The truth about Għadira beach

I refer to the various comments about Ghadira beach and the controversy linked with the coastal road.

During a press conference on the subject, Infrastructure Minister Austin Gatt invited a local environmental adviser to assess what action was needed to save the sandy beach from further erosion. This adviser concluded that the sand at Għadira beach "does not come from the sea" but comes from the onshore system of valleys which are supposedly supplying sediment.

Sedimentological research on southern Mediterranean beaches shows the contrary. Wind erosion at Għadira beach actually supplies more sand to the hinterland (where it forms sandy soil) rather than the other way round, as claimed by the minister's adviser.

Roland Paskoff, an eminent coastal geomorphologist, described the provenance of beach sand in Tunisia and north Africa as "mainly the outcome of shoreward sand movement, initiated during the Holocene marine transgression which brought the sea to approximately its present level some 6,000 years ago".

Sea level rise triggered beach roll-back or back-stepping and finally the flooding of the back beach area, producing the well-known brackish water pools of Għadira and Il-Ħofra.

The discussion on the effects of the road on the beach is more complex. Sand piled up on the windward side of the road is rapidly transported by wind over the smooth surface of the present road, thereby accelerating erosion. However, the road also serves to consolidate the barrier beach, averting catastrophic breaching during exceptionally strong storms, which may be associated with climate change.

The latter is key to understanding the causes of sand erosion triggered by sea level rise, flash floods which erode (not contribute to) the beach sand, and increasing storm frequency, which causes beach roll back and shift equilibrium profile. All these effects are exacerbated by thoughtless human interventions.

It is commendable that the government is effectively trying to tackle the problems created by climate change. However, the authorities should be careful not to initiate projects based on unqualified statements unsupported by scientific analysis of complex processes, since this may derail the expected benefits of such costly interventions.