Impacts of Climate Change and Land Use  on the Southwestern United States

Societal responses to climate and landscape changes

Transboundary Water Resources Management in the Upper Rio Grande Basin

Marvin Waterstone
Department of Geography and Regional Development
The University of Arizona

This paper is a condensed version of a chapter by the same name in: A Transboundary Water Resource Management: Insitutional and Engineering Approaches, Ganoulis J, Duckstein L, Literathy P, Bogardi I (eds.) Springer, New York.


figure 1

Figure 1. Map of the Upper Rio Grande Basin.

The Rio Grande, flowing southward almost 2,000 miles from its headwaters in southern Colorado, drains an area of over 350,000 square miles and is the lifeblood of a semi-arid region supplying water for more than 3.5 million people and for agricultural, recreational, hydropower, and industrial purposes (figure 1). This paper reports on on-going research regarding the physical and institutional resilience of the Upper Basin of the Rio Grande river management system, from its headwaters, to Fort Quitman, Texas. The work looks at the transboundary issues between the three US basin states of Colorado, New Mexico, and Texas, with some attention given to issues concerning the US/Mexico border portion of the Rio Grande. This paper addresses the ability of the Rio Grande system to accommodate stresses induced by a variety of possible future circumstances, including climate change.

Several assumptions have guided the research. The first is that the system has a significant degree of flexibility and resilience under existing operating rules, allowing managers to handle additional burdens on the system, be they from present conditions, or from new and unforseen circumstances. A second assumption however is that this resilience is finite and that at some point it will not be possible to accommodate additional stress on the system under present operating rules. In other words, it is possible to conceive of future changes (be they from additional population and water demand, or from altered climate scenarios and altered water supplies) that will be beyond the ability of the managers to cope, while still complying with all of the operating requirements presently in place. This leads to the final assumption that if and when such conditions arise, the rules (i.e., the institution that governs the Rio Grande System) will have to change at levels above the operational level in order to accommodate the new demands on the Rio Grande.

The Physical System of the Upper Rio Grande

The present physical system of the upper Rio Grande basin comprises a series of eight major linked reservoirs operated principally by the US Army Corps of Engineers (USACE) and the US Bureau of Reclamation (USBR). The reservoirs are managed to fulfill a variety of purposes including flood control, municipal and industrial water supply, irrigation supply, hydropower production, sediment control, environmental enhancement for water quality and wildlife, and recreation. As with any set of multi-purpose reservoirs, these are managed to strike an appropriate balance among varying, and sometimes competing, uses. For this semi-arid region, one concern is to maximize water storage for irrigation supplies, while preserving space in the reservoirs for accommodating flood waters and prevent downstream flood losses. Attaining these multiple objectives is complicated by the fact that the reservoirs are also managed in a multi-state, multi-jurisdictional, transboundary context.

To accomplish the various purposes and satisfy transboundary conditions, the reservoirs are managed on a day-to-day basis under a series of complex rules. These rules constitute the operational level of the water management institution for the Rio Grande basin. These rules, in turn, are nested within (and are compliant with) a set of implementation rules, and a set of policy rules.

The Institutional System of the Upper Rio Grande

A characterization of the water management system enables us to understand how operation level rules come into being, how they articulate with implementation-level and policy-level rules and how they might be changed if they become deficient.

Policy-Level Rules

At this highest level of the institution are several overarching sets of formal requirements which mandate how implementation-level (and eventually operational-level) activities should operate. These rules are themselves formulated under yet other rules, at the constitutional level, which includes rules under which the US Congress and Executive Branch agencies operate. These rules designate the implementation level actors, indicate their goals and objectives, and specify their authorities and scope of activities. These rules also identify the mechanisms for changing the implementation-level rules. Policy level rules are specified by a series of acts, treaties, compacts, and dam authorizations, as well as a series of informal rules which attempt to accommodate the traditional water-using activities of the Rio Grande Basin, but which are not codified into formal statute. The policy level rules indicate the kinds of goals and objectives to be achieved through water management, as well as those who will be responsible for devising the means to meet these goals. Generally, specification of these means is left to the implementation level actors of the institution. Such actors are members of federal or state legislatures, and at the international levels these actors include the heads of state of the US and Mexico, the US Department of State and the Mexican counterpart, and the state level agencies in the US and Mexico.

Implementation-Level Rules

These are the rules which specify precisely how, and under what conditions the reservoirs and other facilities are to be operated. The actors at this level, are mostly members of executive branch agencies (USACE, USBR, EPA, basin states' water agencies and the International Boundary and Waters Commission for international matters), as well as the major water users. These actors, work within the rules at the policy level, which set a variety of goals and objectives but do not specify how these should be met. They develop the strategies and mechanisms (i.e., operational level rules) for day to day operation of the structural and non-structural features of the Rio Grande system. Many actors hold positions all three institutional levels, but will have different authorities and scopes of activity at each level. The rules at the implementation level designate the operational level actors, provide their goals and objectives and specify their authorities and scope of activity. The implementation-level rules also identify the mechanisms for changing the operational-level rules

Informal rules also operate at this level to accommodate implementation level actors' expertise and judgements. The informal rules also provide an added measure of flexibility and resilience to the system. However, unlike the formal rules, these informal rules tend to be associated with individuals' expertise and experience, and are therefore somewhat more ephemeral. One of the more important applications of these rules is for reservoir operations.

Operational-Level Rules

On a day-to-day basis, the features of the Rio Grande are thus operated according to a diverse set of formal and informal rules from the policy and implementation levels. The policy-level rules tend to be goal and objective setting, while the implementation-level rules tend to be mechanism-specifying. Operational level rules are the actual requirements for day to day operation of the reservoirs themselves, as required by the policy and implementation sets of rules. Operational level rules designate the reservoir operators and specify their activities (e.g., gate settings, etc.). If these operational level rules should prove deficient for any reason, it is to the other levels one must turn to develop new rules at the operational level. Operational-level rules include the Standard Operating Procedures (SOPs) for the reservoirs under various conditions. These SOPs determine the gate settings, and in turn, the flow of the river on a daily (or at times hourly) basis. The operational-level rules also include the system of water rights for users, water quality permits and many others. Taken together, these rules determine who may use water and in what ways.


The institution, elaborated here via sets of rules, is by no means comprehensive. Various environmental quality, fish and wildlife, and other federal rules come into play, as well as the rules embodied in state and local regulation of water rights, and water use. Some of these other rules appear at the policy level, some at the implementation level, but all influence the operational level rules, and the actual functioning of the system. Finally, all of these water-related rules are embedded within a larger set of rules governing other (although inter-connected) spheres of social and political life. It is possible however to extract a portion of these rules for critical analysis.

The Simulation Model

A simulation model was constructed using both the physical components of the system and the institutional (i.e., rules at the various levels) parameters, so as to investigate the potential impacts of future, uncertain conditions (e.g., climate change) on the management and use of the Rio Grande. In a general sense this is a look at physical/structural and institutional resilience. Ultimately the model is intended to determine the ability of the Rio Grande system to accommodate stresses induced by a variety of possible future circumstances. Rules have been articulated in such a way as to be included in the simulation model for the Rio Grande system in the form of decision tree structures which determine particular actions under specified conditions. In this way the model is equipped to assess situations which will require changes in the operational or implementation level rules in order to allow additional, unanticipated stress to be accommodated. While the institutional side is in many ways much more complex than thephysical system, this analytic framework makes it manageable.

To date the work has entailed building the simulation model, collecting the necessary data on both the physical and institutional parameters, and calibration of the model. Forecast simulations will begin with base scenarios, which project current supply and demand conditions (including their underlying causal parameters) and seek to identify situations of water over- and under-supply in the future. Analyses of these projections will also seek to determine if these plausible deviations from past and present conditions can be accommodated under the current operating rules of the Rio Grande system, and if so, through what kinds of alterations. If the magnitude of these changes exceeds current operational flexibility, we will analyze what changes would be necessary at the operational level and how such changes could be achieved given the requirements of the rules at the policy and implementation levels. Finally, simulations including changes in supply and/or demand attributable to future perturbations (e.g. climatic changes) will be constructed to identify the incremental contribution of such altered conditions. Again, the ability of the system to accommodate such stresses will be analyzed, and the necessary changes evaluated. The general framework for the analysis (using climate change as an illustrative forcing function) is shown in Figure 2.

Figure 2.

We are interested in exploring both the resilience of the system and the consequences of exceeding this resilience for the many users of the system. In this latter regard, we are therefore concerned to identify the way in which the operating rules for the Upper Rio Grande basin can be modified if future conditions (whether driven by physical forcing functions such as climate change, or by socio-economic forcing functions such as population change, or both) make these rules ineffective. Clearly, this means incorporating the higher level (i.e., the implementation- and policy-level) rules into the simulation model. These higher-level rules operate variously as constraints or objectives in the simulation model. When new conditions force changes in operational-level rules, these changes are frequently constrained by the requirements of implementation-level rules (which are themselves are frequently constrained by the policy-level rules). In many cases, however, it is possible (by appealing to the higher levels of the institution) to alter the nature of the constraints in such a way that the operational-level rules can be changed to meet new conditions.


While the application identified here is not yet complete, it does highlight the utility of defining institutions as rules which can be analyzed in consistent and comparative ways. By including these rules along with the specifications of the physical system in the simulation model, we have the potential to analyze not only the current operational status of the Upper Rio Grande basin, but also the mechanisms by which operations can be changed as new and problematic conditions arise in the future.


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