The exploration of latent river pulsing indexes in Taiwan

The contradictory viewpoints of hydraulic engineers and ecologists have long been a conflict in catchment management. The traditional approach of hydraulic engineering is to use levees to stop water and prevent flooding, but these concrete structures are not very environmentally friendly and are likely to keep people away from the aquatic environment. The harmonious interactions between people and nature are often overlooked. Ecologists, conversely, tend to over-emphasise the aesthetic issues by preserving the natural environment and utilising natural materials instead of man-made materials such as concrete. In some circumstances, such materials have been used without sufficient consideration for hazard mitigation and prevention. Attempts to bring these two conflicting viewpoints into reconciliation face many difficulties. The concept of emergy, developed by Howard T. Odum, is usually used to assess the contribution of natural environment to the human economic system. Emergy is defined as ‘the availability of energy of one kind that is used up in transformations directly and indirectly to make a product or services' (Odum, 1996: p. 13). In this study, emergy synthesis is proposed as a tool for studying the catchment management approach in Taiwan. The emergy contributions of a river at different levels of the global and regional hydrological cycle are evaluated. Two new indicators for river management, river pulsing index and emergy matching index, are developed to judge the trade-off between economy and ecology.