Irrigation scheduling of varied flow in irrigation canal systems: a case study of Ruaha Mbuyuni irrigation scheme, Iringa, Tanzania.
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Date
2000
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Publisher
Sokoine University of Agriculture
Abstract
A study in irrigation scheduling of varied flow canal systems is considered in this
research. A mathematical model was modified to suit irrigation scheduling of varied
flow in irrigation canal systems. Four out of seventeen field canals and twelve fields
plots were selected randomly on the basis of location representation. Different sets of
data were collected at Ruaha Mbuyuni traditional irrigation scheme was taken as a
case study.
A modified model for prediction of water volumes in the scheme during irrigation
event was developed. Irrigation intervals and water volumes computed using the
model were termed as simulated irrigation intervals and simulated water volumes
respectively. Comparison between the simulated, designed and observed parameters
was performed, using t-student distribution test. The test showed that, canal one,
three and four the difference is not significant at 1% significant level. In canal two,
the difference is significant at 5% significant level. It may be because the agricultural
management practiced in the irrigation area is not similar for the whole farm. Thus
the model can be adopted to predict the irrigation intervals. Similarly, simulated and
observed irrigation intervals for selected canals were compared using t-student
distribution test. The test revealed that, in canal one and three the difference is not
significant at 5% significant level. In canal two and four the test showed that there is
a significant difference at 5% significant level. However, comparison between the
measured and the simulated water volumes using the same t-test distribution was performed. The test showed that, in canal one and three the difference is not
significant at 5% significance level. In canal four the difference is no significant at
1% significant level.
It was concluded that, the irrigation intervals (scheduling) and water volumes in the
fields are fairly well predicted by the model, provided the agricultural management is
maintained similar for the whole farm under irrigation.
A computer program was developed to reduce the tedious calculations involved in
the process of computing/determining the irrigation intervals by simply entering the
raw data or some processed data and hence serves some time. It also helps to
eliminate some simple errors that could be encountered in the calculation process.
Further study is necessary in different traditional irrigation schemes so as to validate
the model as a useful tool for predicting irrigation interval for the varied flow canal
systems. The model used in this study was tested in a traditional lowland paddy only,
and performed sufficiently for varied flow canal system in one scheme, therefore,
research work is needed to test it in other traditional irrigation schemes, so as to
make it more widely applicable.
Description
Dissertation
Keywords
Topography, Irrigation scheme, Canal Slopes, Water management