What are the impacts of upstream irrigation on coastal wetlands?
How can these impacts be minimized? Bundala National Park, a Ramsar Convention wetland in Southern Sri Lanka, hosts a vast population of wildlife, migratory birds, and aquatic life. IWMI recently studied the interactions between the wetland and the upstream irrigation project. The research showed that: • Pesticides and fertilizers used by farmers in the irrigation scheme flow into the lagoons along with irrigation drainage water. Because of the elevated nitrogen and phosphate levels, eutrophication is an emerging problem in the lagoons. • The changing water levels affect birds and other wildlife. And the inflow of drainage water has disturbed salinity balances, resulting in fewer shrimp maturing in the lagoons. Shrimpers periodically cut the sandbanks separating the lagoons from the sea to achieve a direct increase in salinity. Based on these findings, the Irrigation Department of Sri Lanka has introduced a rotational water supply. This minimizes water losses to the sea and diminishes
