Spatial-temporal heterogeneity analysis of blue and green water resources for Poyang Lake basin, China

Poyang Lake basin has drought-prone pattern and floods in recent decades, posing a serious threat to water security and human life. In this research, the Soil and Water Assessment Tool (SWAT) was applied to investigate hydrological parameters characteristics, simulating uncertainties as well as spatial and temporal patterns of both blue and green water resources for the whole basin. The results revealed a strong correlation between the observed and simulated streamflow at six hydrological stations. The overall hydrological water balance analysis showed that 58.1 % of annual water yield is contributed by surface runoff, while groundwater flow contributes 38.8 % of annual water yield. The annual average blue water resource was higher accounting for 65.1 % of the total water resources. Green water coefficient was 34.9 % for the entire basin, varying from 26 % to 50 %. The spatial distribution of blue water resource was uneven in the basin with higher value in parts of the Ganjiang, Xinjiang and Raohe subbasins. While distribution of green water resource was more homogeneous. Blue water resource decreased significantly in Raohe subbasin with-37.1 mm/a whereas having no significant variability in other river basins from 1992 to 2010. The change of green water resource is caused mainly by the increase of green water flow in most subbasins. The results provide insights into prediction uncertainty reduction of simulation as well as green and blue water endowments. This research is of great significance to improve water resources management in Poyang Lake basin.