Coupled model of surface runoff and surface-subsurface water movement

Authors: ZHUANGJI, WANG - University Of Maryland; Timlin, Dennis; KOUZNETSOV, MIKALL - Ben Gurion University Of Negev; Fleisher, David; TULLY, KATHERINE - University Of Maryland; LI, SANAI - Us Forest Service (FS); Reddy, Vangimalla

Submitted to: Advances in Water Resources
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/19/2019
Publication Date: 12/24/2019
Citation: Zhuangji, W., Timlin, D.J., Kouznetsov, M., Fleisher, D.H., Tully, K., Li, S., Reddy, V. 2019. Coupled model of surface runoff and surface-subsurface water movement. Advances in Water Resources. https://doi.org/10.1016/j.advwatres.2019.103499.
DOI: https://doi.org/10.1016/j.advwatres.2019.103499

Interpretive Summary: Soil surface water flow as runoff has been recognized as an important component in agricultural water management. Computer simulation models of runoff are important agricultural management tools that can be used to calculate water balances and movement of water and nutrients from agricultural fields to surface waters. Most agricultural models use a correlative relationship between rainfall intensity and soil conditions to calculate runoff. These models cannot calculate ponding of water in furrows between rows of plants. The purpose of this study was to develop a more realistic approach to calculate runoff of rainfall from agricultural soils and associated ponding in furrows using a two-dimensional representation of the row crop system. The model is able to realistically calculate the ponded water height on the soil surface and the infiltration rate based on rainfall and runoff rate, and topography. Numerical tests based on a published experimental dataset were used to evaluate the accuracy of this model. Numerical examples of surface water flow along a hill-furrow cropping system were used to demonstrate the performance. The simulations match the experimental results, and the surface water mass balance errors for the numerical examples are less than 1%. A practical example of using the surface water model to estimate the runoff efficiency in a ridge-furrow water harvesting system provides additional support for the suitability of this model in practical problems. In conclusion, the newly developed surface water model can successfully simulate the surface water movement.

Technical Abstract: Soil surface water flow as runoff has been recognized as an important component in agricultural water management. Extensive studies have been developed to measure the surface runoff, while numerical methods based on kinetic wave equations or diffusive wave equations have been applied to simulate the surface water movement. For such simulations in real agricultural systems, three components should be considered, i.e., (1) the movement of water along the soil surface, (2) the accumulation of water in depressions, and (3) the water fluxes across the soil/atmosphere interface, i.e., infiltration or evaporation. The objective of this study is to develop a new surface water model within 2DSOIL that includes all the three components. Different from most finite element models of soil water flow, which simulate runoff in a simple manner by changing the boundary conditions, the subsurface flow near the soil surface follows a unified boundary condition, expressed with the Heaviside step function. The surface water flow was simulated using kinetic wave equations. The ponded water height on soil surface and the infiltration are adjusted based on the runoff flux and topography. Numerical tests based on the published experimental dataset are used to evaluate the effectiveness of this model, and numerical examples of surface water flow along a variety of topography, such as linear or piecewise linear slopes, are used to demonstrate the performance of this model. The simulations match the experimental results, and the surface water mass balance error for the numerical examples are less than 1%. A practical example of using the surface water model to estimate the runoff efficiency in a ridge-furrow water harvesting system provides additional evidence for the reliability of this model in practical problems. In conclusion, the newly developed surface water model can successfully simulate the surface water movement.