Part of the cost of these activities is financed by consumers through taxes included in the water bills. This makes Barcelona the most expensive city in Spain for water. Over the last 8 years, a significant social revolt has arisen in which some 80,000 families in the metropolitan area refuse to pay the taxes included in their water bills. Physiographic patterns show a narrow coastal plain, occasionally widened by river deltas, and a series of mountain ranges roughly parallel to the coastline and separated by undulating plains. Climate presents mild winters and warm summers, with a warming trend observed in the 1990s.
Population trends parallel the recent history of Mediterranean cities.
That is, rural migration and concentration of population in large cities until approximately the mid 1970s, and the reverse processes in the 1980s and 1990s. The Llobregat River creates a delta of about 100 sq. The Riera of Rub is a good example of the fate of such streams in the Metropolitan Region of Barcelona. Due to the climatological and hydrological peculiarities of Mediterranean ephemeral streams, the Riera of Rub suffers from extended periods of very low or unexisting flows occasionally altered by much shorter and violent flood episodes. Moreover, in periods of low flows the only water circulating in the stream comes from wastewater plants.