Assessment of seasonal groundwater quality and potential saltwater intrusion: a study case in Urmia coastal aquifer (NW Iran) using the groundwater quality index (GQI) and hydrochemical facies evolution diagram (HFE-D)

Abstract

Coastal aquifers are at threat of salinization in most parts of the world. This work investigated the seasonal hydrochemical evolution of coastal groundwater resources in Urmia plain, NW Iran. Two recently proposed methods have been used to comparison, recognize and understand the temporal and spatial evolution of saltwater intrusion in a coastal alluvial aquifer. The study takes into account that saltwater intrusion is a dynamic process, and that seasonal variations in the balance of the aquifer cause changes in groundwater chemistry. Pattern diagrams, which constitute the outcome of several hydrochemical processes, have traditionally been used to characterize vulnerability to sea/ saltwater intrusion. However, the formats of such diagrams do not facilitate the geospatial analysis of groundwater quality, thus limiting the ability of spatio-temporal mapping and monitoring. This deficiency calls for methodologies which can translate information from some diagrams such Piper diagram into a format that can be mapped spatially.Distribution of groundwater chemistry types in Urmia plain based on modified Piper diagram using GQI Piper(mix) and GQI Piper(dom) indices that Mixed Ca-Mg-Cl and Ca-HCO 3 are the dominant water types in the wet and dry seasons, respectively. In this study, a groundwater quality index specific to seawater intrusion (GQI SWI ) was used to check its efficiency for the groundwater samples affected by Urmia hypersaline Lake, Iran. Analysis of the main processes, by means of the Hydrochemical Facies Evolution Diagram (HFE-Diagram), provides essential knowledge about the main hydrochemical processes. Subsequently, analysis of the spatial distribution of hydrochemical facies using heatmaps helps to identify the general state of the aquifer with respect to saltwater intrusion during different sampling periods. The HFE-D results appear to be very successful for differentiating variations through time in the salinization processes caused by saltwater intrusion into the aquifer, distinguishing the phase of saltwater intrusion from the phase of recovery, and their respective evolutions. Both GQI and HFE-D methods show that hydrochemical variations can be read in terms of the pattern of saltwater intrusion and groundwater quality status. But generally, in this case (i.e. saltwater and not seawater intrusion) the HFE-D method was presented better efficiency than GQI method (including GQI Piper and GQI SWI ).

Interaction of groundwater with Lake Urmia in Iran

“…Amirataee and Zeinalzadeh () and Bateni () studied the trends associated with the autocorrelation of the groundwater time series in the west coast of Lake Urmia. Amiri, Nakhaei, Lak, and Kholghi (, ) analysed groundwater in the western part of the Lake Urmia basin to conclude that recharge of groundwater was important in wet seasons. Gorgij, Kisi, and Moghaddam () used the hybrid wavelet‐artificial neural network‐genetic programming as a method to study the water budget in Azarshahr Plain at the eastern bank of Lake Urmia.…”

Temporal Variation of Coastal Groundwater Quality in East Coast of Terengganu, Malaysia

“…Subsequently, the factors affecting groundwater quality in coastal aquifers can be identify [18]. Diamond plot can be divided into six domains that represent six water types where domain I represents Ca-HCO3 water type; domain II represents Na-Cl water type; domain III represents mixed Ca-Na-HCO3 water type; domain IV represents mixed Ca-Mg-Cl water type; domain V represents Ca-Cl water type; and domain VI represents Na-HCO3 water type [8,19,20]. In this study, piper diagram is plotted by using GW_Chart Calibration Plots: A Graphing Tool for Model Analysis software.…”

“…As it is located near the coastline, groundwater in the coastal aquifer is vulnerable to saltwater intrusion phenomenon due to global sea level rise and overpumping [2][3][4][5]. Other contributor for the rise of salinity in coastal aquifer is suggested to be due to meteoric origin, water-rock interaction, salts from irrigation, wastewater, road salt and gypsum applied to enhance agricultural soil quality [6][7][8].…”

“…In order to preserve coastal groundwater, the sources of saline water and mechanisms of mobility need to be identify so that, fresh groundwater resources can be sustained [10]. Three common methods used for water quality assessment in coastal areas are hydrogeochemical methods, geophysical investigations and multivariate technique [8,11]. In this study, hydrogeochemical method is adopt to understand the hydrochemical temporal variations, so that the potential contamination of saltwater into coastal groundwater can be identified.…”

Hydrochemical Facies and Ionic Exchange in Coastal Aquifers of Puducherry Region, India: Implications for Seawater Intrusion

“…Salinization of groundwater is controlled by factors like seawater intrusion, rock-water interaction, over exploitation, rise in sea level, climatic changes, hydrogeological setting of the study area, salt panning, improper sewage disposal, use of chemical fertilizers and pesticides, marine formations, etc. (Nair et al 2015;Batayneh et al 2014;Anders et al 2013;Amiri et al 2015). Among all these factors, seawater incursion is considered to be a major threat to coastal aquifers globally.…”