A spatial decision support system for agricultural land consolidation
Date
1992
Authors
Strapp, James Douglas
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Abstract
Agricultural land consolidation is the process of equitably reallocating agricultural landholdings into fewer, more regularly shaped parcels. Despite its social significance and intrinsically spatial problem solving characteristics, the process of consolidation has received scant attention from geographers. Instead, researchers have concentrated on determining the costs and benefits of existing consolidation methods. This thesis uses this extensive background information to reformulate consolidation into a formal problem, develops a model of an improved solution procedure, and implements the model into a spatial decision support system. This system is able to assist planners in creating improved consolidation plans.
Several countries of the world, particularly in Europe, enforce consolidation on farmers to reduce the problems associated with the present spatial configuration of landholdings. Consolidation seeks to increase agricultural efficiency by redrawing cadastral boundaries and assigning ownership to farmers based on the location and value of their present holdings, other assignments, and the location of the parcel. However, past consolidation initiatives have resulted in more efficient configurations at the expense of ecological diversity, equity, habitat, aesthetics, and employment. Redistributing land by hand to overcome these shortcomings is a formidable task. Existing manual methods are unable to deal with the complexity inherent in the problem. Without more advanced tools planners are forced to oversimplify the problem into a small set of objectives and constraints.
The model presented in this thesis uses more sophisticated methods to enable planners to manage the problem in its more realistic and complex form. The problem is changed from an existing continuous space approach, to a spatial assignment problem where small, discrete units of land are amalgamated to form fields.
Approached in this way a solution can be created as follows. Parcels of land are assigned to farmers based on a series of objectives and constraints. The model adds two constraints to the traditional problem. Firstly, communal equity is managed through tolerances set on the several non-commensurate attributes of parcel worth. This ensures that a more accurate reflection of equity is maintained unless planners take explicit steps to overrule the tolerance.
The second constraint ensures that the personal preferences of farmers are considered. Before consolidation, farmers are asked which parcels they wish to retain and, of the parcels they do not currently own, which they would wish to acquire. Ideally, a parcel should not be taken from, or assigned to a farmer without it being his or her stated preference.
Of those parcels that meet the above constraints, parcels are allocated to farmers using one of five routines. The first three routines assign parcels that are desired by less than two farmers. Users can assign contested parcels using either of two additional routines which seek to maximize contiguity and equity, respectively.
One of the strengths of the routines is their ability to facilitate interaction with the users as the solution emerges. This interaction enables planners to control the solution process so that other, less mathematically amenable objectives are considered. Promoting such interaction defines spatial decision support systems (SDSS).
These routines and assorted ancillary routines are implemented into a SDSS by appending a module onto an existing geographical information system (GIS). This is accomplished by using a soon to be released application program interface (API). With further development, this powerful method of GIS customization will present a promising tool for SDSS creation.
The SDSS is evaluated for its algorithmic validity, human interaction capabilities, and practicality using data from a recent consolidation program in Spain. While additional research is needed to evaluate the model further, and to improve the system's flexibility, the proposed model presents an important first step in improving land consolidation methods.
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UN SDG 2: Zero Hunger