USACE Releases Updated Guidance for Incorporating Climate Change Impacts to Inland Hydrology in Civil Works Studies, Designs, and Projects
ALEXANDRIA, VIRGINIA. Recent scientific evidence shows that in some geographic locations and for some impacts relevant to U.S. Army Corps of Engineers (USACE) operations, climate change is shifting the climatological baseline abo ut which natural climate variability occurs. The range of that variability may be changing in some cases as well.
More extreme seasonal conditions of rainfall and runoff (flooding or drought) may become more prevalent in some regions. These conditions may be exacerbated by future changes in the health and sustainability of native vegetation and social demands for energy and water. Improved knowledge of these changes is important to USACE and our customers because the assumptions of stationary climatic baselines and a fixed range of natural variability as captured in the historical hydrologic record may no longer be appropriate for long-term project planning. However, projections of specific climate changes and their associated impacts to local-scale project hydrology that may occur in the future can be highly uncertain, requiring guidance on their interpretation and use.
USACE has released a new Engineering and Construction Bulletin (ECB 2016-25), Guidance for Incorporating Climate Change Impacts to Inland Hydrology in Civil Works Studies, Designs, and Projects. This ECB supersedes and updates the policy in ECB 2014-10. It applies to all hydrologic analyses supporting planning and engineering decisions that have an extended decision timeframe (i.e., not for short-term water management decisions).
This guidance aims to enhance USACE climate preparedness and resilience by incorporating relevant information about climate change impacts in hydrologic analyses for new and existing USACE projects in accordance with the USACE overarching climate change adaptation policy. This includes direct changes to hydrology through changes in temperature, precipitation, evaporation rates and other climate variables, as well as dependent basin responses to climate drivers, such as sedimentation loadings.
The ECB helps support a qualitative assessment of potential climate change threats and impacts that may be potentially relevant to the particular USACE hydrologic analysis being performed. Such a qualitative analysis includes consideration of both past (observed) changes in climate trends as well as potential future (projected) changes to relevant hydrologic inputs. Examples of this type of analysis are provided in the ECB.
A web-based qualitative Climate Hydrology Assessment Tool (available internally and for public access) has been developed by USACE to assist in this analysis, along with other tools that support assessments of climate preparedness and resilience. Two of the tools supporting this analysis is available on http://www.corpsclimate.us/ptcih.cfm. More tools will be forthcoming.
revised September 28, 2016
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