Characterization of the impacts of the built environment on the hydrologic cycle for life cycle assessment

摘要

The goal of this research is to develop a method to characterize the impacts of the built environment on freshwater resources in life cycle studies. The focus of this methodology is the impacts brought about by changes in land cover on the hydrological cycle.;In order to calculate an impact indicator it is necessary to understand how changes in land cover can influence how water flows within a catchment. To this end, the water balance of a sample of drainage basins in the South Eastern Coastal Plains ecoregion is analyzed on an annual basis using the Budyko framework. The Budyko model provides a catchment coefficient that represents properties of the drainage basin and its effect on the partitioning of rainfall into evapotranspiration and run-off.;The annually calculated catchment coefficient was studied to detect a trend in time and found two diverging trends regardless of the increase in urban development. On one hand, an increase in the catchment coefficient could be partially explained through the cross-correlation of surface water withdrawals at the county level. Nevertheless, further research is necessary to explain the sensitivity of changes in streamflow from water transfers and/or climate variability on the optimization procedure used to calculate the catchment coefficient. In contrast, a reduced sample of basins presented the expected run-off behavior and was used to explore the applicability of the proposed methodology. The resulting panel data regression models included random effects and morphometric parameters that allowed capturing the heterogeneity of the sample. Also, the models represented statistically significant relationships between the catchment coefficient and land cover classes and population parameters. This facilitated the estimation of annual stream-flow based on given urban growth expectations and climate scenarios. Finally, the impact of the built environment on freshwater resources was characterized as the proportion of the run-off ratio of a developed basin to a baseline condition. The methodology allowed assessment of the relative impact of land cover change on the hydrological cycle and could assist planners in the development of sustainable communities.