FOCUSING ENVIRONMENTAL-MANAGEMENT BUDGETS ON NONLINEAR-SYSTEM RESPONSES - POTENTIAL FOR SIGNIFICANT IMPROVEMENTS TO FRESH-WATER ECOSYSTEMS

1. The non-linear responses of environmental systems to changes impose d upon them is well known to scientists. Environmental managers rarely act accordingly, however, because of communication problems, a lack o f imagination and various other constraints. Therefore, we illustrate such non-linear responses to demonstrate that gains in efficiency (ben efit per money spent) can be made by integrating these characteristics into decision making. 2. Identifying three measures that are currentl y the focus of large freshwater management budgets (waste-water treatm ent, riparian buffer strips and discharge allocations to regulated riv ers), we relate the costs of these measures to the environmental impro vements achievable in running waters. For each of these measures, the environmental improvement achieved per currency unit significantly dec reases with an increase in total money spent. 3. Traditional environme ntal management ignores this system behaviour because it invests impor tant parts of budgets in a particular measure before focusing on the n ext among other measures. We therefore advocate alternating investment s in that measure which achieves the greatest environmental improvemen t in the next possible investment step. Compared with traditional mana gement, this alternating decision-making strategy will achieve greater environmental improvements for a given total budget.