Rainfall has traditionally been plentiful for growing tea, especially in India but with recent changes in the climate, surface and ground water are becoming important irrigation systems.
Links:
[1] http://admin.indiaenvironmentportal.org.in/news/efforts-make-tea-industry-climate-smart
[2] http://admin.indiaenvironmentportal.org.in/category/author/indrani-dutta
[3] http://admin.indiaenvironmentportal.org.in/category/newspaper/hindu-new-delhi
[4] http://admin.indiaenvironmentportal.org.in/category/thesaurus/climate-change
[5] http://admin.indiaenvironmentportal.org.in/category/thesaurus/tea
[6] http://admin.indiaenvironmentportal.org.in/category/thesaurus/groundwater
[7] http://admin.indiaenvironmentportal.org.in/category/thesaurus/irrigation
[8] http://admin.indiaenvironmentportal.org.in/category/thesaurus/climate-impacts
[9] http://admin.indiaenvironmentportal.org.in/category/thesaurus/carbon-dioxide
[10] http://admin.indiaenvironmentportal.org.in/category/thesaurus/floods
[11] http://admin.indiaenvironmentportal.org.in/category/thesaurus/brahmaputra
[12] http://admin.indiaenvironmentportal.org.in/category/thesaurus/north-east