Comparing manual versus automated Beerkan runs for the estimation of water infiltration and soil hydraulic parameters for an urban soil
Authors: Saint Louis Saint Martin , Boncourage Fasnet , Di Prima Simone , Prédélus Dieuseul , Angulo-Jaramillo Rafael , Lassabatere Laurent 
Published: March 2024

Adapting cities to climate and global changes requires tremendous progress in managing the water cycle in cities. So far, the water pathways are disconnected from the natural water cycle in urban areas. Runoff water is collected and routed to sewer systems. Best management practices were then developed to restore the natural water cycle by promoting water infiltration into specific urban drainage systems. These are often called &#8220;SUDS&#8221; for Sustainable Urban Drainage Systems and infiltrate the runoff water collected over urban catchments. However, SUDS may lose their capability to infiltrate water as the soil clogs and becomes less permeable. For these devices, soil hydraulic conductivity must be monitored over time.Water infiltration techniques have been developed to characterize the soil hydraulic properties. The Beerkan method was pioneered by Braud et al. in 2005 and then used by many soil scientists (Angulo-Jaramillo et al., 2016). Several algorithms were developed to treat the data and estimate the soil hydraulic properties. In 2006, Lassabatere et al. (2006) initiated the BEST method to identify the saturated hydraulic conductivity and the whole set of unsaturated hydraulic parameters from Beerkan runs combined with field data (bulk density and particle size distribution). Since then, the method has been improved and adapted to many types of soils and configurations (see Angulo-Jaramillo et al., 2019, for a review).The Beerkan run is easy to perform. It requires one operator to prepare known volumes of water, infiltrate them into a ring inserted in the soil, and score the infiltration times. The cumulative infiltration, which assigns the cumulative infiltrated volume to the infiltration time, is the raw data that is used in most hydraulic characterization algorithms. However, its ease of use requires human resources (one operator) and may be time-consuming, particularly for fine soils that infiltrate very slowly. Di Prima et al. (2016) recently designed an automated infiltrometer that replaces the operator. The device automatically supplies the water before desaturation of the soil surface and records the infiltrated volume as a function of time. This device has been deployed for several studies, allowing the hydraulic characterization of several types of soils under several field conditions.However, so far, no studies have focused on comparing the automated infiltration, referred to as &#8220;Automated Beerkan,&#8221; and the manual version of the Beerkan runs. In this study, we performed the two types of runs at the same places in order to avoid uncontrolled variations due to spatial variability in urban soils. We present the cumulative infiltrations obtained at the same point with the automated Beerkan and the original Beerkan (manual version). The cumulative infiltrations were inverted using the BEST methods, and the obtained hydraulic parameters were compared.Di Prima, S., et al.,2016. Geoderma 262, 20&#8211;34. https://doi.org/10.1016/j.geoderma.2015.08.006Angulo-Jaramillo, R., et al., 2016. Springer, Switzerland. https://doi.org/10.1007/978-3-319-31788-5Angulo-Jaramillo, R., et al., 2019. Journal of Hydrology 576, 239&#8211;261. https://doi.org/10.1016/j.jhydrol.2019.06.007Braud, I., et al. 2005. European Journal of Soil Science 56, 361&#8211;374. https://doi.org/10.1111/j.1365-2389.2004.00660.xLassabatere, L., et al., 2006. Soil Science Society of America Journal 70, 521&#8211;532. https://doi.org/10.2136/sssaj2005.002