Roseau Valley Irrigation Project – PHASE I Project
OverviewPhase I of the Roseau Irrigation Project consisted of an Off-Farm Irrigation Infrastructure on 180 acres for twenty-eight (28) farms with a network of 4km of pipes. The works commenced in March 2002 and was completed in May 2003 and remained within the budget of EC$0.6 million.
The construction process involved excavation of trenches for the running of underground water mains, the construction of control heads with 4ft x 8ft housing for each of the 28 farms in the project area, the installation of three (3) pumps (upstream of the Roseau Bridge) and filter station. The Pumping Station and Filter Unit were located on the bank of the river. There were not many delays or setbacks on the project and compensation payments were made, when necessary, to farmers who were unable to transport their bananas to the buying depots due to excavations and heavy rainfall.
The projects were put out to tender both locally and internationally and the irrigation contracts was awarded to the French Company, FARMEX Technologies SARL.
Irrigation techniques have been used from the early days of farming. Pouring water on fields is still a common irrigation method today but other more efficient and mechanized methods are now being used. Early man would have used a “low-tech” method of irrigating crops – collect water in a bucket and pour it onto the fields. Today, this is still one of the most popular methods of crop irrigation. The system is called flood irrigation – water is pumped or brought to the fields and is allowed to flow along the ground among the crops. This method is simple and cheap, and is widely used by societies in less developed parts of the world. The problem is about one-half of the water used ends up not getting to the crops, thereby resulting in tremendous water wasted. A large part of all fresh water used goes to irrigate crops. Much of this water cannot be reused because so much of it evaporates and transpires in the fields. If one considers that the majority of irrigation occurs where water is relatively scarce, it is easy to see how important it is for farmers to find the most efficient methods of using their irrigation water.
To be more efficient, farmers are:
Leveling fields
Flood irrigation uses gravity to transport water and since water flows downhill, it will miss any part of the field that is on a hill. Farmers are using leveling equipment, some of which are guided by a laser beam, to scrape a field flat before planting. This allows water to flow evenly throughout the fields. (Actually, this method of leveling a field is also used to build flat tennis courts).
Surge flooding
Traditional flooding involved just releasing water onto a field. In using surge flooding, water is released at prearranged intervals, which reduces unwanted runoff.
Capture and reuse of runoff
A large amount of flood irrigation water is wasted because it runs off the edges and back of the fields. Farmers can capture the runoff in ponds and pump it back up to the front of the field where it is reused for the next cycle of irrigation.
The drip irrigation system was agreed on for the irrigation of fruits and vegetables as this method is much more efficient than flood irrigation. Water is sent through plastic pipes (with holes in them) that are either laid along the rows of crops or even buried along their root-lines. Evaporation is minimised and up to one quarter of the water used is saved, as compared to flood irrigation.
Drier areas are often irrigated and one would not consider drainage necessary. However, irrigation water also contains minerals and salts which can be concentrated to toxic levels by vapour transpiration. Irrigated land may need periodic flushes with excessive irrigation water and drainage to control soil salinity.
Since the implementation of the irrigation programme, the Irrigations Management Unit (IMU) has been responsible for the maintenance and operation of the system. It was the initial intention of the Ministry of Agriculture, Land, Fisheries and Forestry (MALFF) to train the farmers and pan out the responsibilities, so that the maintenance and the overall running of the unit could be taken up primarily by the beneficiaries. Sadly, as of the high turnover rate and level of personal responsibility of farmers the IMU has remained as the overseer of the system’s infrastructure.
An intensive training course was offered at WIBDECO facility in Roseau to assist farmers in becoming a formal group and to educate them in the basic concepts of drip irrigation. The development of the Farmers Cooperative was the direct result of this workshop.
