Role of Short-Term Weather Forecast Horizon in Irrigation Scheduling and Crop Water Productivity of Rice

Anupoju, Varaprasad and Kambhammettu, BVN P and Regonda, Satish K (2021) Role of Short-Term Weather Forecast Horizon in Irrigation Scheduling and Crop Water Productivity of Rice. Journal of Water Resources Planning and Management, 147 (8). 05021009. ISSN 0733-9496

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Crop simulation models in conjunction with weather forecasts help in understanding soil-water-plant interactions in real time, and thus in effective management of irrigation water. However, selection of the optimal forecast horizon for use with irrigation scheduling is challenging in the context of uncertainties associated with weather forecasts. This study is aimed at evaluating the effectiveness of the Indian Meteorological Department (IMD) short-term weather forecasts with different forecast horizons (1, 3, and 5 days) in simulating crop water and yield dynamics of rice. Rule-based irrigation is triggered by specifying thresholds on the current day's ponding depth (do), precipitation (Po), and evapotranspiration (ETo) as well as their forecast values (σi=1nPi; σi=1nETi; n=1,3,5). The IMD forecasts of temperature, humidity, wind speed, and cloud cover were translated into ETo forecasts using the Penman-Monteith equation and region-specific crop coefficients. The Soil-Water-Atmosphere-Plant (SWAP) model was modified to simulate soil-water and plant growth conditions by considering the three forecast scenarios along with conventional irrigation (ignoring weather forecast), and a hypothetical perfect 5-day forecast (reference). Experiments were conducted in four paddy fields in a command area of south India for two monsoon seasons (2018 and 2019) to calibrate and parameterize the SWAP model. The accuracy of forecast variables is increased with increase in length of forecast horizon (root-mean-square error = 12.5±0.98, skill score = 0.6%±0.03% at 1-day lead to 5.9±2.5, 22.4%±7.8% at 5-day lead) due to averaging. Conventional irrigation has resulted in the highest use of irrigation water (912±12.5 mm), percolation losses (1,245±19.5 mm), and electricity (806.5±100.5 kW), achieving a low yield (2,331±138 kg ha-1). Irrigation scheduling with 5-day forecast horizon outperformed other scenarios (69% water saving and 23% higher yield), and is slightly inferior to the hypothetical perfect forecast. Our results conclude that IMD forecasts, though moderately reliable at multiple lead times, can serve as a valuable tool in scheduling irrigation activities for sustainable management.

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IITH Creators:
IITH CreatorsORCiD
Kambhammettu, B V N PUNSPECIFIED
Regonda, Satish KumarUNSPECIFIED
Item Type: Article
Uncontrolled Keywords: Indian Meteorological Department (IMD); Irrigation schedule; Rice; Soil-water-atmosphere-plant (SWAP); Weather forecast;Crop simulation model; Crop water productivity; Effective management; Irrigation scheduling; Penman-Monteith equations; Root mean square errors; Soil water atmosphere plants; Sustainable managemen
Subjects: Civil Engineering
Divisions: Department of Civil Engineering
Depositing User: . LibTrainee 2021
Date Deposited: 24 Jul 2021 09:43
Last Modified: 02 Mar 2022 07:00
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