Submitted to: Proceedings 2nd International Water Association Conference on Odor and Volatile Organic Compounds
Publication Type: Proceedings
Publication Acceptance Date: 10/7/2009
Publication Date: 10/12/2009
Citation: Shirmohammadi, A., Sexton, A.M., Sadeghi, A.M., Montas, H., Leisnham, P. 2009. Watershed sustainability, modeling, and model uncertainty. In: Proceedings of the 2nd International Water Association Conference on Odor and Volatile Organic Compounds, October 12-15, 2009, Seoul, Korea. 2009 CDROM. Interpretive Summary:
Technical Abstract: The Millennium Ecosystem Assessment (MEA) was the first major integrated global assessment examining degradation of ecosystems and the impacts on humans (Millennium Ecosystem Assessment, 2005). It concluded that unprecedented ecological change has occurred in the last 50 years. Although many of these changes may improve health locally in the short term, detrimental effects are often spatio-temporal and human health is at serious risk in many regions of the world. Watersheds are vital for sustaining health of living systems (e.g., humans, wildlife, aquatic, etc.). Living systems rely on proper ecological functioning for provisioning (crops, aquaculture), regulating (drinking water, disease), and cultural (aesthetic, recreation, ecotourism) services. Watershed is defined as a landscape delineated by topographic and hydrologic features. Folliott (2002) uses a watershed sustainability concept and states, “watersheds provide a useful geographical scale for sustainable management of natural resources.” Watersheds include a range of terrestrial and aquatic environments, which should be managed as a dynamic ecosystem rather than in a fragmented manner, as it has been in the traditional approach. To assess the ecological heath of a watershed and its response to climate, land use, and management systems, mathematical and computer algorithms, otherwise, known as “models” have been developed. Models are either empirical or mechanistic and are built for different scales. Some models are mechanistic process based model, some are fields scale build based on both physical laws and empirical algorithms, and others are watershed/basin scale that are again composed of both physical and empirical algorithms. Literature indicates that regardless of its algorithms and scale, models are used to understand and explain the natural phenomena, and, under some conditions they may provide predications in a deterministic or probabilistic sense. To evaluate an event in our ecosystem, we may need to provide a scientific explanation of it. However, mimicking natural system is beyond our theoretical abilities! Albert Einestein observed,” “Insofar as mathematics applies to the real world, it is not true. Insofar as it is true, it does not apply to the real world”, (Simanek, 2002).” This presentation discusses the concept of watershed sustainability, role of models in watershed management for attaining sustainability, and associated uncertainty with the models as they are applied to natural ecosystems. It concludes that watershed sustainability should consider multiple components of ecosystem health, economic vitality for its habitats, and the human and wildlife health. It also points out that uncertainty in the ecosystem models is real and should be taken into consideration in any watershed assessment exercises including TMDL (Total Maximum Daily Load) assessments.