Modelling and analysis of the impact of urban irrigation on land surface fluxes in the Los Angeles metropolitan area

The current work includes developing and integrating an irrigation module within the Noah LSM-SLUCM (Single Urban Canopy Model) modelling framework. The model is run over a 49-km(2) urban domain in the Los Angeles metropolitan area at a high resolution (30 m) to understand the temporal variability and spatial heterogeneity of urban energy and water fluxes. The irrigation scheme developed is calibrated using residential water-use data and estimates of outdoor water consumption. Our results indicate that updating soil moisture to 75% of field capacity at a 6-day interval reasonably represents irrigation over this study region. To validate the model performance, we introduce a systematic evaluation process using MODIS-Landsat ET and Land Surface Temperature (LST) products as well as CIMIS- (California Irrigation Management Information System) based landscape ET observations. We conclude that addition of an irrigation scheme is critical to adequately simulate urban hydrological cycles, especially in arid and semi-arid regions.