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Evaluation and determination of subsurface drainage spacing in two steady and unsteady flow conditions with closure of the impermeable layer to the ground surface. case study: Markazi province, Iran *
Author(s) -
Moshayedi Behzad,
Najarchi Mohsen,
Najafizadeh Mohammad Mahdi,
Khaghani Shahab
Publication year - 2020
Publication title -
irrigation and drainage
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.421
H-Index - 38
eISSN - 1531-0361
pISSN - 1531-0353
DOI - 10.1002/ird.2457
Subject(s) - drainage , closure (psychology) , unsteady flow , hydrology (agriculture) , precipitation , subsurface flow , flow (mathematics) , environmental science , mathematics , geotechnical engineering , geology , mechanics , groundwater , meteorology , geometry , physics , ecology , economics , market economy , biology
In this paper unsteady methods which are a function of time and steady conditions that are independent of time are used to evaluate the subsurface drainage system established in the upstream lands of the Senejan plain located in the centre of Iran. In order to determine the drain spacing, the steady Hooghoudt model and the unsteady Glover–Dumm, modified Glover and van Schilfgaarde models in rainy periods of 2, 3, 4 and 5 days were used, and the distance between computational drains at two depths install drains (180 and 200 cm) was compared with the results of the subsurface drainage project. To compare the results, the mean absolute error (MAE) and standard error (σ) were used. The results showed that MAE and σ values in the 3‐, 4‐ and 5‐day rainfall in the Glover–Dumm model are 9.75 and 0.196% for the depth of 180 cm and 7.944 and 0.15% for the depth of 200 cm, respectively. The above coefficients obtained in the van Schilfgarde model were 8.098 and 0.162% and 6.685 and 0.134% for 2 days precipitation respectively. The results show that the steady method is not in good agreement with the values of the drain spacing. © 2020 John Wiley & Sons, Ltd.