DOCSLIB.ORG

EFFECTS of DROUGHT on FORESTS and RANGELANDS in the UNITED STATES 15 CHAPTER 2 Characterizing Drought for Forested Landscapes and Streams

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
EFFECTS of DROUGHT on FORESTS and RANGELANDS in the UNITED STATES 15 CHAPTER 2 Characterizing Drought for Forested Landscapes and Streams CHAPTER 2 Characterizing Drought for Forested Landscapes and Streams Charles H. Luce Neil Pederson John Campbell Connie Millar Patrick Kormos James M. Vose Ross Woods C.H. Luce is a Research Hydrologist, U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station (RMRS), Boise, ID 83702. N. Pederson is a Senior Ecologist, Harvard Forest, Petersham, MA 01366. J. Campbell is a Research Ecologist, U.S. Department of Agriculture, Forest Service, Northern Research Station (NRS), Durham, NH 03824. C. Millar is a Paleoecologist, U.S. Department of Agriculture, Forest Service, Pacific Southwest Research Station (PSW), Albany, CA 94710. P. Kormos is a Research Associate, U.S. Department of Agriculture, Agricultural Research Service (ARS), Boise, ID 83712. J.M. Vose is a Research Ecologist, U.S. Department of Agriculture, Forest Service, Southern Research Station (SRS), Center for Integrated Forest Science (CIFS), North Carolina State University, Department of Forestry and Environmental Resources, Raleigh, NC 27695. R. Woods is a Senior Lecturer, Faculty of Engineering, University of Bristol, Bristol, BS8 1TH, UK. 14 CHAPTER 2 Characterizing Drought for Forested Landscapes and Streams Introduction of place. A place can be dry or wet, but droughts occur in given locations over time. For example, the Sonoran The changing nature of drought is a growing global Desert may have a lack of water for many purposes, concern (Cook and others 2015, Dai 2011, Seneviratne but conceptually it has just the right amount of water and others 2010, Sheffield and Wood 2008b, Trenberth for the Sonoran Desert, and it occasionally experiences and others 2014, Wilhite and others 2014). Drought droughts. Wet places, like the coastal rain forests in can be a severe natural disaster with substantial social Washington State, also experience droughts when there and economic consequences affecting large areas with is an unusually dry summer. Consistently dry seasons extended durations (Wilhite and Buchanan-Smith 2005). would not merit the designation of “drought” in and Although it is clear that shifts in circulation patterns, of themselves; however, variations in how dry or long energy for evapotranspiration, and air temperatures are the dry season is from year to year are relevant. In changing in ways that enhance the consequences of places like the Western United States, where there is a drought, there is only weak consensus about the effects coincidence of the dry season with the growing season of climate change on drought occurrence (IPCC 2013, every year, it does not make sense to frame summer as Seneviratne and others 2012, Trenberth and others a “drought” so much as to note the seasonal aridity of 2014). Some of that uncertainty stems from the complex the location (Seneviratne and others 2012, Wilhite and nature of quantitatively defining drought, but also Buchanan-Smith 2005). because some of the changes in drought characteristics are only partially reflected in traditional drought metrics Although drought is generally defined from a climatic [Palmer Drought Severity Index (PDSI) and the perspective (precipitation levels that are much Standardized Precipitation Index (SPI)]. Furthermore, lower than the annual average), short-term moisture although these traditional metrics have adequately fluctuations also provide important ecological context. reflected the consequences of meteorologically derived A wet period leading to a vegetation flush, followed moisture deficits on agricultural commodities and by a long dry spell, for instance, may not constitute water supply, there is a poorer (although improving) a “drought” relative to long-term averages, but the understanding of how drought interacts with forests inability to meet the temporarily increased water and rangelands and their associated aquatic habitats. demand would nonetheless represent a meaningful Understanding the potential impacts of future drought drought. From the perspective of a plant, it may look on forests and rangelands requires knowledge of how like a temporary enhancement of seasonal aridity droughts impact forest, shrub, and rangeland structure contrasts. An example of this is seen in fire risks (covered in other chapters in this assessment) and how in rangeland ecosystems where wet springs can drought projections are characterized in the General produce an overabundance of fine fuels from invasive Circulation Model (GCM) output. annual grasses (Littell and others 2009, Swetnam and Betancourt 1998, Westerling and others 2003). The purpose of this chapter is to explore drought Similarly, such fluctuations have been tied to forest as a hydrometeorological phenomenon and reflect mortality, with timing having an important influence on broadly on the characteristics of drought that influence outcomes (Anderegg and others 2013). forests, rangelands, and streams. It is a synthesis of understanding about drought processes, hydrology, This descriptive definition also speaks to a purpose paleoclimatology, and historical climate variability, for water. Lack of water is most relevant when water and how this understanding can help predict potential requirements for sustaining terrestrial and aquatic future droughts and their consequences to forests and ecosystems or providing for human uses cannot be rangelands. It describes alternative approaches for met. In natural ecosystems, those requirements broadly characterizing drought and highlights additional work relate to climatological expectations (in a statistical that could inform projection and adaptation for future sense) for water supply. Similarly, in rational agricultural droughts. management, climatological expectations should still provide a basic norm for distinguishing drought What Is Drought? conditions, although sometimes drought is claimed when slightly dry conditions endanger marginally suited Drought is a lack of water. This simple wording implies crops. Generally, drought is perceived as a concern potentially complex stories. The most important during the growing season or warm season, as these implication is that drought is characteristic of time, not are when there is a demand for water. However, EFFECTS OF DROUGHT ON FORESTS AND RANGELANDS IN THE UNITED STATES 15 CHAPTER 2 Characterizing Drought for Forested Landscapes and Streams droughts can have substantial ecological consequence terms of the harm it can induce. It is broadly seen as related to lack of snow cover, particularly for wildlife one of the most potentially severe natural disasters (McKelvey and others 2011) or plants that are protected in terms of either human lives or capital loss because from cold extremes by a layer of snow. it covers large areas and can lead to famine for large populations (Wilhite and Buchanan-Smith 2005). Drought Classification Drought has generally been framed in four classes or “types” (Wilhite and Glantz 1985): (1) meteorological Most of the indices applied to classify drought are drought, (2) hydrologic drought, (3) agricultural tied to common meteorological measurements, like drought, and (4) socioeconomic drought (table 2.1). precipitation and temperature, because these are widely These four classes are not mutually independent, available with relatively long records. The long records but refer to different ways to measure, identify, or make it possible to compare particular precipitation conceptualize drought conditions. Almost all types of amounts or water-balance estimates to the local drought relate to meteorological conditions leading climatological distribution, in essence gauging risk or to a lack of water, such as a lack of precipitation or probability levels of current meteorological events. The excess demand from evapotranspiration. Hydrologic, meteorologically based indices are commonly applied agricultural, and socioeconomic drought are filters for drought forecasting based on weather forecasts, placed on meteorological drought to frame how they given that weather is the most fundamental driver affect human demands and values for water, ranging and also the most fundamental uncertainty in drought from food production to electrical power production, estimation. Despite common application, there is recreation, and wildlife management. Generally the some concern about the utility of drought indices in context is economic, although environmental benefits understanding conditions related to changes in land of water are recognized as well. They also frame cover, land use, or climate (Alley 1984, Sheffield and different time scales of response to meteorological others 2012). forcing. Most of these drought types frame drought as an event. In this framing, a drought is a type The context of utility or need for water frames much of disturbance, or even disaster, with a distinct of the traditional way of defining and describing occurrence. This framing is particularly relevant to drought. Drought is most commonly thought of in crops of limited lifespan, seasonal cycles of water Table 2.1—The four drought classes Drought class Primary focus Estimation Meteorological Dry weather Indices built from weather station or weather forecast information targeted toward soil moisture and agricultural or hydrologic drought. Weather changes rapidly, but indices aggregate weather over time. Hydrologic Streamflow and Measured or modeled runoff and reservoir levels reservoir levels. Some meteorological drought indices target this particular outcome. Agricultural Productivity and Measured or modeled crop yields. survival of crops
Load more

Recommended publications
  • Climate Change and Water Management in South Florida
    Interdepartmental Climate Change Group District Leadership Team Subteam: Kenneth Ammon Deena Reppen Sharon Trost Interdepartmental Climate Change Group Members: Wossenu Abtew Chandra Pathak Restoration Sciences SCADA & Hydrological Data Management Matahel Ansar Christopher Pettit Operations & Maintenance Office of Counsel Jenifer Barnes Barbara Powell Hydrologic & Environmental Systems Water Supply Modeling Dean Powell Luis Cadavid Water Supply Hydrologic & Environmental Systems Angela Prymas Modeling Regulation James Carnes Garth Redfield Intergovernmental Programs Restoration Sciences Tibebe Dessalegne-Agaze Keith Rizzardi BEM Systems Inc. (contractor) Office of Counsel Cynthia Gefvert Winifred Said Water Supply Hydrologic & Environmental Systems Lawrence Gerry Modeling Everglades Restoration Natalie Schneider Linda Hoppes Intergovernmental Programs Water Supply Bruce Sharfstein Michelle Irizarry-Ortiz Restoration Sciences Hydrologic & Environmental Systems Modeling Kim Shugar Intergovernmental Programs Jeremy McBryan Restoration Sciences Fred Sklar Restoration Sciences Damon Meiers Intergovernmental Programs Paul Trimble Hydrologic & Environmental Systems John Morgan Modeling Intergovernmental Programs Bob Verrastro John Mulliken Intergovernmental Programs Water Supply Patti Nicholas Dewey Worth Public Information Everglades Restoration Jayantha Obeysekera Nathan Yates Hydrologic & Environmental Systems Restoration Sciences Modeling i Table of Contents Executive Summary ................................................................................................
    [Show full text]
  • Global Warming Impacts on Severe Drought Characteristics in Asia Monsoon Region
    water Article Global Warming Impacts on Severe Drought Characteristics in Asia Monsoon Region Jeong-Bae Kim , Jae-Min So and Deg-Hyo Bae * Department of Civil & Environmental Engineering, Sejong University, 209 Neungdong-ro, Gwangjin-Gu, Seoul 05006, Korea; [email protected] (J.-B.K.); [email protected] (J.-M.S.) * Correspondence: [email protected]; Tel.: +82-2-3408-3814 Received: 2 April 2020; Accepted: 7 May 2020; Published: 12 May 2020 Abstract: Climate change influences the changes in drought features. This study assesses the changes in severe drought characteristics over the Asian monsoon region responding to 1.5 and 2.0 ◦C of global average temperature increases above preindustrial levels. Based on the selected 5 global climate models, the drought characteristics are analyzed according to different regional climate zones using the standardized precipitation index. Under global warming, the severity and frequency of severe drought (i.e., SPI < 1.5) are modulated by the changes in seasonal and regional precipitation − features regardless of the region. Due to the different regional change trends, global warming is likely to aggravate (or alleviate) severe drought in warm (or dry/cold) climate zones. For seasonal analysis, the ranges of changes in drought severity (and frequency) are 11.5%~6.1% (and 57.1%~23.2%) − − under 1.5 and 2.0 ◦C of warming compared to reference condition. The significant decreases in drought frequency are indicated in all climate zones due to the increasing precipitation tendency. In general, drought features under global warming closely tend to be affected by the changes in the amount of precipitation as well as the changes in dry spell length.
    [Show full text]
  • Climate Change and Cultural Response in the Prehistoric American Southwest
    University of Nebraska - Lincoln DigitalCommons@University of Nebraska - Lincoln USGS Staff -- Published Research US Geological Survey Fall 2009 Climate Change and Cultural Response In The Prehistoric American Southwest Larry Benson U.S. Geological Survey, [email protected] Michael S. Berry Bureau of Reclamation Follow this and additional works at: https://digitalcommons.unl.edu/usgsstaffpub Benson, Larry and Berry, Michael S., "Climate Change and Cultural Response In The Prehistoric American Southwest" (2009). USGS Staff -- Published Research. 725. https://digitalcommons.unl.edu/usgsstaffpub/725 This Article is brought to you for free and open access by the US Geological Survey at DigitalCommons@University of Nebraska - Lincoln. It has been accepted for inclusion in USGS Staff -- Published Research by an authorized administrator of DigitalCommons@University of Nebraska - Lincoln. CLIMATE CHANGE AND CULTURAL RESPONSE IN THE PREHISTORIC AMERICAN SOUTHWEST Larry V. Benson and Michael S. Berry ABSTRACT Comparison of regional tree-ring cutting-date distributions from the southern Col- orado Plateau and the Rio Grande region with tree-ring-based reconstructions of the Palmer Drought Severity Index (PDSI) and with the timing of archaeological stage transitions indicates that Southwestern Native American cultures were peri- odically impacted by major climatic oscillations between A.D. 860 and 1600. Site- specifi c information indicates that aggregation, abandonment, and out-migration from many archaeological regions occurred during several widespread mega- droughts, including the well-documented middle-twelfth- and late-thirteenth- century droughts. We suggest that the demographic response of southwestern Native Americans to climate variability primarily refl ects their dependence on an inordinately maize-based subsistence regimen within a region in which agricul- ture was highly sensitive to climate change.
    [Show full text]
  • Additional Arrangements for Drought Under the UNCCD Prospective Assessment
    Additional arrangements for drought under the UNCCD Prospective assessment April 2019 This prospective assessment concerning additional arrangements for drought under the UNCCD looks at a variety of legal instruments of international cooperation, ranging from protocols to gentleman’s agreements, and assesses their suitability for addressing drought under the UNCCD. The assessment uses information of experiences in using these tools under other international processes, and takes into account the specific priorities and working modalities of the Convention in addressing drought. On this basis, the assessment presents conclusions on the likelihood of success of each legal instrument in addressing drought under the UNCCD. This assessment was authored by the UNCCD Evaluation Office with the support of Dr. Sylvestre- José-Tidiane Manga and Ms. Aurore Vernhes in June 2018 – April 2019. 2 Additional arrangements for drought under the UNCCD: a prospective assessment List of content Page 1. Introduction 5 2. Drought in the context of international cooperation 6 2.1 About drought 6 2.2 Addressing drought through international cooperation 7 2.3 Addressing drought in the context of the UNCCD 9 3. Potential legal instruments for addressing drought under the UNCCD 10 3.1 An overview of legal instruments for international environmental 10 cooperation 3.2 Legal instruments 12 a) Protocols 12 b) Annexes and amendments 19 c) Principles 22 d) Declarations 26 e) Decisions 29 f) Standards 31 g) Gentlemen’s Agreements 34 4. Conclusions 36 Annex: Potential legal
    [Show full text]
  • Climate Change and Drought
    Climate Change and Drought What it means to tribes and how we can adapt What is drought? These two issues in concert present serious questions The National Oceanic and Atmospheric Administration about water availability and access into the future. (NOAA) defines drought as “a deficiency in precipitation Quick facts about drought in the Southwest: over an extended period, usually a season or more, The Southwest has been in a consistent state of resulting in a water shortage causing adverse impacts on drought since 1999. vegetation, animals, and/or people[1]”. The West has Historical drought trends along with projected often suffered from extensive drought periods including temperature increases suggest that droughts will some of the longest drought events on Earth - so called become even more severe over time. mega-droughts[2]. As global temperatures rise due to climate change, areas such as the Southwest are likely Reconstructed drought trends (assembled from to experience “increasing and deepening drought tree ring data) indicate longer drought patterns conditions[3]”. This could have devastating effects on over the last 100 years than previously observed. water supply for ecosystems, agriculture, and for human Winter and spring storm tracks, which bring annual consumption. regional rain, are projected to shift northward. What are the facts? Over the last century the average global temperature has increased by approximately 1.2° C (2.2° F)[4]. Comprehensive, long-term research by governmental agencies and academic institutions indicates that this temperature increase is directly linked to human activities - specifically large-scale greenhouse gas emissions. This human-induced, or anthropogenic, temperature change is causing variable global and Prolonged drought conditions can cause severe damage regional climatic effects.
    [Show full text]
  • Resilient Watershed & Fire Management
    PANDEMIC RECOVERY AND BEYOND Resilient Watersheds and Fire Management California is in the midst of the COVID-19 pandemic during the second-worst megadrought in the past 1,200 years.1 Simultaneously,2020 was named the largest wildfire season recorded in California’s modern history,and included the first “gigafire”– the August Complex fire,which burned more than 1 million acres.2 The drought-fire-flood cycle. Drought and fire intensification are intrinsically linked [see graphic on page 2]: Drought increases fire risk while wildfires limit and impair our water supplies. Drying of vegetation from drought creates more fuel for fires. Fire reduces forest carbon sequestration,therefore releasing more greenhouse gases,causing air temperatures to increase. With increased temperatures,more moisture evaporates from land and lakes,rivers and other bodies of water. These waterbodies are additionally impaired because fire erodes the landscape, allowing more runoff and debris into our water supplies. In a post-fire landscape,vegetation crucial for groundwater recharge can take years to regrow. With the pandemic complicating and stressing resource management and emergency response, capacity and priorities,a pause in forest-management approaches, particularly controlled burns,increases our current vulnerability and leaves In 2020, five of California’s six largest fires Californians in a heightened state of risk. Agencies at all levels of governance must in modern history burned simultaneously. develop strategies to contend with the multi-threat challenges that Californians Source:California’s Wildfire Management and Resilience are experiencing now and will continue to experience in the years to come. Plan.10/10/20 draft (numbers not finalized).
    [Show full text]
  • Ramping up Reforestation in the United States: a Guide for Policymakers March 2021 Cover Photo: CDC Photography / American Forests
    Ramping up Reforestation in the United States: A Guide for Policymakers March 2021 Cover photo: CDC Photography / American Forests Executive Summary Ramping Up Reforestation in the United States: A Guide for Policymakers is designed to support the development of reforestation policies and programs. The guide highlights key findings on the state of America’s tree nursery infrastructure and provides a range of strategies for encouraging and enabling nurseries to scale up seedling production. The guide builds on a nationwide reforestation assessment (Fargione et al., 2021) and follow-on assessments (Ramping Up Reforestation in the United States: Regional Summaries companion guide) of seven regions in the contiguous United States (Figure 1). Nursery professionals throughout the country informed our key findings and strategies through a set of structured interviews and a survey. Across the contiguous U.S., there are over 133 million acres of reforestation opportunity on lands that have historically been forested (Cook-Patton et al., 2020). This massive reforestation opportunity equals around 68 billion trees. The majority of opportunities occur on pastureland, including those with poor soils in the Eastern U.S. Additionally, substantial reforestation opportunities in the Western U.S. are driven by large, severe wildfires. Growing awareness of this potential has led governments and organizations to ramp up reforestation to meet ambitious climate and biodiversity goals. Yet, there are many questions about the ability of nurseries to meet the resulting increase in demand for tree seedlings. These include a lack of seed, workforce constraints, and insufficient nursery infrastructure. To meet half of the total reforestation opportunity by 2040 (i.e., 66 million acres) would require America’s nurseries to produce an additional 1.8 billion seedlings each year.
    [Show full text]
  • Climate, Drought, and Sea Level Rise Scenarios for California's Fourth
    CLIMATE, DROUGHT, AND SEA LEVEL RISE SCENARIOS FOR CALIFORNIA’S FOURTH CLIMATE CHANGE ASSESSMENT A Report for: California’s Fourth Climate Change Assessment Prepared By: David W. Pierce1 Julie F. Kalansky1 1 Daniel R. Cayan 1 Division of Climate, Atmospheric Sciences, and Physical Oceanography Scripps Institution of Oceanography, La Jolla, California DISCLAIMER This report was prepared as the result of work sponsored by the California Energy Commission. It does not necessarily represent the views of the Energy Commission, its employees or the State of California. The Energy Commission, the State of California, its employees, contractors and subcontractors make no warrant, express or implied, and assume no legal liability for the information in this report; nor does any party represent that the uses of this information will not infringe upon privately owned rights. This report has not been approved or disapproved by the California Energy Commission nor has the California Energy Commission passed upon the accuracy or adequacy of the information in this report. August 2018 Edmund G. Brown, Jr., Governor CCCA4-CEC-2018-006 ACKNOWLEDGEMENTS We acknowledge the World Climate Research Programme's Working Group on Coupled Modelling, which is responsible for the Climate Model Intercomparison Project (CMIP), and we thank the climate modeling groups for producing and making available their model output. For CMIP the U.S. Department of Energy's Program for Climate Model Diagnosis and Intercomparison provides coordinating support and led development of software infrastructure in partnership with the Global Organization for Earth System Science Portals. This work was supported by the California Energy Commission, Agreement Number 500-14-005.
    [Show full text]
  • Advancing the National Fish, Wildlife, and Plants Climate Adaptation Strategy Into a New Decade
    1 2 0 2 . K R O W T E N N O I T A T P A D A E T A M I L A D V A N C I N G T H E C S T N A T I O N A L F I S H , N A L P W I L D L I F E , A N D D N A , E P L A N T S C L I M A T E F I L D L A D A P T A T I O N I W , H S T R A T E G Y I N T O S I F L A A N E W D E C A D E N O I T A N Advancing the National Fish, Wildlife, and Plants Climate Adaptation Strategy into a New Decade Contributors Joe Burns, USFS/Office of Sustainability Mike Langston, U.S. Geological and Climate Survey/South Central Climate Adaptation Whisper Camel-Means, Confederated Science Center Salish and Kootenai Tribes Dara Marks-Marino, Institute for Tribal Nikki Cooley, Institute for Tribal Environmental Professionals Environmental Professionals Tracy Melvin, Michigan State University Karen Cozzetto, Institute for Tribal Robert Newman, University of North Dakota Environmental Professionals Rachael Novak, Bureau of Indian Rob Croll, Great Lakes Indian Fish and Affairs/Tribal Resilience Program Wildlife Commission Madeleine Rubenstein, U.S. Geological Aimee Delach, Defenders of Wildlife Survey/National Climate Adaptation Science Maggie Ernest Johnson, Association of Fish Center and Wildlife Agencies Ted Weber, Defenders of Wildlife Roger Griffis, NOAA/National Marine Fisheries Service This report was reviewed by members of the Association of Fish and Wildlife Agencies’ Climate Adaptation Committee and the National Fish, Wildlife, and Plants Climate Adaptation Network.
    [Show full text]
  • California's Fourth Climate Change Assessment: Statewide Summary
    CALIFORNIA’S FOURTH CLIMATE CHANGE ASSESSMENT Statewide Summary Report Coordinating Agencies: Introduction to California’s Fourth Climate Change Assessment alifornia is a global leader in using, investing in, and advancing research to set proactive climate change policy, and its Climate Change Assessments provide the scientifc foundation for understanding climate- related vulnerability at the local scale and informing resilience actions. The Climate Change Assessments C directly inform State policies, plans, programs, and guidance to promote effective and integrated action to safeguard California from climate change. California’s Fourth Climate Change Assessment (Fourth Assessment) advances actionable science that serves the growing needs of state and local-level decision-makers from a variety of sectors. Tis cutting-edge research initiative is comprised of a wide-ranging body of technical reports, including rigorous, comprehensive climate change scenarios at a scale suitable for illuminating regional vulnerabilities and localized adaptation strategies in California; datasets and tools that improve integration of observed and projected knowledge about climate change into decision- making; and recommendations and information to directly inform vulnerability assessments and adaptation strategies for California’s energy sector, water resources and management, oceans and coasts, forests, wildfres, agriculture, biodiversity and habitat, and public health. In addition, these technical reports have been distilled into summary reports and a brochure, allowing the public and decision-makers to easily access relevant fndings from the Fourth Assessment. • A concise summary of the Fourth Assessment’s most important fndings and conclusions. • An in-depth report on how California’s people, built KEY FINDINGS environment, and ecosystems will be impacted by climate change and how we can proactively adapt, based on the Fourth Assessment’s fndings.
    [Show full text]
  • Improving Drought Management in the West: the Role of Mitigation and Preparedness
    Utah State University DigitalCommons@USU U.S. Government Documents (Utah Regional Elusive Documents Depository) 1997 Improving Drought Management in the West: The Role of Mitigation and Preparedness Donald Wilhite Follow this and additional works at: https://digitalcommons.usu.edu/elusive_docs Part of the Environmental Sciences Commons Recommended Citation Wilhite, Donald, "Improving Drought Management in the West: The Role of Mitigation and Preparedness" (1997). Elusive Documents. Paper 71. https://digitalcommons.usu.edu/elusive_docs/71 This Book is brought to you for free and open access by the U.S. Government Documents (Utah Regional Depository) at DigitalCommons@USU. It has been accepted for inclusion in Elusive Documents by an authorized administrator of DigitalCommons@USU. For more information, please contact [email protected]. ( PB97204283 . 'n l 1111111111111111111111111111111 \.... IDlproving Drought ManagelTIent in the West The Role 'of Mitigation and Preparedness Donald Wilhite, Director National Drought Mitigation Center University of Nebraska I I PROTECTED UNDE '-- I ! ALL RIGHTS RESER~~~TERNATIONAL COPYRIGHT I i ~~:'g~'1;~~~~~ 6~~~~6~ON SERVICE I I Report to the Western Water Policy Review Advisory Commission June 1997 Contents Page Introduction .................................................... 1 The Concept of Drought. .. .. 2 Crisis Management Versus Risk Management Approach to Drought Management . .. .. 4 The Climatology of Drought in the West: 1895 to 1996 " . .. 6 The Climatology of Drought, 1986 to 1996 . .. 8 State-Level Drought Planning: Current Status ...................... 15 Lessons From Recent Droughts: State-Level Mitigation Tools .... .. 19 Integrating Drought Management and Water Policy .................. 25 Integrating Drought Management and Water Policy: New Directions. .. 36 Australian National Drought Policy: A Model for the United States? ............................................. ;..... 38 Conclusions and .Recommendations ...............................
    [Show full text]
  • Hydrological Droughts in the Southern Andes (40–45°S)
    www.nature.com/scientificreports OPEN Hydrological droughts in the southern Andes (40–45°S) from an ensemble experiment using CMIP5 and CMIP6 models Rodrigo Aguayo1, Jorge León‑Muñoz2,3*, René Garreaud4,5 & Aldo Montecinos6,7 The decrease in freshwater input to the coastal system of the Southern Andes (40–45°S) during the last decades has altered the physicochemical characteristics of the coastal water column, causing signifcant environmental, social and economic consequences. Considering these impacts, the objectives were to analyze historical severe droughts and their climate drivers, and to evaluate the hydrological impacts of climate change in the intermediate future (2040–2070). Hydrological modelling was performed in the Puelo River basin (41°S) using the Water Evaluation and Planning (WEAP) model. The hydrological response and its uncertainty were compared using diferent combinations of CMIP projects (n = 2), climate models (n = 5), scenarios (n = 3) and univariate statistical downscaling methods (n = 3). The 90 scenarios projected increases in the duration, hydrological defcit and frequency of severe droughts of varying duration (1 to 6 months). The three downscaling methodologies converged to similar results, with no signifcant diferences between them. In contrast, the hydroclimatic projections obtained with the CMIP6 and CMIP5 models found signifcant climatic (greater trends in summer and autumn) and hydrological (longer droughts) diferences. It is recommended that future climate impact assessments adapt the new simulations as more CMIP6 models become available. Anthropogenic climate change has increased the probability of extreme events in the mid-latitudes of the South- ern Hemisphere, mainly those linked to severe droughts 1. Projections indicate that these drought events may increase in extent, frequency and magnitude as they superimpose on the gradual decrease in precipitation2,3 and a signifcant increase in heat waves 4.
    [Show full text]