Ch. 3: Water Resources. Climate Change Impacts in the United States: The Third National Climate Assessment

Georgakakos, Aris P.; Fleming, Paul; Dettinger, Michael D.; Peters-Lidard, C.; Richmond, Terese; Reckhow, Kenneth H.; White, Kathleen D.; Yates, David

doi:10.7930/j0g44n6t

Cited by 79 publications

(75 citation statements)

References 165 publications

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“…Consistent with the Third National Climate Report (Georgakakos et al 2014), we define a very heavy precipitation event (P 99% ) at a watershed as any daily event greater than the 99th percentile of wet days (any measured precipitation) computed across the historic period of record. While the exact 99th percentile value varied geographically, the median value across all watersheds was 3.5 cm.…”

Section: Methodsmentioning

confidence: 99%

“…However, the linkage between precipitation and flooding is more nuanced at larger scales, in non-urban areas, and for all but the most extreme precipitation events. In addition, the hydrology literature itself has numerous studies investigating controls on flooding, with most indicating that a primary control besides precipitation is antecedent watershed wetness (e.g., Li et al 2009;Tramblay et al 2010;Shaw and Riha 2011;Radatz et al 2013;Georgakakos et al 2014). Furthermore, nearly all rainfall-runoff models track antecedent watershed wetness such that the fraction of rainfall converted to runoff increases as stored water increases (e.g., Massari et al 2014).…”

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confidence: 99%

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Examining why trends in very heavy precipitation should not be mistaken for trends in very high river discharge

2015

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It is firmly established in the hydrologic literature that flooding depends on both antecedent watershed wetness and precipitation. One could phrase this relationship as "heavy precipitation does not necessarily lead to high stream discharge", but rarely do studies directly affirm this statement. We have observed several nonhydrologists mistake trends in heavy precipitation as a proxy for trends in riverine flooding. If the relationship between heavy precipitation and high discharge was more often explicitly presented, heavy precipitation may less often be misinterpreted as a proxy for discharge. In this paper, we undertake such an analysis for 390 watersheds across the contiguous U.S. We found that 99th percentile precipitation only results in 99th percentage discharge 36 % of the time. However, when conditioned on soil moisture from the Variable Infiltration Capacity model, 62 % of 99th percentile precipitation results in 99th percentile discharge during wet periods and only 13 % during dry periods. When relating trends in heavy precipitation to hydrologic response, precipitation data should, therefore, be segregated based on concurrent soil moisture. Taking this approach for climate predictions, we found that CMIP-5 atmosphere-ocean global circulation model (AOGCM) simulations for a RCP 6.0 forcing project increases in concurrence of greater than median soil wetness and extreme precipitation in the northern United States and a decrease in the south, suggesting northern regions could see an increase in very high discharges while southern regions could see decreases despite both regions having an increase in extreme precipitation. While the actual outcome is speculative given the uncertainties of the AOGCM's, such an analysis provides a more sophisticated framework from which to evaluate the output as well as historic climate data.

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Section: Methodsmentioning

confidence: 99%

mentioning

confidence: 99%

Examining why trends in very heavy precipitation should not be mistaken for trends in very high river discharge

2015

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“…The consensus is that recent increases in the frequency and magnitude of precipitation events [1,[10][11][12][13][14][15] have contributed to these upwards trends in streamflow, particularly since the 1970s. However, streamflow can be altered by a variety of factors, including atmospheric changes (e.g., precipitation type, timing, phase, and volume; temperature; and evapotranspiration), land use and land cover (e.g., urbanization, agricultural practices, ditching and artificial tile drainage), or anthropogenic water management (e.g., dams, impoundment, water abstraction, flow augmentation, and diversions).…”

Section: Introductionmentioning

confidence: 99%

Evaluating the Drivers of Seasonal Streamflow in the U.S. Midwest

Slater

Villarini

2017

Water

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Streamflows have increased notably across the U.S. Midwest over the past century, fueling a debate on the relative influences of changes in precipitation and land cover on the flow distribution. Here, we propose a simple modeling framework to evaluate the main drivers of streamflow rates. Streamflow records from 290 long-term USGS stream gauges were modeled using five predictors: precipitation, antecedent wetness, temperature, agriculture, and population density. We evaluated which predictor combinations performed best for every site, season and streamflow quantile. The goodness-of-fit of our models is generally high and varies by season (higher in the spring and summer than in the fall and winter), by streamflow quantile (best for high flows in the spring and winter, best for low flows in the fall, and good for all flow quantiles in summer), and by region (better in the southeastern Midwest than in the northwestern Midwest). In terms of predictors, we find that precipitation variability is key for modeling high flows, while antecedent wetness is a crucial secondary driver for low and median flows. Temperature improves model fits considerably in areas and seasons with notable snowmelt or evapotranspiration. Finally, in agricultural and urban basins, harvested acreage and population density are important predictors of changing streamflow, and their influence varies seasonally. Thus, any projected changes in these drivers are likely to have notable effects on future streamflow distributions, with potential implications for basin water management, agriculture, and flood risk management.

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“…Downscaled average annual natural flow in the Flint sub-basin was projected to increase 13 % between the historical period and 2040-2059 period in the reference case scenario, which includes RCP8.5 climate change, a finding at odds with some other studies (Georgakakos et al 2014). However, this 13 % change of average surface water supply in the reference scenario due to climate change was less than its interannual variability.…”

Section: Natural Flow Sensitivitymentioning

confidence: 76%

Sensitivity of future U.S. Water shortages to socioeconomic and climate drivers: a case study in Georgia using an integrated human-earth system modeling framework

Scott¹,

Daly²,

Hejazi³

et al. 2016

Climatic Change

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One of the most important interactions between humans and climate is in the demand and supply of water. Humans withdraw, use, and consume water and return waste water to the environment for a variety of socioeconomic purposes, including domestic, commercial, and industrial use, production of energy resources and cooling thermal-electric power plants, and growing food, fiber, and chemical feed stocks for human consumption. Uncertainties in the future human demand for water interact with future impacts of climatic change on water supplies to impinge on water management decisions at the international, national, regional, and local level, but until recently tools were not available to assess the uncertainties surrounding these decisions. This paper demonstrates the use of a multi-model framework in a structured sensitivity analysis to project and quantify the sensitivity of future deficits in surface water in the context of climate and socioeconomic change for all U.S. states and sub-basins. The framework treats all sources of water demand and supply consistently from the world to local level. The paper illustrates the capabilities of the framework with sample results for a river sub-basin in the U.S. state of Georgia.

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Ch. 3: Water Resources. Climate Change Impacts in the United States: The Third National Climate Assessment

Cited by 79 publications

References 165 publications

Examining why trends in very heavy precipitation should not be mistaken for trends in very high river discharge

Examining why trends in very heavy precipitation should not be mistaken for trends in very high river discharge

Evaluating the Drivers of Seasonal Streamflow in the U.S. Midwest

Sensitivity of future U.S. Water shortages to socioeconomic and climate drivers: a case study in Georgia using an integrated human-earth system modeling framework

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