PESERA-DESMICE: Land management evaluation model

Table of Contents

1. Authors
2. Summary
3. Acronyms
4. Introduction
5. Coarse-scale model description
   1. The PESERA model: summary
   2. Alternative approaches to assessing soil erosion
   3. Process representation in PESERA
   4. Extensions of PESERA
   5. Adapting PESERA
   6. Assessment at catchment scales
6. Cost-effectiveness modelling
   1. Step 1
   2. Step 2
   3. Step 3
   4. Step 4
   5. Step 5
   6. Step 6
   7. Step 7
   8. Step 8
   9. Step 9
   10. Step 10
   11. Step 11
   12. Step 12
7. Agent-Based modelling in Spain
   1. Phase 1
   2. Phase 2
   3. Phase 3
   4. Phase 4
   5. Phase 5
   6. Phase 6
8. Input-Output modelling in Spain
   1. Model construction
   2. Scenario analyses
9. References

Step 4

Step 4: Defining a time horizon and preparing a series of on-site effects

This step first of all compares the lifetimes of the technologies considered. For the subsequent cost-benefit analyses (step 6 and 11), it is important that technologies are considered over the same time horizon. However, individual technologies may differ widely in their lifetimes. PESERA can be run for 20 years for all technologies: few technologies are expected to have a lifetime longer than this, and even if they had, the use of discounting (see step 7) makes the contribution of effects distant from now increasingly insignificant. However, if technologies are compared that have a lifetime of e.g. 1, 3, 5 and 15 years, the appropriate time horizon would be 15 years for the last technology, and several cycles of re-investment (respectively 15, 5 and 3) would be assumed for the other technologies. The assumption of re-investment has a drawback: as conditions change over time (as evidenced by the annual output of PESERA), the investment decision is actually not the same each time. A technology may become either more or less attractive with each cycle. However, for the sake of keeping the model simple a single cost-benefit analysis will be performed for the potential multiple cycles of re-investment. On the other hand, it is often justifiable to assume that effects will only gradually develop, and several cycles of re-investment of short-lived technologies might be necessary to realise these effects. For example, a single year of applying no-tillage will not lead to significant build up of soil organic matter; it is the sustained adoption (annual re-investment) that delivers the desired effect. Thus, even if all technologies considered would be short-lived, it would still be sensible to consider a minimum re-investment cycle. If multiple re-investment cycles can be accommodated within the 20 year time-span, the number of cycles resulting in the highest Net Present Values (NPV) in the CBA should be preferred. Where appropriate, a distinction can then be made between initial and sustained adoption of the technology.

When a time horizon has been defined, the data need to be prepared for subsequent valuation (step 6). First of all, investment costs are entered in the relevant years they (re-)occur. Secondly, maintenance costs are added for the years between (re-)investments. In addition to investment and maintenance costs, production costs will be considered. This is important as: 1) adopting a remediation technology may imply a change of land use; and 2) production costs with or without a remediation technology may be different (in some cases the technology modifies the use of inputs, in many cases the technology will lead to increased yields, which require higher labour input for harvesting). In cases where no or reduced investment costs were considered for existing technologies (Step 3), this only holds for the first investment cycle; in all potential re-investment cycles, full investment costs will be attributed.

Data sources: 1) WOCAT QT data; 2) production costs in the with and without case (see also step 3); 3) PESERA output data

Intermediate products: 1) Data series for on-site effects for the time horizon for all pairs of with/without situations;