What causes coastal flooding?
HEAVY rainfall recorded in recent days has proved once again how easy and fast streets can be turned into muddy rivers and roads can be turned into dangerous water traps in coastal towns in Alicante province and Murcia region.
Many seaside towns and cities do not have effective drainage systems, which are crucial to prevent flooding when it rains. A proper drainage system can also protect the beaches from being destroyed every time it rains and reduce the amount of water accumulating on the streets.
However, most systems would be unable to cope with the huge volume of water which is channelled to the coast when it rains heavily, as the rain which falls inland flows to the sea. In this case flooding is not only caused by the rain in situ on the coast, but by water which arrives via the water courses.
This is a very specific problem to the Mediterranean coast, where there are a series of dry river beds, man-made and natural watercourses and ravines running to the sea. According to the map of the Segura river and water authority (CHS), the Mar Menor and the Vega Baja area are full of these natural water courses.
In the Mar Menor area all of them flow into other watercourses or dry river beds, which end up in the Mar Menor. In Pilar de la Horadada, Orihuela Costa and Torrevieja they end up in the Mediterranean and in the inland Vega Baja much of the water flows to the River Segura.
In Orihuela Costa and Pilar de la Horadada some of the ravines crossing inland urbanisations flow into main watercourses such as the Río Nacimiento at Campoamor, which starts near Rebate, and the Río Seco at Mil Palmeras, which starts at Pinar de la Perdiz. In the Mar Menor area the main watercourses are the Rambla de Cobatillas at San Javier; Rambla del Albujón between Los Alcázares and Los Urrutias, which starts at Fuente Álamo; Rambla de la Maraña at Los Alcázares; and the Rambla de la Benipila in Cartagena city. Additionally the D-7 artificial channel between Torre Pacheco and Los Alcázares collects some of the inland rainwater and takes it to El Albujón watercourse.
Moreover there are dozens of smaller watercourses, runoffs and dry beds which cause havoc and great damage at seaside towns – especially at San Javier, Los Alcázares and the southern villages on the Mar Menor near the mining mountains of La Unión.
However, the land and its network of ravines, watercourses and dry river beds cannot be blamed for flooding. The lack of forests, poor maintenance of the watercourses, intensive farming practices, blanket building policies, and works to change the direction of natural water courses have all contributed to aggravating the problem.
The residents and scientists association, Pacto Por El Mar Menor pointed out that floods caused by heavy rain have always occurred on the coast, but these events now cause more damage due to human actions.
According to the scientists, housing and infrastructure have been built too close to watercourses and some of them block the natural water courses running to the sea. Additionally, intensive farming has completely changed the landscape and the natural course of many ravines and water courses.
All these changes to the environment mean that people have to be extremely careful when driving during heavy rain as roads can become flooded very quickly by ‘runoff ’ water heading to the sea.