There are more than 14,000 ha under chaurs in Darbhanga district alone. The other major lake Kawar in Begusari district, covering an area of 7,400 ha. It is considered one of South Asia's largest freshwater lakes. Moreover, Bihar also has vast areas under diara and tal lands. Diara is land situated between natural levees or embankments.
Floods are an annual feature in diaras .
They are periodically eroded or formed due to a river's changing course. Diaras have not been surveyed well, but it is estimated that it accounts for 0.863 mha. Tal lands, bowl-shaped depressions, are found in natural levees of rivers and inundated by backwaters. This land is subject to prolonged flooding. An estimated 80,000-100,000 ha is under tals .