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Hydrology of a groundwater‐irrigated rice field in Bangladesh: Seasonal and daily mechanisms of infiltration
Author(s) -
Neumann Rebecca B.,
Polizzotto Matthew L.,
Badruzzaman A. Borhan M.,
Ali M. Ashraf,
Zhang Zhongyuan,
Harvey Charles F.
Publication year - 2009
Publication title -
water resources research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.863
H-Index - 217
eISSN - 1944-7973
pISSN - 0043-1397
DOI - 10.1029/2008wr007542
Subject(s) - groundwater recharge , infiltration (hvac) , hydrology (agriculture) , hydraulic conductivity , groundwater , aquifer , environmental science , irrigation , surface runoff , surface irrigation , subsoil , interflow , water balance , geology , soil science , soil water , geography , agronomy , geotechnical engineering , meteorology , ecology , biology
Flow through a groundwater‐irrigated rice field in Bangladesh was characterized with data collected from a transect of tensiometers and time domain reflectometry sensors, novel tracer tests, infiltration tests, soil core analyses, and calculated water budgets. The combined data captured the dynamic hydrologic behavior of the rice field over an entire growing season, which included many irrigation events. Recharge to the aquifer flowed from the surface of the rice field through preferential flow paths located in the subsoil beneath the plowed surface of the field and in the bunds, the raised boundaries around the perimeter of the field. Water that remained within the soil matrix did not recharge the aquifer. Bund flow was the dominant loss for the field because the bulk hydraulic conductivity of the soil beneath the bunds was greater than that in the plowed and planted region of the rice field. Each year, farmers plow the rice fields, destroying cracks and decreasing the conductivity of the shallow soil, but leave the bunds unplowed because they follow property boundaries. We determined bund flow with a daily water balance and confirmed its importance by comparing irrigation losses among fields of different sizes and geometries and hence different ratios of perimeter to area. The perimeter‐to‐area ratio predicted the fraction of water lost down the bunds for these and other fields located throughout Southeast Asia. Finally, we determined the economic and environmental benefits of reducing bund flow.