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Showing 2 results for Delbari
Simulation of Water and Nitrate Transport in Soil Using HYDRUS-1D Model in Furrow Irrigation of Sugarcane
N. Salamati, M. Delbari, F. Abbasi, A. Sheini Dashtgol,
Volume 19, Issue 74 (Winter 2016)
Abstract

Simulation of water and solute transport in soil is very useful for optimum management of water and fertilizer use. In this study, the HYDRUS-1D model was used to simulate water and nitrate transport in furrow irrigation of sugarcane. For this putpose, a large-scale experiment was performed as a split plot design based on the randomized complete blocks with 3 replications in a 25-hectare piece of land in the Dehkhoda Sugarcane Agro-Industry Company from March 2012 to October 2013. The main factor was split application of fertilizer at three levels: two, three and four splits. The sub-main factor was fertilizer amount, applied at three levels (i.e. 350, 280 and 210 kg urea corresponding to 100%, 80% and 60% fertilizer requirements, respectively). Soil hydraulic parameters were estimated through inverse modeling using moisture data collected during more than 4 months of the sugarcane growing season. Solute transport parameters were then estimated using the hydraulic parameters and nitrate concentration data. In this study, statistical criteria including R2, RMSE, ME and SSQ were used to compare the observed and simulated values of moisture content and nitrate concentration. The results indicated that R2 for simulated moisture content and nitrate concentration in four splits and 60% fertilizer requirement treatment (i.e. calibrated treatment) were 62.7 and 91.2 percent, respectively. Cumulative infiltration depths were about 46 and 58 mm for calibration and validation treatments, respectively. For these treatments, the cumulative evapotranspiration rates were 50 and 60 mm, respectively. Soil moisture content in the surface layer varied from 21 to 45 and 21 to 42 percent, for calibration and validation treatments, respectively while the changes in the deep layer moisture content were 33 to 38 percent, for both treatments.


Estimation of Soil Hydraulic Properties Curve through Beerkan Infiltration Experiment Algorithms
T. Ahmady, M. Delbari, P. Afrasiab,
Volume 23, Issue 2 (Summer 2019)
Abstract
Nowadays, the Beerkan computational algorithms (BESTslope and BESTsteday) are known as the suitable indirect methods for estimating soil saturated hydraulic conductivity (Ks) and sorptivity (S), as well as the scale parameter (hg) in van Genuchten soil water retention equation through the data collected in the Beerkan infiltration experiment and other required data. The purpose of this study was to compare these algorithms in estimating Ks and S, as well as the soil water content corresponding to the suctions of 33 kPa, 100 kPa, 200 kPa, 300 kPa and 1500 kPa. For this purpose, a total of 40 Beerkan infiltration experiments were carried out in Sistan dam research field. From all Beerkan experiments, 30 tests in loam and sandy loam textures having a relative error less than 5.5% (Er <5.5%) were selected for further analysis. The statistical criteria RMSE, ME and ωr2 were used to compare the measured and estimated water content values at each suction. The results showed that the BESTsteday algorithm, which had a more simple calculating process than the main algorithm (i.e. BESTslope), could provide the Ks and S values and the soil water content of the near field capacity with an acceptable accuracy. The model performance in estimating water content corresponding to the 1500 kpa suction head (i.e. θfc) was not acceptable for both algorithms. Moreover, the relative error of estimating soil water content (Er(h,θ)) was decreased gradually by an increase in clay %.

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