GEOTEXTILE TUBES FOR EROSION CONTROL AND COASTAL CONSERVATION Chris Smith and Emily Zapinski...
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GEOTEXTILE TUBES FOR EROSION CONTROL AND COASTAL CONSERVATION Chris Smith and Emily Zapinski Geotextiles, manmade water-permeable fabrics, are used in erosion control methods due to their high reliability and satisfactory performance. Geotextiles are a type of geosynthetic material wherein the polymer fibers are often woven together by machines, similar to how clothing is produced. The end product is a fabric-like material that is both flexible and liquid permeable [2]. Geotextile tubes, which are similar to large sandbags, can be used in many different coastal conservation methods. In the primary application, a collection FIGURE 1 [1] Figure 1: This figure depicts coastal erosion, although this coastline may not be ideal for the placement of geotextile tubes. FIGURE 2 [4] Figure 2: This figure displays how the geotextile tubes were situated at Young-Jin beach. Erosion Issues Geotextile Tubes as a Solution Sustainability & Durability [6] Measuring Erosion Erosion is a naturally occurring process which affects every surface that is open to weather and environmental elements. The constant exposure to the elements will, over time, break down the strongest of materials. Thus, civil engineers must come up with newer, longer-lasting materials, as well as effective methods to maintain structures and prevent erosion. The erosion of oceanic coastline has many causes, both from nature and human activity. In some cases of coastal erosion, waves, rain, wind, and ice wear away the shoreline, which is comprised of rock and sediment. The effects of waves can be seen in Figure 1. In a healthy beach, storms dislodge shore sediment and carry the particles either out to sea to sand bars or further down the shoreline. After the storm, waves carry sand bar sediment back to shore. This natural process allows beaches to be sustainably nourished. However, when more sediment is dislodged than returned, the coastline begins to continually recede [1]. Causes of Erosion: • Wave Energy • High Tides • Seasonal Currents • Wind Negative Impacts: • Decreased Quality of the Beach • Decreased Land Value Installation of Tubes: • 90-100 meters from shoreline • 3 meter deep waters • Tubes 50 meters long and 1.8 meters in diameter • 240 meter total span • Filling sediment weighs approximately 12.25 kN/m 3 • Arrangement of tubes can be seen in Figure 2 FIGURE 3 [4] Figure 3: This figure shows the change in shoreline length in a year measured from five different reference points. Results: • Change in shoreline was measured and displayed in Figure 3. • Benchmarks (BM) are reference points on the shore. • For the first three months, the shoreline increased due to efforts to rebuild the beach. • After three months, the shoreline remained Erosion is measured by the amount of soil lost annually. This can be calculated using the Universal Soil Loss Equation given by: A = R * K * LS * C * P All the terms in the above equation are determined experimentally and are explained in Table 1. References: [1] American Shore and Beach Preservation. (2012). “Beach Nourishmen.” (online publication). http://www.asbpa.org/publications/fact_sheets/HowBeachNourishmentWorksPrimerASBPA.p df. [2] “Geotextile Lecture.” Monash Geomechanic Group at Monash University. (2010). (Video). https://www.youtube.com/watch?v=QqmrcRfvdJk. [3] Stokes Shawn, et al. (2012). “Geosynthetics: Coastal Management Applications in the Gulf of Mexico.” Duke Center on Globalization, Governance, and Competitiveness. (Online publication). [4] E.C. Shin and Y.I. Oh. (2007, February 03). “Coastal erosion prevention by geotextile tube technology.” Geotextiles and Geomembranes. v 25, n 4-5, p 264-277. Elsevier Ltd. (Article). [5] Menashe, Elliott. (1998, December 10). “Vegetation and Erosion.” Greenbelt Consulting. Environmental Education Assessment & Management. (Article). http://depts.washington.edu/uwbg/wordpress/wp-content/uploads/VegetationAndErosion. pdf. [6] O’Neil, Erin. (2014, June 30). “In NJ back bay communities, flooding concerns continue after Sandy.” NJ.com. (online article). Factor Meaning A Predicted Soil Loss (tons/acre/year) R Rainfall and Runoff Factor K Soil Erodibility Factor LS Slope Factor C Crop and Cover Management Factor P Conservation Practice Factor TABLE 1 [5] Table 1: This table explains all the factors that are experimentally determined in the Universal Soil Loss Equation. Geotextile tubes are affordable, easily installed, and long lasting. The tubes are effective for at least 10 years despite typically being used for a short duration (~5 years). Factors that affect geotextile tube durability are: • Fiber Diameter • Volume to Surface Area Ratio • Polymeric Molecular Weight • Crystallinity of Polymers • Ultraviolet Light Exposure • Degradation due to Wave Energy Case Studies: Young-Jin Beach, South Korea [4]
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Transcript of GEOTEXTILE TUBES FOR EROSION CONTROL AND COASTAL CONSERVATION Chris Smith and Emily Zapinski...
GEOTEXTILE TUBES FOR EROSION CONTROL AND COASTAL CONSERVATIONChris Smith and Emily Zapinski
Geotextiles, manmade water-permeable fabrics, are used in erosion control methods due to their high reliability and satisfactory performance. Geotextiles are a type of geosynthetic material wherein the polymer fibers are often woven together by machines, similar to how clothing is produced. The end product is a fabric-like material that is both flexible and liquid permeable [2]. Geotextile tubes, which are similar to large sandbags, can be used in many different coastal conservation methods. In the primary application, a collection of tubes is placed directly in the ocean and act as a barrier to redistribute wave energy [3].
FIGURE 1 [1]
Figure 1: This figure depicts coastal erosion, although this coastline may not be ideal for the placement of geotextile tubes.
FIGURE 2 [4]
Figure 2: This figure displays how the geotextile tubes were situated at Young-Jin beach.
Erosion Issues
Geotextile Tubes as a Solution
Sustainability & Durability [6]
Measuring Erosion Erosion is a naturally occurring process which affects every surface that is open to weather and environmental elements. The constant exposure to the elements will, over time, break down the strongest of materials. Thus, civil engineers must come up with newer, longer-lasting materials, as well as effective methods to maintain structures and prevent erosion. The erosion of oceanic coastline has many causes, both from nature and human activity. In some cases of coastal erosion, waves, rain, wind, and ice wear away the shoreline, which is comprised of rock and sediment. The effects of waves can be seen in Figure 1. In a healthy beach, storms dislodge shore sediment and carry the particles either out to sea to sand bars or further down the shoreline. After the storm, waves carry sand bar sediment back to shore. This natural process allows beaches to be sustainably nourished. However, when more sediment is dislodged than returned, the coastline begins to continually recede [1].
Causes of Erosion:• Wave Energy• High Tides• Seasonal
Currents• Wind
Negative Impacts:• Decreased Quality of
the Beach• Decreased Land Value
Installation of Tubes:• 90-100 meters from
shoreline• 3 meter deep waters• Tubes 50 meters long
and 1.8 meters in diameter
• 240 meter total span• Filling sediment
weighs approximately 12.25 kN/m3
• Arrangement of tubes can be seen in Figure 2
FIGURE 3 [4]
Figure 3: This figure shows the change in shoreline length in a year measured from five different reference points.
Results:• Change in shoreline was measured and displayed in
Figure 3.• Benchmarks (BM) are reference points on the shore.• For the first three months, the shoreline increased due
to efforts to rebuild the beach.• After three months, the shoreline remained mostly
constant.• Geotextile tubes prove to be very effective.
Erosion is measured by the amount of soil lost annually. This can be calculated using the Universal Soil Loss Equation given by:
A = R * K * LS * C * P All the terms in the above equation are determined experimentally and are explained in Table 1.
References:[1] American Shore and Beach Preservation. (2012). “Beach Nourishmen.” (online publication). http://www.asbpa.org/publications/fact_sheets/HowBeachNourishmentWorksPrimerASBPA.pdf.[2] “Geotextile Lecture.” Monash Geomechanic Group at Monash University. (2010). (Video).https://www.youtube.com/watch?v=QqmrcRfvdJk.[3] Stokes Shawn, et al. (2012). “Geosynthetics: Coastal Management Applications in the Gulf of Mexico.” Duke Center on Globalization, Governance, and Competitiveness. (Online publication).[4] E.C. Shin and Y.I. Oh. (2007, February 03). “Coastal erosion prevention by geotextile tube technology.” Geotextiles and Geomembranes. v 25, n 4-5, p 264-277. Elsevier Ltd. (Article).[5] Menashe, Elliott. (1998, December 10). “Vegetation and Erosion.” Greenbelt Consulting. Environmental Education Assessment & Management. (Article). http://depts.washington.edu/uwbg/wordpress/wp-content/uploads/VegetationAndErosion.pdf .[6] O’Neil, Erin. (2014, June 30). “In NJ back bay communities, flooding concerns continue after Sandy.” NJ.com. (online article). http://www.nj.com/news/index.ssf/2014/06/buffering_njs_back_bay_communities_presents_from_future_flooding_after_sandy_presents_complex_challe.html.
Factor MeaningA Predicted Soil Loss (tons/acre/year)R Rainfall and Runoff FactorK Soil Erodibility FactorLS Slope FactorC Crop and Cover Management FactorP Conservation Practice Factor
TABLE 1 [5]
Table 1: This table explains all the factors that are experimentally determined in the Universal Soil Loss Equation.
Geotextile tubes are affordable, easily installed, and long lasting. The tubes are effective for at least 10 years despite typically being used for a short duration (~5 years). Factors that affect geotextile tube durability are:• Fiber Diameter• Volume to Surface Area Ratio• Polymeric Molecular Weight• Crystallinity of Polymers• Ultraviolet Light Exposure• Degradation due to Wave Energy
Case Studies: Young-Jin Beach, South Korea
[4]
