Decadal Climate Information Needs of Stakeholders for Decision Support in Water and Agriculture Production Sectors: A Case Study in the Missouri River Basin (2024)

a. Land and industry

The basin, shown in Fig. 1, covers more than 500 000 square miles (1 300 000 km²) including a part or all of 10 U.S. states and two Canadian provinces; it is also home to 28 Native American tribes. Inhabitants of the basin depend on the Missouri River system for drinking water, irrigation and industrial needs, hydroelectricity, recreation, navigation, and fish and wildlife habitat. The basin contains some of the United States’ most sparsely populated agrarian counties, as well as more than 2000 urban communities, including large metropolitan areas such as Omaha, Kansas City, and Denver. The basin is a very important agricultural region producing approximately 46% of U.S. wheat, 22% of its grain corn, and 34% of its cattle (USDA 2012). Approximately 117 million acres (47.3 × 10⁶ ha) are in cropland, with 12 million acres (4.9 × 10⁶ ha) under irrigation, much of it dependent upon water withdrawals from the High Plains (Ogallala) Aquifer, the most intensively used aquifer in the United States (USGS 2005). In terms of economic importance, the approximate value of crops and livestock produced in the basin was over $100 billion in 2008. Thus, almost 90% of the basin’s cropland is entirely dependent on precipitation. Directly or indirectly, that precipitation is also the source of water for municipalities and industry, with both greatly influenced by climate variability and change.

b. Manifestations of decadal climate variability in the Missouri River basin

Impacts of major global-scale DCV phenomena such as the Pacific decadal oscillation (PDO; Mantua et al. 1997), the tropical Atlantic sea surface temperature gradient oscillation (TAG; Mehta 1998), and the west Pacific warm pool variability (WPWP; Wang and Mehta 2008) on U.S. climate are reasonably well documented and quantified by analyses of climate observations. There are indications that large-scale climate forcings by the PDO (see, e.g., Ting and Wang 1997; McCabe et al. 2004; Mehta et al. 2011b), the TAG (Schubert et al. 2004; Mehta et al. 2011b), the Atlantic multidecadal oscillation (McCabe et al. 2004), and the WPWP variability (Wang and Mehta 2008; Mehta et al. 2011b) also influence precipitation variability in the basin. Interannual ENSO variability explains less than 20% while decadal time-scale variability explains approximately 40%–50% of the total precipitation, runoff, and streamflow variances within the basin (Guetter and Georgakakos 1993; Lins 1997; Cayan et al. 1998). Approximately 20%–40% of precipitation variance in the basin is explained by the PDO and TAG individually, and 10%–20% is explained by the WPWP. Gurdak et al. (2007) have established a linkage between PDO and groundwater recharge rates and mechanisms in the High Plains Aquifer, which underlies much of the basin. These hydrologic variability estimates are also reflected in the percentage area of the basin under severe to extreme drought conditions; the fraction of the basin experiencing severe to extreme drought in the twentieth century ranged from 20% to 60% or more at interannual-to-decadal time scales (Fig. 2). Portions of the basin also experienced a multiyear to near-decadal drought during the first decade of the twenty-first century. The droughts have alternated with multiyear-to-decadal wet spells.

Recently, Mehta et al. (2011b, 2012) conducted analyses of associations between the three aforementioned DCV phenomena, hydrometeorology in the basin, and their consequent impacts on water resources and crop yields. Objectively analyzed, gridded (from historical station observations) hydrometeorological observations consisting of monthly precipitation rate, surface air temperature, surface wind speed, and relative humidity from 1950 to 1999 at ⅛° longitude × ⅛° latitude resolution (Maurer et al. 2002) were used for this purpose. Streamflow observations from the U.S. Geological Survey were also used in these analyses. It was found that PDO, TAG, and WPWP are associated significantly with decadal precipitation and temperature variability in the basin, with combinations of positive and negative phases of several DCV phenomena associated with drought, flood, or neutral hydrometeorological conditions. Three extreme hydrologic events—droughts in the mid-1950s and mid- to late 1980s and floods in the early to mid-1990s—were reconstructed by means of these statistical analyses.

With the aforementioned as background, Mehta et al. (2011b, 2012) used the Hydrologic Unit Model of the United States (HUMUS; Srinivasan et al. 1993)–Soil and Water Analysis Tool (SWAT; Arnold and Allen 1992; Arnold et al. 1999) system and the Erosion Productivity Impact Calculator (EPIC; Williams 1995) to simulate DCV influences at 75 locations on yields of water, dry-land corn, and winter and spring wheat in the basin. The simulations revealed major impacts on these variables, with locally specific variations as great as 50% of average yield. The basin-aggregated water yield changes in the positive and negative phases of the three DCV phenomena can be substantial for typical values of the three DCV indices (Mehta et al. 2011b). Similarly, the basin-aggregated crop yield changes in response to typical values in opposite phases of the three DCV indices can also be substantial (Mehta et al. 2012).

c. Importance of Missouri River main stem dams

The Missouri River is a managed river system with six dams on its main stem. The total storage capacity of the reservoirs created by these dams is 73.4 million acre-feet (MAF; 1 MAF = 1233.5 × 10⁶ m³), approximately 3 times the annual runoff upstream of the dams. The great storage capacity of the reservoirs provides opportunity for carryover from year to year. Authorized purposes of the reservoir system are flood control, hydropower generation, navigation, recreation, irrigation, assurance of water supply and water quality, and maintenance of fish and wildlife habitat. These uses must be balanced to meet various seasonal demands. Clearly, the ability to meet these demands is affected by variations within the basin.

A major purpose of the reservoirs is to prevent or reduce flood damages to the extent possible. The top zone in each reservoir (4.7 MAF in the system or 6% of total storage) is reserved exclusively for flood storage. It is used to capture runoff during extreme and unpredictable floods; that space is emptied as soon as downstream conditions permit. In addition, the upper part of the normal operating zone (11.6 MAF in system or 16% of storage), used to store annual floods, is normally emptied prior to onset of the annual flood season. There are two primary flood seasons in the basin: (i) late February–April, when precipitation falls as rain and the snow in the plains melts, and (ii) May through July, when the mountain snow melts and additional rainfall occurs in the basin (USACE-NWD 2006). The evacuation of the annual flood control zone is scheduled to meet the other aforementioned uses.

A carryover multiple-use zone of the reservoirs (39.0 MAF or 53% of storage) provides storage for irrigation, navigation, hydropower production, water supply, recreation, and fish and wildlife habitat. The water stored in this zone can support downstream flows during an extended period of drought. The remaining storage (18.1 MAF or 25%) is called the “permanent pool zone” and is used for minimum power head and future sediment storage.

Major services provided by the Missouri River dam system include hydropower generation, maintenance of navigation, municipal water supply, and thermal power cooling. Hydropower is generated at the dams throughout the year. Peak demands for electricity occur during the winter heating season (mid-December–mid-February) and the summer air-conditioning season (mid-June–mid-August). The peak power-generation season extends from mid-April to mid-October. The navigation season in the lower Missouri River generally runs from 1 April to 30 November. During drought years, the navigation season may be curtailed. Releases from the main stem reservoirs also maintain a minimum flow on the Missouri River downstream of the Gavins Point Dam in southeastern South Dakota to support water quality and water intakes for municipal water supply and for cooling thermal electric power plants.

The main stem dams also provide recreational amenities and ecological benefits in their reservoirs and in the downstream Missouri River as well. Maintenance of existing flora and fauna, particularly threatened and endangered species, is a major concern for water management in the basin. The current master manual for operating the main stem dams calls for releasing spring pulses to replicate the natural hydrograph of spring floods in support of downstream ecosystems. Each year, the USACE develops an annual operating plan that takes into account inputs received from a wide range of stakeholders in the basin. The plan lays out just how the reservoirs will be regulated given current conditions in the basin. For example, spring pulses may be foregone during drought years in order to save water for other uses.

Records of Missouri River flow are available since 1898, and the time series of the flow, combined with inflows into the basin’s main stem dams following their construction, is shown in Fig. 3. The time series of basin inflows shows substantial interannual-to-decadal variability. Since 1898, the annual runoff into the basin above Sioux City, Iowa, has varied from a low of 10.7 MAF in 1931 to 49.0 MAF in 1997. As shown in Fig. 3, the basin has been affected over the past 113 yr by four multiyear-to-decadal droughts; these occurred during 1930–41, 1954–61, 1987–92, and 2000–07. The basin experienced periods of extremely high runoff during 1907–09, 1975–78, 1993–97, and 2008–11, as indicated in Fig. 3. As described above, there is substantial decadal variability in water yield (runoff) and crop yields in the basin associated with such events, variability that appears to be associated with three major DCV phenomena.

a. The pilot study

Our aim in the pilot study was to gain an initial understanding of the complex nature of the impacts of DCV on the basin; the sensitivities of the agriculture and water sectors, in particular, to these impacts; the data and information sources currently available to these sectors to cope with DCV-driven climate events; and the constraints that currently exist to coping with them.

Members of the project team interviewed 30 stakeholders responsible for managing and studying the effects of climate variability on agriculture and water resources in the basin. The groups and agencies represented were USACE, Bureau of Reclamation (BoR), National Park Service, Central Nebraska Public Power and Irrigation District, TriBasin Natural Resources District, Nebraska Farm Bureau, American Rivers, Nebraska City Adaptive Management Group, and relevant departments and institutes of the University of Nebraska at Lincoln.

Time and budgetary constraints limited the pilot study to agencies located in eastern and central Nebraska, with two exceptions: a meeting with the Nebraska City Adaptive Management Group held in southwest Iowa, across the river from Nebraska City, and a meeting with the Bureau of Reclamation personnel in Grand Island, Nebraska, that included agency staff members in McCook, Nebraska, and Billings, Montana, by conference call.

Each interview began with a short briefing in which we explained the concept of DCV and described the PDO, TAG, and other ocean–atmosphere phenomena that influence climate in the basin. We explained how these phenomena, alone or in combination, may affect weather and climate patterns around the world in general and the basin in particular. Results of project research done to that time were displayed, showing the coincidence of specific DCV events with well-documented multiyear-to-decadal dry and wet spells in the basin (e.g., 1950s drought, late-1980s drought, and mid-1990s wet spell). Following questions and discussion of the materials presented, information needed to guide our research was elicited through semistructured discussions aimed at gaining perspectives on the impacts of past DCV events, the vulnerability of basin water and food production systems to DCV, and the potential uses of DCV outlooks, should such become available in the future.

Major conclusions of the pilot study were as follows:

1. Impacts of persistent, multiyear-to-decadal hydrometeorological anomalies differ from those associated with anomalies that persist for only a few seasons.

2. Geography determines which sectors are most sensitive to a given DCV. For example, water availability is critical for the recreation sector in Montana and in North and South Dakota; for the irrigation sector in Nebraska and Kansas; and for the navigation sector in the downstream Missouri River states.

3. The basin is much less resilient to multiyear-to-decadal droughts than to those of shorter duration.

4. Vulnerability of the agriculture sector to year-to-year hydrometeorological anomalies is decreasing because of the introduction of improved drought- and heat-resistant crop cultivars.

5. Multiyear-to-decadal hydrometeorological anomalies have adverse impacts on municipalities and power plants throughout the basin.

6. There exists a need for multiyear-to-decadal predictions of basin hydrometeorology that requires that DCVs be forecastable at this time scale.

7. Many agricultural producers and advisors would be receptive to information that identifies increased probabilities for future climate anomalies, and DCV outlooks have the potential for being applied to a variety of management and planning activities if they are presented in a manner that is understandable to users and shown to be credible.

8. Agencies such as USACE and BoR, responsible for management of large water resource infrastructure, would have difficulty applying long-term DCV forecasts (even if credible) because of legal constraints.

9. A more detailed information elicitation effort with information and questions focusing on individual sectors, stakeholders, and subregions of the basin was warranted.

b. Stakeholder workshops

Guided by insights and feedback gained in the pilot study, we carried out a series of three geographically dispersed workshops to gain a deeper understanding of the regional and sectoral effects of DCV on agriculture and water resources in the basin and of the climate information needed by stakeholders to cope with impacts of DCV. The first workshop was held in Kansas City, Missouri, in April 2008; the second was in Helena, Montana, in June 2009; and the third was in Lincoln, Nebraska, in November 2010. The objectives of these workshops were to:

1. demonstrate to stakeholders the relationship between DCV and major historic droughts and wet spells in the basin;

2. gather sector-specific information on impacts of the droughts of the 1980s and the 2000s and the prolonged wetness of the 1990s; and

3. evaluate the potential for developing future decadal climate outlooks as well as management options useful in preparing for and coping with protracted dry and wet spells.

The Kansas City and Helena workshops involved using a purposeful sampling technique to recruit a broad range of expert stakeholders from the lower and upper basin (i.e., federal, state, tribal, and local government; academics; agricultural and environmental groups; and private industry) representing agriculture, water, and other natural resource sectors. The Lincoln workshop targeted medium and large municipalities; state and federal water resource agencies; and consultants and university researchers from Colorado, North Dakota, South Dakota, Nebraska, Kansas, and Montana. In addition to the project investigators purposefully identifying key stakeholders to participate in the workshops, stakeholders were also able to identify other relevant experts that should participate in a “snowball” sampling effect to ensure adequate coverage of the sectors under investigation. In total, 90 stakeholders participated in the three workshops (i.e., 25 stakeholders in Kansas City; 43 stakeholders in Helena; and 22 stakeholders in Lincoln). Full affiliations of the stakeholders are described in reports of individual workshops (Mehta et al. 2010a,b,c).

A standardized methodology for exchange of information was employed at each of these workshops. Information about the project was provided to participants in advance of the workshops through The Missouri Basin Climateer, a newsletter initiated in our project. Further information was provided through a website (http://missouri.crces.org) established specifically for this project. A preliminary description of workshop’s objectives and a list of questions to be discussed were provided to the participants a few days prior to the event. As in the pilot study, each workshop began with presentations by project team members. These dealt with the concept of DCV, statistical associations of DCV phenomena with basin hydrometeorology, and observed and simulated DCV impacts on water resources and crop yields in the basin.

To help ensure stakeholder comprehension of the materials presented, participants were asked to rate their understanding of the information conveyed to them. A handheld device, or “clicker,” allowed participants to answer questions posed to them instantaneously and anonymously. A summary of their answers was then projected on a screen. The responses identified topics that required further clarification; these were addressed in open discussion between the project team and stakeholders.

With a good level of understanding of DCV achieved, a number of facilitated sessions to gather additional stakeholder feedback followed. In the first of these, participants were asked to record their recollections of the impacts of the 1980s drought, 1990s wet spell, and 2000s drought. These were written on notecards and placed onto a “sticky wall” (a large piece of adhesive fabric hung on a wall) where the impacts were arranged by theme under the relevant time period. Then, in open discussions, the recollected impacts were elaborated on and/or challenged by stakeholders to help ensure the primary themes were adequately identified.

Small group discussions followed in which stakeholders presented their ideas on the potential use of DCI, and summaries were reported out to the full group by the individual group leaders. This was followed by a “world café” facilitation exercise (see Brown et al. 2007) where small groups rotate among tables to provide perspectives on the development and dissemination of decadal outlooks, as well as potential barriers to using such outlooks, with a different set of questions posed at each table.

a. Impacts of decadal dry spells in the basin

b. Impacts of decadal wet spells in the basin

a. River flows and reservoirs

Workshop participants judged that DCOs would help with large-scale water management in a variety of ways that would allow proactive, rather than reactive, management of river flows and reservoirs. In the realm of annual reservoir operations, for example, DCOs might be used to determine the water levels to be maintained and when and how much water should be released (particularly in spring). They might also be used to provide early warning of the potential for flooding so that steps might be taken to protect people and critical infrastructure in flood plains such as levees. DCOs might also affect decisions with regard to flood insurance coverage.

For purposes of long-term planning, DCOs might be coupled with hydrology models to predict reservoir inflows. If so, changes in agricultural, industrial, municipal, ecosystem, and fishery requirements for water might be better predicted. Workshop participants judged that DCOs longer than 10–20 yr in advance might not be actionable, except in the case of reservoir and other water infrastructure construction. On the other hand, a reliable estimate of expected inflows over the coming 5–10 yr could be useful because irrigation and fisheries water rights are based on 10-yr forecasts. Reliable DCOs would also enable tradeoffs among agricultural, wildlife, and recreational uses of water, which all affect prospects for tourism.

Participants opined that DCOs that indicate a high probability of a lengthy wet spell forthcoming would encourage and guide significant changes in flood protection strategies: that is, whether to build new levees, install internal drainage infrastructure, or encourage flood zone buyouts. By allowing estimates of possible damage due to climate variability, such DCOs could aid urban water agencies in budgeting exercises and in justifying capital outlays. Similarly, the river- and reservoir-based recreation industry might use DCOs predicting a wet/dry spell in management of existing marinas (e.g., dredging) and in design and construction of new ones (e.g., ramp design and placement).

As they bear on the sustainability of navigation on the Missouri River, it was stated that DCOs may also be useful in making investment decisions by barge and rail companies. The electricity-generation industry might also use DCOs to make decisions with respect to the location and construction of new plants, placement of water intakes, wholesale purchase of fuel, and marketing of electricity. Since thermal power plants, especially nuclear power plants, must meet very stringent regulations about the temperature of cooling water released into the rivers from which it is drawn, DCOs could be used in planning operations of such plants and in management of effluent water temperatures.

b. Urban water

With regard to urban water systems, workshop participants described how DCOs could be used in water management and planning, land-use planning, budgeting, and public education. However, it was also reported that, within a DCO, monthly and seasonal climate predictions are also needed for decision making in the face of impending droughts and floods. Nonetheless, participants stated that a DCO predicting dry conditions could foster community efforts to optimize the conjunctive use of surface and groundwater, where possible. This could include preparations for invoking restrictions on water use and initiating or strengthening water conservation campaigns. It could justify water audits and system upgrades, encourage the acquisition of alternative water supplies, and assist in water management. In the case of groundwater sources, the DCO might help in determination of which well fields to use. If a drought is predicted, aquifers near a river would be used first in anticipation of reductions in aquifer levels as the river flow decreases in response to drought; those farther away would be used later. Similarly, for outlooks of a wet spell, communities could foster emergency preparations for flood events with information campaigns, prepositioning materials for levee reinforcement, and adjustments in reservoir regulation to accommodate an increased volume of water in storage through programmed releases.

Participants reported that a DCO predicting long-term dry conditions could foster support for construction of new reservoirs and development of new well fields, aquifer recharge facilities, and water treatment plants. Cities might also use the DCO to prompt the acquisition of additional water rights or participate in water trading where applicable. The DCOs might also guide reallocation of water stored in federally managed reservoirs for urban use. Such action, however, would require political authorization, possibly triggering demands from other regions and societal sectors. Such predictions might also be used to justify severe water-use restrictions at the onset of a drought, rather than invoking emergency measures after water security has already been endangered.

In terms of land-use planning, a prediction of extended drought might also be used in landscape design: for example, the conversion of city parkland to native vegetation requiring less water for its maintenance. Conservation policies could also be updated, developed, or expanded through new ordinances and incentive programs to increase water-use efficiency and reduce overall water use.

c. Agricultural production

As a whole, workshop participants mentioned many potential uses of DCOs by agricultural producers, such as aiding in the selection of crops and cultivars for planting; for changes in crop rotation and/or tillage practices; and for irrigation planning, including arrangements for access to water supplies and numbers of intakes and types of irrigation equipment to provide. Similarly, for shorter-term decision making, planning for the types and quantities of fertilizers to lay by and possibly the timing of their application (fall and spring) can be aided by DCOs. The decision to purchase or not to purchase crop insurance coverage might also be guided by DCOs. Livestock producers might also use DCOs to determine herd size and whether alternative feeding options may be required (rangeland grazing, supplemental feeding, or feedlots). DCOs could also be used by agencies responsible for wildfire control to guide the purchase of the types and quantities of firefighting equipment that may be needed; for estimating the number of firefighters required; for prepositioning firefighters and firefighting equipment and supplies; and for determining the appropriateness of controlled burns.

It was stated that agricultural producers could also use DCOs for more long-term decision making, such as deciding between dry land or irrigated cropping systems and what types of crops to produce; whether to expand or modify irrigation and water systems; the implementation of conservation measures; if their livestock production system should be modified (e.g., buy or lease more land, make more use of feedlots for cattle, change management practices, etc.); and whether their operation will be viable under projected conditions such as an extended drought. On a larger scale, DCOs could also influence decisions with respect to biofuel production: that is, whether to convert from conventional crops that are heavy water users or that suffer great loss of yields in drought to the more conservative water-using grasses or other types of vegetation that are usable in the production of biofuels. The possible role of DCOs in commodities trading and international agricultural trade agreements is yet to be explored, but DCOs should certainly have a major role.

It was also noted that DCOs would also be useful for decision making on general issues of water and land management. The need for enhanced management efforts to protect habitat critical for fisheries and other wildlife and for protecting the quality of surface and groundwater resources vital to human populations are examples of these issues.

a. Decadal climate variability

Causes of DCV should be described in terms that laymen can understand. Impacts of past DCV instances should be documented fully, and the USACE and BoR should be involved in compiling information on impacts of DCV on the water sector. The difference between climate scenarios and forecasts should also be made clear, and climate scientists and climate information should be readily accessible to stakeholders at key decision-making times for various sectors.

b. Decadal climate information

Climate forecasters should pay much more attention to the DCI needs of stakeholders in the basin. A concerted effort is needed to define DCI requirements in close partnership with users in various sectors, and social scientists should be more engaged in the assessment of DCV impacts. Scenario-planning exercises involving user communities and climate scientists are also needed. Greater engagement of existing user networks and news media is also needed to channel DCI to users. To convey the usefulness of DCI to prospective user communities, early efforts should be focused on a few promising sectors and subbasins.

c. Decadal climate outlook

DCOs should be produced at the spatial and temporal resolutions required by each societal sector and geographical region, and involvement of decision makers is critical in incorporating the DCOs into the overall water-planning process. Perhaps a three-category framework of classification of temperature and precipitation (below average, average, and above average) would convey the confidence of forecasters in their DCOs, and greater credibility may accrue to DCOs were they incorporated in a decision support system provided to users by a federal agency such as NOAA. USACE and BoR should also be involved in disseminating DCO and information on anticipated impacts.

1

The climatic events described throughout this paper are documented in Climatological Data Annual Summaries (by state), published by the NOAA/National Climate Data Center (Ashville, North Carolina).

2

The NEPA of 1970 established national environmental policy and goals for the protection, maintenance, and enhancement of the environment, and it provides a process for achieving these goals within federal agencies.

3

The NPDES permit program controls water pollution by regulating point sources such as pipes or manmade ditches that discharge pollutants into waters of the United States. Individual homes that are connected to a municipal system, use a septic system, or do not have a surface discharge do not need an NPDES permit; however, industrial, municipal, and other facilities must obtain permits if their discharges go directly to surface waters.

4

A typical state governor’s response team/committee serves as a “clearinghouse” for information by bringing together federal partner agency representatives to report on water supply and moisture/crop conditions, while the state member agency officials take note of the federal reports as it pertains to their respective areas of agency purview and implement proactive mitigative measures as necessary or appropriate. Progress of such actions is reported back to the team/committee at the next monthly meeting or to team/committee staff if urgent in nature. Staff would report to the governor’s office if warranted by the nature and importance of the situation.