[Malaysia] IMpacts of PRecipitation from Extreme StormS - Malaysia (IMPRESS - Malaysia)

Lead Research Organisation: University of Exeter
Department Name: Mathematics


In a warmer climate, the amount of precipitation is expected to increase, as warmer air can hold more water. At the regional level - where impacts are felt - patterns of change are less well understood due to uncertainty in the circulation response to warming. In addition to these changes in mean precipitation, increases in precipitation extremes may be considerable, and are expected to increase at around 7% per degree Celsius of warming. Extreme events frequently cause the greatest damage, making understanding the nature of changes in both the frequency and magnitude of such extremes a critical issue given their impact on society.

In Peninsular Malaysia, the majority of the annual total precipitation is produced by a relatively small number of intense events. These extreme precipitation events have been increasing in recent decades. They can lead to considerable damage through flooding, which can be enhanced by changes in land use. Annual, average annual flood losses are currently around RM 915 million in Malaysia. In a warmer climate, a shift to a more intense wet season (which is expected), with increased frequency of the most extreme events, may have significant implications for the hydrology of Peninsular Malaysia and associated impacts on society.

In this project, we will investigate the dynamical features (e.g. tropical storms) that lead to extreme precipitation in Malaysia. We will study both their present-day behaviour and likely changes in the future. In doing so, we will achieve a dynamically constrained understanding of future extreme precipitation events. This represents a considerable advance on our current understanding of future changes in extreme precipitation in Malaysia. We will then use this information to run a hydrological model to estimate future changes in streamflow, flood magnitudes and flood return periods. This model will include estimates of land use change which will also be developed as part of the project. Through this, information of unprecedented detail will be available to Malaysian government and society of the risks and impacts of future changes in extreme precipitation and associated changes in river flow. We will also use this information to assess current intervention strategies and to develop a model of flood management which takes into account our improved understanding of flood risk. This information will be disseminated to a wide array of actors across government and civil society to ensure it has maximum impact. Ensuring that future infrastructural, societal and agricultural development in Malaysia is informed by prospective changes in key climate events is critical if we are to successfully adapt to a warmer climate, whilst mitigating the impact of any changes on society and the economy of Malaysia. This project has the capacity to make a significant contribution to that aim.

The techniques developed as part of this project could be readily applied in other river basins and countries, such that the impact and longevity of this work could be far broader than the scope currently envisaged. The project partners intend to work with other collaborators to ensure that these broader benefits are realised.

Planned Impact

Extreme precipitation, and the associated hydrological response, represents the key hydro-meteorological hazard in Malaysia. The societal and economic impacts of both floods and droughts are considerable. In a rapidly developing society, where agricultural outputs represent a major contributor to GDP, ensuring that society is resilient to these events is critical to sustainable development in the country. Informing water management, flood strategies, investment and management of infrastructure and the response to extreme events with accurate estimates of future precipitation and hydrological change is necessary to ensure they are resilient in a changing climate.

The scientific deliverables will provide information on future flood risk that represents a considerable advance on the current state of knowledge, allowing for better planning and adaptation. The flood management framework that we will generate, based on this science, will be delivered directly to key decision makers within the Malaysian government and NGOs who co-ordinate flood response in the focus regions of this work. The findings of this work will act as a reference to stakeholders in the development of climate change related adaptation policies and will increase public awareness of the impacts of climate change by presenting detailed projections of future changes in the hydro-meteorology of Malaysia.

We have formal support from four key agencies who deal with water management and flooding (see Letters of Support) and have discussed the project more widely with colleagues in the academic and government sectors. Through partnering with Water Watch Penang our capacity to communicate the results of this work directly to the public will be greatly enhanced. These links will ensure that the information generated by this project has maximum impact. In particular, we will organise a seminar towards the end of the project, inviting all related agencies and stakeholders, to share our findings with them, with data, reports and publications discussed and shared with participants.

As discussed above, the primary, direct benefits of IMPRESS will be in Malaysia, though we note that the techniques being developed and applied in this project could be readily applied in other regions once the analysis framework is established. The potential for broader and highly significant indirect impacts from this project are therefore considerable.
Description 1) We have thoroughly analysed the characteristics of extreme rainfall events over Malaysia.
2) We find the majority of events are associated with specific meteorological events called "Borneo vortices".
3) We have assessed the ability of climate models in representing the rainfall extremes and found that, in general, coarse resolution global models are unable to represent the extreme rainfall events with sufficient accuracy. High resolution models are significantly better at representing the extreme rainfall events.
4) Using a hydrological model and down-scaling methods we show that the high resolution models and their low-resolution counterparts produce very different results in terms of flooding events and river flow under future climate scenarios.
5) Higher resolution models indicate much greater flood risk in the future, bust conversely much much less risk from droughts. The results suggest that coarse resolution climate models are inadequate for representing future climate impacts.
6) The implications are that the high resolution methods that we have pioneered should be rolled-out for additional regions that are significantly impacted by intense rain events.
Exploitation Route The methods that we have used are very robust. There is an urgent need to apply such methods to other regions, particularly the SE Asia regions.
Sectors Environment