The extent of aquifer salinization next to an estuarine river: an example from the eastern Mediterranean

Shalem, Yehuda; Weinstein, Yishai; Levi, E.; Herut, Barak; Goldman, M.; Yechieli, Yoseph

doi:10.1007/s10040-014-1192-3

Cited by 33 publications

(16 citation statements)

References 28 publications

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“…For hydrogeologically homogeneous systems, fairly reliable predictions can be made on the basis of the Ghyben-Herzberg relationship. The extent of seawater intrusion into the coastal aquifer can also be estimated by salinity measurements in observation wells [14][15][16][17][18] or by hydrological modeling [15,[19][20][21][22], as well as by geophysical measurements [14,23,24]. While the nature of the seawater-groundwater interface was widely discussed in different coastline In areas where the riverbed is below sea level, it is subjected to seawater encroachment, reaching 4-5 km upstream.…”

Section: Introductionmentioning

confidence: 99%

“…Immediately after such an event, large volumes of seawater penetrate the river channel. In these cases, salinities in the deeper layer may increase to 35 and a sharp halocline is developed, which further prevents vertical mixing of surface and bottom water [16,40].…”

Section: Introductionmentioning

confidence: 99%

“…The connection of the river with the sea is usually blocked by a shallow bar, which is built of sand and pebbles [40,43]. The sandbar exists at the river mouth almost year-long, although it is occasionally breached, mostly during high-sea and high-discharge winter events [16].…”

Section: Introductionmentioning

confidence: 99%

“…This is dependent on the history of seawater encroachments to the river, which are better preserved in the low-permeability unit, and on the hydrogeology of this unit, where sand lenses can serve as high-permeability conduits. However, this unit can efficiently prevent a large extent of salinization of the regional coastal aquifer by the estuary water.2 of 20 settings (e.g., References [10,25] and the references therein) [26][27][28][29], the salinization of coastal aquifers via estuarine streams was hardly studied in the field [14,16,30,31].The rate at which water exchanges between surface water and the aquifer is controlled by hydraulic gradient and sediment permeability. In rivers and estuaries, this exchange is also known as a hyporheic exchange [31][32][33][34].…”

mentioning

confidence: 99%

“…2 of 20 settings (e.g., References [10,25] and the references therein) [26][27][28][29], the salinization of coastal aquifers via estuarine streams was hardly studied in the field [14,16,30,31].…”

mentioning

confidence: 99%

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Aquifer Response to Estuarine Stream Dynamics

Shalem

Yechieli

Herut

et al. 2019

Water

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While seawater intrusions are widely discussed, the salinization of coastal aquifers via narrow rivers is hardly documented. This study investigates groundwater dynamics in an aquifer next to an estuarine stream on the eastern Mediterranean coast. Groundwater levels and salinization patterns were examined as a response to dynamic changes in estuary water, both in low-and high-permeability aquifer units. In the high-permeability unit, the extent of salinization was relatively constant, reaching a distance of at least 80 m from the river, with no long-term changes in fresh-saline interface depth, indicating that the system is in a quasi-steady state. Groundwater salinity in the low-permeability unit showed frequent and large fluctuations (up to 36 and 22 at 5 and 20 m from the river, respectively). We suggest that the river may have a more immediate impact on a low-permeability than on a high-permeability aquifer. This is dependent on the history of seawater encroachments to the river, which are better preserved in the low-permeability unit, and on the hydrogeology of this unit, where sand lenses can serve as high-permeability conduits. However, this unit can efficiently prevent a large extent of salinization of the regional coastal aquifer by the estuary water.2 of 20 settings (e.g., References [10,25] and the references therein) [26][27][28][29], the salinization of coastal aquifers via estuarine streams was hardly studied in the field [14,16,30,31].The rate at which water exchanges between surface water and the aquifer is controlled by hydraulic gradient and sediment permeability. In rivers and estuaries, this exchange is also known as a hyporheic exchange [31][32][33][34]. Groundwater-surface water interaction in the estuarine environment is influenced by density contrasts between the typically fresh groundwater and saline-to-brackish estuarine water, which leads to convective circulation in the aquifer [7,19,[35][36][37]. Circulation occurs even if the hydraulic gradient in the aquifer dips toward the estuary [31,38]. The size of the resultant salt wedge is dependent on the hydraulic gradient, aquifer conductivity, and estuary salinity [31,36,39].In this paper, we investigate the dynamics and mechanisms of aquifer salinization next to a bar-built estuarine river by integrating high-resolution level and salinity measurements in the river and the adjacent aquifer. The Study AreaThe Alexander River is a perennial river on the Mediterranean coast of Israel (Figure 1a). The drainage area of the Alexander River is relatively small (555 km 2 , Figure 1a) and, thus, it experiences relatively small peak discharges (up to~180 m 3 /s in recent years; data from the Hydrological Service of Israel). Although it is a perennial river, the river's natural flow to the sea is insignificant during the dry season (the base flow entering the estuarine part is typically ≤0.3 m 3 /s), which is mostly composed of effluents from sewage treatment plants and aquaculture drainage [40].

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