Before TGR impoundment, the reservoir region was a natural river with high flow velocity and largely uninterrupted hydrology, without algal blooms. After impoundment, the average flow velocity at the outlet of the TGRA decreased by an order of magnitude. This, together with alarming water quality, greatly favoured the occurrence of algal blooms in the backwater areas of TGR tributaries.
To prevent nitrogen, phosphorus and sediment from agricultural land entering into aquatic environments by surface runoff, appropriate tillage methods and land cover patterns have been developed and implemented. However, the effect of individual SWC measures or their combination on water quantity and quality (nutrients and yield) at the catchment scale has rarely been evaluated.
The overall project subdivided into 3 phases: in Phase 1, an inventory of existing SWC measures will be made and a list of new potentially promising measures will be compiled. Phase 2, focusing on the off-site effects on streamflow and water quality, using the SWAT model. In Phase 3, the results will be integrated into a database of existing and promising measures and from this, in combination with the modelling results, new policies will be formulated to achieve the AGD goals.