Thirty‐five year (1971–2005) simulation of daily soil moisture using the variable infiltration capacity model over China

Abstract

We use the Variable Infiltration Capacity (VIC) land surface macroscale hydrology model driven by observed maximum and minimum air temperatures and precipitation to map daily soil moisture values over China for the period 1 January 1971 to 31 July 2005. The model is applied over a grid of 10 458 points with a resolution of 30 km × 30 km. The model is first calibrated using observed hydrographs from 35 catchments with drainage areas varying from 190 to 351 530 km2. The model is then validated over these 35 catchments at different periods, and over an additional eight catchments with drainage areas ranging from 1230 to 10 010 km2. An estimation procedure to determine model parameters is developed and applied to catchments where hydrographs are not available for the standard calibration process. In situ soil moisture measurements from 28 sites around the country are also used for model validation. VIC performs well over both calibration and validation catchments especially in humid and semi‐humid regions. The 35‐year soil moisture climatology for the top 1 m from VIC is consistent with known soil moisture conditions in China.