Environmental-economic evaluation of the filling and reclamation process in the bay of Santander, Spain

Abstract

The historical development of a process of reclamation of intertidal areas in an estuary has been quantitatively studied by means of old engravings, maps, navagation charts, and aerial photographs. These show that about 83 percent of the natural coastline of the estuary has disappeared, nearly two-thirds of its intertidal area has been covered, and over 40 percent of its volume has been lost. The rate of this artificial process is several tens of times faster than that of the natural sedimentation. Extrapolation of the observed trends shows that, if these continue, the intertidal areas would disappear completely in 31 to 105 years.

Theoretical calculations based on comparisons with other estuaries show that the accumulated loss in the productivity of living matter (in the form of primary producers), since the process started about 140 years ago, could reach 1.5·10¹⁰ kg. This could represent, considering several possible food chains, the equivalent of the food necessary to sustain several thousand people for life.

An economic analysis of the impact of the process has been made by considering, first, the decrease in fish and shellfish catches in the bay (using historical data and data about present clam productivity) and the decrease in its aesthetic quality and recreational potential. These were determined by means of interviews with the population to obtain a “demand curve” for the willingness to pay for the preservation and use of the bay. Second, the price of the man-made land obtained was considered. The data obtained show that the economic losses would offset the benefits within 10 to 30 years.