*3.2. Extreme Events*

Precipitation is a crucial component of the water cycle [31], and is the variable most strongly associated with atmospheric circulation in weather and climate studies [32]. Analysis of rainfall data showed that the total annual precipitation is 2233, 2396, 2702, and 2937 mm year−<sup>1</sup> for Indramayu, Ngawi, Sleman, and Sukoharjo, respectively. Figure 3 shows that the average precipitation amount in *Kasa*, *Karo*, and *Katelu* is below 100 mm day−1, with the lowest amount being just 12.63 mm day−<sup>1</sup> (in Karo, Indramayu). The highest rainfall amount was recorded in *Kapitu*, Sukoharjo, at 601.16 mm day<sup>−</sup>1. Monitoring precipitation is crucial to the well-being of local residents; too much rainfall endangers life and property, while too little causes droughts that negatively impact agriculture and can lead to starvation. Hence, analysis of extreme precipitation events (e.g., drought and floods) is necessary.

The SPI is recommended for assessing drought and floods. It has the following advantages: (i) only a single input variable (precipitation) is necessary, (ii) both wet and dry periods can be analyzed, (iii) analyses can be performed at different time scales, (iv) droughts and floods can be categorized, and (v) the probability-based structure can aid risk management and decision analysis [27]. In this study, the SPI was used at the 1-month time scale to identify drought and floods, informed by *Pranata Mangsa* and the Gregorian calendar, with the goal of successful adaptation to extreme events. The SPI is an index for extreme events comparing with the average and results in different values depending on the range of the specific period, even if the same precipitation data is adopted. During the observation period (1998–2015) both drought and flood occurred (in 1998 and 2010, respectively). Figure 4 (upper) illustrates the superiority of *Pranata Mangsa* over the Gregorian calendar for mitigating the effects of extreme drought events in all regions, except Indramayu. However, *Pranata Mangsa* was not useful for mitigating the effects of extreme floods, except in Sleman, as shown in Figure 4 (bottom). These results suggest that *Pranata Mangsa* has limitations in the size and location of the community; in line with the term of local knowledge, which is composed of understanding, skills, and philosophies developed by the local society with long histories of interaction with their natural surroundings.

**Figure 3.** The intensity of precipitation during 1998–2015.

**Figure 4.** The severity levels and number of drought (**a**) and floods (**b**).
