**2.7.2 Rice Relative Water Supply (RRWS)**

After clicking on the Command Button "Rice Relative Water Supply (RRWS)" in Fig. 3, irrigation delivery performances from the beginning to the current days for the current irrigation season are plotted as shown in Fig. 6. The irrigation performance characterizes as over supply for RRWS > 1.0, undersupply for RRWS < 1.0 and good performance for RRWS = 1.0. Therefore, the irrigation manager can easily quantify how irrigation water ought to be delivered with respect to the available water resources for the next day.

Fig. 6. Characterizing Daily Irrigation Delivery Performance using RRWS for Main Season 2003

The RRWS\_I, RRWS\_II and RRWS\_III represent Rice Relative Water Supply for Irrigation Service Areas I, II and III where irrigation supply is staggered by one month, respectively. From Fig. 6, the following decisions can be drawn (Table 2):


Table 2. Characterization of Irrigation Delivery Conditions

Paddy Water Management for Precision Farming of Rice 123

(a) Main Season in 2003/04

(b) Off Season in 2003/04

Fig. 7. Characterizing Daily Irrigation Delivery Performance using CRRWS

From this scenario, it is noticed that oversupply conditions were found only during the presaturation period in the first month for each ISA. Undersupply condition was found during the normal irrigation supply for all ISAs. If irrigation supply would follow the RRWS guideline, then it could be possible to overcome the oversupply and undersupply conditions. If irrigation supplies would be curtailed for the ISA II and increase for the ISA I then irrigation delivery might have maintained good conditions as shown in the middle of the plot in Fig. 6.
