Identifying the spatiotemporal patterns of drought-flood alternation based on IMERG product in the humid subtropical Poyang Lake basin, China

Abstract

Study RegionA humid subtropical basin, Poyang Lake Basin, China. Study focusDrought-flood alternation (DFA) is sub-seasonal precipitation anomaly, which has more serious impact on agricultural production, ecology and environment than a single drought or flood event. The study evaluated the suitability of high-resolution satellite-based precipitation product for identifying the DFA event and quantified the spatiotemporal patterns of the frequencies and intensities of DFA at various time scales. New hydrological insights for the regionThe Integrated Multi-satellite Retrievals for Global Precipitation Measurement (IMERG) product could effectively identify the DFA events at 1-month scale, with high consistency with the results based on traditional rain-gauge data, however, its performance was not very satisfactory at 3-month and 6-month scales. Drought-to-Flood (DTF) events usually occurred from March to June, while Flood-to-Drought (FTD) events mainly occurred during from July to September. Frequencies and intensities of both DTF and FTD exhibited significant spatial heterogeneity. The lake area was mainly affected by DTF events, and the Ganjiang sub-catchment was mainly affected by FTD events. Especially, the southern part of the basin was a high-risk area affected by DFA, with higher frequencies of both severe DTF and FTD events. Furthermore, although the total area affected by DFA events showed a long-term decreasing trend from 2000 to 2019, the area affected by severe DTF and FTD events was gradually expanding in Poyang Lake basin.