Economic irrigation water productivity of wheat and potato: An earth observation perspective on policy implications in the Litani Basin, Lebanon

Efficient water management is critical in addressing the challenges posed by water scarcity and resource sustainability in agriculture. However, the utilization of remote sensing technology to monitor and enhance water productivity in data-scarce environments remains an open question. This study underscores the importance of integrating earth observation systems into agricultural water management policies, elucidating their potential to shape crucial policy decisions and investment strategies, particularly in regions facing data limitations. To address this issue, we provide a comprehensive framework that blends remote sensing data with field-based economic information, to develop the concept of economic productivity of irrigation water. Leveraging FAO’s Water Productivity Open-access portal (WaPOR) data, we spatially assess yields, water use, crop water productivity, economic water productivity, and economic irrigation water productivity (EIWP) for wheat and potatoes in the Upper Litani Basin of Lebanon's Bekaa Valley. Early season potatoes outperform irrigated wheat significantly, providing up to ten times higher returns on irrigation water ($6/m3 vs. $0.6/m3). Spatial analysis shows that southern areas have 30 % lower potato EIWP than northern areas of the valley but 55 % higher wheat EIWP, mainly due to higher rainfall. Our findings reveal that merely considering crop water productivity is insufficient when deciding what to plant, as it fails to account for profitability. While transitioning to crops or practices with greater EIWP can enhance economic productivity on the short-term, it may simultaneously lead to increased water consumption. As a result, the shift towards highly water-productive systems may require measures such as controlling irrigated areas or implementing restrictions on water withdrawals to maintain stable water consumption levels. This study offers valuable insights for water resource management, agricultural policy, and sustainable water utilization, especially in semi-arid regions like the Litani Basin, providing a foundation for informed decision-making in these resource-constrained environments.