Impacts of Physical Clogging in the Soil Surface on Groundwater Recharge Using Experimental Models

Groundwater recharge basin is an important method widely implemented to compensate the excessive stress and overexploitation of the natural groundwater resources. Rain water harvesting is one of the largest main sources for groundwater recharge such as recharge dams, urban flood filtration systems, trenches, recharge basins, ... etc. Physical, biological and chemical clogging is by far the major hinder in front of the practical wide use of such systems and rapidly shorten the life span of existing application. Soil clogging is the main cause for the rapid reduction in the soil hydrogeological efficiency (infiltration and hydraulic conductivity) to nourish aquifers and utilize surface water. Not to mention, Soil clogging has many impacts not only hydro-geologically but also environmentally, ecologically, and geologically. Despite the huge efforts took for finding acceptable approaches for pre-treating and filtering, yet percentage of fine suspended sediments find their way through and participate in clogging in the surface soil layers.

There are many geological, hydrological, hydrogeological and hydraulic factors affecting clogging, which makes it complex phenomena to be fully covered. There is gap in the scientific knowledge to understand the basic relations between such factors and the impact of clogging on the infiltration process.

This study focuses on one-dimensional experimental model to investigate the physical clogging (PC) process that may occur in the surface spreading basins caused by the migration and deposition of the fine suspended particles into the soil surface top most layer. The main target of this research is to find basic relations between different factors, the PC occurrence and the reduction in the infiltration rate. Various soil conditions are examined in the laboratory to compare various combinations of different parameters.

Size of bed material (BM), size of suspended sediments (SS), and SS concentration are commonly highlighted to be the main variables causing the PC. Different hydrogeologic parameters such as hydraulic pressure, hydraulic conductivity, soil sample analyses as well as sample photos has been used to identify the occurrence and the extend of PC.

The preliminary analysis of the previous studies revealed that: 1) few variables used to monitor the PC and each has wide ranges, and more variables needs to be considered, 2) no basic relations that could be widely adapted, 3) the need of more insight on such phenomena, 4) general definitions and guidance regarding PC extend and the degree of occurrence, and 5) combinations between variables has to be considered for more reliability.