Lateral terrestrial water flow in the Weather Research and Forecasting (WRF) Model and its hydrologically enhanced version, WRF-Hydro, is calculated on a routing grid based on the infiltration excess in Noah/Noah-MP grid disaggregates to the routing grids. However, this design neglects the lateral terrestrial water flow in land surface model (LSM) grids and does not resolve water lateral transport in LSM. To address this knowledge gap and evaluate its influence on land surface hydrological processes, we developed a lateral terrestrial water flow scheme and pipe drainage scheme in the Noah-MP of WRF-Hydro and carried out a series of sensitivity experiments with WRFHydro. WRF-Hydro is firstly calibrated and validated using gauge observed streamflow data at Baiguan with the dynamically dimensioned search algorithm, achieving a Nash-Sutcliffe Efficiency value of 0.87 for calibration and 0.68 for validation. The spatial distribution of ponded water depth (SFCHEADRT) is nearly identical with the rainfall in the default WRF-Hydro simulation. However, SFCHEADRT is redistributed due to the lateral terrestrial water flow in LSM, although the magnitude does not change obviously. Especially, about 53.12 % of SFCHEADRT is reduced after considering pipe drainage, resulting in a remarkable reduction of the hydraulic gradients between adjacent grid cells, and subsequently weakening lateral flow over the urban areas. Further analysis shows that lateral flow in LSM primarily reduces overland flow and increases streamflow in routing grids, particularly in mountainous areas, through redistributing water from the steep slopes toward lower elevations and ultimately converting it to streamflow in the channel network.

WRF-Hydro,lateral terrestrial water flow