Preprints
https://doi.org/10.5194/egusphere-2023-1323
https://doi.org/10.5194/egusphere-2023-1323
14 Jul 2023
 | 14 Jul 2023

Validation of a new global irrigation scheme in the land surface model ORCHIDEE v2.2

Pedro Felipe Arboleda-Obando, Agnès Ducharne, Zun Yin, and Philippe Ciais

Abstract. Irrigation activities are important for sustaining food production, and account for 70 % of total global water withdrawals. In addition, due to increased evapotranspiration (ET) and changes on leaf area index (LAI), these activities have an impact on hydrology and climate. In this paper we present a new irrigation scheme within the land surface model ORCHIDEE. It restrains actual irrigation according to available freshwater by including a simple environmental limit and using allocation rules depending on local infrastructure. We perform a simple sensitivity analysis and parameter tuning to set the parameter values and match the observed irrigation amounts against reported values, assuming uniform parameter values over land. Our scheme matches irrigation withdrawals amounts at global scale, but we identify some areas in India, China and the US (some of the most intensively irrigated regions worldwide) where irrigation is underestimated. In all irrigated areas, the scheme reduces the negative bias of ET. It also exacerbates the positive bias of the leaf area index (LAI) except for the very intensively irrigated areas, where irrigation reduces a negative LAI bias. The increase of ET decreases river discharge values, in some cases significantly, although this does not necessarily lead to a better representation of discharge dynamics. Irrigation, however, does not have a large impact on the simulated total water storage anomalies (TWSA) and its trends. This may be partly explained by the absence of non-renewable groundwater use, and its inclusion could increase irrigation estimates in arid and semiarid regions by increasing the supply. Correlation of irrigation biases with landscape descriptors suggests that inclusion of irrigated rice and dam management could improve the irrigation estimates as well. Regardless of this complexity, our results show that the new irrigation scheme helps simulating acceptable land surface conditions and fluxes in irrigated areas, which is important to explore the joint evolution of climate, water resources and irrigation activities.

Pedro Felipe Arboleda-Obando et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2023-1323', Anonymous Referee #1, 24 Aug 2023
  • RC2: 'Comment on egusphere-2023-1323', Anonymous Referee #2, 02 Sep 2023

Pedro Felipe Arboleda-Obando et al.

Pedro Felipe Arboleda-Obando et al.

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Short summary
In this study, we show a new irrigation scheme included in ORCHIDEE land surface model. The new irrigation scheme restraint irrigation due to water shortage, includes water adduction, and represents environmental limits and facility to access water due to infrastructure in a simple way. Our results show that the new irrigation scheme helps simulating acceptable land surface conditions and fluxes in irrigated areas, even if there are difficulties due to shortcomings and limited information.