1 October 2020
Global Irrigation Characteristics and Effects Simulated by Fully Coupled Land Surface, River, and Water Management Models in E3SM
Irrigation supports agricultural production, but widespread use of irrigation can perturb the regional and global water cycle. The one-way coupling scheme used in most global irrigation modeling studies assumes surface water demand is always met and ignores the surface water constraints at short time scales, leading to overestimation of surface water usage, underestimation of groundwater pumping, and unrealistic simulation of their seasonal variability. To overcome these limitations, a two-way coupling irrigation scheme is developed within the Energy Exascale Earth System Model (E3SM). The new irrigation scheme consists of a land surface model (E3SM Land Model, ELM), in which irrigation water demand is estimated and applied, and a river routing model coupled with a water management model (MOSART-WM) that simulate streamflow, reservoir operations, and irrigation water supply. With two-way coupling, surface water irrigation is constrained by the available runoff, streamflow, and reservoir storage. Simulations were performed for 1975-2004 at ~100 km spatial resolution to estimate irrigation surface water and groundwater use and their seasonality in global and large river basin scales. Compared to one-way coupling, the two-way coupling scheme: (1) estimates less surface water withdrawal and less return flow due to the constraint; (2) better represents groundwater recharge and water level decline at global scale; and (3) is able to capture the seasonal dynamics of irrigation water allocations which reflect the local water conditions. The new development is an important step to more realistically account for the interactions between human water use and the terrestrial water system.
“Global Irrigation Characteristics And Effects Simulated By Fully Coupled Land Surface, River, And Water Management Models In E3Sm”. 2020. Journal Of Advances In Modeling Earth Systems 12. doi:10.1029/2020ms002069.
Funding Program Area(s)