In situ water retention monitoring system of an operational dyke

The severe droughts in recent decades and lack of regular flooding have caused considerable fissures to develop on clay embankments. Previous surveys in Hungary have identified the examined dyke section as prone to desiccation cracks. It is essential to determine the possible extent of these desiccation cracks, as they degrade the dykes’ resistance against several failure mechanisms. A representative dyke cross-section was equipped with a unique water retention monitoring system comprising 17 sensors, including 14 soil moisture sensors and three water potential sensors. These devices were validated with laboratory measurements to obtain accurate results. The gravimetric water content (w) ranged from 8·3% to 31·3%, and the matric potential was recorded between 0·1 and 2350·7 kPa over one and a half years. The study examined the differences in soil behaviour under pavement and turf cover, identifying common moisture content distribution patterns and areas of the cross-section prone to desiccation cracking. The unique quality of the monitoring system lies in the fact that it was established in an operational embankment, which regulates the flow of a river. Furthermore, it was instrumented along the Tisza River, which is among Europe’s most significant watercourses. The results may help better understand the moisture content change in clay embankments and the role of the crest pavement in the moisture content distribution.