बिहार का शोक किस नदी को कहा जाता है?

The Kosi River is known as the 'Sorrow of Bihar' (Bihar ka Shok). Originating in the Himalayas of Nepal, the river carries colossal sediment loads that cause its braided channels to frequently shift their courses—shifting over 130 km westward over the past 250 years—and unleash catastrophic floods across north-eastern Bihar.