Simulation of Saltwater Intrusion in Coastal Aquifer of Kg. Salang, Tioman Island, Pahang, Malaysia

Azrul Normi Idris,Mohd Khairul Nizar Shamsuddin,Saim Suratman,Sarva Praveena Mangala,Ismail Tawnie,Ahmad Zaharin Aris,Anuar Sefie,Tahoora Sheikhy Narany,M.J Zainorizuan,L Alvin John Meng Siang,L Yee Yong,O Mohamad Hanifi,R Siti Nazahiyah,A Mohd Shalahuddin

doi:10.1051/matecconf/201710304024

Abstract

Numerical models are capable of simulating various groundwater scenarios and relate it towards groundwater management. A mesh based density dependent flow model, FEFLOW is used to simulate groundwater flow and transport for a coastal island aquifer in Kg. Salang, Tioman Island, Malaysia. FEFLOW is designed to simulate 2D and 3D, variable density groundwater flow and multi-species transport. The impacts of pumping and recharge rates represented by three different groundwater scenarios, which were investigated by means of hydraulic heads, TDS concentrations and water balance components. Scenario A showed the standard saturated groundwater flow and the steady state fluid flow. Over pumping and inconsistency in recharge rate are the stresses shown in Scenarios B and C. Scenario B involved in the maximum pumping rate of 96m3 per day and recharge rate of 300mm per year has shown a drawdown of 1.5 m. Scenario C showed the extreme pumping rate of 1000m 3 per day and without recharge has shown a decrease in groundwater levels of 6.3 m.and groundwater storage (50%). Scenario B presented the most promising finding compared with Scenario C. Highest hydraulic heads, lowest mass concentration and positive groundwater storage (2578.6m 3 /day) were obtained in Scenario B. Additionally, and further progress is needed in obtaining the water usage data from each part to determine the best pumping rate. A sustainable groundwater management plan is crucial to maintain the natural resources and social benefits as well as to protect the ecological balance.

Highlights

The fresh water of small tropical islands is often very limited and mostly depend on recharge quantity and storage capability of groundwater resources [1]
Seaward freshwater gradient gets reduced and even sometimes may be reversed to landward direction due to the excessive pumping activities. This leads to aggressive saltwater intrusion from the sea contaminating inland fresh water aquifers to a large extent which may take several years to get remediated [2]
The impact of climate change such as recharge rate and human pressure pumping rate on freshwater/groundwater have been controlling the shape and thickness of the freshwater lens [3]. To address this issue effectively, density dependent groundwater model is required to track the movement of the solute in coastal aquifers [4]

Summary

Introduction

The fresh water of small tropical islands is often very limited and mostly depend on recharge quantity and storage capability of groundwater resources [1]. Seaward freshwater gradient gets reduced and even sometimes may be reversed to landward direction due to the excessive pumping activities This leads to aggressive saltwater intrusion from the sea contaminating inland fresh water aquifers to a large extent which may take several years to get remediated [2]. The impact of climate change such as recharge rate and human pressure pumping rate on freshwater/groundwater have been controlling the shape and thickness of the freshwater lens [3]. To address this issue effectively, density dependent groundwater model is required to track the movement of the solute in coastal aquifers [4]

Objectives

Methods

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Conclusion