Mohammad Bakhshi Tiregani; Hamid reza Moradi; Hamid reza Sadeghi
Volume 18, Issue 2 , September 2011, , Pages 269-279
Abstract
Land use utilization based on its capability and susceptibility is necessary for proper management of different regions. In this regard, the conversion of rangeland areas to dry farming and its consequent effects on soil erosion is a crucial problem that has to be carefully investigated. The present ...
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Land use utilization based on its capability and susceptibility is necessary for proper management of different regions. In this regard, the conversion of rangeland areas to dry farming and its consequent effects on soil erosion is a crucial problem that has to be carefully investigated. The present study therefore attempted to study the runoff and sediment rates in experimental plots located in two land uses of rangeland and dry farming lands with a slope of 5 percent by using rainfall simulator. The research was conducted during summer 2009 in Tiregan watershed located in Daregaz Township, Khorasan Razavi Province. The experiments were taken place through simulation of rainfall with intensity of 1.7 mm min-1 in two upper and lower positions, in eastern and western aspects of the slope in both the land uses. Afterwards, the runoff threshold was determined and the runoff samples were collected in small containers. The results of the study showed that the average runoff threshold in rangeland was 3.36 minutes earlier than that occurred in dry farming land. The runoff volume in rangeland plots was also 2.3 times more than dry farming land did. The sediment yield in the upper position in eastern aspect of rangeland treatment was lesser than dry farming treatment did. The difference was not significant in other treatments. The turbidity rates were also significantly more in dry farming lands compare to what recorded for rangeland areas
Aziz Arsham; Ali mohammad Akhund ali; Abdolkarim Behnia
Volume 16, Issue 4 , January 2010, , Pages 445-455
Abstract
Antecedent soil moisture is one of runoff and sedimentation crucial factors affected by parameters such as soil properties, topographic-, climatic-, and coverage circumstances etc. The work aimed at determining effects of soil properties and rainfall on runoff and sediment load at various antecedent ...
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Antecedent soil moisture is one of runoff and sedimentation crucial factors affected by parameters such as soil properties, topographic-, climatic-, and coverage circumstances etc. The work aimed at determining effects of soil properties and rainfall on runoff and sediment load at various antecedent moisture levels. Heavy, medium and light textured field soils were selected, exposed to a constantly intensified 80mm/hr rainfall under air-dried, air-dried to field capacity point, field capacity point and nearly saturated conditions, and two slopes of 5 and 15%. Recording runoff and sedimentation values every 2-5 min; populated values were calculated within 10, 20 and 30 min. intervals. All experiments were carried out with simulated rainfall technique in a 1×1×0.1m flume. Treatments showed most significant differences within first 10min. decreased with increasing rainfall duration. Maximum runoff coefficients increased as 2-5 folds as minimum ones with all durations. When moisture increased to field capacity point, light, medium and heavy textured soils had the lowest to the highest values of runoff coefficient, respectively. Under nearly saturated condition, increasing runoff trend decelerated with heavy textured soils and decreased to a lesser extent as compared to medium textured samples. Also, sedimentation process was consistent with runoff fluctuations. Medium textured soils showed a significant level of sedimentation under nearly saturated conditions. Runoff coefficients were unnoticeably different with 5 and 15% slopes; however, a more significant sedimentation increase occurred with 15% slope.