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| Study on simulation test of different underground drainage effect of measures in farmland |
| REN Xiaolei1,2, WANG Shaoli1, YANG Peiling1, TAO Yuan2 |
| 1. China Institute of Water Resources and Hydropower Research, Beijing 100048, China; 2. College of Water Resources and Civil Engineering, China Agricultural University, Beijing 100083, China |
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Abstract In southern China, where the groundwater level is high and the surface is easy to form ponding, farmland drainage measures can timely remove excess surface ponding and quickly reduce the groundwater level, so as to achieve the purpose of drainage and water logging and coordinated regulation is still an urgent problem to be solved. Based on the indoor sand tank test, this paper reveals the law and effect of conventional subsurface drainage, open ditch drainage, different filter heights of filter drainage and improved subsurface drainage, etc. The results showed that the improved subsurface drainage can significantly improve the flow rate by replacing the soil around the pipe with a highly permeable soil medium. When the soil displacement height reaches 2 cm(corresponding to 40 cm in field conditions), its flow rate was higher than that of other drainage measures at the same drain depths, which was 1.59-1.66 times that of conventional subsurface drainage. The improved subsurface drainage can still maintain a more significant flow rate at the critical point before the disappearance of ponding water, which can reach more than 2 times of the conventional subsurface flow rate of the same drain depth in the process of water receded. And after the disappearance of the ponding water, the improved subsurface drainage can rapidly reduce the waterlogging stress of soil water in agricultural fields and reduce the groundwater level until the height reaches the drain depth. When the ponding water disappears, various drainage measures have a significant change in the flow rate and water head per unit time. The improved subsurface drainage has apparent advantages in removing flooding and waterlogging, the flow and head changes greatly when compared with all kinds of subsurface drainage measures. The research results can provide a reference for the design and construction of efficient removing flooding and waterlogging of disaster reduction projects in waterlogging prone areas.
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Received: 10 May 2021
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