The Ernakulum District has an area of 895.3Sq.k.m and can be divided geographically in to three well-defined parts such as Highland, Midland and Coastal area. The last one is also called as low land consisting of hills and forests, plains and the seaboard respectively. The altitude of Highland is about 1000 feet.
The borders of the district that is the four sides by which the district is surrounded are as follows: in the West the Arabian Sea, in the North Thrissur District, in the East Idukki District and in the South Alappuzha and Kottayam District. Periyar, which is Kerala`s second largest river, flows through all the Taluks except Muvattupuzha. Average rainfall of the district is 3431.8 mm, which is based on yearly basis and the total no of rainy days are 139. As there are rivers, lakes and seas the region has a moderate climate. Temperature is between 31.3oC and 25.8oC.
The hilly or Eastern portion is formed by a section of Western Ghats. We can define as Muvattupuzha, Kothamangalm and Aluva can be called the hilly taluks. The midland consists mainly of plain land having natural facilities of drainage via backwaters and canals. The Parur taluk which lies in the flat delta region of the Periyar river and cut by several canals, which have resulted in the formation of many islands and entire Kochi Taluk as well as the western part of Kanayannur come under lowland region. Major part of Kunnathunadu and eastern portion of Kanayannur taluk come under mid land region. It can be seen, as 20 percent of the total area is mainly low land region.
Thodupuzha, Muvattupuzha, Aluva, Kunnathunadu and Parur taluks. The Chalakudi River, which flows through north of Aluva, also joins Periyar at Elanthikara. The rivers Kaliyar, Thodupuzhayar and Kothamangalamar join together to form Muvattupuzha River. During rainy season these rivers are full and heavy floods affect the low-lying areas on the banks, but in the summer season they generally go dry and narrow. The Periyar is stretched over with a length of 229 Kms. The river plays a prominent role in the development of agriculture, industrial and commercial sectors of the district.
The seacoast in this district falls entirely in Kochi Taluk. One of the major natural Harbours is Kochi Harbour and is also situated in this taluk. Many Islands can be seen scattered in the backwaters in Kochi and Kanyannur Taluk. The Main islands of this district are Willingdon Island, Vypeen, Ramanthuruth, Cheriya kadamakkudi, Bolgatty The district has two main rivers Periyar and Muvattupuzha out of which the former flows through Ponjikara, Vallarpadam, Valiya Kadamakudi, Kumbalam, Panangad, Chellanam, Nettoor, Pizhala, Korampadam and Chennur. Most of these islands are very small in size extending from less than a 1 sq.km. To 4 sq.kms.
A portion of the Vembanad Lake falls within the Kochi Taluk. The Kodungalloor Kayal and Varappuzha kayal are also present in this district.
