Yamuna floodplains

• The Yamuna on July 13 crossed the record set in 1978 of 207.49 metres.
• Causes, experts argue, can be traced to haphazard construction activities, urbanisation, lack of proper housing and lax regulations.
• The floodplain along Yamuna’s 22 km run in Delhi, designated as the O zone by the Delhi Development Authority, has an area of approximately 9,700 hectares.
• As part of river systems, floodplains slow water runoff during floods, recharge groundwater and store excess water, replenishing the city’s water supply.
• If you lose the floodplain, you also lose the storage of water.

Delhi’s Master Plan

The Yamuna floodplain was designated as a protected area free from construction in the Delhi Masterplan of 1962.

The Central Ground Water Authority in 2000 also notified the floodplains as ‘protected’ for groundwater management.

The South Asia Network on Dams, Rivers and People (SANDRP) in 2020 found large parts of the Yamuna floodplains and riverbed were “grossly abused” due to lax implementation.

About floodplain?

• A floodplain (or floodplain) is a generally flat area of land next to a river or stream. It stretches from the banks of the river to the outer edges of the valley.

A floodplain consists of two parts.

– The first is the main channel of the river itself, called the floodway.

• Floodways can sometimes be seasonal, meaning the channel is dry for part of the year.
• It is the main channel where the river flows.

– Beyond the floodway is the flood fringe.

• It is the land between the banks of the floodway and the valley wall or anywhere the valley land starts to rise.
• The width of a flood fringe can vary according to the river, but they can be surprisingly wide

How do floodplains form?

• Floodplains develop in two common ways: erosion and deposition (also known as aggradation).
• The erosion of a floodplain describes the process in which earth is worn away by the movement of a floodway.
• Aggradation (or alluviation) of a floodplain describes the process in which earthen material increases as the floodway deposits sediment.
• A river erodes a floodplain as it meanders, or curves from side to side.
• A meandering stream can contribute to a floodplain’s aggradation, or build-up in land elevation, as well as its erosion.
• The deposition of sediment that happens in floodplains can be the source of major fertility.
• This sediment is usually built up of alluvium, or silt, which is considered some of the richest soil, containing nutrients like potash, phosphoric acid and lime.

Yamuna River System

• Yamunotri, which is north of Haridwar in the Himalayan Mountains, is the source of the Yamuna.
• The river Yamuna, a major tributary of river Ganges, originates from the Yamunotri glacier near Banderpoonch peaks in the Mussourie range of the lower Himalayas.
• The river after originating from the state of Uttarakhand in India passes through the states of Himachal Pradesh, Haryana, Delhi, and Uttar Pradesh and joins the Ganga River at Prayagraj.
• The total length of the Yamuna River is 1376 km.
• The Yamuna River basin accounts for 40.2% of the total basin of the Ganga River and 10.7% of the total area of India.
• Left bank tributaries of Yamuna River – Hindon, Hanuman Ganga, and Sasur Khaderi are the left bank tributaries of the river Yamuna.
• Right bank tributaries of Yamuna River – Tons, Giri, Chambal, Betwa, Sindh, Dhasan, Ken are the important right bank tributaries of river Yamuna.