The total area is estimated at 29,524 km², 30,000 km² and 41,440 km². The active area is estimated at 4,762 km², and 6,000 km². The length of the total delta along the axis of Indus is estimated at 240 km, whereas the current delta stretches from the Arabian Sea to just south of Thatta (~100 km or 62 mi). There are currently 17 major creeks(Including Sir Creek, Bhitiaro Creek and Kori Creek) and numerous minor creeks. Average temperatures for the delta region range from 21 to 30 °C (70-85 °F) in July, and 10-21 °C (50-70 °F) in January. The climate of the delta is described as arid. It receives only 250–500 mm (9.8–19.7 in) of rain in a normal year. Mangrove forests are one of the most abundant ecological communities of the delta, but they have declined over the years. According to Haq et al.(1997), they covered an area of 600,000 hectares (1,500,000 acres) until the 1980s and could be found along the entire 240 km coastline, in 40% of the tidal zone, and in 10% of the delta fan. Memon(2005) reports that the area of mangrove forests was 263,000 hectares in 1977 and 158,500 ha (392,000 acres) in 1990. Both agree that they were sixth-largest mangrove forests in the world. Previously there had been eight species of mangroves, although only four now remain: Aegiceras corniculatum, Avicennia marina, Ceriops tagal, and Rhizophora mucronata. Among these Avicennia marina constitutes 99% of the mangrove population. As of 2007, the mangroves of the Indus delta are the largest desert climate mangrove forests in the world. However the Indus Delta saw an increase in number of mangroves after preservation and plantation initiatives. Mangrove forests of Indus delta now cover an area of around 600, 000 hectares. The mangroves are under control of three different organizations, namely: - Sindh Forest Department (280, 470 Ha) - Port Qasim Authority (64, 400 Ha) - Sindh Board of Revenue (255, 130 Ha). Arthrocnemum macrostachyum is also found growing in the delta.