Rao et al. (2025) Long-term assessment of crop water dynamics and irrigation dependency for selected major Kharif crops under climate variability using the CROPWAT Model in the Araniar command area, Andhra Pradesh, India (1990–2024)

Identification

• Journal: Discover Plants.
• Year: 2025
• Date: 2025-11-28
• Authors: P P Rao, Rajesh Gudihalli Munivenkatappa, Bikramdeep Singh, M. Venkata Ramana
• DOI: 10.1007/s44372-025-00396-w

Research Groups

• Department of Soil and Water Conservation Engineering, Kelappaji College of Agricultural Engineering and Food Technology, Kerala Agricultural University, Tavanur, Kerala, India
• Department of Agricultural Engineering, Aditya University, Surampalem, Kakinada, Andhra Pradesh, India
• Department of Agricultural Engineering, Sri Venkateswara Agricultural College Tirupati, Tirupati, Andhra Pradesh, India

Short Summary

This study estimated crop water requirements (CWR), net irrigation requirements (NIR), and irrigation dependency ratios (IDR) for major Kharif crops (Paddy, Groundnut, Bajra) in the Araniar command area, India, from 1990-2024 using the CROPWAT 8.0 model, revealing significant variations in water dependency among crops. The findings highlight Paddy's high irrigation dependency and provide insights for sustainable water management.

Objective

• To estimate reference evapotranspiration (ET₀), crop water requirement (CWR), and net irrigation requirement (NIR) for major Kharif crops (Paddy, Groundnut, Bajra) in the Araniar command area, Andhra Pradesh, India, under climate variability.
• To assess the irrigation dependency ratio (IDR) for these crops to inform efficient irrigation planning and sustainable water resource management.

Study Configuration

• Spatial Scale: Araniar command area, Chittoor district, Andhra Pradesh, India (total command area of 3682.6 hectares). Meteorological data specific to Pichatur village (latitude 13.35°, longitude 79.25°).
• Temporal Scale: 35 years, from 1990 to 2024.

Methodology and Data

• Models used:
  • CROPWAT 8.0 model for estimating ET₀, CWR, and NIR.
  • FAO Penman–Monteith method for computing reference evapotranspiration (ET₀).
  • Fixed percentage Method and United States Department of Agriculture, Soil Conservation Service (USDS-SCS) formula for effective rainfall estimation.
• Data sources:
  • Meteorological data: Rainfall, minimum and maximum temperature, wind speed, air humidity, and sunshine duration for Pichatur village from the NASA POWER website (1990–2024). Additional rainfall data from the Chief Planning Office (CPO) in Chittoor district (1990–2024).
  • Crop data: Crop coefficient (Kc) values, crop heights, growth stage durations (initial, development, mid-season, late-season), planting months, root zone depths, yield response factors, and depletion fractions for Paddy, Groundnut, and Bajra.
  • Soil data: Red sandy loam-type soils for the Araniar command area, with an available water capacity of 140.0 mm/m and a fundamental infiltration rate varying from 30 mm/h to 35 mm/h.

Main Results

• The average daily reference evapotranspiration (ET₀) for the period was 4.91 mm/day, with the highest value in May (5.85 mm/day) and the lowest in December (3.23 mm/day).
• The annual average total rainfall was 1235.9 mm, of which 926.6 mm (74.9%) was effective rainfall.
• The estimated crop water requirements (CWR) were: Paddy (801.3 mm), Groundnut (531.0 mm), and Bajra (380.4 mm).
• The corresponding net irrigation requirements (NIR) were: Paddy (431.8 mm), Groundnut (74.3 mm), and Bajra (44.2 mm).
• The irrigation dependency ratios (IDR) were highest for Paddy (53.9%), followed by Groundnut (14.3%) and Bajra (11.6%).
• Paddy alone accounted for 65.2% of the total crop water requirement in the Kharif season (7.66 million cubic meters out of 11.76 million cubic meters).

Contributions

• Provides a comprehensive, long-term (35 years) assessment of reference evapotranspiration, crop water requirement, and net irrigation requirement for major Kharif crops in the Araniar command area, addressing a research gap for precise, localized irrigation planning in this canal-dependent region.
• Integrates site-specific ET₀ and effective rainfall estimates with crop-wise irrigation dependency percentages, offering a detailed understanding of water demand.
• Presents crop water demand in both volumetric terms (million cubic meters) and as percentage contributions to the basin total, a novel approach that enhances the clarity of basin-level water allocation and stress compared to previous studies.
• Highlights the significantly higher proportional dominance of Paddy (65.2% of total CWR) in the Araniar command area compared to other semi-arid basins, underscoring the urgent need for targeted water management interventions and crop diversification.

Funding

This research did not receive any specific funding from public, non-profit funding agencies, or commercial sources.

Citation

@article{Rao2025Longterm,
  author = {Rao, P P and Munivenkatappa, Rajesh Gudihalli and Singh, Bikramdeep and Ramana, M. Venkata},
  title = {Long-term assessment of crop water dynamics and irrigation dependency for selected major Kharif crops under climate variability using the CROPWAT Model in the Araniar command area, Andhra Pradesh, India (1990–2024)},
  journal = {Discover Plants.},
  year = {2025},
  doi = {10.1007/s44372-025-00396-w},
  url = {https://doi.org/10.1007/s44372-025-00396-w}
}