Initial environmental examination : taro field water control system at Gan, Gdh. Atoll

Abstract

1. The island of Gan has been infamous for agricultural produce, especially taro production in Huvadhoo Atoll. It has been especially designated by (MOFA) as a farmland for Gadhdhoo island community and is locally administered by the Gadhdhoo Island Council. 2. Among the crops grown in Gan, taro with a cylindrical central corm is found to be the most extensively cultivated crop. Taro is generally cultivated as a wetlands crop. It has been estimated that there are about 150 farmers where the taro fields have been managed and handed over through several generations of same family. 3. Due to the taro farming practice used by farmers water stagnation during the rainy season within the plot for a longer time period has been the case. According to farmers, about half meter of standing water does exist in taro fields. As a result the taro fields get damaged during the rainy season affecting taro cultivation. 4. This assessment report presents the present situation, and strategies and recommendations for water control of taro cultivation in the Gan Island. 5. There are three major areas of taro cultivation in the Gan Island; Hutuwarumaththa, Galakondiyaa and Katamaththa. The total area of the Gan Island as 246 hectares and the relative areas for Hutuwarumaththa, Galakondiyaa and Katamaththa were found to be 12, 12 and 2 ha, respectively. 6. In the process of preparation and designing water management strategy meetings were held with farmers, IDC members and GP members. During these meetings, it was revealed that excess water should be removed from taro field, but needed to retain within the island without directly draining into the sea. 7. Three drain outlets from each of major taro field will be constructed. Two major drains are identified while four sub-drains are identified. These drain outlets will discharge water to nearby areas using absorption canals through a main control gate located several meters away from taro fields. The main drain canal in each taro field will be connected to three absorption drains and each of sub-main canals will be connected to two absorption drains. 8. Locations of main drainage canals and absorption areas were decided based on the general surface water flow pattern considering the lowest possible elevation points, shape of the entire taro field, and by observing the surrounding area. 2 The directions of main canals were decided mainly according the groundwater direction. 9. Three options of water level management in taro plots were identified (i) few centimeters [5-10 cm] of water level on the soil surface, (ii) water level just below the soil surface and (iii) water level below the root zone. The best option found during the discussions as well as experiences from other Islands is the maintaining of few centimeters [5 to 7 cm] of water in plots. The storage of drainage water within the island can be done either as a surface storage or as sub-surface water. 10. All the receiving water from rainfall is retaining within the Island which helps to recharge the groundwater resource and the freshwater lens aquifer as it is the only freshwater resource available in this island. 11. Considering benefits in constructing these drainage Systems, it is expected to have an increase of about 30-40% of taro yield with a proper drainage water management strategy in this island. 12. Farmers are willing to do the operation and maintenance (O & M) of proposed drainage canals with the help of island officials. They want to have a drainage system with control gates where they will be able to manage the amount of water that should be maintained within their fields. With regular O & M the systems can be used for a longer period. In addition, island officials are expected to form farmer organization during this project period where farmer organization will be given more responsibilities in managing their works and other societal activities. 13. The investment on constructing these proposed drainage canals will help farmers to enhance their socio economic status by cultivating taro crop. With a proper water management system, young generation will also engage in taro cultivation which is not very common at present 14. The main maintenance works associated with drainage system would be the removals of silts from drain canals and proper maintenance of the control gates. However, special attention should also be given to absorptions canals especially until the system become a natural wetland. Regular maintenance works such as removal of debris and widening and/or lengthening of absorption canals as required in order to facilitate the infiltration process are necessary.