Estimating Future Rainfall Distributions in a Changing Climate for Water Resource Planning: Victoria, Australia

Here we use observations and simulations from 40 global climate models from phase 5 of the Coupled Model Intercomparison Project (CMIP5), under preindustrial, historical, and a high emission scenario (RCP8.5) to provide estimates of Victorian cool season (April-October) rainfall for the coming century. This includes a new method which exploits recent research that estimated the relative contribution of external forcing and natural variability to the observed multidecadal decline in cool season rainfall in Victoria from 1997s. The new method is aimed at removing the influence of external forcing on Victoria's cool-season rainfall, effectively rendering a stationary time-series. The resulting historical record is then modified by scaling derived from the mean projected change evident in climate models out to 2100. The results suggest that the median value of the All-Victoria rainfall PDF will decrease monotonically over the remainder of the 21st century under RCP8.5. The likelihood that All-Victoria rainfall in any given year from 2025 onward will be below the observed 5th percentile of the observations (291 mm) increases monotonically, becoming three times larger by the end of the century. The new method is assessed using cross-validation and its ability to hindcast observed multidecadal rainfall change. The latter indicates that CMIP5 models poorly replicate recent interdecadal rainfall change. So, while we have more confidence in the new method because it accounts for the non-stationarity in the observed climate, limitations in the CMIP5 models results in us having low confidence in the reliability of the estimated future rainfall distributions.

Researching trends of rainfall change in Ninh Thuan in the context of climate change by the non-parametric method

The purpose of this study is to analyze the trend of precipitation change in Ninh Thuan province in the context of Climate Change. In this study, the authors used precipitation data at rain gauges with a minimum duration of 24 years and a maximum of 36 years. The main method was used in this study is the non-parametric method, namely Mann-Kendall analysis and the Theil-Sen slope. The research was conducted under the support of ProULC 5.1 and MAKESEN 1.0 software. The results showed that annual rainfall in Ninh Thuan province tended to increase in the time series of observation. Specifically, the downward trend of rainfall was mainly in March and increased from July to November. Along with that, through the index regarding the trend of increase and decrease of rainfall, the study also showed a prediction of the trend of increasing rainfall for the area. Forecast results of 2035 rainfall in Ninh Thuan the highest the increase is expected 7.7% and in 2050 is 13.8%. The study results have reflected the actual situation of rainfall change in the context of climate change with the stations having statistical significance (p <0.05). The research results are the basis for Ninh Thuan province to develop solutions to adapt and mitigate climate change in the fields of Socio-Economic life.