Field Experimental Study on the Infiltration and Clogging Processes at Aksu Research Site, Kazakhstan

Abstract

The challenge of a good quality drinking water supply to southeastern Kazakhstan’s local population from far-away natural surface water sources motivates groundwater utilization from local aquifers. To prevent groundwater resource deficits, artificial groundwater recharge is needed. To this end, infiltration and clogging processes were evaluated through comprehensive field research in southeastern Kazakhstan’s typical river drainage basin (Aksu experimental site). The infiltration scenario included constructed mini pools and their typical soil profile clogging and silting processes. The local aquifer unsaturated and upper saturated zones underwent a detailed study of water balance, hydrodynamic setting, and filtration properties. The research results suggest that the infiltration rate decreased from 15 m/day until the saturation steady state and remained at 0.75 m/day until the end of the experiment. In summer, clogging layers with thicknesses ranging from 3 mm for the clayey silt layer to 6 mm for muddy clay began to form at the mini pools nearly one month after the test began. During infiltration, the mini pools’ upper soil layer dirt-holding capacity varied from 3.72 to 5.25 kg/m2. The field study results serve as a factual basis for artificial replenishment system design and groundwater replenishment methodology optimization in southeastern Kazakhstan and similar regions.

MODFLOW and HYDRUS Modeling of Groundwater Supply Prospect Assessment for Distant Pastures in the Aksu River Middle Reaches

“…The river flow is regulated by a reservoir system, and a small hydroelectric power station was built on the river near the Zhansugurov settlement for local needs. The river section in the study site has a width of 40-50 m and a gradient of 16.3 m. At the study site's western border, the river's bottom height above sea level is 411.6 m, and at the eastern border, it is 427.9 m. The depth of the river in this area varies from 0.9 to 1.5 m and from 0.6 to 1.15 m, respectively, depending on the annual rainfall [19].…”

“…Since the system consists of one aquifer layer and the HYDRUS-1D supplies the input to this layer, a 2D MODFLOW In the first step, all available data needed for modeling were collected and arranged as a Geographical Information System Data Base (GIS-DB). The data were obtained from official Kazakh hydrogeological survey reports, the personal communication of the government program and field research in the area [19]. In the second step, a reasonable assumption that the flow from the mini pools to the aquifer vertically enabled the use of the HYDRUS-1D model that was created to evaluate the infiltration and clogging processes at the infiltration mini pool and in the unsaturated zone.…”

“…The initial data for the infiltration process modeling were the in-situ test carried out at the Aksu experimental site [19]. Two infiltration process variants were modeled using HYDRUS-1D software.…”

“…Infiltration is a process by which water enters the soil, and it is one of the key fluxes in the hydrological cycle that affect the soil water balance [15][16][17]. The experimental studies carried out at the Karatal experimental site evaluated the infiltration and clogging processes and the silting in the mini pool's infiltration profile [18,19]. Detailed assessments of cover deposits, upper aquifer layers and water-physical, hydrodynamic and filtration properties play a significant role in infiltration and colmatation processes [20].…”