摘要:

ABSTRACT:In arid regions of rapid economic and population growth, adverse effects of droughts are likely to be increasingly serious. This article presents an introduction and overview of the papers collected in this special issue of theWater Resources Bulletin. The papers report on the second phase of a study of the impacts of and responses to a potential severe sustained drought in the Colorado River Basin in the southwestern U.S. The analyses were performed by a consortium of researchers from universities and the private sector located throughout the Basin. Tree ring studies suggest that droughts of duration and magnitude much more serious than any found in the modern records probably occurred in the Basin during earlier centuries. Taking the present‐day configuration of the storage and diversion structures and the economic conditions in the Basin as the base‐point, the general objectives of the study are three: first, to define a representative Severe Sustained Drought (SSD) and assess its hydrologic impacts; second, to forecast the economic, social and environmental impacts on the southwestern U.S.; and finally, to assess alternative institutional arrangements for coping with an SSD. The evaluation of impacts and policies was conducted with two distinct modeling approaches. One involved hydrologic‐economic optimization modeling where water allocation institutions are decision variables. The second was a simulation‐gaming approach which allowed “players” representing each basin state to interact in a real‐time decision making mode in response to the unfo

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1995.tb03400.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

ABSTRACT:Frequent and persistent droughts exacerbate the problems caused by the inherent scarcity of water in the semiarid to arid parts of the southwestern United States. The occurrence of drought is driven by climatic variability, which for years before about the beginning of the 20th century in the Southwest must be inferred from proxy records. As part of a multidisciplinary study of the potential hydrologic impact of severe sustained drought on the Colorado River, the physical basis and limitations of tree rings as indicators of severe sustained drought are reviewed, and tree‐ring data are analyzed to delineate a “worst‐case” drought scenario for the Upper Colorado River Basin (UCRB). Runs analysis of a 121‐site tree‐ring network, 1600–1962, identifies a four‐year drought in the 1660s as the longest‐duration large‐scale drought in the Southwest in the recent tree‐ring record. Longer tree‐ring records suggest a much longer and more severe drought in 1579–1598. The regression estimate of the mean annual Colorado River flow for this period is 10.95 million acre‐feet, or 81 percent of the long‐term mean. The estimated flows for the 1500s should be used with caution in impact studies because sample size is small and some reconstruc

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1995.tb03401.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

ABSTRACT:This paper considers the risk of drought and develops drought scenarios for use in the study of severe sustained drought in the Southwestern United States. The focus is on the Colorado River Basin and regions to which Colorado River water is exported, especially southern California, which depends on water from the Colorado River. Drought scenarios are developed using estimates of unimpaired historic streamflow as well as reconstructions of streamflow based on tree ring widths. Drought scenarios in the Colorado River Basin are defined on the basis of annual flow at Lees Ferry. The risk, in terms of return period, of the drought scenarios developed, is assessed using stochastic models.

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1995.tb03402.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

ABSTRACT:The impacts of a severe sustained drought on Colorado River system water resources were investigated by simulating the physical and institutional constraints within the Colorado River Basin and testing the response of the system to different hydrologic scenarios. Simulations using Hydrosphere's Colorado River Model compared a 38‐year severe sustained drought derived from 500 years of reconstructed streamflows for the Colorado River basin with a 38‐year streamflow trace extracted from the recent historic record. The impacts of the severe drought on streamflows, water allocation, storage, hydropower generation, and salinity were assessed. Estimated deliveries to consumptive uses in the Upper Basin states of Colorado, Utah, Wyoming, New Mexico, and northern Arizona were heavily affected by the severe drought, while the Lower Basin states of California, Nevada, and Arizona suffered only slight shortages. Upper Basin reservoirs and streamflows were also more heavily affected than those in the Lower Basin by the severe drought. System‐wide, total hydropower generation was 84 percent less in the drought scenario than in the historical stream‐flow scenario. Annual, flow‐weighted salinity below Lake Mead exceeded 1200 ppm for six years during the deepest portion of the severe drought. The salinity levels in the historical hydrology scenario never exceeded

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1995.tb03403.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

ABSTRACT:The waters of the Colorado River are divided among seven states according to a complex ‘Law of the River’ drawn from interstate compacts, international treaties, statutes, and regulations. The Law of the River creates certain priorities among the states and the Republic of Mexico, and in the event of a severe sustained drought, the Law of the River dictates the distribution of water and operation of the elaborate reservoir system. Earlier work indicated that there is remarkable resilience in the system for established uses of water in the Lower Basin of the Colorado River. This work shows, based on an application of the Law of the River using computer modeling of operations of facilities on the Colorado River, that there may be serious environmental consequences and related legal restraints on how the water is used in times of shortage and that the existing legal and institutional framework governing the Colorado River does not adequately address all the issues that would be raised in a severe sustained drought. Several possible legal options for dealing with drought in the context of the Law of the River are identif

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1995.tb03404.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

ABSTRACT:In many interstate river basins, the institutional arrangements for the governance and management of the shared water resource are not adequately designed to effectively address the many political, legal, social, and economic issues that arise when the demands on the resource exceed the available supplies. Even under normal hydrologic conditions, this problem is frequently seen in the Colorado River Basin. During severe sustained drought, it is likely that the deficiencies of the existing arrangements would present a formidable barrier to an effective drought response, interfering with efforts to quickly and efficiently conserve and reallocate available supplies to support a variety of critical needs. In the United States, several types of regional arrangements are seen for the administration of interstate water resources. These arrangements include compact commissions, interstate councils, basin interagency committees, interagency‐interstate commissions, federal‐interstate compact commissions, federal regional agencies, and the single federal administrator. Of these options, the federal‐interstate compact commission is the most appropriate arrangement for correcting the current deficiencies of the Colorado River institution, under all hydrologic condi

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1995.tb03405.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

ABSTRACT:Survey data collected in the San Joaquin Valley of southern California and the Grand Valley of western Colorado reveal that residents of both areas believe that a severe sustained drought is likely to occur within the next 20–25 years and that their communities would be seriously impacted by such an event. Although a severe sustained drought affecting the Colorado River Basin would cause major economic and social disruptions in these and other communities, residents express little support for water management alternatives that would require significant shifts in economic development activities or in water use and allocation patterns. In particular, residents of these areas express little support for strategies such as construction and growth moratoriums, mandatory water conservation programs, water transfers from low‐to high‐population areas, water marketing, or reallocations of water from agricultural to municipal/industrial uses. This rejection of water management strategies that would require a departure from “business as usual” with respect to water use and allocations severely restricts the capacity of these and similar communities to respond effectively should a severe sustained drou

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1995.tb03406.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

ABSTRACT:Evaluation criteria for reservoir and stream resources were developed to provide decision makers with feedback on environmental consequences of water allocation decisions under conditions of severe sustained drought within the Colorado River Basin by using the AZCOL gaming simulation model. Seven categories of flow dependent resources were identified which highlight resource states associated with reservoirs or river reaches within the AZCOL model. AZCOL directly simulates impact of water management decisions on five resource categories: threatened, endangered or sensitive fish; native nonlisted fish; wetland and riparian elements; national or state wildlife refuges; and hatcheries or other flow dependent facilities. Two additional categories ‐ cold and warm water sport fish ‐ are not modeled explicitly but are incorporated in the evaluation of monetary benefits from recreation on Colorado River waters. Each resource category was characterized at each time step in the simulation according to one of four environmental states: stable, threatened, endangered, or extirpated. Changes in resource states were modeled by time and flow‐dependent decision criteria tied to either reservoir level or stream flows within the AZCOL model structure. Gaming results using the AZCOL model indicate environmental impacts would be substantial and that water allocation decisions directly impacted environmental resource s

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1995.tb03407.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

ABSTRACT:Economic benefit functions of water resource use are estimated for all major offstream and instream uses of Colorado River water. Specific benefit estimates are developed for numerous agricultural regions, for municipal uses, and for cooling water in thermal energy generation. Economic benefits of hydropower generation are given, as are those for recreation on Colorado River reservoirs and on one free‐flowing reach. Marginal and total benefit estimates for Colorado River water use are provided. The estimates presented here represent a synthesis of previous work, providing in total a comprehensive set of economic demand functions for competing uses of Colorado River water. Non‐use values (e.g., benefits of preserving endangered species) are not estima

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1995.tb03408.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

ABSTRACT:A severe sustained drought in the Colorado River Basin would cause economic damages throughout the Basin. An integrated hydrologic‐economic‐institutional model introduced here shows that consumptive water users in headwaters states are particularly vulnerable to very large shortfalls and hence large damages because their rights are effectively junior to downstream users. Chronic shortfalls to consumptive users relying on diversions in excess of rights under the Colorado River Compact are also possible. Nonconsumptive water uses (for hydropower and recreation) are severely affected during the worst drought years as instream flows are reduced and reservoirs are depleted. Damages to these uses exceeds those to consumptive uses, with the value of lost hydropower production the single largest economic impact of a severe sustained drought. Modeling of alternative policy responses to drought suggests three general policy approaches with particular promise for reducing damages. Consumptive use damages can be reduced by over 90 percent through reallocation from low to high valued uses and through reservoir storage strategies which minimize evaporation losses. Reservoir management to preserve minimum power pool levels for hydropower production (and to maintain reservoir recreation) may reduce damages to these nonconsumptive uses by over 30 percent, but it may increase consumptive use shortfa

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1995.tb03409.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY