Theoretical analysis and experimental verification of the improved subsurface drainage discharge with ponded water

Yuan Tao, Shaoli Wang, Di Xu, Xiaoyan Guan, Mengzhe Ji and Jing Liu

Agricultural Water Management, 2019, vol. 213, issue C, 546-553

Abstract: The improved subsurface drainage is a new drainage technique which has large discharge verified by experiments. It can be used to solve the problems of frequent floods and cultivated land shortage in South China. Considering large-scale applications, a general drainage formula of the improved subsurface drainage with ponded water in a homogeneous and isotropic soil was proposed based on Kirkham equation. Firstly, the drainage formulas based on different assumptions were deduced and verified by laboratory experiment and field test. Additionally, further validation and simplification were studied by numerical simulation in which the critical conditions to distinguish whether the filter was saturated or not were given. Results showed that the proposed formulas passed the validation by laboratory experiment and field test based on Method 1 and Method 2 in which the bottom of the simplified boundary overlapped with the bottom of the drain pipe and the center of simplified boundary located at the center of filter were assumed respectively. The numerical simulation results showed the formula based on Method 1 was more applicable than that based on Method 2. Moreover, for Method 1, that (b0+h0)/d equaled 0.6 could be regarded as the critical boundary between filter saturated and unsaturated working condition. Considering the ratio of drain distance and impermeable layer depth, a more simplified formula was given. In this simplified formula, that drain spacing was three times of impermeable layer depth was a critical condition. The research results could provide scientific basis for improved subsurface drainage design and lay a good foundation for its application. Meanwhile, it would be beneficial to enrich agricultural drainage technologies and promote development of agricultural drainage in China.

Keywords: Improved subsurface drainage; Drainage formula; Laboratory experiment; Field test; Numerical simulation (search for similar items in EconPapers)
Date: 2019
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Citations: View citations in EconPapers (6)

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Persistent link: https://EconPapers.repec.org/RePEc:eee:agiwat:v:213:y:2019:i:c:p:546-553

DOI: 10.1016/j.agwat.2018.10.035

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