Numerical modeling of seawater intrusion in the aquifer of Manukan Island

This study presents an understanding of seawater intrusion in the low lying area of Manukan Island. A three dimensional numerical model (SEAWAT-2000) was developed based on modeling protocol using low lying area of Manukan Island. SEAWAT-2000 output indicated that there is about 1.4% of freshwater...

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Main Author:	Sarva Mangala Praveena
Format:	Thesis
Language:	English
Published:	2011
Subjects:	TC Hydraulic engineering Ocean engineering
Online Access:	https://eprints.ums.edu.my/id/eprint/10189/1/ph000000024.pdf
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spelling	my-ums-ep.101892017-10-30T04:00:43Z Numerical modeling of seawater intrusion in the aquifer of Manukan Island 2011 Sarva Mangala Praveena TC Hydraulic engineering. Ocean engineering This study presents an understanding of seawater intrusion in the low lying area of Manukan Island. A three dimensional numerical model (SEAWAT-2000) was developed based on modeling protocol using low lying area of Manukan Island. SEAWAT-2000 output indicated that there is about 1.4% of freshwater and seawater mixing ratio at sea level in low lying area of Manukan Island illustrates the seawater intrusion problem. Upconing process simulated by SEAWAT-2000 showed the current status of seawater intrusion in Manukan Island is about 14.6% of freshwater and seawater mixing ratio at the beneath of pumping well (W6). Moreover, the calibrated model was also used to predict current and potential extent of seawater intrusion in low lying area of Manukan Island two years with all conditions assumed to remain same as those in December 2009 under different scenarios of varying recharge and pumping rates. The SEAWAT-2000 model's output showed pumping rates are higher than recharge rates in all of the selected scenarios, thereby indicating that overpumping is the main factor behind seawater intrusion in the low lying area of Manukan Island. The seawater-freshwater mixing ratio moves landwards after two years of simulation in Scenario 1. In order to control overpumping in this study area, Scenario 2 has resulted in backward movement of the 1.4% seawater-freshwater mixing ratio towards to coast after two years of prediction. The current contamination of the coastal aquifers by seawater intrusion will be more severe with an impact of El-Nino events on groundwater resources depletion in Scenario 3. Reductions of pumping and recharge rates in Scenario 4 have worsened seawater intrusion problem. With an aid of artifidal recharge, highest hydraulic heads and lowest chloride concentration were observed (Scenario 5). In addition to this, water balance components have illustrated sustainable groundwater management. selected for Manukan Island's current situation will be Scenario 2. In view of the effects of EINino events in the future, Scenario 5 can be implemented to restore groundwater resources. Moreover, a suitable groundwater management plan in Manukan Island must also include economic, social and environmental issues together with further adjustment of pumping rate using water usage data from various parts (restaurant, tourism, office and chalets).!n a nutshell, this study has provided a management foundation for restoration of the groundwater resources of Manukan Island which can be applied in other small islands with similar hydrogeological conditions. 2011 Thesis https://eprints.ums.edu.my/id/eprint/10189/ https://eprints.ums.edu.my/id/eprint/10189/1/ph000000024.pdf text en public phd doctoral Universiti Malaysia Sabah School of Science and Technology
institution	Universiti Malaysia Sabah
collection	UMS Institutional Repository
language	English
topic	TC Hydraulic engineering Ocean engineering
spellingShingle	TC Hydraulic engineering Ocean engineering Sarva Mangala Praveena Numerical modeling of seawater intrusion in the aquifer of Manukan Island
description	This study presents an understanding of seawater intrusion in the low lying area of Manukan Island. A three dimensional numerical model (SEAWAT-2000) was developed based on modeling protocol using low lying area of Manukan Island. SEAWAT-2000 output indicated that there is about 1.4% of freshwater and seawater mixing ratio at sea level in low lying area of Manukan Island illustrates the seawater intrusion problem. Upconing process simulated by SEAWAT-2000 showed the current status of seawater intrusion in Manukan Island is about 14.6% of freshwater and seawater mixing ratio at the beneath of pumping well (W6). Moreover, the calibrated model was also used to predict current and potential extent of seawater intrusion in low lying area of Manukan Island two years with all conditions assumed to remain same as those in December 2009 under different scenarios of varying recharge and pumping rates. The SEAWAT-2000 model's output showed pumping rates are higher than recharge rates in all of the selected scenarios, thereby indicating that overpumping is the main factor behind seawater intrusion in the low lying area of Manukan Island. The seawater-freshwater mixing ratio moves landwards after two years of simulation in Scenario 1. In order to control overpumping in this study area, Scenario 2 has resulted in backward movement of the 1.4% seawater-freshwater mixing ratio towards to coast after two years of prediction. The current contamination of the coastal aquifers by seawater intrusion will be more severe with an impact of El-Nino events on groundwater resources depletion in Scenario 3. Reductions of pumping and recharge rates in Scenario 4 have worsened seawater intrusion problem. With an aid of artifidal recharge, highest hydraulic heads and lowest chloride concentration were observed (Scenario 5). In addition to this, water balance components have illustrated sustainable groundwater management. selected for Manukan Island's current situation will be Scenario 2. In view of the effects of EINino events in the future, Scenario 5 can be implemented to restore groundwater resources. Moreover, a suitable groundwater management plan in Manukan Island must also include economic, social and environmental issues together with further adjustment of pumping rate using water usage data from various parts (restaurant, tourism, office and chalets).!n a nutshell, this study has provided a management foundation for restoration of the groundwater resources of Manukan Island which can be applied in other small islands with similar hydrogeological conditions.
format	Thesis
qualification_name	Doctor of Philosophy (PhD.)
qualification_level	Doctorate
author	Sarva Mangala Praveena
author_facet	Sarva Mangala Praveena
author_sort	Sarva Mangala Praveena
title	Numerical modeling of seawater intrusion in the aquifer of Manukan Island
title_short	Numerical modeling of seawater intrusion in the aquifer of Manukan Island
title_full	Numerical modeling of seawater intrusion in the aquifer of Manukan Island
title_fullStr	Numerical modeling of seawater intrusion in the aquifer of Manukan Island
title_full_unstemmed	Numerical modeling of seawater intrusion in the aquifer of Manukan Island
title_sort	numerical modeling of seawater intrusion in the aquifer of manukan island
granting_institution	Universiti Malaysia Sabah
granting_department	School of Science and Technology
publishDate	2011
url	https://eprints.ums.edu.my/id/eprint/10189/1/ph000000024.pdf
_version_	1747836367208972288

Numerical modeling of seawater intrusion in the aquifer of Manukan Island

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