in  the  prior  research  two  environmental  factors 
defined the water use behavior, and in the level of the 
whole basins, the WUAs devised their way to adapt 
to  environmental  changes.  In  our  study,  social  and 
environmental  factors  were  mainly  influential  to 
water  use  behavior,  and  adaptation  methods  were 
developed only among the downstream WUAs.  
Although  exploring  customary  laws  can  reveal 
factors of current conditions, it does not always let us 
find  solutions  for  problems  or  predict  future 
conditions. To examine customary laws on water use 
we applied game theory. We supposed three values; 
α, β and γ (0≥α>β>γ) showing negative impacts 
and  made  a  payoff  table  (Table  6).  For  Subak  B 
through Subak E, coordinating with other Subaks 
took  efforts  and  time  to  arrange  water  use,  but  the 
restrained decline in rice production. On the contrary, 
disarranging  water  use  saved  efforts  and  time  but 
caused a decline in rice production. From submissive 
laws,  we  can  see  that  for  farmers  decline  in  rice 
production (=γ) is more serious damage than taking 
efforts  and  time  ( =β).  In  the  case  of  Subak  A, 
coordinating with other Subaks did not benefit Subak 
A nor increased rice production, but only took efforts 
and time. However, uncoordinated water use with the 
other Subaks yielded the same rice  production as it 
coordinated  with  the  others  and  took  none  of  the 
efforts and time, too (=α). As Table 6 presents when 
Subak  A  is  uncooperative  and  Subak  B  through 
Subak  E  are  cooperative,  they  achieve  Nash 
equilibrium  and  Pareto  optimality.  It  suggests  that 
with the current customary laws their water allocation 
system not be changed and uncooperative water use 
behavior  of  Subak  A  not  change.  This  reveals  that 
focusing on one case study will not be enough to find 
solutions.  We  can  also  see  that  predicting  future 
conditions should be difficult because future changes 
of externalities cause changes in factors. Therefore, to 
enhance sustainable resource management, we need 
to understand what factors and their rules and/or laws 
are useful to enhance the resilience and adaptability 
of institutions. However, as prior researchers pointed, 
although  case  studies  have  similarities,  to  employ 
rules  and/or  laws  found  in  other  areas  to  solve 
problems, we need to carefully tailor them to fit into 
the  target  condition  (
Mukherji  et al.,  2010).  At  this 
point,  digital  technologies  have  the  potential  to 
facilitate analysis. 
Field  research  results  suggested  that  labor  force 
also influences changes in cropping schedules. Hence, 
considering  rainfall  and  Saba  intake  weir  inflow  is 
unlikely enough to conduct time series analysis at the 
current stage of the model development. With further 
development  of  digital  technologies  such  as  ABM, 
Table  6:  Payoff  table  between  Subak  A  and  Subak  B 
through Subak E.  
 
Subak B through Subak E
Uncooperative  Cooperative 
Subak A 
Uncooperative 
(α, γ)  (α, β) 
Cooperative
(β, γ)  (β, β)
 
analysis  of  time  series  and  massive  information  in 
resource  management  could  be  conducted.  In  our 
study, we found that water resources were the main 
factor  of  water  users’  behavior,  but  other  natural, 
social  and  institutional  factors  also  govern  their 
behavior. So far, factors could be divided into three 
categories; irrigation facilities, cropping systems, and 
institutions.  Irrigation  facilities  are  designed  to 
convey  water  supply  using  gravity  so  that  they  are 
influenced by  topographical features  of  an irrigated 
area. For example, paddy field engineering in Japan 
has  been  developed  for  more  than  500  years,  and 
paddy  field  expansion  reached  physical  limits  (The 
Japanese  Society  of  Irrigation,  Drainage  and  Rural 
Engineering, 2010
). Cropping systems and cropping 
patterns reflect preferences and strategies of farmers 
to fit in natural conditions (Corselius et al., 2002 and 
Dury  et  al.,  2013).  Institutions  define  rules  for 
collective  resource  use  (Ostrom,  2005).  This  study 
mainly  focused  on  factors  of  institutions.  To 
understand and find out robust WUAs, factors in all 
three categories are needed to consider together. If we 
accumulate and analyze factors and their rules and/or 
laws  related  to  resource  use  in  areas  of  both 
developing and developed countries, we will be able 
to  grasp  the  nexus  of  factors.  It  will  also  help  us 
understand  how  a  factor  activates  another  factor(s) 
and induce rules and/or laws. Understanding resource 
use  behavior  in  a  factor  level  will  enable  us  to 
improve  resource  management  by  changing  some 
behavior  in  a  more  tailored  manner.  Applying  the 
method  of  this  study  to  other  agricultural  resource 
management  needs  further  research.  For  instance, 
agricultural land change may be more influenced by 
economic change  such as land price  and  market. In 
such  a  case,  economic  models  may  need  to  be 
incorporated into our method.  
6  CONCLUSIONS 
Recently,  to  improve  food  and  water  security,  the 
agriculture  sector  has  attempted  to  systematize 
agricultural  management  which  currently  mainly 
relies  on  farmers’  experience.  In  addition  to  the 
challenge,  climate  change  and  population  growth