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At least 1,189 records · Page 66Linked to original sources
USGS2018

Turning on the faucet to a healthy coast

Coastal re-engineering and freshwater extraction have reduced water flow into the estuaries of the world. Because of these activities, stressed coastal vegetation is especially vulnerable to die-off during droughts, contributing to a loss of human services related to storm protection, fisheries and water quality. The subsequent collapse of vegetation is often as related to the loss of flow as to the rise in salinity. The solution to the problem in regions with rapidly expanding human populations may be to apply strategically timed freshwater releases to estuaries. To be successful, the water requirements of both humans and natural environments need careful assessment. Flow management projects have been successful in reviving vegetation in a number of settings including The Everglades, Murray River, Mississippi River and Nueces River. These projects can be contentious, for example, if the projects have caused negative impacts to the oyster industry. Beyond the human services provided, flowing water has an intrinsic personal value for which many people are willing to pay.

Solutions Journal↗
USGS2017

Growth of coast redwood and Douglas-fir following thinning in second-growth forests at Redwood National Park and Headwaters Forest Reserve

Managers of second-growth forests at Redwood National Park and the Bureau of Land Management’s Headwaters Forest Reserve encourage the development of late seral forest characteristics using mechanical thinning, where competing vegetation is removed to promote growth of residual trees. Yet the ability to quantify and reliably predict outcomes of treatments such as these is hindered by the long time scales at which forests respond to thinning. Here we present analyses of tree growth at Redwood National Park (RNP) and Headwaters Forest Reserve (HDWT) from sites that have had > 5 years to respond to thinning treatments. Compared to untreated stands, thinned stands had lower stem density (trees ha -1 ) and basal area (m 2 ha -1 ), primarily due to removal of Douglas-fir ( Pseudotsuga menziesii (Mirb.) Franco). Individual tree growth (basal area increment, BAI, m 2 yr -1 ) was related to tree size (basal area, m 2 ) and treatment history, with the highest growth rates observed in large trees. Both redwood ( Sequoia sempervirens (D. Don) Endl.) and Douglas-fir appeared to have a small, but detectable, positive growth response to thinning treatments. Early results suggest a large degree of variation among sites, with possible systematic differences in growth responses between RNP and HDWT. Future work will focus on identifying site-level differences (site quality, local competition, slope, aspect, stand age, distance from the ocean) to improve our understanding of the growth response.

Redwood National Park and Headwaters Forest Reserv↗
USGS2021

Digital Twin Earth - Coasts: Developing a fast and physics-informed surrogate model for coastal floods via neural operators

Developing fast and accurate surrogates for physics-based coastal and ocean mod- els is an urgent need due to the coastal flood risk under accelerating sea level rise, and the computational expense of deterministic numerical models. For this purpose, we develop the first digital twin of Earth coastlines with new physics-informed machine learning techniques extending the state-of-art Neural Operator. As a proof-of-concept study, we built Fourier Neural Operator (FNO) surrogates on the simulations of an industry-standard coastal and ocean model – Nucleus for Euro- pean Modelling of the Ocean (NEMO). The resulting FNO surrogate accurately predicts the sea surface height in most regions while achieving upwards of 45x acceleration of NEMO. We delivered an open-source CoastalTwin platform in an end-to-end and modular way, to enable easy extensions to other simulations and ML-based surrogate methods. Our results and deliverable provide a promising approach to massively accelerate coastal dynamics simulators, which can enable scientists to efficiently execute many simulations for decision-making, uncertainty quantification, and other research activities.

Conference Paper↗