southwest monsoons. There are several small lakes of ponds (known as Kulam) in the city. These include Nainar Kulam, Veinthan Kulam, Elantha Kulam and Udayarpetti Kulam. The area around the Tamirabarani River and the Chittar has five streams: Kodagan, Palayan, Tirunelveli, Marudur East and Marudur West, and the Chittar feeds fifteen other channels. The soil is friable, red and sandy. Climate Tirunelveli has a hot semi-arid climate (Köppen: BSh) bordering on the relatively rare dry-summer tropical savanna climate (Köppen: As), scattered irregularly across the world but relatively common in areas near the Laccadive Sea. The climate of Tirunelveli is generally hot and humid. The average temperature during summer (March to June) ranges from to , and to during the rest of the year. The average annual rainfall is . Maximum precipitation occurs during the northeast monsoon (October–December). Since the economy of the district is primarily based on agriculture, flooding of the Tamarabarani River or a fluctuation in monsoon rain has an immediate impact on the local economy. The primary crops grown in the region are paddy and cotton. Pineapples were introduced during the 16th century, chilly and tobacco during the late 16th and potatoes during the early 17th centuries. The most common tree is the palmyra palm, a raw material in cottage industries. Other trees grown in the region are teak, wild jack, manjakadambu, venteak, vengai, pillaimaruthu, karimaruthu and bamboo. Livestock of the city and district comprises cattle, buffalo, goats, sheep and other animals in smaller numbers. Demographics According to 2011 census, Tirunelveli had a population of 473,637 with a sex-ratio of 1,027 females for every 1,000 males, much above the national average of 929. A total of 46,624 were under the age of six, constituting 23,894 males and 22,730 females. Scheduled Castes and Scheduled Tribes accounted for 13.17% and 0.32% of the population respectively. The average literacy of the city was 81.49%, compared to the national average of 72.99%. The city had a total of 120,466 households. There were a total of 182,471 workers, comprising 2,088 cultivators, 5,515 main agricultural labourers, 18,914 in house hold industries, 142,435 other workers, 13,519 marginal workers, 166 marginal cultivators, 913 marginal agricultural labourers, 1,828 marginal workers in household industries and 10,612 other marginal workers. According to provisional data from the 2011 census the Tirunelveli urban agglomeration had a population of 498,984, with 246,710 males and 252,274 females. The overall sex ratio in the