For this project we were allowed to pick a group of three. Each person was responsible for one section of the project, the science of El Nino/La Nina plus two other elements of El Nino of your choice. My group chose marine Life Effected by El Nino and La Nina and Cliff Erosion caused by El Nino and La Nina. My part was cliff erosion, it was my job to become an expert on cliff erosion. In order to do this I had to search the internet for information on cliff erosion, look in the news paper for stories on it happening here and also go interview people about cliff erosion. After finding all of this I was to write a three page report on my topic.

Have you looked at our cliffs lately? They are falling apart and getting closer and closer to the houses sitting on top. Some houses have even fallen off. Why is this happening? It is the result of cliff erosion. The most noticeable effects happened during last years El Nino but it's still happening during this years la Nina. I would like to show you the science behind why this is happening, what happened to our local beaches and what people are doing about it.

Many things contribute to cliff erosion such as storms, waves and salt. Storms like El Nino aid in cliff erosion by causing enormous waves to form and hit the cliff with immense force which brakes it down. Waves are a major cliff eroder because they slam into the cliffs and push water into the crevasses which causes the cliff to crack and over time, pieces will fall off and wash into the ocean until they are broken up into sand. Size of the waves determine how much erosion will occur. Under normal wave conditions, about 1.5 meters of sand will erode in a year. However when the wave size increases there could be 25 meters of eroded sand in a single day. (For more detailed information on wave erosion see figure 1 found at http://www.arabassador.com/wavesanderosion.htm, attached in back pages.) Another factor that aids in cliff erosion is vegetation. When we plant things such as ice plant which has large roots it will eventually fall, and when it does, it pulls down all the bluff that was in it's roots. Our cliffs are made out of sedimentary rock (sandstone) which when water is added it turns into mud. The mud is unstable so it gets washed into the ocean. The ocean is made of salt water and that itself helps to brake up the bluff. In addition, our coastline is emergent so the taller and steeper it is the greater the erosion. These are all natural things that contribute to cliff erosion.

Humans contribute to erosion by building seawalls, houses and routing irrigation and planting vegetation. Seawalls add to erosion by allowing water to build up behind them and hence soften the bluff. Seawalls also cause faster than natural erosion to occur at the beginning and end of the wall. Houses aid in erosion by causing mass wasting which is the process of the lower part of the cliff under cuts which leaves a large portion of land unsupported and eventually collapsing on itself. (For more detailed information see figure 2 found at http://hss.sd54.bc.ca/school/pages/student/geog12/Robbyn_Meighan/page3.htm, attached in back pages.) The irrigation around our community is not routed in a bluff friendly manner. Drains are routed directly off of the bluff which cause large crevices to form and enhance the natural erosion process. Vegetation is planted with good intentions but in fact non-indigenous plants can pull the bluff down by storing large amounts of water which the bluff can not support. One of the most common forms of erosion is caused by humans walking on and near the edge of our bluff and causing the breaking and weakening of the bluff tops.

Have you ever been to the beach and set up all your beach gear near or under a cliff? Next time you might want to think twice about it because when you come back it could very well be buried in eroded sand. Our beaches bluffs are eroding faster then we think as shown in figure 3 found at http://www.csc.noaa.gov/crs/ALACE/cliff.html. When you look at this you can see that the house is much closer to the cliff then it was it the picture before. This is just one example and there have been many more right here in our own community. Some home owners have even lost their homes to cliff erosion. Many were lost in El Nino but La Nina still had a few surprises, the most resent being the La Jolla incident where the home owners lost a large portion of there back yard, due to mass wasting.(Mass wasting is explained in paragraphs above.)

You may think that only happened to them because they did something to mess up the cliff. This is exactly what local residents thought until they came back from a trip to find a peace of the cliff that there house was sitting on fallen. Not there house but the supporting bluff under it, this happened at the beginning of El Nino. Then at the height of El Nino, a piece between their property and there neighbors property fell. This time they were home! The home owner said, "My wife and I jumped at the noise and movement, we thought that it had been and earth quake." It was not until morning that they would discover chunks of their supporting cliff had fallen due to erosion and a little help from El Nino's powerful storms. The citizen said, "We knew it was only a mater of time before it would happen but had not expected it to happen so soon." They also added that, "They were very glad it had happen during the night and nobody was there to get hurt." These people had lived there for 13 years had never seen "Anything thing like this happen on this side of moonlight for quite a while." All it took was for El Nino to challenge the cost line and these unfortunate people lost pieces of the cliff that their house sits on.

There are many things that can be done to help slow down the erosion. When these home owners where asked what measures they had taken to save there cliff they replied, "We have planted ice plant." This is one of the thing that can help to erode the cliff even more, pulling the cliff down with the ice plant. They also said, "We try not to water the grass in the back yard to much." This is a start. To help save the cliff they must cut down on the water that seeps down into it, slowing down the process of the cliff erosion. The residents said that La Nina has not given them that much trouble compared to El Nino, but nature will eventually erode it by itself from the water it gets from rain and the waves. When nature takes it's coarse all of these million dollar beach front homes will be gone and soon, if we don't slow down the erosion.

In conclusion, I would like to say that now that you know how El Nino works, what is happening to our beaches and what people are doing to help save the coastal cliffs. What more can we do to help the cliffs and the homes of those who live above it? Could it be an enormously long chain of sea walls? That has been done and is still being tested, but it is still only a temporary solution. There is no perfect solutions that we have found yet, but with all the new discoveries science is making we have yet to find one. When we do let's hope that they it El Nino and La Nina proof.