The coastal and alluvial plains of Iran's Hormozgan Province occur. However, the low coastal strip quickly gives way to broken foothills and mountain ranges that are part of the southern extension of the impressive Zagros mountain range.

  By : Pablo Rodas-Martini

Former Chief Economist and Op-Ed writer. Maritime and LinkedIn expert

Although I love ships, I am exhausted by all the news about shipping in the Strait of Hormuz. Most ships are anchored, a few have been attacked and others are playing Russian roulette with their seafarers' lives by passing through. This post is about the Strait... with no mention of ships.

1) Two different underwater worlds

The bathymetry (the 'topography' of the seabed) of the Strait of Hormuz can be understood as a transition between the shallow waters of the Persian Gulf and the much deeper waters of the Gulf of Oman (image 2).

Moving westward from the Strait into the Persian Gulf, the seabed remains shallow for a long distance, with the Gulf averaging roughly 35 metres in depth and with extensive shallow shelves along its southern side, even though deeper channels do appear locally in other parts of the Gulf.

At the Strait itself, the cross-section becomes markedly asymmetrical. The seabed is deepest on the southern side near the Omani coast, where a trough exceeds 200 metres, and it shoals northward toward the Iranian side (image 1).

In practical terms, one moves from the relatively shallow 'pan' of water that is the Persian Gulf into the true deep-sea basin of the Gulf of Oman, which reaches depths of up to 3,700 metres, and the two are connected by a 'giant tube' (the Strait).

2) Two massive 'rivers' flow in opposite directions

The current system of the Strait of Hormuz is based on a simple physical fact: the Persian Gulf loses far more water through evaporation than it gains through rainfall and river input. As a result, the Gulf gradually produces water that is saltier, denser, and heavier than ocean water. 

Consequently, water exchange through the Strait occurs in two layers: relatively lighter water from the Gulf of Oman flows inwards near the surface, while denser water from the Persian Gulf flows outwards below. This is the 'engine' of the whole system.

As the deeper southern part of the Strait is the main pathway for the dense outflow, most of the deeper layer leaving the Persian Gulf occurs below 40 metres, while the upper-layer inflow is more variable and is often concentrated toward the northern side.

3) The land is as striking as the Strait!

The land around the Strait of Hormuz is as contrasting as the waters it encloses (image 3). In Iran's Hormozgan Province, coastal and alluvial plains occur. However, the low coastal strip quickly gives way to broken foothills and mountain ranges belonging to the southern continuation of the impressive Zagros system.

In contrast, Musandam in Oman has a completely different coastal landscape. Rather than a plain backed by mountains, it is essentially mountains at the water's edge. The coastline is deeply indented with narrow inlets known as khors that resemble fjords. This is why Musandam is often compared to Norway, a comparison that is purely geomorphological, of course, not geological. There, the mountains seem to fall directly into the sea.

Pablo Rodas-Martini writes :The centenary celebrations of the port of Gdynia

#Musandam #Pablo Rodas-Martini #The 'topography' #Strait of Hormuz#Gulf of Oman #Zagros mountain