Loss or gained? an analysis of green spaces in city of colombo between 2010-2015

Abstract

Green spaces are an essential component in urban infrastructure and their heterogeneity influence the services they provide to mankind. During the last five year period a significant change in the landscape of City of Colombo was observed as many improvements were incorporated into various components of its infrastructure. We mapped vegetation cover of green spaces in 47 wards in the City of Colombo in 2010 and 2015 using Google Earth, ArcGIS 10.3 and ArcMap software and assessed their change in extent. In 2015 street trees, and vegetation in residential and commercial areas covered 86.06% of the city area while amenity and green open areas (such as lawns and playgrounds) covered 5.50 %. Cinnamon Gardens exhibited the highest cover for both these vegetation types. Patchy mix vegetation cover of the City was 4.49% and the highest extent was observed in Fort. Mattakkuliya had the highest extent of lake and canals, and associated wetlands which showed a city wide cover of 3.3%. Scattered patches of abandoned paddy fields and related marsh cover were highest in Kirullapone ward. Between 2010-2015 the total extent of green spaces in Colombo City has not been significantly changed, instead changes among vegetation types were identified. These included a 1.5% decrease in open green areas, patchy mixed vegetation, marshlands and a slight increase (>0.5% %) in vegetation at roadside, residential, commercial and amenity areas. A remarkable reduction of 13.26% in green spaces was reported from Modara while 3-6% decrease was reported from Thimbirigasyaya, Bambalapitiya, and Kirullapone wards. A 5-25% improvement of green spaces was reported in Panchikawatte, Pamankada, Kotahena West and East, Lunupokuna and Bloemendhal wards. While reflecting the recent changes in landscape in Colombo wards, this paper also highlights the need of strategic improvement of different vegetation types to receive optimum services and values from city’s green spaces. Thus, it is expected that findings of this work will be used for planning of further modifications to the existing landscape in the City of Colombo.