Great Plains Regional Technical Input Report

Dennis Ojima, Jean Steiner, Shannon McNeeley, Karen Cozzetto, Amber Childress

• Publisher: NCA Regional Input Reports
• Year: 2015
• ISBN:
  9781610915106
• Topic: Biological Sciences
• Subtopic: Science General
• Index: Biological Sciences

Prepared for the 2013 National Climate Assessment and a landmark study in terms of its breadth and depth of coverage, Great Plains Regional Technical Input Report is the result of a collaboration among numerous local, state, federal, and nongovernmental agencies to develop a comprehensive, state of the art look at the effects of climate change on the eight states that encompass the Great Plains region.
The Great Plains states are already experiencing the impacts of a changing climate, and will likely continue to experience warming temperatures, more extreme precipitation events, reduced snow and ice cover, and rising relative sea levels. The book presents a review of the historic, current, and projected future climate of the region; describes interactions with important sectors of the Northeast and examines cross-sectoral issues, namely climate change mitigation, adaptation, and education and outreach.
Rich in science and case studies, it examines the latest climate change impacts, scenarios, vulnerabilities, and adaptive capacity and offers decision makers and stakeholders a substantial basis from which to make informed choices that will affect the well-being of the region's inhabitants in the decades to come.

SECTION 2

Natural Resource Vulnerabilities and Challenges Faced by the Great Plains

The changing environmental factors faced by the Great Plains and its residents will affect social and economic activities in the near and long term. Recent trends have concentrated populations in more urban centers with rural areas still providing significant economic development through agricultural production.

Climate change will affect water availability and other environmental elements as well as energy production in the Great Plains, and also test community infrastructure and current land management impacting both economic and ecological health. A change or increase in the frequency and intensity of extreme weather events pose a particular risk to human and environmental systems, including agriculture, water resources, energy development, biodiversity and wildlife. Residents, land managers and government officials can plan for changes through mitigation and adaptation measures, which may require major shifts in individual and institutional practices and mindsets.

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Chapter 4

Water Management

Water in the Great Plains is a critical natural resource that determines the social-ecological processes related to conservation, agriculture, energy, and urban development, among others. Climate regimes across the Great Plains vary tremendously and affect seasonal distribution of water inputs and availability. Changes in precipitation patterns, such as the variability and intensity of rain or snowfall, and seasonality of precipitation have major impacts on water resources in the region. In addition, the river systems dissecting the Great Plains, such as the Red River of the North, the Missouri, the Platte, the Arkansas, and the Rio Grande basins, emerge from the Rocky Mountains, so the hydrologic flow is connected to the snow deposition in this region. This is complicated by a legal allocation system that determines when, where, and how much water can be diverted and used in the region. Determinants of these allocation rules were developed during the past century and evolved under more ample precipitation conditions; and when population was sparser; industrial, energy, and urban demands were lower; and environmental water flow requirements were of lower priority. Water usage across the Great Plains is dominated by agriculture demands, though increased concentrations of regional urban development have affected water rights and usage. Changes in water ownership during the past few decades have also caused increased transfer of water rights to various municipalities. This has resulted in conflicts and legal battles between states and between various uses and users.

Local water development has been augmented greatly over the decades through development of diversions and reservoirs (primarily public investment) and the drilling of wells into aquifers (large private investment as well as public). These water infrastructure developments have altered stream and river flows, wetland extent, hydrological dynamics, and sedimentation rates that affect river and stream morphology and reservoir storage capacity. Climate scientists predict that water cycles will be altered so that the past precipitation patterns no longer provide a guide for the future (Milly et al. 2008). This will require new ways to manage and govern water resources in the context of all the multiple climatic and non-climatic stressors involved (Ison et al. 2007, Steyaert and Jiggins 2007, Pahl-Wostl 2007, Norgaard et al. 2009, Birkmann et al. 2010, Lebel et al. 2010, Farrelly and Brown 2011, van de Meene et al. 2011, Huntjens et al. 2012).

Water Use and Management

Multiple and diverse users compete for water in the Great Plains region. Agriculture, however, is by far the biggest user of water, accounting for 65% of combined fresh water withdrawals (Kenny et al. 2009). Other uses include urban and rural domestic and municipal entities, energy extraction and power production, industry, recreation, and wetlands and riparian ecosystems, as well as aesthetic and spiritual uses. Thermoelectric power and public supply account for 21% and 10% of Great Plains water withdrawals, respectively. In North Dakota and Texas, thermoelectric power accounts for the majority of withdrawals, 79% and 41%, respectively (Kenny et al. 2009). In Oklahoma, public water supply (42%) is the largest user (Kenny et al. 2009). Maintaining ecosystems services provided by water and the well-being of all life that depends on clean and available water requires careful management and policies to sustain adequate water quality and quantity in a variable and changing climate (Rosenzweig et al. 2004).

When considering fresh surface and groundwater sources separately, surface water supplies 68% of Great Plains water needs and groundwater provides 32% (Table 4.1). For irrigated agriculture, surface water provides 57% and groundwater 43% of total withdrawals. However, at a state level, the distribution is more skewed. In Colorado, Montana, and Wyoming, surface water provides over 80% of irrigation needs. In Kansas, Nebraska, and Texas, groundwater provides over 75% of irrigation needs.

Groundwater Issues as They Relate to Climate Variability

Water level changes in the High Plains (Ogallala) Aquifer from the time prior to extensive groundwater irrigation (before about 1950) to 2009 ranged between a rise of 41 feet (12.5 m) and a decline of 178 feet (54.3 m) with an average water-level decline of 14 feet (4.3 m) since predevelopment (McGuire 2011). Total storage of the Ogallala Aquifer has declined by 274 million acre-feet (333,040 million m³) since predevelopment (McGuire 2011). Groundwater withdrawals from the High Plains Aquifer in 2000 accounted for 20% of the total US groundwater withdrawn, 97% of which is used for irrigation (Maupin and Barber 2005). Groundwater extraction for drinking water supports about 82% of the people in the High Plains aquifer region (Gurdak et al. 2011). Groundwater from the vast Ogallala Aquifer in the Central Plains, one of the largest aquifers in the world, is predicted to continually decline as long as irrigation remains viable given escalating pumping costs and overall farm production costs for seed, fertilizer, equipment, and other related expenses (Howell 2009). Water right transfers from agriculture to urban and industrial uses will further exacerbate this inevitable resource strain. Weather directly affects the water requirements of crops and, thus, their irrigation requirements (Howell 2009). An indirect effect of climate change is increased groundwater pumping, which could affect hydraulic heads in many aquifers, allowing upward leakage of groundwater with poorer water quality, such as in the High Plains aquifer (McMahon et al. 2007).

Groundwater depth determines regions’ relative susceptibility to precipitation and temperature changes, and groundwater storage acts as a moderator of watershed response and climate feedbacks (Maxwell and Kollet 2008). There is a “critical zone” of groundwater depth – between 7 to 16 ft (2 to 5 meters) deep – where there is a very strong correlation between water-table depth and surface evaporative demand (Maxwell and Kollet 2008). Playa lakes are unique hydrological formations to the High Plains area and essential for recharging the Ogallala Aquifer, which means they play an important role in groundwater management and aquifer sustainability (Gurdak and Roe 2010). There are approximately 61,000 playas in the region, with the highest concentration in the southern region in Texas and part of the central and northern High Plains aquifer region in Kansas and Nebraska (Gurdak and Roe 2009, 2010). New techniques monitor surface and sub-surface groundwater levels using the Gravity Recovery and Climate Experiment satellite, which uses gravity to measure groundwater, soil moisture, surface water, snow and ice, and biomass. These new practices will become increasingly important for understanding how to manage for irrigation and sustainable agroecosystems and the relative influences of climate change versus agricultural practices (Strassberg et al. 2009, Scanlon et al. 2010).

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Table 4.1 Total surface water and groundwater withdrawals in the Great Plains region by state and water-use category in 2005, in thousand acre-feet per year (3.1a) and in thousand cubic meters (3.1b) (values may not sum to totals because of independent rounding)

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	Public		Domestic		Irrigation		Livestock		Aquaculture		Industrial		Mining		Thermoelec		Total
State	SW	GW	SW	GW	SW	GW	SW	GW	SW	GW	SW	GW	SW	GW	SW	GW	SW	GW
Colorado	855	114	0	39	11,200	2,600	12	25	80	91	156	4	1	6	131	7	12,400	2,810
Kansas	272	180	0	17	128	2,940	27	95	4	2	7	40	5	11	499	15	942	3,300
Montana	84	75	1	25	10,700	157	31	13	44	3	33	42	38	1	100	0	11,00	317
Nebraska	106	264	0	58	1,290	8,190	23	99	83	10	0	13	11	0	3,970	9	5,480	8,650
North Dakota	39	36	0	10	82	87	10	15	7	0	11	6	0	6	1,190	0	1,340	160
Oklahoma	597	127	0	28	150	405	120	61	21	0	18	9	2	1	183	1	1,090	634
South Dakota	39	74	0	9	160	167	32	22	16	21	0	5	7	5	4	1	258	303
Texas	3,440	1,350	0	288	1,890	6,860	108	182	10	6	1,190	210	72	30	10,800	63	17,500	8,990
Wyoming	52	56	0	7	4,000	474	11	7	24	3	2	5	15	43	248	1	4,350	595
GP Totals	5,484	2,276	1	481	29,600	21,880	374	518	289	64	1,417	333	152	104	17,125	98	54,360	25,759
Colorado	855	114	0	39	11,200	2,600	12	25	80	91	156	4	1	6	131	7	12,400	2,810
Kansas	272	180	0	17	128	2,940	27	95	4	2	7	40	5	11	499	1...

Table of contents

• Cover
• About Island Press
• Title Page
• Copyright
• About This Series
• Contents
• Acknowledgments
• Acronyms
• Executive Summary
• Section I: Great Plains: Scope, History, and Recent Trends
• Section II: Natural Resource Vulnerabilities and Challenges Faced by the Great Plains
• References
• Editor Biographies
• Island Press | Board of Directors