نوع مقاله : مقاله پژوهشی
نویسندگان
علوم و مهندسی خاک، دانشکده کشاورزی، دانشگاه تهران، کرج، ایران
چکیده
کلیدواژهها
موضوعات
عنوان مقاله [English]
نویسندگان [English]
One of the most important problems in the field of soil erosion research is the dependency of measurements and estimates on the scale. Recently, studies in the field of soil erosion scaling have resulted in development of some different models. This research aimed to investigate the scaling of rill erosion in field conditions. Artifitial rills with length of 1 to 8 meters and width of 5 cm were created in a plot with a slope of 5% in an agricultural soil with sandy loam texture and weak aggregate stability. The experiments were caried out under two target flow rates of 0.11 and 0.24 liters per second. Sediment concentration was measured during the event for 30 minutes, and its time changes were investigated along different rills. To scale rill erosion, the changes with rill length of the mean sediment concentration and particle detachment rate, both at three initial unsteady, final steady and total event conditions, were evaluated and modeled. The temporal changes of sediment concentration exhipited an exponentially decreasing trends almost in all cases. The average sediment concentration increased linearly with rill length (spatial changes) at lower flow rates, and exponentially (reaching a certain limit) under the higher flow rates in all three conditions. Also, the particle detachment rate decreased exponentially with rill length under both flow rates in all three cases of unsteady, steady and total event averages. The results generally confirmed the models and theories of the exponential decrease in the particle detachment rate with increasing rill length.
کلیدواژهها [English]
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