Hydropower is always related to rainfall. Area that is dry (low rainfall) suppose to be not very attactive for hydropower investment. Let's take a look only on the rainfall information. According to the latest document of Bappenas, the Indonesia Climate Change Sectoral Roadmap (ICCSR), rainfall in all areas in Indonesia will change. The changes are either an increase or a decrease. The simulation reported that Sumatera and Papua will have mostly increases of rainfall. Download ICCSR report here.
In Sumatera, central to south Sumatera might have significant increase of rainfall intensity. Siginificant increase means bigger than 25 mm and lower than 50 mm. Central to North Sumatera might have significant increase and very significant increase (higher than 50 mm). In Papua, all areas will have significant increase of rainfall with some months might have very significant increases of rainfall intensity.