Spatio-Temporal Patterns in Soil Water Content Time Series: Influence of the Time Series Length and Precipitation Events

摘要

Soil water content is a key link among environmental compartments. We discuss the influence of the time series length and precipitation events on the spatio-temporal patterns in soil water content time series as an ex post assessment of the operatingmonitoring network. To analyze different spatio-temporal patterns in the soil water content, we applied the concept of time stability and wavelet filtering (wavelet power spectra and wavelet coherency). Wavelet filtering allowed us to get insight into the response of the monitoring points at different time scales, while the time stability concept allowed us to identify representative locations, i.e., monitoring points which have the property of representing some statistical features of the whole monitoring system. Our results show that the representative monitoring points change as new data is added, and that the location of the most stable point depends on the hydrological condition of the sites (e.g. precipitation and lateral flows). Also, in our case study upper strata are proxies for hourly-to-daily changes in soil water content, while deeper strata are proxies for medium-term stored water. The coupling between precipitation and soil water content depends on the precipitation volume, the number ofevents, the monitoring depth and the hydrogeological setting.