Academic journal article URISA Journal

GeoFIS Flood Insurance System for Trinidad: A Case Study for San Juan Downstream

Academic journal article URISA Journal

GeoFIS Flood Insurance System for Trinidad: A Case Study for San Juan Downstream

Article excerpt


Flood is one of the most common natural disasters resulting in threats to life and property throughout the world (Sharma and Priya 2001). Flooding occurs when heavy and continuous rainfall exceeds the absorbing capacity of the soil or the flow of the water is greater than the normal carrying capacity of a stream channel. Statistically, streams equal or exceed the mean annual flood level once every 2.33 years (Leopold et al. 1964) and cause streams to overflow their banks onto flanking lands. Flood often accompanies other natural disasters such as brief torrential rain, monsoonal rain, cyclones, hurricanes, or tidal surges (Brakenridge et al. 2004). In addition, increasing impermeable layers, such as roads, residential buildings, and industrial complexes, reduce the land's natural ability to absorb water, which increases runoff as well as disturbs the natural water flow, thus increasing the risk of flooding (Ramroop 2005).

In Trinidad, flood is one of the major hazards affecting the country every year and during all seasons (Ramroop 2005). In recent years, the number of flood occurrences has increased throughout the country. In addition to the previously mentioned common causes, factors contributing to flood occurrences in Trinidad are particularly indiscriminate dumping into streams and improper or illegal hillside land development and agricultural practices (WRA/MIN. Env. 2001). Flood damages can be categorized as physical damages to houses and infrastructure, casualties of people and livestock as a result of drowning, spreading of diseases, scarcity of clean drinking water because of water contamination, and damages to food crops (Mileti 1999). According to Mileti (1999), flood hazards severely impede the economy of the United States; translated into the context of Trinidad, damage caused by flooding events in 1993, 2002, and 2006 are $580,000, $3,300,000, and $2,500,000, respectively (WRA/MIN. Env. 2001, Brakenridge et al. 2003, Brakenridge et al. 2007).

After a decade of economic growth, mainly driven by the energy sector (IMF Country Report 2005), housing development in Trinidad has increased considerably even in flood-prone areas. Economic values of houses have increased with the use of costly fixtures, which further add to the losses. Unfortunately, flood insurance has not kept up with housing development and insurance providers lack the tools to properly predict potential losses and recommend mechanisms to benefit both parties in the insurance market. The insurer, more often than not, is an agent in a chain of transfer of premiums in return for potential compensation. This kind of risk transfer is depicted in Figure 1.

However, potential clients are not readily purchasing flood-insurance policies because of high premiums (Browne and Hoyt 2000, Miller 1997, Preist et al. 2005). Thus, implementing flood insurance for private households with affordable premiums is in the best case difficult and in the worst case plainly not profitable (Miller 1997). For these reasons, it is very important to classify areas based on their flood risk. Geographic information systems (GIS) can be used to categorize flood-risk zones by analyzing complex spatial data sets from different sources (Gangai et al. 2003). In this study, GIS forms the basis for a private household flood-insurance system for Trinidad to calculate premiums based on household exposure to flood risk and to speed up the underwriting process.



Trinidad is situated at the southernmost end of the Caribbean island chain located at latitude 10.5[degrees] N, longitude 61.5[degrees] W, and is approximately 5,126 km2 in size. The climate of Trinidad is tropical wet, with an average rainfall of 2,200 mm (WRA/MIN. Env. 2001) and its monsoonal character results in high-intensity rainfall and subsequent frequent flooding (Bryce 2007).

The flood history of Trinidad shows that the frequency and intensity of flooding events is increasing (Bryce 2007). …

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