نوع مقاله : پژوهشی
نویسندگان
1 استادیار بخش تحقیقات حفاظت خاک و آبخیزداری، مرکز تحقیقات و آموزش کشاورزی و منابع‌طبیعی فارس، سازمان تحقیقات، آموزش و ترویج کشاورزی، شیراز، ایران
2 مربی، مرکز تحقیقات و آموزش کشاورزی و منابع‌طبیعی فارس، سازمان تحقیقات، آموزش و ترویج کشاورزی، شیراز، ایران
3 کارشناس ارشد ایستگاه آبخوانداری کوثر، مرکز تحقیقات و آموزش کشاورزی و منابع‌طبیعی فارس، سازمان تحقیقات، آموزش و ترویج کشاورزی، شیراز، ایران
4 استادیار پژوهشکده ی حفاظت خاک و آبخیزداری، سازمان تحقیقات، آموزش و ترویج کشاورزی، تهران، ایران
چکیده
کلیدواژه‌ها
عنوان مقاله [English]
نویسندگان [English]
Introduction and Goal
The aquifer recharge rate is one of the most difficult items to measure in GW resource evaluation. The techniques used in quantifying recharge are categorized in three main groups: unsaturated zone, saturated zone and surface water techniques. The saturated zone method is devided into physical methods (including Darcy's law and tracers), numerical modeling (the purpose of this research), groundwater level fluctuations, and water balance.
Materials and methods
Hydres and LitchW models were used to simulate soil moisture movement to simulate aquifer recharge in this study. The models were then calibrated by optimizing the water flow factors of the aquifer layers in the Gareh Bygon with the inverse solution method. The water characteristics of the unsaturated soil layer in three wells with an approximate depth of 30 m in one of the floodwater spreading basins were measured by field and laboratory methods. The soil moisture measuring device, TDR, was calibrated for the stony soils of the research area The sensors are then placed in holes with insulated walls from the surface to the depth.walls of oneof the wells Amount of soil-water contents were continuously measured from Sep. 2010 to Sep. 2020. The height of floodwater inundation and rainfall were also recorded. Recharge through unsaturated layers was assessed based on the soil water balance method as the observed data set.
Results and discusion
Validation flow simulation results from the of Hydrus and LEACHW models with observed measurements. The results showed that the Hydrus and LEACHW model very accurately estimated the water flow after the flood event (R2 and RMSE equal to 0.994 and 45.3 cm respectively in Hydrus model and 0.993 and 37.11 cm in LEACHW, respectively). In addition, the results of the Hydrus model were closer to measurements. The discharge ratio (the amount of infiltration divided by the amount of flood + precipitation) in the three methods of soil water balance, the Hydrus model and the LEACHW model were 47, 44 and 52 respectively, with an average of 48 for all flood events and 75, 71 and 92 with an average of 80% for large flood events. In the event of precipitation without flooding, practically all precipitation was spent on evaporation-transpiration, and for this reason, the size of the average infiltration ratio decreased in all events.
Conclusion and recommendation
Validation simulated flow results with Hydrus and LEACHW were compared with the observed measurements, demonstrating that these models accurately estimated the water flow after the flood event. In addition, , the results of the Hydrus model were closer to measurements. The mean data of the LEACHW and Hydrus models were overestimated by approximately 5 units less than 1 unit respectively. In simulations of water movement in soil using models such as Hydrus, a certain amount of water conductivity for the entire vertical column of the soil profile commonly considered. The results of this research showed how unrealistic such an assumption is. Therefore, in multi-layer soils, special attention should be given to the difference between layers and the use of water conductivity estimation equations. For the researched area, one-dimensional Hydrus model was recalibrated and its validation results were completely acceptable. This model can be used in three-dimensional mode for larger areas as a tool for applying different scenarios to manage the floodwater spreading system and increase their efficiency.
کلیدواژه‌ها [English]
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