Based on the data that are available for this project, the following socioeconomic variables are incorporated to identify areas of human activity/development that induce coastal erosion: streams and dams, types of land use, the presence of hotels, boat harbors and roads. See appendix for a list of all data used for this study.
Streams and Dams
Inland water resource variables are used, which include dams constructed by humans. The presence of dams are known to cut off the supply of sediments reaching the coast (Hsu et al., 2007). Chaibi and Sedrati (2009) note that sediment can be trapped above the dam and interfere with the transport of the sediment travelling downstream, which can reduce the amount of deposit on coastlines. This affects the natural process of depositing sediment in coastlines that counteracts against coastal erosion (Chaibi & Sedrati, 2009). Thus, the presence of dams on streams that run off the coasts are regarded as a contribution to coastal vulnerability and are considered high risk while an absence of dams on streams are considered no risk.
Previous literature provides evidence of a variety of human activities and development that contributes to coastal erosion. For example, Fletcher et al. (1997) note the use of shoreline hardening structures in Hawaii. There is no available data that indicates the exact locations of shoreline hardening structures in Hawaii, but land use data can indicate where higher amounts of human development are, which are the areas that shoreline hardening is typically implemented (Gittman et al., 2016).
In urban areas, construction can alter sediment transport which can also lead to coastal erosion (Mujabar & Chandrasekar, 2013), while land with intensive agricultural cultivation causes siltation which results in changes to shorelines (Norman et al., 2012). A study evaluating coastal vulnerability by Mclaughlin and Cooper (2010) considered conservation areas as being at high risk from coastal erosion. For this research project, however, conservation areas are seen as areas with no human activity contributing to coastal erosion, so conservation areas are considered least impactful to coastal areas. To reiterate, the focus of this project is to target areas that are of high vulnerability due to human activity alone. Therefore, coastlines near urban areas are considered high risk, agricultural areas are medium risk, rural areas are low risk and conservation areas have no risk in causing coastal erosion.
Another variable examined is the presence of hotels, which are indicative of locations with higher tourist activity. Hotels near coastlines are seen as supporting tourism development which can result in changes to coastline morphology, making them more vulnerable to erosion (Ferrer-Valero et al., 2017). Therefore, areas with the presence of hotels are regarded as high risk while areas without are seen as lower risk.
Harbors are included as a variable as they are known to disrupt sediment supply to the coasts (Chaibi & Sedrati, 2009). As noted by Chaibi and Sedrati (2009), the construction of harbors can alter the waves that bring sediment to the coasts and in turn make the coastline more vulnerable to erosion. Hence, areas with commercial harbors are considered high risk as they are more extensive than small boat harbors, which are assessed as lower risk.
Ali and El-Magd (2016) note that the presence of roads is indicative of urban growth as they allow for increased connectivity and accessibility from place to place, especially to coasts. The presence of roads also implies that surrounding forestry would have been affected during construction. As previously stated, Xue et al. (2009) mention deforestation as a contributor to coastal erosion. Therefore, the presence of roads (and the potential of creating more road networks) near coasts are listed in the model. As this variable is a more indirect contributor to coastal erosion, small roads are valued as low risk and major roads/highways as medium risk.