Bihar Rivers and Floods: Kosi, Gandak and Kabartal

The correct answer is B, the Kosi. The Kosi earns the name because it brings an exceptionally heavy load of silt down from Nepal, drops it the moment it reaches the flat North Bihar plain, raises its own bed above the surrounding land and then breaks out into a new channel. Over about two hundred years the river swung roughly 112 kilometres to the west, so the flood did not return to the same tract but ruined a fresh one each time.

Option A, the Gandak, floods Champaran and Muzaffarpur badly but is controlled from the Valmikinagar barrage and has no such record of shifting. Option C, the Son, is a southern plateau river, seasonal and comparatively well behaved, and is remembered as the largest southern tributary of the Ganga rather than for floods. Option D, the Punpun, is a small Chotanagpur stream that joins the Ganga near Fatuha. For the paper, remember the pairing of sorrows: the Kosi is the Sorrow of Bihar, the Damodar the Sorrow of Bengal and the Hwang Ho the Sorrow of China.

The correct answer is A, Chausa in Buxar district. The Ganga comes into Bihar from Uttar Pradesh near Chausa, flows from west to east for about 445 kilometres and leaves the state for West Bengal near Rajmahal, splitting Bihar into the North Bihar plain and the South Bihar plain on the way.

Option B, Maner, is the place west of Patna where the Son, the largest southern tributary, joins the Ganga, so it is a confluence inside the state and not the point of entry. Option C, Kursela in Katihar district, is where the Kosi meets the Ganga in the east of the state, again a confluence and not an entry point. Option D, Rajmahal, is the exit: the Ganga passes into West Bengal there, and papers often swap the entry and the exit to see whether a candidate has learnt both. Chausa is also worth remembering for history, as the site of the battle of 1539 in which Sher Shah Suri defeated Humayun.

The correct answer is B, Sonpur, opposite Patna. The Gandak rises in Nepal, where it is called the Narayani or the Sapt Gandaki, enters Bihar at Valmikinagar in West Champaran and flows south-east to meet the Ganga at Sonpur, across the river from Patna. The confluence is the site of the Sonepur cattle fair, which makes the pair easy to remember.

Option A, Doriganj in Saran district, is the confluence of the Ghaghara, the river that comes from Nepal as the Karnali and forms part of the western boundary of Bihar. Option C, Khagaria, is where the Burhi Gandak reaches the Ganga, and the similar name is exactly the trap the question is built on: the Gandak and the Burhi Gandak are different rivers with different mouths. Option D, Kursela in Katihar district, is the confluence of the Kosi. Learn the four mouths as a set, because match-the-following questions use all of them together.

The correct answer is B, the Son. The Son rises at Amarkantak in Madhya Pradesh, the same plateau that gives birth to the Narmada, flows north-east through Rohtas and joins the Ganga near Maner, a little west of Patna. It is the largest of the rivers that reach the Ganga from the south, and the Indrapuri barrage at Dehri-on-Sone diverts its water into the Sone canal system, one of the oldest canal networks in India.

Option A, the Punpun, is a much smaller Chotanagpur stream joining the Ganga near Fatuha, south-east of Patna. Option C, the Kiul, drains the Jamui and Lakhisarai tract and meets the Ganga near Surajgarha. Option D, the Chandan, comes from the Jharkhand hills into Banka and Bhagalpur. All three are southern rivers, so the question is really asking which is the largest, and the Son is also the second longest southern tributary of the Ganga in the country after the Yamuna.

The correct answer is A, Begusarai. Kabartal, also called Kanwar Jheel, lies in Begusarai district and is an ox-bow lake left behind by the Burhi Gandak. It was listed as a wetland of international importance under the Ramsar Convention in 2020, the first site in Bihar to be listed, and it is often described as the largest freshwater ox-bow lake in Asia. It is an important halt for migratory waterbirds on the Central Asian Flyway.

Option B, Jamui, is the district of the Nagi and Nakti bird sanctuaries, two irrigation reservoirs that were later added to the Ramsar list, and it is the distractor most often used against Begusarai. Option C, Katihar, has the Gogabil wetland, protected as a community reserve, and is where the Kosi meets the Ganga. Option D, Samastipur, has chaur wetlands of its own but no Ramsar site. The pairing to memorise is Kabartal with Begusarai and 2020.

The correct answer is B, Bhimnagar. The Kosi project that followed the 1954 agreement between India and Nepal has three parts: a barrage at Bhimnagar on the border, long embankments on both banks of the river downstream, and canals, of which the Eastern Kosi Main Canal is the largest. The barrage both feeds the canals and allows the flood discharge to be regulated.

Option A, Valmikinagar, also called Bhainsalotan, in West Champaran, is the barrage on the Gandak, not the Kosi, and the two are the classic pair in a match-the-following question. Option C, Dehri-on-Sone in Rohtas district, is the Indrapuri barrage on the Son, which feeds the old Sone canal system. Option D, Farakka, is in West Bengal on the Ganga, built to flush silt from the Hooghly and keep Kolkata port navigable, and it lies outside Bihar altogether. Learn the three barrage and river pairs together: Bhimnagar on the Kosi, Valmikinagar on the Gandak and Indrapuri on the Son.

The correct answer is A, the Karmanasa. The Karmanasa rises on the Kaimur plateau, flows north along part of the boundary between Bihar and Uttar Pradesh and meets the Ganga near Chausa in Buxar district, the same place at which the Ganga enters Bihar. In folk belief the river is held to be inauspicious, which is how it got its name, and that story is often what a question hangs on.

Option B, the Punpun, is a southern river that joins the Ganga near Fatuha, well to the east of Patna, and does not touch the state boundary. Option C, the Son, also comes from the south-west, but it joins the Ganga near Maner and flows inside the state rather than along its border. Option D, the Burhi Gandak, is a north bank river that rises in the Someshwar hills of West Champaran and joins the Ganga near Khagaria, at the other end of the state. The Ghaghara is the other river associated with the western boundary, but its confluence is at Doriganj in Saran.

The correct answer is A, Kusaha in Nepal. In August 2008 the eastern embankment of the Kosi gave way at Kusaha, upstream of the Bhimnagar barrage and inside Nepal. The river left its embanked course, took an old abandoned channel to the east and poured across Supaul, Madhepura, Araria and Saharsa districts, displacing lakhs of people. It was declared a national calamity, and it remains the standard example of what the Kosi's shifting habit can do even after a century of embankment building.

Option B, Birpur in Supaul district, is the headquarters of the Kosi project works on the Indian side, not the breach site. Option C, the Bhimnagar barrage itself, held; the failure was in the earthen embankment upstream of it, which is the point the question is testing. Option D, Kursela in Katihar, is the confluence of the Kosi with the Ganga, far downstream of the breach. Remember the year 2008 with the place Kusaha.

The correct answer is A, Bhagalpur. The sanctuary was notified in 1991 along a stretch of about sixty kilometres of the Ganga between Sultanganj and Kahalgaon in Bhagalpur district. It is the only protected area in the country created specifically for the Gangetic river dolphin, which is India's national aquatic animal, and it takes its name from the ancient Vikramshila university that stood nearby at Antichak.

Option B, Patna, lies on the Ganga and has a riverfront dolphin research centre associated with it, but the sanctuary is not there. Option C, Munger, is immediately upstream of the sanctuary stretch and is a plausible-looking answer for that reason. Option D, Katihar, is downstream at the Kosi confluence. Two facts travel together in papers: the Gangetic dolphin was declared the national aquatic animal in 2009, and its only sanctuary is Vikramshila in Bihar.

The correct answer is B, chaur. A chaur is a shallow, saucer-shaped basin in the flat North Bihar plain that holds water for much of the year because the land has almost no slope and the rivers have raised their own beds. The chaurs of Darbhanga, Madhubani and Katihar are the heart of makhana cultivation, and Bihar grows most of the country's makhana; Mithila Makhana carries a geographical indication tag.

Option A, diara, is the sandy riverine land lying between the channels of the Ganga, cropped with melons, cucumbers and vegetables after the flood recedes. Option C, tal, is the belt of heavy clay flats in South Bihar, such as the Mokama Tal in Patna and Nalanda districts, which grows rabi pulses once the water drains away. Option D, maun, is an ox-bow lake, the cut-off loop of a river that has changed its course, as Kabartal in Begusarai is. All four words appear together in objective questions, so each must be learnt separately.

The correct answer is A, Gaya. The Phalgu, or Falgu, is formed by the union of the Lilajan and the Mohana a little above Gaya and flows past the city with a wide bed that stays sandy and dry for most of the year. Pilgrims come to its bank at Gaya during Pitrapaksha to perform tarpan for their ancestors, which is why the river appears in Bihar papers as a culture question as much as a geography one.

Option B, Rajgir, in Nalanda district, is known for its hot springs and the hills that ring the old Magadhan capital, not for the Phalgu. Option C, Sasaram in Rohtas district, lies in the Son basin and is remembered for the tomb of Sher Shah Suri. Option D, Bodh Gaya, is close to Gaya and on the same river system, but the ritual bank and the city that papers name is Gaya itself. The Phalgu is also a good example of a southern river that is seasonal rather than perennial.

The correct answer is A, the Tamur. The Kosi is called the Sapt Kosi because seven head streams gather in the Nepal Himalaya to make it, and of these the three main ones are the Sun Kosi from the west, the Arun from the north and the Tamur from the east. They meet in Nepal above Barahkshetra, where a high dam has long been proposed but never built, and the combined river then enters Bihar near Bhimnagar.

Option B, the Bagmati, rises in the Shivapuri hills near the Kathmandu valley and is a separate river that later joins the Kosi inside Bihar, in Khagaria district. Option C, the Kamla Balan, comes from the Mahabharat range and also joins the Kosi within Bihar, so it is a tributary of the Kosi rather than a head stream of the Sapt Kosi. Option D, the Mahananda, rises in the Darjeeling hills, flows through Kishanganj and Katihar and belongs to a different basin altogether, reaching the Ganga only after leaving Bihar.