Impact of capillary rise and recirculation on simulated crop yields
Upward soil water flow is a vital supply of water to crops. The purpose of this study is to determine if upward flow and recirculated percolation water can be quantified separately, and to determine the contribution of capillary rise and recirculated water to crop yield and groundwater recharge....
| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2018-05-01
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| Series: | Hydrology and Earth System Sciences |
| Online Access: | https://www.hydrol-earth-syst-sci.net/22/2937/2018/hess-22-2937-2018.pdf |
| Summary: | Upward soil water flow is a vital supply of water to crops. The purpose of
this study is to determine if upward flow and recirculated percolation water
can be quantified separately, and to determine the contribution of capillary
rise and recirculated water to crop yield and groundwater recharge.
Therefore, we performed impact analyses of various soil water flow regimes on grass,
maize and potato yields in the Dutch delta. Flow regimes are characterized by
soil composition and groundwater depth and derived from a national soil
database. The intermittent occurrence of upward flow and its influence on
crop growth are simulated with the combined SWAP-WOFOST model using various
boundary conditions. Case studies and model experiments are used to
illustrate the impact of upward flow on yield and crop growth. This impact is
clearly present in situations with relatively shallow groundwater levels
(85 % of the Netherlands), where capillary rise is a well-known source of
upward flow; but also in free-draining situations the impact of upward flow
is considerable. In the latter case recirculated percolation water is the
flow source. To make this impact explicit we implemented a synthetic
modelling option that stops upward flow from reaching the root zone, without
inhibiting percolation. Such a hypothetically moisture-stressed situation
compared to a natural one in the presence of shallow groundwater shows mean
yield reductions for grassland, maize and potatoes of respectively 26, 3 and
14 % or respectively about 3.7, 0.3 and
1.5 t dry matter per hectare. About
half of the withheld water behind these yield effects comes from recirculated
percolation water as occurs in free-drainage conditions and the other half
comes from increased upward capillary rise. Soil water and crop growth
modelling should consider both capillary rise from groundwater and
recirculation of percolation water as this improves the accuracy of yield
simulations. This also improves the accuracy of the simulated groundwater
recharge: neglecting these processes causes overestimates of 17 % for
grassland and 46 % for potatoes, or 63 and 34 mm yr<sup>−1</sup>, respectively. |
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| ISSN: | 1027-5606 1607-7938 |