EXTREME WEATHER IMPACTS ON CITARUM CASCADE RESERVOIR OPERATION PATTERN 2011

Abstract

The actual operation pattern of Citarum Cascade Reservoir 2011 deviated from plan, particularly in January-March 2011. The water level in Saguling, Cirata and Djuanda reservoirs on 9 April, 2011 was far below the dry pattern, consecutively 3.36m, 4.81m and 7.32m, when implementation of the Weather Modification Technology (WMT) was stopped. With application of the descriptive analysis method it is possible to understand the cause of reservoir operation deviation. Based on Citarum average basin rainfall data is known that rainfall in January 2011 is only about 70mm, much smaller than the average basin rainfall in the same month, that is 208mm. Impact of this condition caused inflow into the Saguling reservoir in January, February and March 2011, respectively 60.7 m3/s, 56.3 m3/s and 67.8 m3/s, to be far below the average inflow of these same months. Scarcity of rainfall or inflow is caused by the SST anomaly in the waters around Java, decreasing sea surface temperature and causing not much evaporation. The existing Asia-Australia monsoon circulation and ITCZ moving southeast also influences the atmospheric dynamics in the Indonesian waters. With such conditions from January to March 2011, the Citarum watershed in particular was experiencing the dry season.