244
The damming of the river that delimits the system to the south in 1968 cutoff the
natural the sedimentary supply to the extensive beach and dunes, leaving the wetlands in a situation of vulnerability before climate change and variability, anthropic
pressure, ocean swells and tsunamis. In the present chapter is illustrated the degradation that the wetlands system is suffering, by means of the estimation of tendencies of the long term records available in the zone, antecedents about its natural
history, anthropic pressure and natural disasters like earthquakes, tsunamis, ocean
swells and ENSO, along with field monitoring that has been carried out with the
objective of implementing an ecological restoration. These antecedents show a
decrease of precipitations and river discharges, an increase of ambient temperature
and sea surface temperature, a rising of sea level and a change of the incident waves.
El Yali was severely affected by the earthquake and tsunami in 2010, which
destroyed 800 ha of beach and coastal dunes that provided natural protection. In
many opportunities, El Yali was affected by earthquake and tsunamis, intense ocean
swells and ENSO, all phenomena that dissipate energy destroying the natural barrier
the dunes represent. However, before the construction of Rapel reservoir, the sedimentary supply allowed a rapid recovery of the beach, sandbar and dunes. When this
sediment supply was cutoff, the dunes has enough material to support the equilibrium of the system for some decades, but when tsunami waves destroyed the dunes,
there was no sand supply to restore the beach nor the dunes. This generated a substantial change in the system, turning it more vulnerable to tsunamis, even smaller,
ocean swells, and sea-level raising associated to ENSO Kelvin waves and climate
change. For this reason, the first proposed restoration action is to restore the dunes
and plant a vegetal cover with native species that reinforce and maintain the dunes.
Keywords Ramsar site • ENSO • Dune • Beach • Sandbar
8.1 Introduction
Coastal wetlands in central Chile are extremely dynamic and fragile environments,
whose existence is conditioned by a number of natural and anthropic factors, including hydrologic and climatic variability, high littoral energy content, variability of
sediment deposition, seismicity, and tectonic processes on the Chilean coast, which
generate large morphological changes in coastal areas. This so particular combination only has similar referents in some areas of South Africa, Australia (Cienfuegos
et al. 2012) or New Zealand (Nichol et al. 2007).
This chapter aims to show the degradation that El Yali coastal wetland system
(33°45′S; 71°43′W) is currently suffering, from a multidisciplinary perspective, as
result of a combination of different factors:
(a) The effects of the contemporary climate change by a diminution of precipitations and the increase of temperature seem to be changing the hydrologic equilibrium of these systems and this represents a pressure forcing changes in
agriculture and use of soils that increase the demand for hydric resources.
M. Contreras-López et al.
The damming of the river that delimits the system to the south in 1968 cutoff the
natural the sedimentary supply to the extensive beach and dunes, leaving the wetlands in a situation of vulnerability before climate change and variability, anthropic
pressure, ocean swells and tsunamis. In the present chapter is illustrated the degradation that the wetlands system is suffering, by means of the estimation of tendencies of the long term records available in the zone, antecedents about its natural
history, anthropic pressure and natural disasters like earthquakes, tsunamis, ocean
swells and ENSO, along with field monitoring that has been carried out with the
objective of implementing an ecological restoration. These antecedents show a
decrease of precipitations and river discharges, an increase of ambient temperature
and sea surface temperature, a rising of sea level and a change of the incident waves.
El Yali was severely affected by the earthquake and tsunami in 2010, which
destroyed 800 ha of beach and coastal dunes that provided natural protection. In
many opportunities, El Yali was affected by earthquake and tsunamis, intense ocean
swells and ENSO, all phenomena that dissipate energy destroying the natural barrier
the dunes represent. However, before the construction of Rapel reservoir, the sedimentary supply allowed a rapid recovery of the beach, sandbar and dunes. When this
sediment supply was cutoff, the dunes has enough material to support the equilibrium of the system for some decades, but when tsunami waves destroyed the dunes,
there was no sand supply to restore the beach nor the dunes. This generated a substantial change in the system, turning it more vulnerable to tsunamis, even smaller,
ocean swells, and sea-level raising associated to ENSO Kelvin waves and climate
change. For this reason, the first proposed restoration action is to restore the dunes
and plant a vegetal cover with native species that reinforce and maintain the dunes.
Keywords Ramsar site • ENSO • Dune • Beach • Sandbar
8.1 Introduction
Coastal wetlands in central Chile are extremely dynamic and fragile environments,
whose existence is conditioned by a number of natural and anthropic factors, including hydrologic and climatic variability, high littoral energy content, variability of
sediment deposition, seismicity, and tectonic processes on the Chilean coast, which
generate large morphological changes in coastal areas. This so particular combination only has similar referents in some areas of South Africa, Australia (Cienfuegos
et al. 2012) or New Zealand (Nichol et al. 2007).
This chapter aims to show the degradation that El Yali coastal wetland system
(33°45′S; 71°43′W) is currently suffering, from a multidisciplinary perspective, as
result of a combination of different factors:
(a) The effects of the contemporary climate change by a diminution of precipitations and the increase of temperature seem to be changing the hydrologic equilibrium of these systems and this represents a pressure forcing changes in
agriculture and use of soils that increase the demand for hydric resources.
M. Contreras-López et al.