Rainfed rice - IRRI books - International Rice Research Institute
Rainfed rice - IRRI books - International Rice Research Institute
Rainfed rice - IRRI books - International Rice Research Institute
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Influence of Agro-Ecosystem Components on <strong>Rice</strong> Production<br />
Table 1. Influence of rainfall and landform/physiography on the hydrology of rainfed <strong>rice</strong> lands<br />
Landform/physiography<br />
Rainfall<br />
(amount/intensity) 1 Plains Gently sloping Low-lying<br />
High amount<br />
High intensity Abrupt accumulation Abrupt accumulation but fast Abrupt accumulation<br />
but slow recession recession (flood: shorter but slow recession (flood:<br />
(flood: intermediate duration and shallow). longer duration and deep).<br />
duration, and depth).<br />
Low intensity Gradual accumulation Gradual accumulation but fast Gradual accumulation and<br />
but fast recession recession (flood: shorter slow recession (flood: longer<br />
(flood: intermediate duration and shallow). duration and deep).<br />
duration and depth).<br />
Normal amount<br />
High intensity No accumulation Gradual accumulation but fast<br />
(no flood and no recession (no flood and no<br />
drought). drought).<br />
Abrupt accumulation but<br />
slow recession (flood: longer<br />
duration and deep).<br />
Low intensity No accumulation No accumulation (no flood Gradual accumulation and<br />
(no flood and no and no drought). slow recession (flood:<br />
drought). shorter duration and<br />
intermediate depth).<br />
Low amount<br />
High intensity No accumulation No accumulation (no flood, Abrupt accumulation (also<br />
(flood, but may have but drought occurs). because of drainage from<br />
drought)'. catchment) but slow<br />
recession (flood: longer<br />
duration and intermediate/<br />
shorter depths).<br />
Low intensity No accumulation (no No accumulation (no flood, Gradual accumulation, slow<br />
flood, but drought but drought occurs). recession (flood: shorter<br />
occurs). duration and shallow).<br />
1 Amount refers to total annual rainfall and intensity refers to one occurrence.<br />
Rainfall and water depth<br />
The rainfall in June-October during<br />
1984-92 and peak water depth<br />
accumulation in Ghaghraghat,<br />
Bahraich District, show that<br />
accumulation of water depends not<br />
only on total rainfall in an area, but<br />
also on the duration, intensity and<br />
period of rainfall as well as drainage<br />
from the catchment area.<br />
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