Question

Discuss the availability of water resources in the country and factors that determine its spatial distribution?

Answer 1

India accounts for about 2.45 percent of the world’s surface area, 4 percent of the world’s water resources, and about 16 percent of the world’s population. The total water available from precipitation in the country in a year is about 4,000 cubic km. The availability of surface water and replenishable groundwater is 1,869 cubic km. Out of this only, 60 percent can be put to beneficial uses. Due to topographical, hydrological, and other constraints, only about 690 cubic km (32 percent) of the available surface water can be utilized. Water flow in a river depends on the size of its catchment area or river basin and rainfall within its catchment area.

Precipitation in India has very high spatial variation, and it is mainly concentrated in the Monsoon season. Rivers in the country like the Ganga, the Brahmaputra, and the Indus have huge catchment areas. Given that precipitation is relatively high in the catchment areas of the Ganga, the Brahmaputra, and the Barak rivers, these rivers, although account for only about one-third of the total area in the country, have 60 percent of the total surface water resources. Moreover, Himalayan rivers are glacial-fed perennials whereas Southern rivers are rainfed seasonal rivers. Much of the annual water flow in south Indian rivers like the Godavari, the Krishna, and the Kaveri has been harnessed, but it is yet to be done in the Brahmaputra and the Ganga basins.

Groundwater Resources: The total replenishable groundwater resources in the country are about 432 cubic km. The level of groundwater utilization is relatively high in the river basins lying in the north-western region and parts of south India. The groundwater utilization is very high in the states of Punjab, Haryana, Rajasthan, and Tamil Nadu. However, there are states like Chhattisgarh, Odisha, Kerala, etc., which utilize only a small proportion of their groundwater potentials. States like Gujarat, Uttar Pradesh, Bihar, Tripura, and Maharashtra are utilizing their groundwater resources at a moderate rate.

Lagoons and Backwaters: India has a vast coastline and the coast is very indented in some states. Due to this, a number of lagoons and lakes have formed. The States like Kerala, Odisha, and West Bengal have vast surface water resources in these lagoons and lakes. Water is generally used for fishing and irrigating certain varieties of paddy crops, coconut, etc.

Surface Water Resources: There are four major sources of surface water. These are rivers, lakes, ponds, and tanks. In the country, there are about 10,360 rivers and their tributaries longer than 1.6 km each. The mean annual flow in all the river basins in India is estimated to be 1,869 cubic km.