. The first treatment conventional drainage, second and third treatment controlled drainage with water table controls set at 70 and 90 centimeter. Results showed that controlled drainage system does not have negative impact on soil salinity and sodium adsorption ratio. Average soil salinity In the FD, CD90 and CD70 was respectively 3, 2.16 and 2.50ds/m at the depth of 0-60cm in the beginning of period and was 1.6, 2.09 and 1.89ds/m at the end of period. Average sodium absorption ratio In the FD, CD90 and CD70 was respectively 3.68, 4.14 and 3.20 at the depth of 0-60cm in the beginning of period and was 2.71, 4.64 and 2.85 at the end of period. In the all treatment Soil pH was not significantly different between beginning and end of period. Variation in soil pH was negligible in all treatments during study period. The amount of Cl-ion in soil solution had a decreasing trend from the beginning to the end of period in conventional drainage and controlled drainage treatments.

Recognition of growth pattern and folding mechanism in the fold-thrust belts with hydrocarbon resources is important in exploration and development planning of oilfields. As the processes of tectonics, erosion, and geomorphology impact on each other, therefore, the investigation of a process, one can obtain information about the other process. In this research the tectonic process of transverse growth of fold, was investigated based on the erosion pattern of the streams on the fold limb and geomorphological and hydrological indices in the Khaviz oilfield which is located in the Dezful Embayment. The results of investigation of the erosion pattern of the streams and the indices showed that the fold growth pattern in this oilfield in the south limb is limb lengthening through the toe and in the north limb is lengthening through the crest and toe.