Looking at this topographic map, it is easy to see why Madeira’s capital city, Funchal, is situated where it is. Funchal covers the gentlest slopes and largest area of low-elevation ground on the rugged island. The grade of the slopes can be judged by how rapidly the color changes from green near sea level to tan and then white at the highest points on the island. Along the northern shore, the change happens rapidly, revealing the steep mountains and high sea cliffs that compose much of that shoreline. In the south, however, the descent to the shore takes longer. These relatively gentle slopes (gentle only compared to other locations on the island) provide the most feasible location for a city on Madeira.
The city center sits on slightly sloped ground, while outer suburbs perch on the mountain slopes around the city. On February 19-20, 2010, when heavy rain poured down on the island, the high suburbs suffered mudslides and floods. As this map illustrates, the slopes around Funchal surround the city in a semicircle, so water flowing down the mountains was concentrated in the bowl where the city is located. The devastating floods killed at least 42 with 18 still missing as of February 23, according to the government of Madeira.
The other community damaged by extreme flooding in February 2010 is Ribeira Brava, to the west of Funchal. This small town sits at the base of a ravine. Indeed, literally translated, the name means “rough stream or riverside.” The topographic map shows clearly how rain falling on the mountains on either side of the deep ravine would naturally converge near the town.
NASA Earth Observatory image created by Jesse Allen, using a digital elevation model from the Direcção Regional de Informação Geográfica e Ordenamento do Território (DRIGOT) of Madeira and the Telecommunication Advanced Networks for GMES Operations (TANGO). Special thanks to Pedro Soares and Antonio de la Cruz (European Union Satellite Centre).
This topographic map of the Portuguese Island of Madeira helps illustrate why population centers on the island are prone to flooding.
On February 20, 2010, torrential rain inundated the Portuguese island of Madeira. Water, rocks, and mud gushed down the slopes of the steep-sided island and though the streets of Funchal and other cities on the islandâ€™s populated southern coast.
This detailed image, taken by the Advanced Land Imager on NASA’s EO-1 satellite on March 7, 2007, illustrates how the steep mountains and deep ravines contributed to a flooding disaster in February 2010.
The compact Italian city of Venice with its renowned canals is situated on a small, fish-shaped island in the Laguna Veneta at the northwest corner of the Adriatic Sea. In this photo taken from the International Space Station by the Expedition 1 Crew on February 21, 2001, one can see part of the causeway connecting the city to the mainland. The sinuous Canal Grande bisecting the city is easily visible in this scene as is the larger Canal Giudecca to the west, which leads to the port facilities on the northwestern end of the island. For centuries, the low-lying city has successfully coped with the three-foot tidal range experienced at this end of the Adriatic Sea, and the series of barrier islands has offered some protection from storm waves. However, a combination of both regional land subsidence and recent slight rises in sea level pose a significant threat this historic city and its priceless art treasures.