Premium
Rice Drain Management to Reduce Seepage Exports in the Sacramento–San Joaquin Delta, California
Author(s) -
Bachand Philip A.M.,
Bachand Sandra M.,
Stern Dylan,
Deverel Steven,
Horwath William R.
Publication year - 2018
Publication title -
journal of environmental quality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 171
eISSN - 1537-2537
pISSN - 0047-2425
DOI - 10.2134/jeq2018.03.0089
Subject(s) - environmental science , san joaquin , hydrology (agriculture) , water quality , ditch , subsurface flow , groundwater recharge , groundwater , irrigation , subsidence , surface water , drainage , delta , environmental engineering , water resource management , aquifer , agronomy , geology , soil science , engineering , ecology , paleontology , geotechnical engineering , structural basin , aerospace engineering , biology
Many deltas worldwide face subsidence issues due to increased anthropogenic activity. The Sacramento–San Joaquin delta similarly faces ongoing subsidence, more than 8 m in some areas, that increases levee failure risks and threatens the security of this water source for 25 million California residents and 1.2 million ha of agriculture. Rice ( Oryza sativa L.) fields are an integral part of a proposed new strategy for managing subsidence because they have been shown to stop subsidence and provide an alternative crop for growers. Two important considerations for implementing rice fields are additional water requirement and the effect on water quality from mobilized dissolved organic carbon (DOC) and disinfection byproduct precursors. To understand constituent transport and potential management opportunities for rice farming, a plug flow reactor mass balance model was used to quantify surface and subsurface hydrologic pathways. Management of adjacent drainage ditch water levels under low and high scenarios were tested as a strategy to reduce seepage and water quality loads. Under high drains, groundwater met 10% of evapotranspiration (ET). Low drains resulted in a 100% increase in ET demand, which was met by surface water applied for irrigation. High drains reduced subsurface seepage by 95%. Subsurface DOC, trihalomethane, and total dissolved nitrogen loads were reduced 10‐fold in high drains compared with low drains. Flow rate accounted for 74 to 90% of load variance and was the primary determinant of constituent loads. Thoughtful implementation of rice cultivation, with high water levels in adjacent drains, can be leveraged to reduce irrigation water demand and constituent load outputs. Core Ideas High drain reduced subsurface seepage flow losses by >10× compared with low drain. High drain reduced groundwater seepage by 99% and surface water seepage by 90%. High drain reduced water quality loads from subsurface sources by 10×. Flow rate was the primary determinant of loads, accounting for 74–90% of variance.