ayoub moradi; Ali Nakafinejad; Majid Ownagh; Choghi Bairam Komaki; mehrangiz foladi mansouri
Abstract
Indiscriminate land utilization methods, forest and rangeland degradation, land abandonment and development of residential areas contribute to the changes in flow intensity, erosion rate and sedimentation. Therefore, having knowledge on the effect of land use changes on discharge flow and sediment yield ...
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Indiscriminate land utilization methods, forest and rangeland degradation, land abandonment and development of residential areas contribute to the changes in flow intensity, erosion rate and sedimentation. Therefore, having knowledge on the effect of land use changes on discharge flow and sediment yield has been found necessary. The present research aims at investigating the effects of these factors by means of the semi-distributed Soil and Water Assessment Tool (SWAT) in Galikesh watershed, Golestan province (as a tributary of the River Gorganroud), in an area covering approximately 39000 hectares. This model was used in a 27-year period for simulation, calibration, validation and optimization of the parameters affecting flow and sediment yield. Land-use maps were prepared form the Landsat imageries dated 1987, 2000 and 2013. The SUFI2 model was used for model calibration and validation. Nash-Sutcliffe (NS) index was used as the objective function during model calibration (1990-2007) for the simulation of discharge and suspended load, which resulted in 0.63 and 0.61 that could be interpreted as satisfactory compared to the standards set in previous research. To evaluate the effect of land use changes on runoff and sediment yield, all model inputs, other than land use, were assumed constant. The results demonstrated that land use changes since 1987 to 2013 have led to an increase in annual runoff height by 1.40 mm and annual sediment concentration by 2 t.ha-1.
Roya Vazirian; Hamid Reza Asgari; Majid Ownegh; Chooghi Bairam Komaki
Abstract
Understanding the relationship between soil and plant is essential for reclamation of degraded lands. In order to investigate the relationship between Atriplex halimus density with carbon sequestration the rangeland of Incheborun was studied. Soil samples were collected randomly by Auger in the depth ...
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Understanding the relationship between soil and plant is essential for reclamation of degraded lands. In order to investigate the relationship between Atriplex halimus density with carbon sequestration the rangeland of Incheborun was studied. Soil samples were collected randomly by Auger in the depth of 0-30 cm of the soil profile in three different plant densities (<200, 200-400 and >400 stand per hectare) with 30 replications. The data were subjected to ANOVA using statistical software SPSS 21.0. Means were separated by T-test at P≤0.5. The results of this research showed that the soil organic carbon have ranging from 0.48 to 0.64 (with an average of 0.56%) in Atriplex plantation areas, while the organic carbon have ranging from 0.03 to 0.12 (with an average of 0.078%) in the control region.Therefore, plantation measures caused significant difference in soil organic carbon contents per unit area in Atriplex plantation areas as compared to that observed in the control area. Sequestered carbon in per unit is 26.27, 27.85 and 30.66 ton/ha respectively for low, medium and high Atriplex density areas. The results indicated that the rate of organic carbon as well as soil carbon sequestration increased with plant density. There were no significant difference among sequestered carbon and soil organic carbon values under those three different levels of densities, while significant difference were observed between three plantation areas and control area.
