Field-Scale Monitoring of Urban Green Area Rainfall-Runoff Processes

Rainfall-runoff-generating mechanisms in urban green areas are scarcely understood, and limited knowledge and data on rainfall-runoff processes are available. Therefore, a large-scale experimental field station was established to investigate the inherent hydrological processes of a grass-covered 4,300  m2 urban catchment consisting of sandy loam soil. A facility to collect surface runoff from the area was designed. Runoff, soil moisture properties, and rainfall were measured simultaneously by a flow meter, in-ground soil sensors, and rain gauges, respectively. Measured soil volumetric water content was above 0.34  m3 H2O m−3 soil during fall and winter and ranging between 0.13 and 0.34  m3 H2O m−3 soil during late spring and summer. Measured runoff recorded from September 2016 until July 2018 strongly indicates that subsurface throughflow was the dominant runoff type. There was good correlation between the dynamics of soil water content and runoff. Accumulated rainfall and runoff was linearly correlated for soil volumetric water contents above 0.34  m3 H2O m−3 soil. The relationship between runoff and rainfall shows a runoff coefficient of 0.18 for the 4,300  m2 area.