Simulation of the water balance for plants growing on coarse textured soils

Carbon, BA; Galbraith, KA

doi:10.1071/sr9750021

Cited by 9 publications

(2 citation statements)

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“…Empirical and physically based mathematical models describe unsaturated flow in the root zone and both can be used to predict changes on a field scale [Baier et al, 1972;Carbon and Galbraith, 1975;Feddes et al, 1975]. The concept of 'field capacity,' now defined as the 'percentage of water remaining in a soil 2 or 3 days after having been saturated, and after free drainage has practically ceased' [Rich, 1971], is usually incorporated in the empirical models.…”

Section: Introductionmentioning

confidence: 99%

Modeling soil water changes in a well‐structured, freely draining soil

Parkes¹,

O’Callaghan²

1980

Water Resources Research

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Changes of soil water content were measured in three monolith lysimeters and compared with changes predicted by a soil water budgeting program and a program incorporating a finite element solution of the unsaturated soil water flow equation. Both models underestimated water uptake during periods of high evapotranspiration. While the physically based model gave accurate estimates of flow from a lysimeter in the absence of root water uptake, the empirical budget provided the more practical approach to long‐term water balance calculations.

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Section: Introductionmentioning

confidence: 99%

Modeling soil water changes in a well‐structured, freely draining soil

Parkes¹,

O’Callaghan²

1980

Water Resources Research

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“…When LAI is less than 1, E is split into transpiration, E t , and evaporation from bare soil E b . Then, E = LAIxE t + (l-LAI)xE b , LAI<1 LAI = GRNMAT/1000 E t and E b are determined by a special soil water sub-routine (Carbon & Galbraith, 1975).…”

Section: The Leyfarm Modelmentioning

confidence: 99%

Critical Evaluation of Systems Analysis in Ecosystems Research and Management

Barlow¹,

Arnold²,

Wit³

1978

The Journal of Animal Ecology

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This book is a collection of papers presented at and inspired by the First International Congress of Ecology, 9-14 September 1974, the Hague, the Netherlands. The symposium aroused considerable interest and so the organisers decided to bring together the proceedings, together with other papers, some of which were presented at the Congress, into this book. As pointed out in the introductory paper it is only in the last decade that some biologists have adopted the systems analysis approach to their problems, an approach long used by engineers and in operations research. It is appropriate to look at the value the approach has proved so far, and to its future role in ecosystems research and management. The physicist has almost perfect knowledge about the behaviour of the systems with which he works. But the biologist often works with systems about which little is known, and where the response of an organism to a given change in its environment is not fixed. Also, biological systems often have many more feedbacks which means that a change in one part of the system can cause changes in other parts. Thus the construction of simulation models of biological systems for predictive purposes, whilst technically feasible, requires considerable care. The objectives of the model must be explicit since these will largely determine the structure of the model, the functions included and the degree of resolution to which the system is simulated. Some of the problems of modelling ecosystems are introduced by de Wit and Arnold in the first paper. GoodalPs paper gives an illustration of how to use the hierarchical approach to model building. Van Keulen goes on to consider the principles which should govern decisions on the structure of a model in more detail, i.e. the objectives, the boundaries of the model, the processes incorporated in the model, evaluating the output of the model, and the model's behaviour in response to changes in inputs or in the rates of certain processes. 1Two papers illustrate divergent uses of modelling ecosystems. Jameson considers the problem of developing generalized models of grassland ecosystems which will provide the input data for management models; Miller and Mooney use a biological process model to consider the most efficient vegetation forms and functions in two Mediterranean environments and compare these with the vegetation that occurs. The most widespread effort in ecosystem modelling has been in producing models of grassland systems used by man for livestock production. Seligman critically reviews some of these models. Such criticism should allow future models to be more soundly constructed for their given objectives. Finally, Jeffers discusses the future prospects of systems analysis in ecology. He looks at the broad application of models and discusses not only the problem of defining and bounding models but also the management of the team needed for model construction and validation and, most importantly, how to communicate the model and its results. Systems analysis, it has been argued, allo...

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