Hydrological Characterisation of a Live Pole Drain
E. Benschop (TU Delft - Civil Engineering & Geosciences)
T.A. Bogaard – Mentor (TU Delft - Water Resources)
Alejandro Gonzalez-Ollauri – Graduation committee member (Glasgow Caledonian University)
Slobodan Mickovski – Graduation committee member (Glasgow Caledonian University)
Massimo Menenti – Graduation committee member (TU Delft - Optical and Laser Remote Sensing)
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Abstract
Climate change causes an increase of precipitation intensity and frequency, which leads to an increased amount of landslide occurrences. Therefore, there is an urgent need for prevention measures. The risk of landslide occurrence can be mitigated by decreasing the pore water pressure in a hillslope, e.g. by drainage from the subsurface. The implementation of Nature Based Solutions (NBS) is advantageous, as these are not disruptive for the hillslope ecosystem. A Live Pole Drain (LPD) is a type of NBS which is inexpensive and can be installed at remote locations. However, its effect on hillslope hydrology has not been studied before.
In this study, fieldwork at an Open Air Lab, a laboratory experiment with miniature LPDs and the development of a conceptual model were used to characterise the hydrological behaviour of a slope in which a LPD is installed. After comparison of this hydrological behaviour to that of a slope with bare soil, it was found that a LPD facilitates rapid infiltration and drainage of precipitation and subsurface water. Furthermore, runoff volumes decrease after installation of a LPD and this effect is enhanced through plant development. Vegetation also contributes to the decrease of the stored volume of water in the subsurface through evapotranspiration. An increase of the design aspects diameter and macropore fraction of the LPD increases its drainage capacity. This study resulted in a first version of a numerical model to quantify the hydrological processes in a hillslope with LPD and the confirmation of the expected effect of drainage through preferential flow by a LPD.