CHARACTERISTICS OF LOCAL PUMP SCHEMES REUSING DRAINAGE WATER IN A MAJOR RICE-BASED IRRIGATION AND DRAINAGE AREA IN THE RED RIVER BASIN, VIETNAM

Abstract

A comprehensive study was undertaken in a major rice-based irrigation and drainage area, with the objective of assessing the characteristics and importance of the wide-spread use of drainage water from canal irrigation schemes by local schemes. The irrigated area of 18,308 ha consisted of the public managed Cau Son canal scheme and 208 electric-powered pump schemes, of which 109 were classified as drainage reuse schemes using drainage water from the canal scheme. The reuse pump schemes covered 27% of the irrigated area, including 6 public and 103 local managed pump stations, the latter with about 21,000 households engaged in reuse irrigation. The local schemes were typically 25 years old and showed a high degree of variability in irrigated area, total dynamic head, design capacity, and energy use. The seasonal irrigation delivery ranged by a factor 10 with about 65% “lost” in return flow mostly as surface drainage. The use of electric power was excessive, associated with low pumping and irrigation efficiencies related to poor maintenance, inadequate water management and capacity overdesign. A significant scope was identified for improved use of water and energy and for integrating local reuse schemes in performance evaluations and water management frameworks in canal-irrigated areas.