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Evaluating The Use of “Goodness-of-Fit” Measures in a Water Movement Model
Published in Ajai Singh, Wastewater Reuse and Watershed Management, 2019
A DI system was designed for cauliflower crop in sandy loam soil using the standard design procedures. The control head of the system consisted of sand media filter, disk filter, flow control valve, pressure gauges, etc. Drip emitters with rated discharge 1.0×10–6 m3s–1 at a pressure of 100 k Pa were placed on the lateral line at a spacing of 40 cm. The best treatment, i.e., WW filtered by the combination of gravel media and disk filter with the placement of lateral at surface and subsurface (15cm) was considered for the simulation study. The crop water demand for irrigation was estimated on the basis of Penman-Monteith’s semi-empirical formula. The actual evapotranspiration was estimated by multiplying reference evapotranspiration with crop coefficient (ET = ET0 × KC) for different crop growth stages. The crop coefficient during the crop season 2008–2009, and 2009–2010 was adopted as 0.70, 0.70, 1.05 and 0.95 at initial, developmental, middle, and maturity stages, respectively (Allen et al., 1998).
Water Requirement of Crops
Published in Balram Panigrahi, Megh R. Goyal, Modeling Methods and Practices in Soil and Water Engineering, 2017
A. Dalei, C. R. Subudhi, B. Panigrahi
The crop coefficient approach is for calculating the crop evapotranspi- ration under standard conditions (ETc). The standard conditions refer to crops grown in large fields under excellent agronomic and soil water conditions. The crop evapotranspiration differs distinctly from the reference evapotranspiration (ETo). Crop evapotranspiration is calculated by multiplying ETo by Kc. Differences in evaporation and transpiration between field crops and the reference grass surface can be integrated in a single crop coefficient (Kc) or separated into two coefficients: a basal crop (Kcb) and a soil evaporation coefficient (Ke), i.e., Kc = Kcb + Ke. The approach to follow should be selected as a function of the purpose of the calculation, the accuracy required and the data available.
Tensiometer-Based Irrigation Scheduling: Drip-Irrigated Bell Pepper Under Naturally Ventilated Polyhouse
Published in Ajai Singh, Megh R. Goyal, Micro Irrigation Engineering for Horticultural Crops, 2017
Ashwani Kumar Madile, P. K. Singh
In eq (4.7): ETcrop = crop evapotranspiration (mm/day), Kc = crop coefficient (dimensionless), ET0 = reference crop evapotranspiration (mm/ day). The crop coefficients, KC were used based on the FAO-56 curve methods. The crop coefficient values depend on the type of crop and its growing stage, growing season, and the prevailing weather conditions. The shape of the curve represents the changes in the vegetation and ground cover during plant development and maturation that affect the ratio of ETc to ETC The Kc values for the capsicum under the study were used daily from Fig. 4.1.
A numerical model for simulating soil moisture dynamics and root water uptake under saline irrigation
Published in ISH Journal of Hydraulic Engineering, 2023
Satendra Kumar, K S Hari Prasad, C S P Ojha
Crop transpiration is evaluated by subtracting the soil evaporation from the crop evapotranspiration on the jth day of the crop growth. The crop evapotranspiration is obtained by multiplying the reference/potential evapotranspiration with an appropriate crop coefficient. is obtained as per the Penman-Monteith equation (Allen et al. 1998), which uses meteorological data such as maximum and minimum temperature, relative humidity, sunshine hour and wind speed. For most climate conditions, the FAO Penman-Monteith method is taken as the standard method and is widely accepted worldwide (Allen et al. 1998) given as,
Water distribution in community irrigation using a multi-agent system
Published in Journal of the Royal Society of New Zealand, 2023
Kitti Chiewchan, Patricia Anthony, Birendra KC, Sandhya Samarasinghe
Figure 1 shows the multi-agent environment and the decision-making algorithm for the individual agent. The role of each agent is twofold; to work out the crop water needs in its farm and to negotiate with other agents in the environment to buy/sell water. Each agent estimates their crop water needs on a daily basis. The crop water needs are calculated based on crop type, crop evapotranspiration, the crop coefficient (which is determined based on the crop type and growth stage), soil type and irrigation system (more details can be found in Chiewchan et al. 2019). Based on this, agents who have excess water will take up the role of seller agents, while agents with water shortages will take up the role of buyer agents. Before the start of the auction, each agent decides on its reserve price (for seller agents) or private valuation (for buyer agents) based on the farm's total marginal profit. The sellers will then auction off their excess water to the buyers or bidders.
Evapotranspiration estimation using SEBAL algorithm integrated with remote sensing and experimental methods
Published in International Journal of Digital Earth, 2021
Nazila Shamloo, Mohammad Taghi Sattari, Halit Apaydin, Khalil Valizadeh Kamran, Ramendra Prasad
Estimation of actual evapotranspiration based on crop coefficient is another important consideration for effective water resources management. In this study, the potential evapotranspiration from respective methods was used to calculate the corresponding crop coefficient values. Since ETrF is considered to be approximately equal to the crop coefficient in the SEBAL algorithm, the actual evapotranspiration obtained from SEBAL algorithm was used to acquire the ETrF values. The crop coefficients obtained from the SEBAL algorithm and the coefficients from the comparative methods are shown in Table 5. The results presented are also a comparison of crop coefficients at different growth stages obtained through FAO techniques, SEBAL algorithm and other experimental techniques.