Document Abstract
Published:
2009
Joint water quantity/quality management analysis in a biofuel production area: using an integrated economic-hydrologic model
Is it feasible to model water quality and quantity management?
Water management in the Pirapama River Basin in northeastern Brazil is affected by both water quantity and water quality constraints. The region is known for significant sugarcane-based ethanol production. Sugarcane production in the region goes hand in hand with controlled fertirrigation practices with potentially significant adverse impacts on the environment. Fertirrigation is a joint process of irrigation and fertilisation that uses irrigation water to carry and distribute fertilisers to crops.
The authors discuss the methodology of the integrated economic-hydrologic model. The model integrates essential relationships of hydrology, water quality, and economics at the river basin scale which is adopted to study both water quantity and water quality aspects. The model is used to estimate the impact on the marginal value of water uses and water allocation from the restriction of total biochemical oxygen demand (BOD) and dissolved oxygen (DO) at a certain level.
The model contains a large number of physical and economic relationships and allocation decisions at various scales. At the basin level, water allocation among various demand sites and sectors is carried out; at the individual system level, the optimal quantity and timing for effluent application among sugarcane areas are determined. Eight major tributaries are simulated as well as other major inflow sources, including water for refrigeration released by the agroindustries.
The paper concludes that the model’s main advantage is its ability to reflect the interrelationships between essential hydrologic, agronomic, and economic components and to explore both economic and environmental consequences of various policy choices. The model results show that:
The authors discuss the methodology of the integrated economic-hydrologic model. The model integrates essential relationships of hydrology, water quality, and economics at the river basin scale which is adopted to study both water quantity and water quality aspects. The model is used to estimate the impact on the marginal value of water uses and water allocation from the restriction of total biochemical oxygen demand (BOD) and dissolved oxygen (DO) at a certain level.
The model contains a large number of physical and economic relationships and allocation decisions at various scales. At the basin level, water allocation among various demand sites and sectors is carried out; at the individual system level, the optimal quantity and timing for effluent application among sugarcane areas are determined. Eight major tributaries are simulated as well as other major inflow sources, including water for refrigeration released by the agroindustries.
The paper concludes that the model’s main advantage is its ability to reflect the interrelationships between essential hydrologic, agronomic, and economic components and to explore both economic and environmental consequences of various policy choices. The model results show that:
- incorporating water quality aspects into water allocation decisions leads to a substantial reduction in application of vinasse to sugarcane fields
- for the water quantity model, without water quality constraints almost all water demands can be met, even during harvest months
- if water quality restrictions are introduced, net benefits are significantly reduced, particularly for industrial water use and fertirrigation.
- to enforce water quality restrictions, the shadow price for maintaining water in the reservoir could be used as a pollution tax for fertirrigated areas
- further research is necessary to study the issue of water quality restrictions in detail
- additional analyses can be undertaken to examine the impact of alternative water and pollution charges on fertirrigated areas.
