A watershed-based land prioritization model for water supply protection

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Forest Ecology And Management


Water quality management at a watershed scale is important for water supply protection. Escalating costs of water treatment, along with the need for cooperative solutions among various water users in a watershed, reinforce the need for such approach. In a watershed approach, optimum water quality benefits can be achieved by targeting practices to those areas that have the maximum marginal value of water quality protection. To accomplish this, prioritization based on marginal benefits and costs is essential. The information that is crucial for developing an effective prioritization method includes geographic information, relationship between land criteria and effects, and travel-time of runoff water. By integrating these three types of information, a watershed level prioritization model was developed and applied to the Ware River watershed in Massachusetts, USA. It was observed that the time of travel of surface runoff followed a complex spatial distribution. Use of zones based on distance from the outlet or drainage zones may not accurately reflect the spatially explicit nature of travel path and travel-times. The area under each category of travel-time as a function of travel-time followed a nonlinear trend in the Ware River watershed. The distribution of the prioritization index showed that sensitive areas do not clearly fall within the boundaries of any single land characteristic (e.g. riparian buffer, steep slopes, sensitive soils, etc.). Low priority areas covered the highest percent of the watershed and this percentage decreased with increase in land sensitivity. Focusing on fewer areas in the watershed can maximize benefits to water quality and result in lower expenditures. By adjusting criteria and weights, this approach can be adapted to prioritize a wide variety of land-protection and land-use decisions such as preserving prime forestland, protecting critical wildlife habitats, recreational and open space planning, and ecological–economic planning.









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