Impact of capillary rise and recirculation on simulated crop yields

Abstract

Abstract. 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 −1 , respectively.

Delineation of Hydraulic Flow Regime Areas Based on the Statistical Analysis of Semicentennial Shallow Groundwater Table Time Series

“…Shallow groundwater (SGW) is an important source for irrigation and food production in many countries, and also serves as an important secondary source of water supply during natural droughts [13]. Furthermore, the state of the SGW table plays an important role in groundwater-dependent ecosystems [14], and thanks to capillary action, SGW, and therefore its level, also has an effect on surface vegetation and yield of agricultural crops [15,16]. Consequently, any decline in the water table, due to changes in precipitation patterns and rises in temperature, can reduce well yield and increase pumping costs.…”

A Comprehensive Distributed Hydrological Modeling Intercomparison to Support Process Representation and Data Collection Strategies

“…For this reason, soil moisture simulated by mHM for deeper soil layers is more dynamic and it is still strictly coupled to the atmospheric forcing. As this dynamic could be relevant also for capturing land surface fluxes (Kollet & Maxwell, ; Kroes et al, ), comparisons with groundwater observations are highly recommended even when groundwater prediction is not intended to identify limitations also for other simulated states and land surface fluxes. Simple parametrizations to account for groundwater contributions on ET should be, for instance, included also in mHM to partially compensate this unresolved hydrological process (Liu et al, ).…”

SWAP 4 : technical addendum to the SWAP documentation

“…Recently Kroes et al (2018) analysed the impact of capillary rise and recirculation of percolation water below grassland, maize and potatoes in Dutch soils. They concluded that 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.…”