摘要：This paper extends an integrated framework that combines economic, environmental and GIS modeling to evaluate the cost effectiveness of land retirement programs. The modeling framework is applied to the Lower Sangamon Watershed in Cass County of Illinois to examine the economic costs and environmental benefits of three land retirement scenarios: land actually enrolled in the Illinois CREP, land selected by a land rental cap mechanism and land identified by a least cost model. We find that land retirement in the watershed successfully achieved the program goal of 20% sediment abatement. However, in achieving the same level of sediment abatement, the costs of actual land retirement are 1.3 times and 2.1 times of those in a land rental cap mechanism and a least cost model respectively. The model results also reveal that cost effective land retirement parcels are more sloping, close to river, with higher upland sediment inflow, more on-site erosion and lower quasi-rents. The results indicate that governments may improve the cost effectiveness of land retirement program through targeting. And there is a need to modify current Illinois CREP eligibility criteria to include sloping cropland adjacent to the river in the program. Furthermore our results suggest that in the program implementation land retirement contracts could be selected based on several measurable parameters such as distance from the river and slope.
