Test: Drainage - 2

The Government of India and many concerned state governments have started implementing various programmes to deal with the problems arising out of river pollution. They have made action plans and are vigorously implementing these plans.

The self cleansing capacity of a river refers to the natural ways in which the river gets rid of the pollutants discharged into it. The flow of the river, the presence of bacteria which decompose the pollutants and make them into harmless substances, are some factors which contribute to the self cleansing capacity of the river. But this can work to a certain limit only. Natural processes can help to keep the river clean to a certain extent but they cannot overcome uncontrolled pollution.

The aquatic organisms cause no harm to rivers it’s the human activities that causes pollution to happen breaking the ecosystem balance.

The correct option is Option D.

Rivers have been of fundamental importance throughout human history. Water from the rivers is a basic natural resource, essential for various human activities. The river banks have attracted settlers from ancient times. These settlements have also become big cities, that is why rivers are considered the lifelines of human civilization.

Nagarjuna Sagar Dam is one of the world's largest and tallest Masonry dams built across the Krishna river at Nagarjuna Sagar which straddles the border between Nalgonda District, Telangana State, India and Guntur district, Andhra Pradesh State, India. Constructed between 1955 and 1967, the dam created a water reservoir with gross storage capacity of 11.472 billion cubic metres (405.1×109 cu ft). The dam is 590 feet (180 m) tall from its deepest foundation and 0.99 miles (1.6 km) long with 26 flood gates which are 42 feet (13 m) wide and 45 feet (14 m) tall.

Nagarjuna Sagar was the earliest in a series of large infrastructure projects termed as "modern temples" initiated for achieving the Green Revolution in India. It is also one of the earliest multi-purpose irrigation and hydro-electric projects in India. The dam provides irrigation water to the Nalgonda, Suryapet, Krishna, Khammam, West Godavari, Guntur and Prakasam districts along with hydro electricity generation. Nagarjuna Sagar dam is designed and constructed to use all the water impounded in its reservoir of 312 TMC gross storage capacity which is the second biggest water reservoir in India.

Barapani Lake is not created by human being. It’s a Natural Lake. Located at a distance of around 15 km from Shillong, Barapani Lake is a picnic spot. It is also known as Umiam Lake.

Wular Lake (also spelt Wullar) is one of the largest fresh water lakes in Asia. It is sited in Bandipora district in the Indian state of Jammu and Kashmir. The lake basin was formed as a result of tectonic activity and is fed by the Jhelum River.

Tapi river rises near Multai in the Betul district of Madhya Pradesh at an elevation of about 752 m and flows for about 724 km before outfalling into the Arabian Sea through the Gulf of Cambay.

India's most freshwater lakes are found in the Himalayan region. Because they are of glacial origin which means that they were formed when glaciers dug out a basin which was later filled with snow melt.

Wular Lake (also spelt Wullar) is one of the largest freshwater lakes in Asia. It is sited in Bandipora district in the Indian state of Jammu and Kashmir. The lake basin was formed as a result of tectonic activity and is fed by the Jhelum River.

Brahmaputra is a braided river because it one of the number of channel type and has a channel which consists of network of small channels which are separated by small islands which braids.

The Godavari flows from North to South in Dharmapuri, hence the river is locally called 'Dakshina Vahini' Kaleshwaram – Sri Kaleswara Mukhteswara Swamy Temple is situated here on the banks of Triveni sangamam of rivers Godavari and pranahita. 

Narmada and tapi are western rivers and Western rivers do not form Delta whereas they form Estuaries because Hard Rocks of Western ghat don't allow Western flowing rivers to widen their mouth into sea, so these rivers form Estuaries whereas Eastern rivers flow through broken hills and mountain ranges.

The Narmada, also called the Rewa, is a river in central India and the fifth longest river in the Indian subcontinent. It is the third longest river that flows entirely within India, after the Godavari, and the Krishna. It is one of only three major rivers in peninsular India that run from east to west (longest west flowing river), along with the Tapti River and the Mahi River. It is one of the rivers in India that flows in a rift valley, flowing west between the Satpura and Vindhya ranges. The other rivers which flow through rift valley include Damodar River in Chota Nagpur Plateau and Tapti. The Tapti River and Mahi River also flow through rift valleys, but between different ranges.

Nagarjuna Sagar Dam is a masonry dam across the Krishna river at Nagarjuna Sagar which straddles the border between Guntur district, Andhra Pradesh and Nalgonda district, Telangana.

The term drainage describes the river system of an area. Look at the physical map. You will notice that small streams flowing from different directions come together to form the main river, which ultimately drains into a large water body such as a lake or a sea or an ocean. The area drained by a single river system is called a drainage basin. A closer observation on a map will indicate that any elevated area, such as a mountain or an upland, separates two drainage basins. Such an upland is known as a water divide (Figure 3.1).