Abstract
Identification of the sources of the spatio-temporal information of flooding is important for flood control and understanding the water dynamic. Flood disasters are generally caused by two main sources: fluvial and pluvial flooding. However, there is a gap in information and challenge of such particular information in the Mekong River Basin (MRB) known as the largest river basin in Southeast Asia. This paper aims to analyze the spatio-temporal hydrograph separations of flooding and to determine the fluvial and pluvial sources of inundation water in the Lower Mekong Basin (LMB) by using a distributed rainfall–runoff–inundation (RRI) model and time–space accounting scheme (T–SAS) method. This study focuses on the two major flood events in 2000 and 2011, whose characteristics were different. The one in 2000 was long in terms of flood duration and it was the historically largest annual total flood water with twice the peak times in July and September. The 2011 flood had the highest flooded water during the peak time; however, its annual total flood water was less than the one in 2000. The results of spatio-temporal sources of flooding indicated that during the flow peak time in 2000 and 2011, the flow at Kratie was mainly contributed by 30-day (67%) and 100-day (98%) precipitation from the upstream. The drainage area of the MRB in China, northern Lao PDR, southern Lao PDR and eastern Thailand, and Cambodia and Vietnam contributed to peak flood at Kratie by 13%, 27%, 33%, and 27% for the 2000 flood and 12%, 33%, 38%, and 16% for the 2011 flood. The source of inundated water in the LMB was derived from upstream flow (fluvial source) of 35–36% and local rainfall (pluvial source) of 64–65%. Even though flood events in 2000 and 2011 had different characteristics, the sources of flood inundation in the LMB for both events were majorly from the local rainfall rather than the upstream flow. The large annual flood volume and long during of flooding in 2000 caused severe total economic damages up to 517 million US$ in the LMB countries (Cambodia, Lao PDR, Thailand, and Vietnam), while the high peak inundated water in 2011 with shorter flood duration caused damages of 493 million US$.
Highlights
The Mekong River Basin (MRB) is the largest river basin in Southeast Asia, extending over an extensive area of 795,000 km2 with an enormous average discharge of 14,500 m3/s (MRC 2005)
This paper aims to investigate the spatio-temporal sources of rainfall causing flooding through a distributed rainfall–runoff–inundation (RRI) model and a time–space accounting scheme (T–SAS) on the two large historical flood events in 2000 and 2011 which were classified as the largest historical flood events in the MRB (MRC 2005; ADB 2012)
This paper provides further understanding of flood dynamics and the information of fluvial and pluvial sources contributed to flooding inundation in the Lower Mekong Basin (LMB)
Summary
The Mekong River Basin (MRB) is the largest river basin in Southeast Asia, extending over an extensive area of 795,000 km with an enormous average discharge of 14,500 m3/s (MRC 2005). It is estimated that almost 80% of the approximately 70 million people from the four countries in the Lower Mekong Basin (LMB) depend on the river and its rich natural resources for their livelihoods, living in the flood-prone area (Try et al 2019). Intense rainfall, generated by tropical storms sweeping over the LMB, often causes a rise of water level in tributary catchments, as well as later in the main river channel. Such an event results in severe damages to social infrastructure (e.g., houses, roads, and bridges) and sometimes even leads to loss of human life (ADB 2012). The spatio-temporal information of flooding is important for flood control and understanding the water dynamic, especially for a large and complex system like the MRB
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