Introduction Trip report Description of Kaashidhoo
INDOEX observatory and tower Description of Hulule and Male General information

Description of Kaashidhoo

Kaashidhoo is located at 4.946° N, 73.465° E, about 85 km (straight line) away from Male / Hulule and is a single island surrounded by its own coral reef (Figure 3). The island is bean-shaped, about 2.9 by 1 km large, oriented SW-NE, and has a square town in the center with two main roads crossing the island. No vehicles are operated on Kaashidhoo, boats land at the inside lagoon / NW-side jetty at a rate of 3-4 dhonis (=two-stroke diesel engine driven, wooden boats) per day, which approach from the south and around the NE corner, about 500 m offshore. No regular speed boat (diesel or gas motor boats) or air taxi (Cessna water aircraft) shuttles approach the island. Transport from Male to Kaashidhoo by speed boat takes about 2 hours, air taxi is expected to take about 20 minutes, dhoni transport takes about 8 hours.

Figure 3: Outline and details of the island of Kaashidhoo. The approximate outline of the town is shown as a grey square, the suggested INDOEX observatory site is market in red, the power house is marked blue, the island’s office in yellow and the different air quality sectors are shown in transparent shades of grey (lighter meaning cleaner) with directions indicated as angles (see text).

The power house is located in the center of the town and the proposed location for the INDOEX observatory is on the NE corner, about 200-300 m away from the settlements, about 50 m away from shore and 150 m away from the reef (no direct sea spray!). Except for the town, most of the island is covered with vegetation, mostly palm trees mixed with some lower trees and bushes. The highest palm trees are found in the center of the island and are about 25-40 years old, up to 10 m high. Other plants are screw pine, sceviola and sea hibiscus. The NE corner has an average foliage height of about 6-7 m and tapers off towards the 1-3 m wide beach. The coral beach is subject to erosion depending on the season (the different monsoons erode one side of the island and accumulate material on the opposite side) but the vegetated area is usually stable.

Currently, the power house uses diesel fuel at a rate of approximately 6000 l per month. Linearly extrapolated, this consumption will go up to about 8000 l/month once the fourth generator is online. Most of the power is used for lighting, cooking is done with kerosine and fuel wood. There is also some burning of trash going on at random times. It was indicated that we could request to minimize this activity and have it restricted to one place on the island, preferably in the exclusion sector (see below).

Figure 4: A composite photo of the island seen from the north inside lagoon. The white building to the right of the boat (a small dhoni) is the location of the landing jetty and the beginning of one of the main roads. The observatory would be at the far left end of the island. The island's red/white radio tower is visible to the right of the center, about 1-2 km away from the NE tip.

Kaashidhoo had 1325 inhabitants in 1995 with an annual growth rate in the Maldives of 2.8%. The island’s office is located centrally (marked yellow in Figure 3) and there is one public place to eat and no guest houses. Accomodation for INDOEX scientists during the field phases and for visits will be organized locally.

With respect to local and distant pollution, the following air-quality sectors can be defined, which are visualized in Figure 3 using different shades of grey, lighter shades indicating cleaner air:

  1. Clean air without any impact between the observatory and India, Africa, or Sri Lanka. These sectors are defined by angles that exclude all other Maldivian atolls and the entire island of Kaashidhoo and are between 30° and 125° of the wind rose and between 240° and 260° (clockwise for all).

  2. Semi-clean air with low impact from Maldivian atolls that are 40-100 km away. This sector still excludes the entire island of Kaashidhoo, but includes atolls that are further away and is a continuous zone between 240° and 120° (Figure 5).

  3. Semi-polluted air, impacted by occasional emissions from locals. This sector includes portions of the island that are mostly vegetated and not permanently inhabited and increases the above sector to 225° - 165°.

  4. Exclusion sector with permanent, direct and significant impact of local pollution by the power house and island operation. This sector is between 165° and 225°.

The clean and semi-clean air sectors will include the NE and SW monsoon winds, the inclusion of the semi-polluted air sector will provide us with further data from more than 80% of all possible wind directions. In order to cover the remaining 60° exclusion sector, we would have the possibility to set up a secondary site at the SSW end of the island with few key measurements such as CO, aerosol and/or O3. This, however, will be considered as a long-term option and might not be initiated immediately.

Figure 5: Two photos taken at the very NE tip of the island, standing at the coral beach and looking SE and SW towards the visible extents of the island. This view basically describes the semi-polluted island sector (120° - 240°). The observatory would be right in front of the viewer, between the two pictures and about 50 m inland. Point A in the left picture and point B in the right picture depict the respective points shown in Figure 3.

Next section: INDOEX observatory and operation

C4 - 07 August, 1997