[A-GE34] Subsurface Mass Transport and Environmental Assessment

[AGE34-P02] Assessing moisture transport in soil-superabsorbent hydrogel system for drought stress management

*Abhisekh Saha¹, Sreedeep Sekharan² (1.Malaviya National Institute of Technology Jaipur , 2.Indian Institute of Technology Guwahati)

Keywords:hydrogel, Drought, Moisture transport, Horizontal absorption, Diffusion

Superabsorbent hydrogel (SAH) is a special type of hydrophilic polymers that can absorb and store large quantities of water and solute molecules due to the presence of several hydrophilic functional groups, such as carboxyl, hydroxyl, etc. SAH is gaining lot of attention in the field of geoenvironmental engineering and climate resilient agriculture for its ability to store water inside soil matrix. It has been reported that SAH particles act like an additional water reservoir, which absorbs the water during rain or irrigation and releases the water back to the soil when it is dry. Therefore, it is very important to understand the basic phenomenon involved in the movement of moisture from swollen hydrogel to dry soil to evaluate its effectiveness under drought conditions. The present study developed a horizontal absorption test (HAT) to characterize the moisture transport from swollen SAH to dry soil. For this purpose, a laboratory synthesized fly ash modified hydrogel (FAH) was used along with two different soil texture [sand and clay loam]. The HAT was performed in a diffusion cell where two portions of the cell, containing swollen hydrogel and dry soil were placed together to allow movement of moisture in the liquid phase from swollen hydrogel to dry soil. Soil moisture profiles (by destructive gravimetric sampling) and inspection of wetting front versus time along the horizontal soil column in contact with swollen SAH were evaluated to obtain the moisture diffusivity through soil column. It was observed that the moisture diffusivity value largely depends on the soil texture and soil pore structure. Coarse textured soil (sand) has the highest moisture diffusivity values as compared to the fine textured soil (clay loam) due to the higher available pore space between sand particles. The results revealed that the swollen SAH was able to release the stored water to the dry soils during water stress conditions.