According to the Assessment Report 4 of Working Group II of Inter-Governmental Panel on Climate Change (2007), there are five approaches in Climate Change Impact, Adaptation and Vulnerability (CCIAV) assessment. Notably, there has been shifting from research-driven approaches to assessments integrated toward policy-making, where decision-makers and stakeholder either participate in or drive the assessment (UNDP, 2005). Unlike the other four approaches which are more research oriented, the risk assessment approach has started to be applied in mainstreaming adaptation option into policy-making globally. Since 2008, the Government of Indonesia has explored the use of risk assessment approach for climate change adaptation planning. Several case studies have been done including the preparation of a national document namely Indonesia Climate Change Sectoral Roadmap, Climate Change Risk and Adaptation Assessment in the Province of South Sumatra, the Province of Nusa Tenggara Barat, Greater Malang, and the City of Tarakan. South Sumatra Province is one of the areas in Indonesia which tipped to be prone to the impact of climate change. In the face of climate change impact such as increased temperature, precipitation rate, and sea level, South Sumatra is very vulnerable due to its low-land areas that it may threat coastal, water, agriculture, and health sectors of the province. In terms of temperature, the analysis suggested that there was an increased trend for the last 25 years around 0.31 Celcius in Palembang City and 0.67 Celcius for the whole South Sumatra. In terms of precipitation rate in South Sumatra, the analysis showed that the climate hazard until 2030 will be dominated by climate uncertainty due to the inter-annual variability which could cause extreme precipitation. Based on projection, in the period of 2020 2030, the risk of extreme precipitation will actually increase compared to the period 1991 2000. Similarly, estimation of future sea level rise based on altimeter satellite, model, and tide gauge will be around 0.5 0.7 cm annually. As a result, the projection of sea level rise in 2030 will be 13.5+6.15 cm above the sea level in 2000.The science basis data above then is to be used for flood hazards assessment, which then overlaid with vulnerability map to produce risk map. Based on the risk map, several adaptation options to Flood are identified as follows: Canalization, polder, retention pond, and infiltration measurement for Lowland areas; Detention basin and dam construction for Midland areas; Reforestation for Highland areas. The identified adaptation option above then is mainstreamed into development plans of South Sumatra Province.

The water sector is one of the most important sectors to be influenced by climate change impacts, in the form of water shortage. Currently, for an example, the Java- Bali regions have already faced a deficit in its water balance. Based on climate projections, most regions in Indonesia will suffer from a gradual decrease of water supply due to temperature increase and rainfall changes that will affect the water balance. Combined with estimated population growth rates, increased water demand will cause severe water shortages to occur, especially in Java and Sumatra for the period of 2020-2030. This paper identifies several high risk regions throughout Indonesia based on the national level of climate risk study. It is found that areas which possess high risk on water shortage stretch in some parts of the Java-Bali region, especially in a few locations in the northern and southern of West Java, middle and southern of Central Java and East Java; as well as in the capital of the North Sumatra, West Sumatra, Bengkulu and Lampung (Sumatra), Nusa Tenggara Barat and South Sulawesi. This paper concludes with some possible actions to adapt to the impacts of climate change to water shortage.