An optimality-based model of the coupled soil moisture and root dynamics

Sci. China Ser. E-Technol. Sci.

et al. 2008

Evapotranspiration constitutes more than 80% of the long-term water balance in Northern China. In this area, crop transpiration due to large areas of agriculture and irrigation is responsible for the majority of evapotranspiration. A model for crop transpiration is therefore essential for estimating the agricultural water consumption and understanding its feedback to the environment. However, most existing hydrological models usually calculate transpiration by relying on parameter calibration against local observations, and do not take into account crop feedback to the ambient environment. This study presents an optimality-based ecohydrology model that couples an ecological hypothesis, the photosynthetic process, stomatal movement, water balance, root water uptake and crop senescence, with the aim of predicting crop characteristics, CO 2 assimilation and water balance based only on given meteorological data. Field experiments were conducted in the Weishan Irrigation District of Northern China to evaluate performance of the model. Agreement between simulation and measurement was achieved for CO 2 assimilation, evapotranspiration and soil moisture content. The vegetation optimality was proven valid for crops and the model was applicable for both C 3 and C 4 plants. Due to the simple scheme of the optimality-based approach as well as its capability for modeling dynamic interactions between crops and the water cycle without prior vegetation information, this methodology is potentially useful to couple with the distributed hydrological model for application at the watershed scale.crop transpiration, CO 2 assimilation, optimality, feedback, ecohydrological model

Section: Water Balance and Root Water Uptakementioning

confidence: 99%

Section: Water Balance and Root Water Uptakementioning

confidence: 99%

Section: Optimality Principles and Their Formulationsmentioning

confidence: 99%

“…Root water uptake from each soil layer (Q r,i ) was modeled using an electrical circuit analogy [20] :…”

Section: Water Balance and Root Water Uptakementioning

confidence: 99%

“…[22]. W l and W a denote the mole fractions of water vapor inside and outside the leaf, respectively [20] . It was assumed that the air inside the leaf was saturated.…”

Section: Optimality Principles and Their Formulationsmentioning

confidence: 99%

See 3 more Smart Citations

Modeling the crop transpiration using an optimality-based approach

Lei

Yang

Sci. China Ser. E-Technol. Sci.

et al. 2008

Ecohydrological Optimality

Encyclopedia of Hydrological Sciences

Kleidon

Roderick

2005

Hydrological systems are governed by an incredible wealth of interactive processes, ranging from small‐scale processes within the soil domain such as unsaturated flow, bioturbation, and root water uptake to large‐scale feedbacks between the water balance and the global atmospheric circulation. Optimality approaches aim toward a simpler and more general representation of hydrological systems. As the hydrology of land is strongly affected by the presence of vegetation, these optimality approaches generally need to be explored in the context of how purely hydrological processes are linked to ecological processes. This article summarizes the different optimality assumptions that have been used to describe ecohydrological processes and how these are related to each other. Most approaches can be classified as either physical or ecological optimality. A range of examples are given for applying optimality approaches at various temporal and spatial scales, ranging from the scale of individual leaves and how they control water loss in relation to carbon uptake to the larger scale attributes of vegetation types, ecosystem properties, and river basin networks. The article concludes with a discussion of the usefulness of optimality approaches and their advantages as well as their disadvantages and the need for improvement.

Climate controls how ecosystems size the root zone storage capacity at catchment scale

Gao

Hrachowitz

Geophysical Research Letters

et al. 2014

Self Cite

197

216

The root zone moisture storage capacity (S R ) of terrestrial ecosystems is a buffer providing vegetation continuous access to water and a critical factor controlling land-atmospheric moisture exchange, hydrological response, and biogeochemical processes. However, it is impossible to observe directly at catchment scale. Here, using data from 300 diverse catchments, it was tested that, treating the root zone as a reservoir, the mass curve technique (MCT), an engineering method for reservoir design, can be used to estimate catchment-scale S R from effective rainfall and plant transpiration. Supporting the initial hypothesis, it was found that MCT-derived S R coincided with model-derived estimates. These estimates of parameter S R can be used to constrain hydrological, climate, and land surface models. Further, the study provides evidence that ecosystems dynamically design their root systems to bridge droughts with return periods of 10-40 years, controlled by climate and linked to aridity index, inter-storm duration, seasonality, and runoff ratio.