Title : A laboratory study on the geohydraulic properties of sand under saline water submergence
Abstract:
Rising sea levels have a significant impact on saltwater intrusion, which has been researched for decades. The issue gets significantly worse when the effects of overpumping and sea level rise are coupled. It is yet in the preliminary phases to consider real sloping seaward borders of saltwater concerns in unconfined aquifers. From the theoretical analysis of previously done studies it is noticed that when there is excessive extraction of ground water from coastal aquifers the saline water moves towards the extraction area by significantly altering the hydraulic conductivity of the coastal soil. The saline water intrusion is more sensitive to pumping and recharges rates of ground water as compared to aquifer properties. In the theoretical analysis it is found that there are various methods available for preventing saline water intrusion, out of them extraction of ground water through Qanat-well structure linked with artificial recharge supported by percolation ponds and recharge wells is effective method to minimize saline water intrusion in areas having significant annual precipitation, superior hydraulic conductivity and low depth of fresh groundwater. Another efficient methodology found in theoretical analysis which prevents saline water intrusion was Abstraction De-salanisation & Recharge methodology. This method is found to be efficient where extraction rate of ground water is more. The present study emphasizes on the engineering properties of sand which get affected by the saline water. For analyzing the affects of salt water on sand laboratory experiments (tests on Specific gravity, Relative Density, Hydraulic Conductivity) were conducted. The tests were first conducted on normal sand which was not submerged in concentrated saline water solution and results were observed for comparison. In case of relative density it is observed that the maximum and minimum dry density of sand decreases with the increase in salt particles. On the other hand the relative density increases with increase in salt water concentration and submergence period of sample. In case of permeability it is observed that the overall hydraulic conductivity of the sample decreases significantly with increases in concentration of salt and submergence period. From the present study it can be said that when salt particles gets dissolved in sand by either filling up the voids between two sand particles or by forming a layer on each sand particle the engineering properties of the sand drastically changes. Further detail study is required to determine whether the salt particles gets dissolved in sand by either filling up the voids between two sand particles or by forming a layer on each sand particle.
Audience Takeaway:
- Major causes of Saline Water Intrusion
- Discussion on hydraulic conductivity
- Outcomes of extensive laboratory investigation to determine saline water interface
- Preventive design Recommendation
