Kerala 's western coastal belt is relatively flat compared to the eastern region , and is criss-crossed by a network of interconnected brackish canals , lakes , estuaries , and rivers known as the Kerala Backwaters . The state 's largest lake Vembanad , dominates the backwaters ; it lies between Alappuzha and Kochi and is about in area . Around eight percent of India 's waterways are found in Kerala . Kerala 's 44 rivers include the Periyar ; , Bharathapuzha ; , Pamba ; , Chaliyar ; , Kadalundipuzha ; , Chalakudipuzha ; , Valapattanam ; and the Achankovil River ; . The average length of the rivers is . Many of the rivers are small and entirely fed by monsoon rain . As Kerala 's rivers are small and lacking in delta , they are more prone to environmental effects . The rivers face problems such as sand mining and pollution . The state experiences several natural hazards like landslides , floods and droughts . The state was also affected by the 2004 Indian Ocean tsunami , and in 2018 received the worst flooding in nearly a century
the worst flooding
2018 Kerala floods
Kerala