Modeling and control of saltwater intrusion in a coastal aquifer of Andhra Pradesh, India (original) (raw)
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Environmental Earth Sciences, 2016
Puri city is situated on the east coast of India, and groundwater is the only source available to meet city water supply. Due to increase in population and urbanization of the city, groundwater withdrawal is continuously increasing, which may lead to the movement of saline water interface toward the fresh groundwater. Therefore, the objective of this study was to assess the hydrodynamics of groundwater flow and to predict withdrawal for future water demand of the city without affecting the saltwater intrusion. For this, a groundwater flow model was conceptualized and validated for the present withdrawal coupled with the saltwater intrusion model. To assess the safe yield of groundwater withdrawal, various iterations were carried out with different withdrawal rates and movement of fresh and saltwater interface. This helped in quantifying the future demand of city water supply without affecting the interface between fresh groundwater and saltwater. Based on the simulation results, various measures were suggested to safeguard the groundwater resource against saltwater intrusion.
"Modeling of Saline Water Intrusion using MODFLOW in Una Coastal Aquifer of Gujarat, India."
International Journal for Research in Applied Science & Engineering Technology (IJRASET), 2022
Groundwater is the most valuable and extensively dispersed resource on the planet, and unlike any other mineral resource, it is replenished annually by meteoric precipitation. The present study would include simulation and modelling of the problem of seawater intrusion in the Una coastal area of Gujarat. The interrelationships of two miscible fluids in porous media have been widely explored both theoretically and experimentally. Because of the extreme salinity, many agricultural wells are no longer used. This high salinity is a sign of a process known as saltwater intrusion, which occurs mostly in coastal aquifers due to excessive pumping. Modelling software has also been utilized to analyze the behavior of groundwater flow models. Numerical models may simulate diverse groundwater scenarios and link them to groundwater management. To simulate seawater intrusion, MODFLOW-2005, a grid-based variable density-dependent flow model, is used. Water balance research reveals that rainwater recharge is the aquifer's primary input. To compute the water level in the area and estimate the position of the seawater intrusion barrier, the saltwater intrusion phenomena were simulated using the MODFLOW software combined with the SWI2 package. The model was used to visualize the salinity levels of the coastal aquifer's groundwater and their fluctuation over time and space from May 2004 to October 2014. The model was developed for a 10-year stress period with 100-time steps, which included a 5-year steady state and 5 years transient state stress period using the previous 10 years of pre-monsoon and postmonsoon data. This research would assist to describe Pumping's impact on groundwater levels and seawater intrusion was studied.
Numerical Simulation and Prediction of Groundwater Flow in a Coastal Aquifer of Southern India
Chennai is one of the most water-stressed cities in south India due to rapid industrialization and urbanization. The well fields located in north and south of the Chennai city meet part of the city's water requirement. The south Chennai aquifer is surrounded by saline surface water on all sides. Since 1990, the influence of seawater in to this freshwater aquifer has been reported as an issue for consideration and mitigation measures. Therefore, in the present study an attempt is made to comprehend the status of aquifer with present level of pumping/recharge and to predict the behavior with different hydrologic stresses. Numerical modeling was carried out by finite element approach using FEFLOW software. The model has been developed with three subsurface layers and simulation was processed from January 1998 to December 2020. The groundwater usage had varied from 11.3 MLD to 17.2 MLD during the period of study. If the recharge and discharge continue in a similar pattern, the maximum level of freshwater decline will be 0.32 m at the end of 2020. Hence, prediction of behavior of this aquifer for increased discharge and decreased recharge scenario has been carried out. It is found that with an increase of discharge, there is a sharp change in interface of seawater and freshwater. This model can be used as a tool to understand the aquifer regionally and to plan proper groundwater management measures.
Salt Water Intrusion Modeling of an Aquifer in the Northwest of Maharlu Lake
2010
Coastal aquifers are important supply sources of fresh water in numerous area of earth. The problem of saltwater intrusion has been widely caused the deterioration of water qulity in these sources. As fresh water flows from the aquifer near the coastline. Eventually dynamic equilibrium is reached between the fresh and saltwater. Intrusion of pumping wells within coastal aquifer has the
Modeling saline water intrusion in Nagapattinam coastal aquifers, Tamilnadu, India
Abstract Unexpected mistreatment of groundwater from coastal aquifers may possibly cause salt water intrusion in coastal aquifers. Coastal areas are mostly overpopulated with productive agricultural lands and expanded irrigated farming actions. Field and modeling studies were started to consider the special effects of possible seawater intrusion into the coastal aquifers. Groundwater levels were measured at 61 locations in Nagapattinam and Karaikal coastal region, identified flow direction pointing toward the coast with no major change in groundwater table. Groundwater samples were collected and analyzed for major ionic parameters, represented higher concentration of conductivity, total dissolved solids, sodium and chloride along the coastal parts of the study area. A computer package for the simulation of dimensional variable density groundwater flow, SEAWAT, has been used to model the seawater intrusion in the coastal aquifers of the study area. The model was stimulated to predict the amount of seawater incursion in the study area for a period of 50 years. The simulation results signify saline water intrusion mainly due to up coning of saline water owing to over drafting of groundwater.
Simulation of Saltwater Intrusion in Coastal Aquifer of Kg. Salang, Tioman Island, Pahang, Malaysia
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 96m 3 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.
Analysis and Control of Saline Water Intrusion into a Coastal Aquifer in West Bengal, India
Saline water intrusion into fresh groundwater aquifers takes place in the vicinity of coastal regions having hydraulic continuity with sea. India has significantly long coastal belt and contamination in the aquifers in these regions by saltwater intrusion has been evidenced. Such intrusion is likely to cause serious consequence if such aquifers are tapped for domestic water supply, irrigation or any other specific purpose. This paper is based on extensive field study on subsurface and groundwater characterization in a coastal city of West Bengal, India. An innovative methodology was developed to control the saltwater intrusion into coastal aquifers.
Pumping management of coastal aquifers using analytical models of saltwater intrusion
Water Resources Research, 2003
1] Analytical models of saltwater intrusion in coastal aquifers of finite size are developed and utilized in an optimization methodology for determining the optimal pumping rates. The models are based on the sharp interface approximation and the Ghyben-Herzberg relation. The governing equations are expressed in terms of a single potential and are solved analytically using the method of images to account for the aquifer boundaries. The analytical models consider ambient flow and surface recharge. The results are compared to numerical simulations indicating a good match as the number of images is increased. The objective of optimization is to maximize the total pumping from the aquifer and a set of constraints protect the wells from saltwater intrusion. The constraints are expressed using the analytical saltwater intrusion models. Two different constraint formulations are investigated. The ''toe constraint'' formulation protects the wells from saltwater intrusion by not allowing the toe of the interface to reach the wells. This formulation results in a nonlinear optimization problem which is solved using sequential quadratic programming (SQP). The ''potential constraint'' formulation, on the other hand, protects the wells by maintaining a potential at the wells larger than the toe potential. This formulation results in a linear optimization problem which is solved using the Simplex method. Several simulation runs indicate that the optimal solution is very sensitive to variations of recharge rates, hydraulic conductivity heterogeneities, etc. The linear programming formulation, besides being computationally simpler, provides a safer solution than the nonlinear formulation. Citation: Mantoglou, A., Pumping management of coastal aquifers using analytical models of saltwater intrusion, Water Resour.
Control of saltwater intrusion by aquifer storage and recovery
Proceedings of the Institution of Civil Engineers - Engineering and Computational Mechanics, 2016
This paper presents the results obtained from the application of aquifer storage and recovery (ASR) technique to control seawater intrusion (SWI) in coastal aquifers. The study is based on the numerical modelling experiments performed using the SUTRA (Saturated-Unsaturated TRAnsport) finite-element code on the Wadi Ham aquifer in the UAE. A three-dimensional numerical model of this aquifer is developed and calibrated based on the available hydrogeological data in real scale. A significant amount of SWI has been calculated for the year 2015 due to the high rates of pumping from the available local well fields. To study the future responses of the aquifer to different control actions, the transient responses of SWI are simulated over a 10-year planning horizon. The proposed management measure (ASR) is implemented in repeated cycles of artificial recharge, storage and recovery using an additional set of wells defined in the model. The results show that ASR is a reliable method in controlling SWI in coastal aquifer systems besides its conventional role in subsurface water banking.