Water Productivity from Integrated Basin Modeling
Tóm tắt
It is obvious that real water saving measures are only possible if the current water resources are clearly understood. For a basin in western Turkey, simulation modeling at three different scales, field, irrigation scheme and basin level was performed to obtain all terms of the water balance. These water balance numbers were used to calculate the Productivity of Water (PW) at the three levels. The four performance indicators considered were: PWirrigated (yield / irrigation), PWinflow (yield / net inflow), PWdepleted (productivity / depletion), and PWprocess (productivity / process depletion), all expressed in kg yield per m3 water. For the two cotton fields considered at the field scale level, the more upstream field performed better than the field at the tail-end. This was partly a result of the difference in climatic condition, but was mainly due to the location of the two fields: upstream vs. downstream. At the irrigation scheme level PWirrigated was higher than at the individual cotton field, since non-irrigated crops were also included. Other PW values were lower as crops more sensitive to drought were also found in the irrigated areas. Basin scale PWs are lower than those at the irrigation scheme, as large areas of the basin were covered with less productive land covers. It is concluded that performance indicators are useful ways of representing water dynamics with clearly understandable numbers, and that it is important to consider all the spatial scales at the appropriate level of detail.
Tài liệu tham khảo
Bastiaanssen, W.G.M., Huygen, J., Schakel, J.K. & Van Den Broek, B.J. 1996. Modelling the soil-water-crop-atmosphere system to improve agricultural water management in arid zone (SWATRE). In B.J. Van Den Broek (ed.) Dutch experiences in irrigation water management modelling. Report 123, Winand Staring Centre, Wageningen, The Netherlands. p. 13–27.
Doorenbos, J. & Kassam, A.H. 1979. Yield response to water. FAO irrigation and drainage paper 33. Rome, Italy.
Droogers, P., Kite, G.W. & Bastiaanssen, W.G.M. 1998. Land cover classification using public domain datasets: example for Gediz Basin, Turkey. Proceedings of International Symposium on Arid Region Soils. 21-24 September 1998, Menemen, Turkey. p. 34–40.
Droogers, P., Bastiaanssen, W.G.M., Beyazgül, M., Kayam, Y., Kite, G.W. & Murray-Rust, H. 1999. Agro-hydrological analyses of an irrigation system in Western Turkey using simulation modeling. Agricultural Water Management (in press).
FAO. 1976. A framework for land evaluation. FAO Soils Bulletin 32. Rome, Italy.
Feddes, R.A., Kowalik, P.J. & Zaradny, H. 1978. Simulation of field water use and crop yield. Simulation monographs, Pudoc, Wageningen, The Netherlands.
Feddes, R.A., Kabat, P., Van Bakel, P.J.T., Bronswijk, J.J.B. & Halbertsma, J. 1988. Modelling soil water dynamics in the unsaturated zone - state of the art. Journal of Hydrology 100: 69–111.
Hanks, R.J. 1974. Model for predicting plant growth as influenced by evapotranspiration and soil water use relationship: An overview. In Limitations to efficient wate use in crop production. H.M. Taylor, W.R. Jordan, and T.R. Sinclair (eds). American Society of Agronomy, Madison, Wisconsin, USA. p. 393–411.
Kite, G.W. 1998. Manual for the SLURP hydrological model. NHRI, Saskatoon, Canada.
Kite, G.W. & Droogers, P. 1999. Irrigation modelling in a basin context. Water Resources Development 12: 43–54.
Molden, D. 1997. Accounting for water use and productivity. SWIM Paper 1. International Irrigation Management Institute, Colombo, Sri Lanka.
Molden, D., Sakthivadivel, R., Perry, C.J. Fraiture, C. de & Kloezen, W.H. 1998. Indicators for comparing performance indicators of irrigated agricultural systems. Research Report 20. International Water Management Institute, Colombo, Sri Lanka.
Molden, D. & Sakthivadivel, R. 1999. Water accounting to assess use and productivity of water. Water Resources Development 15: 55–71.
Seckler, D. 1996. The new era of water resources management. Research Report 1. International Irrigation Management Institute, Colombo, Sri Lanka.
Van Dam, J.C., Huygen, J., Wesseling, J.G., Feddes, R.A. Kabat, P., VanWalsum, P.E.V., Groenendijk, P. & van Diepen, C.A. 1997. Theory of SWAP version 2.0. Technical Document 45. Wageningen Agricultural University and DLO Winand Staring Centre.
Van Diepen, C.A., Wolf, J., Van Keulen, H. & Rappoldt, C. 1989. WOFOST: a simulation model of crop production. Soil Use and Management 5: 16–25.