Hydrochemical Indicators Analysis of Seawater Intrusion in Coastal Karstic Aquifers on the Example of the Bokanjac-Poličnik Catchment Area in Zadar, Croatia

Abstract

Monitoring and detection of seawater intrusion in coastal aquifers in Croatia are one of the water management measures that attempt to notice an increase in salinity in time. Bokanjac-Poličnik is the coastal aquifer in Croatia that is at the risk of seawater intrusion. In that area, analysis of hydro-chemical indicators will be conducted due to the occasional seawater intrusion that occurs on wells that are included in the water supply system for the City of Zadar and surrounding villages. Due to the increased exploitation during the tourism season in summer and climate changes, salinization process is more intense. The presented results indicate that two of four wells on the case study area are under the influence of salt marine water.

Saltwater Intrusion of Coastal Karstic Aquifer on the Example of the Boljkovac Water Supply Pumping Station near Zadar, Croatia

“…In the Bokanjac-Poličnik catchment area, where the Boljkovac water pumping station is located, the analysis of trends in annual precipitation, average annual air temperature, average annual flow of Miljašić Jaruga watercourse, and average annual sea level for the period 1961 to 2009 indicates reduced average annual precipitation in analyzed period of almost 200 mm, increase of average annual air temperature by 1.5 • C, increase of average annual sea level by about 5 cm and decrease of flow on Miljašić Jaruga by about 0.4 m 3 /s [6]. Climate models with forecasts indicate a further reduction in precipitation by 2100 [29].…”

“…The problem of salinization of coastal springs and the impact of salinization on coastal aquifer zones has been studied in numerous aquifers and coastal springs throughout Croatia [2,[6][7][8][9] and the Mediterranean area [10][11][12][13][14][15].…”

Selective recovery of calcium from estuarine sediments of Raša Bay

“…6a, which con rms a possible intrusion of sea water in the chosen location . Geochemical evolution owing to the mineralization and salinization, affects the chemical content of the groundwater and the associated soil sediment (Plantak et al, 2021). The presence of high concentration of calcium throughout the entire depth was noteworthy, which was expected to be in the form of carbonate minerals (Table 2, Fig.…”

“…Likewise, the primary mineral phases detected in the soil sediment were that of calcite (CaCO 3 ), dolomite [CaMg(CO 3 ) 2 ] along with sporadic distribution of quartz (SiO 2 ) and magnetite (Fe 2 O 3 ) (Fig.6a). Such a mineralogical pro ling is quite a typical scenario for sedimentation in the estuary where the river ow is dominant and the in uence of waves and the tide is relatively low leading to long surface oating duration of clay particles(Plantak et al, 2021).…”

Multidisciplinary investigations of a karst reservoir for managed aquifer recharge applications on the island of Vis (Croatia)

“…Furthermore, some islands have composite water supply solutions, such as small desalination plants for salinized water from brackish lakes (e.g., Borović et al 2019). The most significant problem regarding the water supply on Croatian islands is represented by seawater intrusions into aquifers (e.g., Lukač Reberski et al 2020;Plantak et al 2021;Terzić et al 2008). This problem is mostly inherent due to: (i) their small surface area resulting in small catchments and aquifers, (ii) intense fracturing and karstification with a karst base level below the present sea-level resulting in high permeability of the rock mass and preferential seawater intrusion through karstic conduits, and (iii) relatively low precipitation and high evapotranspiration.…”