Evaluation of Drainage Water Detention Efficiency of Off-Line Ditch-Pond Systems and Its Influencing Factors
Ditch-pond systems can effectively alleviate the adverse effects of agricultural drainage on downstream canals and flood control in downstream areas. In this study, peak flow reduction rate (PFR) and drainage volume detention rate (DVD) are used to evaluate the effectiveness of an off-line ditch-pon...
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| Autores principales: | , , , |
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| Formato: | article |
| Lenguaje: | EN |
| Publicado: |
MDPI AG
2021
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| Materias: | |
| Acceso en línea: | https://doaj.org/article/aeb9080ce6834320a9e0b922eac08323 |
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| Sumario: | Ditch-pond systems can effectively alleviate the adverse effects of agricultural drainage on downstream canals and flood control in downstream areas. In this study, peak flow reduction rate (PFR) and drainage volume detention rate (DVD) are used to evaluate the effectiveness of an off-line ditch-pond system for reducing peak flow, retarding agricultural drainage water, and examining the key influencing factors. The results show that the PFR and DVD of the off-line ditch-pond system are significantly affected by three parameters: weir depth (<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msub><mi>L</mi><mi>d</mi></msub></mrow></semantics></math></inline-formula>), weir width (<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msub><mi>L</mi><mi>w</mi></msub></mrow></semantics></math></inline-formula>), and pond area-to-drainage area ratio (<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msub><mi>K</mi><mrow><mi>s</mi><mi>p</mi></mrow></msub></mrow></semantics></math></inline-formula>). Both the PFR and DVD increase with the increase in <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msub><mi>L</mi><mi>d</mi></msub></mrow></semantics></math></inline-formula>, <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msub><mi>L</mi><mi>w</mi></msub></mrow></semantics></math></inline-formula>, and <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msub><mi>K</mi><mrow><mi>s</mi><mi>p</mi></mrow></msub></mrow></semantics></math></inline-formula>. The effects of <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msub><mi>L</mi><mi>d</mi></msub></mrow></semantics></math></inline-formula> and <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msub><mi>L</mi><mi>w</mi></msub></mrow></semantics></math></inline-formula> on the PFR and the DVD are significant, whereas that <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msub><mi>K</mi><mrow><mi>s</mi><mi>p</mi></mrow></msub></mrow></semantics></math></inline-formula> is relatively small. Adjusting <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msub><mi>L</mi><mi>d</mi></msub></mrow></semantics></math></inline-formula> and <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msub><mi>L</mi><mi>w</mi></msub></mrow></semantics></math></inline-formula> increases both the PFR and DVD up to 80%. Specifically, <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msub><mi>L</mi><mi>d</mi></msub></mrow></semantics></math></inline-formula> contributes 75% of the variations in the PFR and the DVD, and <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msub><mi>L</mi><mi>w</mi></msub></mrow></semantics></math></inline-formula> affects only 17% of the PFR variations and 11% of the DVD variations. These findings confirm that an off-line ditch-pond system can be effectively used for the detention of agricultural drainage water. Thus, when such a system is designed with an appropriate diversion weir, the impact of agricultural drainage water on downstream canals and downstream areas can be reduced remarkably. |
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