PATNA 24 JULY: In this article, we're going to learn why rivers in Bihar flood every monsoon .now Bihar is India's most flood-prone state, especially the region of northern Bihar. Northern Bihar shares its border with Nepal. if you look at the topography of Bihar it is very much influenced by the flowing of both perennial and non-perennial rivers. Although the state has many rivers in this article I will only tell you about those rivers that are flowing above the danger level. Due to which there are floods in the northern part of Bihar and it happens only during the monsoon period. Every year the first river is Gandaki river i am going to copy the explanation from one of my old research just to make you understand where the river originates and how it flows into the state of Bihar. Now this river originates in northern Nepal near Tibet border from the Nubian Himal glacier. in the mustang region of Nepal here this river is named kali-Gandaki river. it flows through the entire breadth of Nepal and enters into the Tehran region of northern Uttar Pradesh and Bihar. after entering India this becomes the Gandaki. Now it enters india in such a way that the river meanders and flows along with the Uttar Pradesh and Bihar border for about 30 to 35 kilometers. Before flowing fully into the state of Bihar the reverse course is in the southeastern direction. where it heads towards the capital city of Patna and joins the river Ganga at sonpur, before it becomes its left bank tributary now that you have understood the flowing pattern of Kanak river. many nearby villages are flooded when the Gandaki river overflows even the meteorological department issued. An alert regarding its overflow of the second river is the Kamla river. the kamala river originates from churya range near sindhuli district of Nepal and flows through the Indian state of Bihar .it enters Indian territory in Madhubani district in Bihar. the river continues to flow south and finally joins river kosi ,even this river is capable of flooding and an alert has been issued by the meteorological department. The third river is the Bagmati river. the bhagmati river originates high in the shelf puri hills near the village of bhagwar. some 15 kilometers north of the Kathmandu valley it flows south and enters in the state of Bihar .Through sitamari district the river flows south and drains into the Kosi river, even this river is capable of flooding and an alert has been issued by the meteorological department. the fourth river is Kosi . the river originates and how it flows into the state of bihar. it originates in southern tibet and northern nepal border that means it is a transboundary river. kosi river is part of the arun river, it flows through the entire breath of nepal and enters india to the state of bihar. after entering Bihar if you see it makes a long curve before joining the river Ganga at kursaal. It is a known fact that Bihar is India's most flood-prone state and it is because of river kosi in fact the entire river has shifted from 115 kilometer westward due to the sedimentation and tectonic activities, that's why the entire river forms a long sea curve before joining the river Ganga . otherwise, the coast of the Kosi river is pretty straight forward from nepal to ganga but over the years it has shifted in this curve form and that causes heavy flood in this region. anyhow by joining the river Ganga river kosi becomes its left bank tributary as i have mentioned river kosi has shifted its course 150 kilometers from east to west during the last 200 years. the reason behind the shift in kosi reverse course is due to tectonic movement and also due to the rising volume of incoming water during heavy monsoon, that's why the entire river forms a long sea curve before joining the river Ganga. This entire region to the east of river Kosi is a flood zone. the fifth river is mahananda river the mahananda river originates in the Himalayas near chimli east of cursing in Darjeeling district of northern west Bengal. it flows south along the west Bengal bangladesh border and then turns southwest where it descends to the plains of Siliguri and enters Bihar through kishanganj . district of Bihar as soon as the river enters the northeastern district of Bihar the flow of the river increases due to land slope the northern part of Bihar, A plain area land elevation increases towards the north and northeastern side. that is why most of these rivers that come from Nepal enter into the state of Bihar due to the low land elevation. you also have to understand the fact that the northern region of Bihar and southern region of Nepal is a terai region. meaning this area is at the foothills of the Himalayas, you can also call it the north of the Indo-Gangetic plain that means it is low land. The belts then obviously the rivers that originate in the Himalayan region will flow naturally towards the low land areas of northern Bihar during heavy monsoon it rains heavily in northern Bihar as well as in Nepal due to that water level of these rivers increase when the water level of the rivers in Nepal increases. obviously, it will rush towards the lowland areas which is also known as the catchment area and most of that lowland area or the catchment area lies in the northern part of Bihar. villages that reside on the bank of all these rivers that I've mentioned faces heavy floods and finally all these rivers flow south and drains into the river Ganga which splits Bihar into two parts north Bihar and south Bihar.