1.2 Problem Statement
The sprinkler irrigation system at the PHP Group, Njombé,
covers a surface area of about 3500 ha (Boa, 2005). The putting into place,
management and monitoring of this
system is subjected to several constraints which are becoming
more and more difficult to handle if one is to consider:
· the diversity and complexity of the irrigation
networks;
· the simultaneous exigencies of water on various plots
with different sensibility to water stress, and the incapacity of the system to
meet these needs at once by operating as scheduled;
· pressure from international organizations, such as the
European Union, to show improved water use efficiency, increasing the necessity
to record, organize and present large amounts of data that were not originally
needed for day-to-day operations,
· the exigencies on water economy, with the strict
application of the law on the use of water resources in Cameroon.
Several equipment and materials are used in the irrigation
networks of this company. The qualities as well as the performance level of
irrigation materials are essential factors in the efficiency and durability of
the systems which they constitute (Adam & Beaudequin, 1997). However, the
management, the conditions of use of these equipments, and the percentage of
the energy component used in the transport and distribution of water
constitutes 70-75% of the irrigation cost (Thomé, 2007). The system no
longer provides the crop water requirements during peak periods because of the
low flow rates required by all the hydrants expected to operate simultaneously.
This therefore leads to a situation of non satisfaction. Because of this non
satisfaction, only few hydrants situated downstream can be operated at the
detriment of the others for which the flow rates and pressures become
insufficient. The irrigation managers therefore, usually adopt only some
empirical methods for the distribution of water, with their most important
rationale being the reduction of energy consumption without necessarily
providing the crop water requirements. The areas eventually irrigated are often
less than planned, efficiencies are lower and crop yields are not as high as
expected.
1.3 Objectives of the Study
The goal of this study is to develop a GIS supported database
which will be a tool for the improvement of water management techniques and
irrigation scheduling; providing
better decisions for irrigation managers. Elimination of
deficiencies of management and organization is seen as an important tool in
solving problems of water management in irrigation systems. Monitoring and
evaluation are therefore, getting more importance in irrigation management
(Sisodia, 1992). Many studies indicate that, the main reason for poor
performance of irrigation systems is the lack of efficient irrigation
management rather than technical deficiencies (Sisodia, 1992). Information
which should help system managers should thus be easily accessible in
irrigation management.
The specific objectives of the study will be to:
· Develop a database for rapid access and orderly storage
of information regarding the irrigation system,
· Develop thematic layers for the GIS,
· Calculate the water requirements in each plot,
· Evaluate the functioning of the irrigation network,
· Spatially represent the main aspects with regards to the
irrigation system.
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