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Nitrate and phosphate export coefficient models were developed for coastal watersheds along the Santa Barbara Channel in central California. One approach was based on measurements of nutrient fluxes in streams from specific land use classes and included a watershed response function that scaled export up or down depending on antecedent moisture conditions. The second approach for nutrient export coefficient modeling used anthropogenic nutrient loading for land use classes and atmospheric nutrient deposition to model export. In an application of the first approach to one watershed, the nitrate and phosphate models were within 20% of measured values for most storms. When applied to another year, both nitrate and phosphate models generally performed adequately with annual, storm-flow, and base-flow values within 20% of measured nutrient loadings. Less satisfactory results were found when applied to neighboring watersheds with difference percentages of land use and hydrologic conditions. Application of the second approach was less successful than the first approach.(KEY TERMS: nutrient export coefficient modeling; nitrate; phosphate; nutrient flux; watersheds; streams; event-based modeling; coastal; watershed response function; high-frequency sampling.)Robinson, Timothy H., and John M. Melack, 2013. Modeling Nutrient Export from Coastal California Watersheds.

Traditional approaches to establishing critical water quality conditions, based on statistical analysis of low flow conditions and expressed as a recurrence interval for low flow conditions (e.g., 7Q10), may be inappropriate for drier watersheds. The use of 7Q10 as a standard design flow assumes year-round flow, but in these watersheds, 7Q10 is zero or very small. In addition, the increasing use of multiple year dynamic water quality models at daily time steps can supercede the use of steady state approaches. Many of these watersheds are also under increasing urbanization pressure, which accentuates the flashiness of runoff and the episodic nature of critical water quality conditions. To illustrate, the conditions in the Santa Clara River, California, are considered. A statistical analysis indicates that higher inorganic nitrogen concentrations correlate strongly with low flow. However, peaks in concentrations can occur during the first storms, particularly where nonpoint source contribution is significant. Critical conditions can thus occur at different flow regimes depending on the relative magnitude of flow and pollutant contributions from various sources. The use of steady state models for these dry semi-urbanized watersheds based on 7Q10 flows is thus unlikely to accurately simulate the potential for exceeding water quality objectives. Dynamic simulation of water quality is necessary, and as the recent intense storm event sampling data indicate, the models should be formulated to consider even smaller time steps. This places increasing demand on computational resources and datasets to accurately calibrate the models at this temporal resolution. (KEY TERMS: TMDL; watershed modeling; low flow; runoff; loads; storm water; inorganic nitrogen.)

Faith in the Anthropocene requires a re-imagined account of Christian hope. Research on the emergence of eco-anxiety disorder shows that climate crisis and ecological destruction have psychological and emotional effects on persons and communities, producing fear, despair, and hopelessness. Accounts of hope in recent environmental literature and in traditional Christian formulations rely on faith in political will, technological innovation, or an omnipotent divine sovereign to intervene and save. Such accounts are inadequate for this moment. A re-imagined notion of Christian hope will embrace hopelessness, understood as the relinquishment of false optimism that the climate crisis can be reversed and a commitment to act without expectation of success, but with a commitment to nurturing the wisdom to live more humanly.