Reasons for decline in traditional water harvesting system
Some of the reasons for the decline in  traditional water harvesting system in our country are-
1. British westernized  the whole water distribution system and took over the role of main provider of  water thus replacing traditional decentralized system with centralized ones.
2. Apathy  of policy makers towards water harvesting structures after independence and  lack of innovative ways to deal with water related issues. (With a basic  reliance on big dams, surface transport of water through canals and inter-basin  transfers).
3. Growing  use of subsidized energized system (Subsidized electrical powers) to exploit  deep aquifers.
4. Declining  interest on the part of community to nurture various traditional water  harvesting systems.
5. Subsidized  supply of fertilizers reduced the dependence of farmers on the tank silt.
6. Some of  these tanks were encroached for farming, sand mining, expansion of city, waste  dumping, industry, etc.

Contemporary relevance of rainwater  harvesting
The question arises as to  why rainwater harvesting matters more today? According to Jackson et al3., there are several  reasons -
1. Over half of the accessible fresh water run off  globally is already appropriated for Human  use.
2. A large percentage of people currently lack access  to clean drinking water and almost lack basic sanitation services.
3. As human population will grow faster than increases  in the amount of accessible fresh water, per capita availability of fresh water  will decrease in the coming century.
4. Climate change will cause a general intensification  of the earth’s hydrological cycle in the next 100 years with generally increase  in precipitation, evapotranspiration, occurrence of storms and significant  changes in biogeochemical processes influencing water quality.

As summers get hotter and anthropogenic climatic changes  exert further strain on economic, social and natural systems, water scarcity is  likely to grow in India and elsewhere. Under such circumstances, harvesting  rain shall become crucial.