Optimal installation depth of subsurface drains with the aim of reducing construction costs

مدل‌سازی و مدیریت آب و خاک

Majid Sharifipour¹  Ali Heidar Nasrollahi¹  Mehri Saadinia¹  Fatemeh Saadatpour²  Abdolmajid Liaghat³ 

[1] Assistant Professor/Department of Water Engineering, Faculty of Agriculture and Natural Resources, Lorestan University, Khorram Abad, Iran;M.Sc. Student/Department of Water Engineering, Faculty of Agriculture and Natural Resources, Lorestan University, Khorram Abad, Iran;Professor/Department of Irrigation and Reclamation Engineering, Faculty of Agriculture and Natural Resources, University of Tehran, Tehran, Iran;

关键词: capital cost;    collector drainage;    drainage pipe;    trencher;   

DOI  :  10.22098/mmws.2021.1175

来源: DOAJ

【 摘 要 】

IntroductionMillions of hectares of the world's irrigated lands need subsurface drainage, but lack of funding is hindering the timely development of these systems, so a solution is required to minimize construction costs (Ritzema and Braun, 2006; Sharifipour et al., 2015). The purpose of this paper is to provide a way to find the "lowest cost depth" for installing subsurface drains.Materials and MethodsThe costs can be divided into three groups. The first group is the costs that do not depend on the digging time and the depth of the drainage installation; if the drains are installed at any depth, these costs do not change per unit length of subsurface drains. These include the cost of purchasing the filtered pipe, the cost of constructing lateral outlets to collectors, etc. The second group is the costs that depend on the depth of drainage installation and the digging time, such as the cost of capital depreciation to purchase a trencher. By increasing the installation depth of the drain, the digging speed will be reduced, thus reducing the total length of the digging. The third group is the costs that are a function of the drainage installation depth but are not a function of the digging speed, including the cost of constructing of collector drain, which increases with the installation depth of the drain. This paper developed a method for converting these costs into cost per unit area :CA = C′I + C′V + C′C                                                                                                                                                                                   (1)CA is the total cost of constructing a subsurface drainage system; C′I, C′V, and C′C represent first, second and third groups of construction costs, all in Rial per unit area (ha).Results and DiscussionAccording to the drainage equations, the distance between the drains will increase with increasing depth, so increasing drainage depth decreases the first group of costs per unit area. As the drainage depth increases, the volume of soil displacement increases. The trench digging speed decreases, so the second group of costs, including the depreciation costs of the trencher, fuel, and wages increase per unit length of lateralization. C′C cost, which includes the cost of collector drainage, increases by the depth of drainage installation.ConclusionAlgebraic operations are possible by converting costs to costs per unit area. Since the drainage density in deep drains is lower and by determining the density of drainage per unit area at each installation depth, the depth that has the lowest cost can be selected as the optimal depth. The raw data for each project may be different; so this data must be collected and used with acceptable accuracy. The cost model is general, but special conditions in some drainage projects may lead to extraordinary costs. In that case, those costs should be converted into costs per unit area similarly and considered as well.

【 授权许可】

Unknown