07. AN EVALUATION OF PRECIPITATION VARIABILITY OVER THE VIETNAMESE MEKONG RIVER DELTA BASED ON CMIP5 MULTI-MODEL ENSEMBLE SIMULATIONS AND 21ST CENTURY PROJECTIONS

Tóm tắt

Vietnamese Mekong River Delta (VMRD) is one of the most bio diverse rivers in the world and is greatly affected by distinct wet and dry seasons. It is also the largest agriculture and aquaculture production region of Vietnam. Precipitation variability has major economic, social and environmental impacts across the globe in general and on VMRD in particular. The historical precipitation variability (1911 - 2005) based on 26 global circulation models from the Coupled Model Intercomparison Project Phase 5 (CMIP5) archive over the 20^th century relative to observational data and two future emission scenarios used (representative concentration pathways (RCP) 8.5 and RCP 4.5 referred to the twenty-first century projections of precipitation are evaluated. The results showed that CMIP5 models can reproduce the spatial pattern of precipitation better in winter than in both summer and entire year over the VMRD during the 20^th century. However, the models overestimate the magnitude of seasonal and annual precipitation in most regions of the VMRD and underestimate summer precipitation in some parts of Ca Mau province and eastern south of Vietnam. Throughout the 20^th century, both the observations and models show a decreasing trend in precipitation in winter over entire the VMRD and some parts of western VMRD. There is poor agreement in annual and summer precipitation trends in eastern VMRD. In general, multi-model means can capture the amplitude of observed multidecadal precipitation variability better in winter than in summer and entire year. In the 21^st century, annual and summer precipitation generally increases while winter precipitation decreases over the VMRD under two scenarios. Both the RCP 8.5 and RCP4.5 scenarios show precipitation trend at a rate of about +24 mm/decade by the end of the century.