RICEWQ-VADOFT (Rice water quality—vadose zone flow and transport)

Rice water quality—vadose zone flow and transport (RICEWQ‐VADOFT) is a model developed from the coupling of a surface runoff model (RICEWQ) and a vadose zone flow and transport model (VADOFT) for determining predicted environmental concentrations in paddy water and sediment, runoff, and groundwater.

surface runoffvadose zoneflowtransportpaddy watersedimentgroundwater



Initial contribute: 2019-12-17


Istituto di Chimica Agraria ed Ambientale, Università Cattolica del Sacro Cuore, Piacenza, Italy
Is authorship not correct? Feed back


Application-focused categoriesNatural-perspectiveLand regions

Detailed Description

English {{currentDetailLanguage}} English

Quoted from: Miao, Zewei, Mark J. Cheplick, Martin W. Williams, Marco Trevisan, Laura Padovani, Mara Gennari, Aldo Ferrero, Francesco Vidotto, and Ettore Capri. "Simulating pesticide leaching and runoff in rice paddies with the RICEWQ–VADOFT Model." Journal of environmental quality 32, no. 6 (2003): 2189-2199. https://doi.org/10.2134/jeq2003.2189 

Assessments were made to evaluate the dissipation, leaching, and runoff of agro‐chemicals in aquatic systems. These assessments were conducted using an integrated model that linked two fate and transport models, RICEWQ version 1.6.2 and VADOFT.

RICEWQ simulates water and chemical mass balance associated with the unique flooding conditions, overflows, and controlled water releases that are typical in a rice cropping system (Williams et al., 1999). The model applies the principle of mass balance to simulate water volume changes in the paddy and chemical residues in three media of the rice paddy (rice foliage, water column, and benthic sediments) from the point of chemical application:
where ∂C (mg kg−1) is the change in concentration over time ∂t (s); ∑Minflux (10−6 kg) and ∑Moutflux (10−6 kg) are cumulative influx and outflow of chemical mass from the control volume; V (m3) (i.e., the rice paddy), and ∑Mreact (10−6 kg) is mass transformation from all processes.
The pesticide mass‐balance equations in water, sediment, and foliage subecosystems are listed as follows:
where ∂MW (mg), ∂MS (mg), and ∂MF (mg) are the change in chemical mass in water, sediment, and foliage, respectively, over time (∂t) (s); MWapp (mg) is the mass of the applied pesticide not lost to drift and arriving at the water surface; MFapp (mg) is the mass of the applied pesticide intercepted by foliage; Mwash(mg) is the mass washed off from foliage; MW deg (mg), MS deg (mg), and MF deg (mg) are the masses of pesticide degraded in water, sediment, and foliage, respectively; MWtran (mg), MStran(mg), and MFtran (mg) are the masses of metabolite formed by transformation of parent compound in water, sediment, and foliage, respectively; Mvolat(mg) is the mass volatilized across the air‐water interface; Mout (mg) is the mass lost in overflow or drainage; Mseep (mg) is the mass lost in seepage; Mbed (mg) is the mass transfer to bed sediment by direct partitioning; Msetl (mg) is the mass transfer to sediment by particulate settling; Mresus (mg) is resuspended mass; Mdifus (mg) is the mass diffusion between the water and sediment; and Mharv (mg) is the mass of pesticide removed after harvest (this mass may be removed from the ecosystem, left alone and available for wash off, or be applied to bed sediment).
VADOFT performs one‐phase one‐dimensional transient or steady‐state simulations of downward water flow and chemical solute transport in variably saturated porous media (Carsel et al., 1998). The code employs the Galerkin finite‐element technique to approximate the governing equations for water flow and chemical transport with spatial discretization (expressed as nodal points [NPs]) performed using linear elements. It allows for a wide range of nonlinear flow conditions, and handles various transport processes, including hydrodynamic dispersion, advection, linear equilibrium sorption, and first‐order decay. The VADOFT code solves the Richards' equation, the governing equation for infiltration of water in the vadose zone:
Where Ψ is the pressure head (m), K is the saturated hydraulic conductivity (m s−1), krw is the relative permeability (dimensionless), z is the vertical coordinate (m), t is time (s), and η is an effective water storage capacity (m−3) defined as:
where Ss is specific storage (m−3), Sw is water saturation (dimensionless), and Φ is the effective porosity (dimensionless).
The governing equation for one‐dimensional transport of a nonconservative chemical solute species in a variably saturated soil takes the form:
where D is the apparent dispersion coefficient (m2 s−1), c is the solute concentration (μg L−1), θ is the volumetric water content (m3 m−3) (θ = ΦSw), the vertical Darcy velocity (m s−1) R is the retardation coefficient (dimensionless), and λ is the first‐order decay constant (s−1). Note that D is defined as:
where αL is the longitudinal dispersivity (m); and D* is the effective molecular diffusion coefficient (m2 s−1).
As for water balance, RICEWQ and VADOFT both use a water‐balance model to calculate the water balance in the paddy and soil profile, respectively:
where the change in storage (∂S) (m3) over time (∂t) (s) is equal to the cumulative sum of inflow sources (∑I) (m3 s−1), minus the cumulative sum of outflow (∑O) (m3 s−1), and:
where ∂Si (m3) is the moisture storage of Soil Layer i over time (∂t) (s), ∑Ii(m3 s−1) is soil water inflow into Soil Layer i, and ∑Oi(m3 s−1) is the water moisture outflow from Soil Layer i

The models were integrated by transferring water and pesticide flux predicted as seepage by RICEWQ as prescribed boundary condition loadings into VADOFT. The top 5 cm of the profile was represented by the active sediment layer in RICEWQ. The remainder of the soil profile was represented as multiple compartments in VADOFT. The bottom of the active sediment layer is the crossed interface between two subsystems represented by RICEWQ and VADOFT. As only one pivot link between the two submodels, the water and chemical seepage out of paddy sediment predicted by RICEWQ becomes the water and chemical input of VADOFT.

RICEWQ is driven by daily weather data and operates at a subdaily time step to obtain the daily decay, seepage, runoff, and leaching amount by integration. When the soil moisture in the paddy exceeds field capacity, seepage to VADOFT occurs. As the paddy dries, soil moisture can decrease down to the wilting point through evapotranspiration. Pesticide residues in seepage water interact with the bed sediment through sorption and degradation.

The models are not implicitly coupled. That is, seepage is not dependent on the status above and below the interface at a given time. Water and chemical flux across the interface is one‐dimensional. However, upward movement of soil water and chemical are accounted for in VADOFT.

Herein, the term seepage refers to water and chemical percolating from paddy sediment into the vadose zone (i.e., mass transfer from RICEWQ to VADOFT), and leaching refers to downward movement of water and chemical within the vadose zone or from vadose zone to ground water. For a full description of both models, RICEWQ and VADOFT, the reader is referred to Williams et al. (1999)Carsel et al. (1998), and Capri and Miao (2002)



Zewei Miao, Ettore Capri, et al. (2019). RICEWQ-VADOFT (Rice water quality—vadose zone flow and transport), Model Item, OpenGMS, https://geomodeling.njnu.edu.cn/modelItem/9bc724de-7d76-4375-8518-682a71e59f59


Last modifier
Last modify time
Modify times
View History


Initial contribute : 2019-12-17



Istituto di Chimica Agraria ed Ambientale, Università Cattolica del Sacro Cuore, Piacenza, Italy
Is authorship not correct? Feed back


Last modifier
Last modify time
Modify times
View History

QR Code


{{curRelation.author.join('; ')}}



Drop the file here, orclick to upload.
Select From My Space
+ add


Cancel Submit
{{htmlJSON.Cancel}} {{htmlJSON.Submit}}
{{htmlJSON.Localizations}} + {{htmlJSON.Add}}
{{ item.label }} {{ item.value }}
{{htmlJSON.Cancel}} {{htmlJSON.Submit}}
名称 别名 {{tag}} +
系列名 版本号 目的 修改内容 创建/修改日期 作者
摘要 详细描述
{{tag}} + 添加关键字
* 时间参考系
* 空间参考系类型 * 空间参考系名称

起始日期 终止日期 进展 开发者
* 是否开源 * 访问方式 * 使用方式 开源协议 * 传输方式 * 获取地址 * 发布日期 * 发布者

编号 目的 修改内容 创建/修改日期 作者

时间分辨率 时间尺度 时间步长 时间范围 空间维度 格网类型 空间分辨率 空间尺度 空间范围
{{tag}} +
* 类型

* 名称 * 描述
示例描述 * 名称 * 类型 * 值/链接 上传

{{htmlJSON.Cancel}} {{htmlJSON.Submit}}
Title Author Date Journal Volume(Issue) Pages Links Doi Operation
{{htmlJSON.Cancel}} {{htmlJSON.Submit}}
{{htmlJSON.Add}} {{htmlJSON.Cancel}}


Authors:  {{articleUploading.authors[0]}}, {{articleUploading.authors[1]}}, {{articleUploading.authors[2]}}, et al.

Journal:   {{articleUploading.journal}}

Date:   {{articleUploading.date}}

Page range:   {{articleUploading.pageRange}}

Link:   {{articleUploading.link}}

DOI:   {{articleUploading.doi}}

Yes, this is it Cancel

The article {{articleUploading.title}} has been uploaded yet.

{{htmlJSON.Cancel}} {{htmlJSON.Confirm}}