DAP (Delta Agricultural Production Model)
General Description | Based on the SWAP (http://swap.ucdavis.edu) model, DAP is used to model agricultural land models agricultural crop production and water use and economic performance but unlike SWAP, DAP disaggregates by agricultural islands and includes the effects of salinity in the water supply on crop yieldsfor a selection of islands in the Delta and incorporates crop yield response to salinity from root zone which is linked to irrigation water supply and drainage. Model website is at: http://swapdap.ucdavis.edu |
Model Domain | Agricultural Crop agricultural economics economics of the Delta |
Developer | Howitt and Medellin-Azuara (UC Davis) based on the SWAP model |
Hardware computing requirementsNot specified | Runs in MS Windows environment. |
Code language | Generalized Algebraic Modeling System (GAMS) |
Original application | Developed for use in PPIC Public Policy Institute of California report "Envisioning Futures for the Sacramento-San Joaquin Delta" (Lund et al., 2007). Peer review publication is in Medellin-Azuara et al. (2014) |
Public/proprietary and cost | Based on SWAP model, modifications to algorithms available in Lund et al. (2007), runs on GAMS. |
Physically or empirically based | Empirical |
Mathematical methods used | Expansion of SWAP methods, which use positive mathematical programming (PMP) (Howitt, 1995). Salinity response in DAP is based on the Van Genuchten & Hoffman (1985) inverse sigmoid yield response function. |
Input data requirements | Input data requirements include : (brackets include example datasets)source datasets are identified in parentheses):
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Outputs | Outputs for 71 regions in the Sacramento San Joaquin Delta
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Pre-processing and post-processing tools | None specified |
Representation of uncertainty | None specified |
Prevalence | Used in policy analysis by both academic, private consultants, and state agencies |
Ease of use for public entities | Requires knowledge of GAMS software, economic optimization and production economics theory, and access to program applications through UC Davis in addition to DAP algorithmsCenter for Watershed Sciences or UC Merced Water Systems Management Group (Medellin-Azuara). |
Ease of obtaining information and availability of technical support | Manuals or information on technical model beyond policy publications model runs is not currently available. |
Source code availability | None |
Status of model developmentSeveral iterations use different disaggregation units, or additional areas of the Central Valley. | Model continues to be updated with new land, water use and cost information through the UC Merced Water Systems Management group and the UC Davis Center for Watershed Sciences |
Challenges for integration | Similar to those of SWAP, however DAP is also disaggregated into 71 smaller regions of the Delta. Model output scale map might not match outputs of other models. |
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Medellín-Azuara, J., Hanak, E., Howitt, R., Lund, J., Ferrell, M., Kramer, K., Stryjewski, E. (2012). Transitions for the Delta Economy Appendix A: Estimates of Acreage and Land Use. Public Policy Institute of California. San Francisco, CA.
Medellín–Azuara, J., Howitt, R. E., Hanak, E., Lund, J. R., & Fleenor, W. (2014). Agricultural Losses from Salinity in California's Sacramento-San Joaquin Delta. San Francisco Estuary and Watershed Science, 12(1), 1–16. https://doi.org/10.15447/sfews.2014v12iss1art3
Van Genuchten, M., and G. Hoffman. 1985. "Analysis of Crop Salt Tolerance Data." In Soil Salinity under Irrigation, Processes and Management, ed. Shainberg, I., and J. Shalhevet (Berlin: Springer: Ecological Studies), 258–71.