Qanats’ assistance in reviving groundwater resources using numerical groundwater model
摘要
A qanat, an ancient engineering technique known as a sustainable groundwater resource, helps humans to abstract water from underground for agriculture and drinking in arid countries like Iran. Regretfully, a portion of qanat’s water is wasted during non-crop seasons. To overcome this issue, ancient Iranians constructed underground dams within the qanats to trap water under the ground and control the flowrate. This study employs a meshless numerical method, namely MLPG, to investigate the effects of underground dam construction on a qanat in Birjand unconfined aquifer. The qanat, known as Haji-Abad, is one of the most famous in this region. Two scenarios are considered: one without an underground dam and one with an underground dam. In the first scenario, the groundwater level is simulated over 5 years (2018–2023) and its fluctuations are drawn for the nearest piezometers of the qanat. The results show a decreasing trend in the groundwater level in all piezometers. For example, piezometers #1, #2, #3 and #4 present drawdowns of 4.59 m, 2.05 m, 3.43 m and 3.27 m, respectively, during the simulation period. In the second scenario, the groundwater level with considering an underground dam is recalculated. In piezometer #1, which is the closest to the considered location of the underground dam, the groundwater level shows a slight increase after 41st month of modeling. It means that the underground dam contributes to recharge the aquifer and by injecting water into it. The total injected volume of water during this period (41–60th month) is 1,008,750 m3. This value is meaningful for Birjand aquifer, demonstrating that construction of underground dams on qanats in this aquifer is a beneficial practice.