The technical issues involved in soil conservation projects are diverse. A major technical issue is that of defining the proper numeraire in which to measure soil erosion as it relates to productivity. The same issue is present in the case of projects that have off-farm or downstream effects. Technical measures must include the quantification of parameters that are directly linked to the economic productivity of activities taking place outside the project area. Where projects are designed to change the rate at which soils are being eroded over time, analysts face the problem of quantifying an acceptable relationship between agricultural productivity and changes in soil characteristics. Another major technical issue is how to predict the effectiveness of soil conservation practices in bringing the soil to an acceptable level of productivity. Soil erosion and deposition of sediments in water reservoirs are not solely the result of farmers' actions upstream. Erosion is a natural geologic process that will continue, regardless of human actions.