(>2000 m). Flood events in the larger rivers result in influential plumes of fine
suspended sediments along both margins (Lobo et al. 2006). In contrast, the shorter
rivers and streams remain dry for most of the year but have sporadic torrential
regimes, discharging anything from gravels to silty sediments (El Moumni and
Gensous 1992; Liquete et al. 2005; Lobo et al. 2006; Fernández-Salas et al. 2007).
Most of the rivers flowing into the Alboran Sea display a seasonally contrasting
pattern, with maximum water discharges in winter and very low discharges for the
rest of the year (Stanley et al. 1975; Liquete et al. 2005; Lobo et al. 2006). In
addition, water discharge is also very irregular on an inter-annual basis, with
alternating dry and humid years.
6.2.2 Oceanographic Settings
Present-day circulation is largely influenced by the exchange of water through the
Strait of Gibraltar, the AW flowing into the Alboran Sea and the MWs flowing out
into the Atlantic Ocean (e.g. Parrilla et al. 1986). This exchange of water masses is
conditioned by the high evaporation rates of the Mediterranean basin (exceeding
precipitation and river runoff), which are compensated for by the inflow of the AW.
The AW flows at a maximum water depth of 150–200 m and describes two
anticyclonic gyres (Chap. 4) (Fig. 6.1a). Water masses with a Mediterranean origin
can be grouped by density (e.g. Millot 1987, 1999). Intermediate water comprises
the Western Intermediate Water (WIW) flowing at a depth of 150–200 m in the
western Mediterranean; the Levantine Intermediate Water (LIW), which forms in the
western Mediterranean and flows towards the west between depths of 200–600 m;
and the lightest part of the Tyrrhenian Deep Water (TDW), formed in the Tyrrhenian
Sea and flowing below a depth of 500 m. The properties of this water mass vary from
being similar to LIW to more like the Western Mediterranean Deep Water
(WMDW). Deep water includes the TDW, the densest; and the WMDW, which
fills the Alboran sub-basins at greater depths. On the western Moroccan slope,
WMDM mixes locally and seasonally with AW, forming the Shelf Water flowing
to the northwest (ShW, Gascard and Richez 1985) (Fig. 6.1a).
In the Alboran Sea, the intermediate Mediterranean water masses (WIW, LIW,
and upper TDW) are less dense and saline, and are grouped into the Light Mediterranean Water (LMW) (Fig. 6.1a) (Ercilla et al. 2016). LMW circulates mainly along
the Spanish margin. The deep Mediterranean water masses (lower TDW and
WMDW) are denser and are grouped into the Dense Mediterranean Water (DMW)
(Ercilla et al. 2016). DMW circulates along the Moroccan margin and in the deep
basin and is forced upwards by the topography (Fig. 6.1a) (Parrilla et al. 1986).
⁄
ä
Fig. 6.1 (continued) Serrata-Carboneras Fault; DB Djibouti Bank; EAB Eastern Alboran Basin; FP
Francesc Pagès seamount; NB Nekor Basin; NF Nekor Fault; SAB Southern Alboran Basin; TF
Trougout Fault; WAB Western Alboran Basin; YF Yusuf Fault; Alboran Is. Alboran Island
6 Seafloor Morphology and Processes in the Alboran Sea
161
suspended sediments along both margins (Lobo et al. 2006). In contrast, the shorter
rivers and streams remain dry for most of the year but have sporadic torrential
regimes, discharging anything from gravels to silty sediments (El Moumni and
Gensous 1992; Liquete et al. 2005; Lobo et al. 2006; Fernández-Salas et al. 2007).
Most of the rivers flowing into the Alboran Sea display a seasonally contrasting
pattern, with maximum water discharges in winter and very low discharges for the
rest of the year (Stanley et al. 1975; Liquete et al. 2005; Lobo et al. 2006). In
addition, water discharge is also very irregular on an inter-annual basis, with
alternating dry and humid years.
6.2.2 Oceanographic Settings
Present-day circulation is largely influenced by the exchange of water through the
Strait of Gibraltar, the AW flowing into the Alboran Sea and the MWs flowing out
into the Atlantic Ocean (e.g. Parrilla et al. 1986). This exchange of water masses is
conditioned by the high evaporation rates of the Mediterranean basin (exceeding
precipitation and river runoff), which are compensated for by the inflow of the AW.
The AW flows at a maximum water depth of 150–200 m and describes two
anticyclonic gyres (Chap. 4) (Fig. 6.1a). Water masses with a Mediterranean origin
can be grouped by density (e.g. Millot 1987, 1999). Intermediate water comprises
the Western Intermediate Water (WIW) flowing at a depth of 150–200 m in the
western Mediterranean; the Levantine Intermediate Water (LIW), which forms in the
western Mediterranean and flows towards the west between depths of 200–600 m;
and the lightest part of the Tyrrhenian Deep Water (TDW), formed in the Tyrrhenian
Sea and flowing below a depth of 500 m. The properties of this water mass vary from
being similar to LIW to more like the Western Mediterranean Deep Water
(WMDW). Deep water includes the TDW, the densest; and the WMDW, which
fills the Alboran sub-basins at greater depths. On the western Moroccan slope,
WMDM mixes locally and seasonally with AW, forming the Shelf Water flowing
to the northwest (ShW, Gascard and Richez 1985) (Fig. 6.1a).
In the Alboran Sea, the intermediate Mediterranean water masses (WIW, LIW,
and upper TDW) are less dense and saline, and are grouped into the Light Mediterranean Water (LMW) (Fig. 6.1a) (Ercilla et al. 2016). LMW circulates mainly along
the Spanish margin. The deep Mediterranean water masses (lower TDW and
WMDW) are denser and are grouped into the Dense Mediterranean Water (DMW)
(Ercilla et al. 2016). DMW circulates along the Moroccan margin and in the deep
basin and is forced upwards by the topography (Fig. 6.1a) (Parrilla et al. 1986).
⁄
ä
Fig. 6.1 (continued) Serrata-Carboneras Fault; DB Djibouti Bank; EAB Eastern Alboran Basin; FP
Francesc Pagès seamount; NB Nekor Basin; NF Nekor Fault; SAB Southern Alboran Basin; TF
Trougout Fault; WAB Western Alboran Basin; YF Yusuf Fault; Alboran Is. Alboran Island
6 Seafloor Morphology and Processes in the Alboran Sea
161