نوع مقاله : پژوهشی
نویسندگان
گروه مهندسی آبیاری و آبادانی، دانشکدهی مهندسی و فناوری کشاورزی، دانشگاه تهران
چکیده
کلیدواژهها
موضوعات
عنوان مقاله [English]
نویسندگان [English]
Groundwater resources play an essential role in water supply for drink, griculture, and industry sectors. Nowadays, for various reasons, such as urban and opulation growth, indiscriminate use of fertilizers and chemical poisons, groundwater resources have been populated. Therefore, studying the pollutions and their fate and preventing groundwater resources from the pollutants is necessary. In this research study, a laboratory physical model has been designed and performed in order to obtain enough data of pollution movement in homogeneous porous media. In other words, the main aim of this paper is to track the distribution of a conservative tracer in porous media in a laboratory-scale model to estimate the longitudinal and transverse dispersion coefficients. In this study, non-cohesive sands were used to create the porous media body in the laboratory model, and the grain diameter of the sand was 1-2.5 mm. Salt with concentrations of 5, 7.5, and 10 gr/l was used as a tracer. The porosity of the sand was measured equal to 39\%, and the hydraulic conductivity of that was measured equal to 172.26 cm/hr using the constant load
test. In order to control changes of flow velocity, to minimize test errors, a
constant head of water was created over the entrance of the sand body. The flow
velocity was measured equal to 1.21 mm/sec. An EC-meter apparatus was used to
measure the EC values of the tracer inside model; then, these data were used to
calculate the concentration of tracer in different points over time, during
each test. Then, the values of the concentration were compared with those of
concentration which were obtained from the analytical solution of Fick's second
law. Root Mean Square Error criterion (RMSE) was used to compare the measured
and calculated mentioned data. According to the results, the values of the
longitudinal coefficient tracer for the studied conditions, concentrations of
5, 7.5, and 10 gr/l, obtained 3.36e-6, 3.08e-6, and 3.52e-6 for transverse
coefficients 6.58e-7, 6.49e-7, and 6.79e-7 m2/s, respectively.
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