There are 44 major rivers in Kerala, all but three originating in the Western Ghats. 41 of them flow westward and 3 eastward. The rivers of Kerala are small, in terms of length, breadth and water discharge. The rivers flow faster, owing to the hilly terrain and as the short distance between the Western Ghats and the sea. All the rivers are entirely monsoon-fed and many of them shrink into rivulets or dry up completely during summer. Features Kerala is wedged between the Lakshadweep Sea and the Western Ghats. Geographically, the state can be divided into three climatically distinct regions: the eastern highlands; rugged and cool mountainous terrain, the central mid-lands; rolling hills, and the western lowlands; coastal plains. The eastern region of Kerala consists of high mountains, gorges and deep-cut valleys immediately west of the Western Ghats' rain shadow. 41 of Kerala's west-flowing rivers, and 3 of its east-flowing ones originate in this region. The 41 west-flowing rivers, each of which having at least a length of 15 km, gradually slopes towards the Arabian Sea coast in the western region and empty either into backwaters or Arabian Sea there. The longer rivers have several tributaries and streams too. The Western Ghats form a wall of mountains interrupted only near Palakkad; hence also known Palghat, where the Palakkad Gap breaks. The river Bharathappuzha flows through the Palakkad Gap. The 3 east-flowing rivers also originate in Western Ghats, but flow eastwards either into Karnataka or Tamil Nadu. 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. Kuttanad, also known as The Rice Bowl of Kerala, has the lowest altitude in India, and is also one of the few places in world where cultivation takes place below sea level. The country's longest 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