Thesis Abstract of AGS Students

Productivity and equity in irrigation system at lateral level of Maetaeng irrigation project

Porntip Polperm (1990)

This study on the productivity and equity in an irrigation system is intended to analyze the system properties of population component of he system in order to reveal problems and potentials inherent to demonstrate the techniques to measure farm level's productivity and equity within the irrigation system. The nature of productivity and equity can be used to describe the degree of difficulty, locate the area having problems, and indicate the efficiency in water management by farmers which is the fundamental mechanism of water management in the system.

This study proposes to examine two main factors underlying the difference in productivity and equity in water allocation to various areas: the orders of water availability which is the physical determinant and the traditional system of irrigation water management which is the social deter- minant of water management in an irrigation system.

Data is obtained through stratified-random sampling by dividing the population under study into two main groups according to cultivation areas: area with and area without previous experience of traditional irrigation system where different management methods are expected. Each main group is further divided into 3 sub-groups according to the orders of water availability head, middle, and tail of the irrigation canal. Each sub-group contains 4 samplings located in beginning head, ending head, beginning tail and ending tail. This samplings design is used in order to cover 24 samples with different access to irrigation supply to test the hypothesis and to fulfil the objective of this study. The study area is located on the 7th left side lateral in Maetaeng irrigation project in Mae Rim District, Chiang Mai Province.

Crop Water Stress Index - CWSI and yield are used as indicator of water productivity and as measurement of return of water resource whereas the variances of CWSI and yield are used to assess the equity. The crop under study in soybean.

In addition, from interviewing farmers, information on production inputs apart from water are used to describe in support of quantitative assessment on productivity, and information on social factors in the study area such as on-farm water management, extent of cooperation and participation in water management as well as problems and solution criteria to critical water shortage situation are used to further explain the degree of equity.

From the results of the study it is found that productivity performance is satisfactory as CWSI for soybean averaged at 0.355, because the value approaching 0.0 signifies adequate water supply. Yield level as a measure return of water is found to be 299.8 kg/rai which is higher than provincial, regional and national averages at 205.91, 146.48 and 149.41 kg/rai, respectively. Equity is not found for both water availability and return of water since there is significant statistical difference in CWSI and yield at head middle and tail of canal.

The results of this study, refuses the hypothesis that productivity is determined by the orders of water availability as physical condition is not appropriate for supplying water and water management problems exist. Instead, opportunity or ability to get water into the field at proper time and amount is more important. It is accepted that previous experience in Traditional irrigation system management has an influence on the equity because the farmers as a group help solving problem in critical water demand period by geting water into the fields and hence, reduces the values of productivity and CWSI variances for those participating farmers.

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