Production of clean water in agriculture headwater catchments: A model based on the payment for environmental services

摘要

This study aimed to present a payment for ecosystem services model that promotes a symbiotic coexistence between agriculture and clean water production. The model favors application to headwater catchments where clean water production is expected. However, the frequent invasion of these areas with intensive agriculture and livestock production systems affects water quality threatening the use of this resource, namely as drinking water. The proposed Agriculture for Clean Water Yield (ACWY) model reconciles agriculture with clean water production through the incentive approach, giving the farmers a financial compensation if they are willing to replace intensive by sustainable agriculture and livestock production systems, namely agro-forestry systems. The reconciliation through the incentive approach is justified because clean water and food are both vital goods for human survival. The compensation rises as function of increasing catchment water yield capacity and conversion costs. For example, landowners receive more if land conversion occurs in slopping than undulated landscapes. The model applied to Fazenda Gloria watershed, composed of 19 headwater catchments (96.7 ha on average), proposed financial incentives in the range 218.73-576.5 US$/ha/year depending on the catchment's water yield capacity, which rise to 284.35-749.45 US$/ha/year if conversions occur in extreme vulnerable areas. The watershed, located in Sao Paulo state, Brazil, covers 18.4 km~2 and is the source of drinking water to 70,000 people living in Jaboticabal city. Monitoring is essential to assess the performance of ACWY and adjust the compensation dynamically. For instance, noteworthy improvements in water yields and water quality or land conversions performed in short periods can expect the most generous compensation. Two concerns about implementing the model in Fazenda Gloria rely on the lack of political will in spite of existing federal and state legal support, as well as on the financial sources to make the model a real project.