TIME SERIES OF SOIL WATER CONTENT MEASUREMENTS IN THE TARO RIVER GIANT ALLUVIAL FAN

The soil water content profile in the surface soil has been measured at two stations located between the town of Parma and the Taro River (Po valley) for few years. At one of the two stations, some meteorological data are also collected, including air temperature and relative humidity at two levels besides atmospheric pressure and precipitation. The soil water content measurements are performed with Frequency Domain Reflectometry (FDR) sensors; the scaled frequencies and the meteorological data are automatically collected and stored in a data logger and then transmitted when required. The aim is to study the partition of the water entering the surface of the soil in: evaporation, run off, water stored in the measured soil column and percolation towards the deeper layers. The readings show a clear dependence on the soil depth; a high variability characterizes the superficial probes while the deeper ones show smoother trends. Due to the reduced precipitation during 2008 summer-autumn seasons, the soil water content at 1.5 m reached the maximum value measured the previous year only about at the middle of January. Vice versa, the soil water content at 2 m depth never reached the previous winter value; it had its maximum in February. During some drying periods, a linear trend of the soil water content well represents the measurements collected at the shallowest levels. These data also show a daily oscillation damping with the depth. A new hydrological station is going to be installed very close to the Taro River. Moreover, the meteorological station, located in the Enia area of the well #1 of Roncopascolo, is now completed with new sensors, which permit to compute all the terms of the energy balance equation required to estimate the evaporation into the atmosphere.