An integrated foundation is presented to study the impacts of external forcings on
irrigated agricultural systems. Individually, models are presented that simulate
groundwater hydrogeology and econometric farm level crop choices and irrigated water
use. The natural association between groundwater wells and agricultural parcels is
employed to couple these models using geographic information science technology and
open modeling interface protocols. This approach is used to study the collective action
problem of the common pool. Three different policies (existing, regulation, and incentive
based) are studied in the semiarid grasslands overlying the Ogallala Aquifer in the
central United States. Results show that while regulation using the prior appropriation
doctrine and incentives using a water buy-back program may each achieve the same level
of water savings across the study region, each policy has a different impact on spatial
patterns of groundwater declines and farm level economic activity. This represents the first
time that groundwater and econometric models of irrigated agriculture have been
integrated at the well-parcel level and provides methods for scientific investigation of this
coupled natural-human system. Results are useful for science to inform decision
making and public policy debate.
