Review of the New York City Department of Environmental Protection Operations Support Tool for Water Supply (2018) / Chapter Skim
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Appendix B: Use of Climate and Hydrologic Models for Projecting Future Water Resources
Appendix B: Use of Climate and Hydrologic Models for Projecting Future Water Resources
Pages 179-190
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From page 179... ...
. To characterize how a changing climate may affect hydrologic processes and water resources at regional scales, many studies utilize downscaled projections of future temperature and precipitation from global climate models to drive hydrologic models to estimate impacts on streamflow, sediments, and pollutants at the watershed scale.
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180 NYC DEP OPERATIONS SUPPORT TOOL FOR WATER SUPPLY FIGURE B-1 Chain-of-models concept. SOURCE: Vogel et al.
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Correcting these boundary conditions is extremely problematic, and so a feasible approach is to bias-correct the RCM outputs using observed meteorology before their use as inputs to hydrologic models (e.g., Yang et al., 2010)
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From page 182... ...
As long as significant statistical relationships exist, empirical downscaling can yield regional information for any desired variable such as precipitation and temperature, although care must be taken when downscaling multiple variables in order to maintain correlations. This approach encompasses a range of statistical techniques from simple linear regression (e.g., Wilby et al., 2000)
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From page 183... ...
The only thing that changes is the intensity of precipitation within the events. The challenges of downscaling and bias correction, through either RCMs, statistical methods, or a combination of approaches, led to the Chapter 5 recommendation that is repeated here: the NYC DEP should establish selection criteria for GCMs used as inputs based on how well the GCMs reproduce current climate and major climate trends over recent decades in this region.
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. We highlight here issues related to global and regional climate models, downscaling techniques, and hydrologic models.
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From page 185... ...
. Regional Climate Model Limitations As previously mentioned, an important limitation for regional climate model simulations is that they are dependent on boundary conditions supplied from other sources, often GCMs (CCSP, 2008)
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Further, BCSD corrects biases in mean levels, but does not address biases in trends. Hydrologic Model Limitations Rigorous validation is essential when using hydrologic models to ensure that they represent past and current conditions appropriately (Demaria et al., 2016)
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In: Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change, T
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2013. Suspended sediment source areas and future climate impact on soil erosion and sediment yield in a New York City water supply watershed, USA.
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2010. Distribution-based scaling to improve usability of regional climate model projections for hydrological climate change impacts studies.
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