By Joanna El Khoury
Environmental Scientist with GHD Global Pty Ltd
Construction of Qatar's Doha International Airport (NDIA) commenced in 2004, with an expected opening date in 2011. The project covers a total area of 22 square kilometers and is set to handle an annual passenger capacity of 50 million at full capacity. The airport’s runways were built through the reclamation of dredged material from surrounding borrow pits off Qatar’s nearshore coastal waters.
As part of its overall statutory environmental management program approval requirements, NDIA engaged GHD Global to undertake a long-term environmental monitoring program. The two-year effort involves quarterly monitoring and assessing of marine ecology in the vicinity of the NDIA and the borrow pits.
This project is one of the biggest projects in Qatar. Whenever there is a project of this size, with the risk of environmental impact, the Ministry of Environment requires monitoring post construction. One very crucial parameter to monitor was temperature.
Around the airport there is sea grass and corals and these are very reliant on temperature. If temperatures go above or below a threshold, this might impact the coral or sea grass. It’s good to have long-term data on water temperatures in case anything happens to biota in the water.
GHD is also monitoring the water quality and sediment quality and submitting reports to both the client and the Ministry. The airport project has drastically changed the environment and it's important for them to know what’s happening.
The principal objectives of the marine ecology monitoring program are to:
To satisfy the requirements of the first objective, in May 2008 GHD’s commercial divers deployed HOBO Temperature Loggers at six nearshore sites with depths ranging from 1.5m to 9m. The loggers were easily deployed by attaching them to a sediment trap with cable ties, as shown in Figure 1. The HOBO Temperature Loggers were downloaded underwater on a monthly basis using the HOBO Waterproof Shuttle, a quick and reliable mechanism for data retrieval in-situ (Figure 2 and Figure 3).
The HOBO Temperature Loggers were used to monitor water temperature over an extended period of time. Monitoring water temperature is important as water temperature is known to influence the chemical, physical, and biological processes within a water body, including growth and other responses in organisms.
Water temperatures at the nearshore sites of the NDIA are typical of the Arabian Gulf and generally range from a minimum of 10°C during the months of December and January to the high 30ºCs June through August. Figure 4 shows a temperature high of 38°C in June. GHD has also utilized HOBO temperature sensors on other long-term environmental monitoring projects in the Arabian Gulf, including a marine ecological survey at Ras Az Zawr in Saudi Arabia, where water temperatures in near shore coastal waters were recorded below 9ºC in January 2008.
It’s important to gather all this data for a long period of time. The Arabian Gulf environment, in general, is very harsh with wide extremes in temperature. These temperatures affect the availability of heavy metals and nutrients in the water. Every quarter GHD does a water quality and sediment analysis.
It’s so easy to use the data loggers because they don’t need to be taken in and out of the water. Instead, the data are simply downloaded via the HOBO Waterproof Shuttle. And the data are analyzed using HOBOware software, which allows easy export of the data into a statistical analysis package.