impacts of the 1976–77 drought in the u.s.a
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Impacts of the 1976–77 Drought in the U.S.A.Bruce K. Gilbert a & Thomas J. Buchanan aa Hydrologists, U.S. Geological Survey Reston , Virginia, U.S.A.Published online: 22 Jan 2009.
To cite this article: Bruce K. Gilbert & Thomas J. Buchanan (1977) Impacts of the 1976–77 Drought in the U.S.A.,Water International, 2:2, 3-33, DOI: 10.1080/02508067708685756
To link to this article: http://dx.doi.org/10.1080/02508067708685756
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Impacts of the 1976-77 Drought in the U.S.A. by Bruce K. Gilbert and Thomas J. Buchanan Hydrologists, U.S. Geological Survey Reston, Virginia, U.S. A.
The quantity of water resources on the planet Earth has remained virtually constant through geologic time. The world's total water supply is about 1,360 million cubic kilometers (Nace, 1967), and in general is estimated to be distributed principally as follows:
Water Volume Percentage of Location (cubic kilometers) Total Water
Oceans 1,321,000,000 97.2 Icecaps and glaciers 29,200,000 2.1 5
level 12,900 0.001 Atmosphere, at sea
Subsurface
Vadose water, including soil moisture 66,700 0.005 Ground water, within a depth of about 800 meters 4,170,000 0.31 Ground water, deep-lying 4,170,000 0.31
Surface
Freshwater lakes 125,000 0.009 Saline lakes and inland seas 104,000 0.008 Average in stream channels 1,250 0.0001
TOTALS (rounded) 1,360,000,000 100
Although the total quantity has an astonishingly uneven distribution, the world's water is in continuous processes of transfer and mixing through the hydrologic cycle. And excluding cataclysmic events such as the advent of an ice age or a dramatic alteration in the level of the oceans - some of the most potent stresses that can be applied to society come as the result of com- paratively minuscule changes which occur within this system. Variations in the normally expected quantities of water from time to time and place to place cause floods and droughts, frequently with devastating en- vironmental and socio-economic effects, both nationally and internationally.
Today (May, 1977), millions of people are relating to a common plight; much of the United States, and particu-
larly the Far West and the Great Plains, is in the midst of a serious water shortage. There is no escaping the fact that the current drought is severe in some areas, and the situation in some places is expected to get much worse. All United States citizens will feel the resulting effects either directly as a decrease in water availability, or because of increased costs especially for energy and agricultural goods.
Hydrologists can pragmatically report on recorded data which show that almost every year, some area of the United States experiences the conditions that con- stitute a drought. Now, however, many parts of the country have had greatly deficient precipitation during the past 15 months and, thus, are comin'g together in facing an unusually widespread problem. A number of places have instituted voluntary conservation programs and, in northern California, rationing is in effect.
In addition to dealing with shortages of water supplies for domestic, municipal, industrial, and agricultural uses, a number of undesirable environmental effects are already evident or in prospect. For example, fish and wildlife habitats are becoming increasingly deficient, the potential for explosive brush and forest fires is growing. and wind erosion of rich topsoil is underway. Legislators, managers, and planners, consequently, face a real challenge in trying to find ways to tide the country through.
South-Central Canada is also experiencing drought And, of course, most streams that drain drought- stricken areas of the United States into this and other parts of Canada have been carrying much less water than normal. Characteristic of these streams are the Red River of the North and the Souris River, which flow from North Dakota and Minnesota into Manitoba. In contrast, streamflow in British Columbia has been greater than average. As a consequence, U.S. Government agencies and power companies in the Columbia River basin are considering arrangements with Canada to purchase electric power and additional water to keep hydroelec- tric plants generating at maximum capacity. Also, parts of Mexico are being affected by decreasing availability of water.
Effects of Drought on Water Resources
A . Quantities of Streamflow and Ground Water. When a drought occurs, the effect on water resources continually grows more noticeable. Stream-
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flow decreases, ground-water levels drop, reservoir storage is depleted, and water-quality is degraded. One simpiistic, but direct and quantitative means of deter- mining how serious the situation is, is to compare current streamflow with the historical record. Although the areas most severely affected by drought thus far have been the Far West and the Upper Midwest, drought conditions were most widespread at the end of February 1977 when streamflows in all or parts of every State except Florida and Louisiana were generally much below normal, as shown in Figure 1. It should be em- phasized that the Northeast experienced the most
severe winter of record, during which exceedingly heavy snowfalls took place in some parts of the area. The below-normal streamflow thus was a result of water being stored in place as ice and snow and not directly indicative of the drought severity. Figure 2 shows by areas the number of months of deficient streamflow from February 1976 through January 1977. It can be seen from this figure that in Northern California and in the Upper Midwest, as many as 9 of the 12 months during this period have had below-normal streamflow.
Fig. 2. NUMBER OF MONTHS OF BELOW NORMAL STREAMFLOW WRING THE PERIOD
~
MAR 1976 FEB 1977 \ \
During March and early April 1977, conditions im- proved somewhat in the eastern half of the United States as a result of rainfall and runoff from the
unusually deep snowpack in parts of the Northeast. Figure 3 shows streamflow conditions at the end of March 1977. It can be seen from this figure that the western part of the United States was still experiencing
below-normal streamflows, whereas, east of the Missis- sippi River, streamflow was normal or above normal. In fact, some parts of Virginia, West Virginia, Kentucky, and Tennessee were reporting high runoff conditions and even disastrous flooding in parts of the Appalachian Mountain region. In early April in the Upper Midwest, flows in some streams were approaching normal and ground-water levels were beginning to recover. Paradoxically, however, floods are not always the universal remedy for droughts. Often during ex- ceedingly rapid runoff, the normally slow process of recharge to ground-water reservoirs cannot take place. So, the flood waters may come and go leaving the aquifers (underground water-bearing formations) only slightly better off than before.
In large areas of the United States, ground-water levels have been declining as the result of a lack of recharge and because of increased pumpage. Figure 4 shows those regions where the water table was at a record or near-record low in mid-March 1977, areas where well drilling has increased significantly, and where ground-water pumpage is being used to sup-
Fig. 4. _- ' \
/' =- EFFECT OF CURRENT DROUGHT ON GROUND.WATER DEVELOPMENT ' I i .?
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plement below-normal surface supplies. In the northern parts of Wisconsin and Minnesota, and in the western part of Michigan's Upper Peninsula, the decline cf the water table to record or near-record lows has caused many shallow wells to go dry. The number of dry wells in March is conservatively estimated to have been about 1,900 in Minnesota, 500 in Wisconsin, and 1,400 in the Upper Peninsula of Michigan. Although most of these wells are less than 8-meters deep, they provide adequate water supplies for domestic use in normal years. With water-table levels in mid-March in western Minnesota, for example, at record lows (about 1 to 4 meters below average), many shallow wells either went dry or the yields were no longer adequate even for a home supply. The water table did not always drop below the bottom of the wells, but the productive aquifer zones were dewatered.
In parts of California, Nevada, Oregon, and Washington, well drilling and ground-water pumpage have been increased significantly in an effort to sup- plement deficient surface-water supplies. Pumping of ground water to supplement the normal surface sup- plies is planned for four basins in northern Nevada and pumpage for the cities of Reno and Sparks is expected to increase threefold. To compensate for the scarcity of the normal surface-water supplies in the agriculturally rich San Joaquin Valley of California, development of ground-water sources is on the rise. For example, there is a trend toward reactivating thousands of unused or abandoned irrigation wells in the Valley.
As a result of the drought, storage in many major water-supply and hydropower reservoirs is far below normal, especially in parts of California, Oregon, and Washington. The U.S. Bureau of Reclamation has re- ported that they have been able to collect all the runoff generated in the Yakima River basin reservoir system. But, during the last 6 months, they have accumulated only about 364 million cubic meters, which is about the same amount collected in 3 days during a flood in December 1975. Furthermore, because the small water content of the existing snowpack will produce scant ad- ditional runoff, it is estimated that less than half the nor- mal supply of irrigation water will be available this sum- mer from the Yakima River reservoirs. Figure 5 shows
i Fig. 5.
CONTENTS OF SELECTED RESERVOIRS NEAR END OF MARCH 1977
the contents of selected reservoirs in the conterminous United States near the end of March 1977.
B. Quality of Water. During a drought, the first con- cern is with the diminishing quantities of water, but water-quality problems can be expected to follow close behind. Already there has been degradation of stream quality in areas of the West and Midwest, and continued low flows will create further and more pervasive deterioration. One of the most critical problems likely to affect water quality as a result of a prolonged drought is simply a lack of sufficient water to flush and dilute con- taminants in stream channels. Wastes from upstream discharges can conceivably build to the extent that the reduced flows available downstream will become unusable.
Dissolved-solids concentrations are used to indicate the quality of water resources. The concentration of dissolved solids in some streams in parts of Ohio, North Dakota,' South Dakota, and western Colorado has reached near-record highs. If streamflows continue to decline, these concentrations will increase. This can cause the affected water to have an unpleasant taste, and may interfere with sensitive industrial processes. The combination of drought and severe winter con- ditions greatly increased the concentration of dissolved solids in streams. In normal winters the dissolved-solids concentration increases because the ground-water out- flow to the stream is diluted less by surface-water runoff. As a result of the February cold spell in Ohio, for example, record high dissolved solids concentrations were measured at several monitoring sites because nearly all the flow was from ground water. Con- centrations in the Cuyahoga River at Independence, Ohio, reached almost 2,000 milligrams per liter-50 per- cent greater than ever measured before.
Oxygen deficiency is also a characteristic of prolonged low flows. Less flow means less water to assimilate oxygen-demanding wastes. In Minnesota, for example, dissolved-oxygen concentrations were nearing zero in some reaches of the Mississippi and Minnesota Rivers until late March and early April when rains more than tripled flows. Such "sags" in oxygen concentrations can be lethal to fish and other aquatic life, cause odor problems, and decrease a stream's natural ability to purify itself. In California, the flow of the Russian River has declined to the extent that sewage discharges from oxidation ponds account for 40-50 per- cent of the total flow-normally at this time of the year, sewage discharges account for less than 10 percent. Undesirable odors and heavy growths of algae have already occurred and even lower dissolved-oxygen concentrations may result as water temperatures in- crease during spring and summer.
In general, the shallow water associated with low streamflow tends to be warmer than usual. Also, stream temperatures downstream from depleted reservoirs are expected to be higher because of the lack of release of deep, cool water from storage. This is particularly noticeable when snowmelt runoff is deficient. Increased
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water temperatures can seriously impact aquatic life; trout, in particular, cling to life tenuously as streams grow warmer. Obviously, those who use streams as sources of cooling water face problems. And the rate of evaporation is increased, which further decreases the limited supply of surface water. In coastal zones, fresh water in streams and aquifers is always in contact with seawater. Decreased streamflow and additional with- drawals of ground water in these areas increases the inland movement of salt water and further threatens existing sources of supply.
Water-Supply Problems
Water-supply problems are legion but the most severe so far are in the northern half of California. In that area, water rationing with various mandatory and volun- tary restrictions is being implemented in many com- munities. The most significant rationing plan is the one implemented on April 1 by San Francisco which aims to lower water use by 25 percent. Both home-owners and industries must reduce their water consumption and, if the reductions are not met, plans are to place restrictors in the water lines of individual users. These devices will cut the flow of water through the affected lines to a trickle. In addition, the user will be charged for the cost of the installation and eventual removal of the restrictor. In some areas of Oregon, there have been industrial layoffs because of water cutbacks, and similar actions are anticipated in other stricken areas. Further unem- ployment can be anticipated if power production in the Northwest is as low as is forecast for late summer.
Agriculture has been seriously affected throughout the period of the current drought. Even in 1975, areas in the Upper Midwest produced poor quality crops and a diminished yield because of insufficient precipitation. This effect of drought spread throughout much of the western United States in 1976 and early 1977. Many farmers have been forced to delay plowing and seeding because of dry conditions and, in some areas, seed and seedlings have been damaged because of the lack of moisture. Rangelands have also been affected and many ranchers have been forced to sell their stock before the market was right, or have had to buy high- priced feed to maintain their stock. Many farmers have been forced to haul water to accommodate their most urgent needs. Another serious effect on agriculture is the loss of soil to the combined forces of wind and drought. The dust-bowl conditions in the Midwest in the mid-1930’s created disastrous problems in Colorado, Kansas, Nebraska, Oklahoma, and the panhandle of Texas. The current drought has already revived these old memories.
The drought has had, and will continue to have, serious effects on power production in the United States. In the Northwest, which relies on hydropower for 80 percent of its electricity, reservoir content is well below normal, the snowpack is extremely deficient, and, consequently, the outlook for power production this summer is very bleak. Many agencies are currently trying to develop contingency plans for attempting to
satisfy the power needs of the Pacific Northwest as the drought continues.
Fish and wildlife resources have also been severely affected by the current drought. In many places, there has been insufficient water in the streams for spawning by various species of fish; in other areas streams have dried up killing the entire fish population. In the Pacific Northwest, decisions must soon be made on how much water to release from the reservoir systems for fish migration and how much must be saved for later hydropower generation. In many of the wetland areas in the West, the normal forage areas are not capable of maintaining the wildlife and migrating water fowl as in normal years.
Recreational opportunities have also been curtailed. Ski resorts in the West by and large have reported a most depressing season. Millions of dollars in income have been lost as the result of the lack of snow. In ad- dition, many park areas have been closed, and many others are on alert because of the threat of fires due to the extremely dry conditions. Economic conditions in these resort areas are likely to be impacted severely.
Another problem is the potential threat of land sub- sidence in northern California, which generally had been controlled through importation of surface-water sup- plies. Aquifer withdrawals have been reduced in recent years in the San Joaquin Valley, and, thus, ground- water levels have risen. Now, because of the serious drought, abandoned wells are being put back into production and pumpage is increasing. If large-scale pumping is resumed, however, ground-water levels will fall again, and land subsidence may be reinitiated.
The Outlook
In addition to voluntary conservation measures and rationing, efforts are underway in many areas to tap new supplies and redevelop old ones. Thousands of wells have been drilled and a multitude of existing wells are being deepened in an attempt to provide relief to domestic, municipal, industrial, and agricultural users. Some of the power companies in Washington State are seeding clouds in an effort to produce rain to replenish reservoir storage. However, there have been few suitable clouds to seed, and the effectiveness of seeding operations is hard to evaluate. To assist people in the affected areas, President Carter has signed into law a comprehensive drought-assistance bill that provides $1 00 million in loans and emergency grants. In addition, some States have voted emergency funds to assist with drought problems. For example, in Washington State, Governor Dixie Lee Ray signed a bill providing $33 million for aid to irrigation developments in eastern Washington and for domestic drinking water projects.
Despite legislated financial aid and efforts to con- serve and more efficiently manage water supplies, the prospects for the summer and autumn of 1977 are
(concluded on page 33)
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Meguro-ku, Tokyo 153, Japan
Oct. 17-22, 8th International Conference on Water Pollution . Research, Sydney, Australia, Contact: S.H. Jenkins, Headington Hill Hall, Oxford OX3 OBW, U.K.
Oct. 24-26, Symposium on Problems Associated with Design and Construction in Developing Countries, Munich, W. Ger- many. Contact: Secretariat of IABSE, ETH- Hongger berg, CH-8093 Zurich, Switzerland
November, 8th World Dredging Con- ference, Amsterdam, The Netherlands. Con- tact: WODCON, P.O. Box 1800-Berth 84, San Pedro, CA 90733, U.S.A.
Nov. 2-4, Second International Symposium on Dredging Technology, College Station, Texas, U.S.A. Contact: BHRA Fluid Engineering, Cranfield, Bedford MK 43 OAJ, England
1978 Summer, International Symposium on En- vironmental Effects of Hydraulic Engineering Works, Knoxville, Tennessee, U.S.A. Contact: G.H. Toebes, School of Civil Engineering, Purdue University, Lafayette, IN 47907, U.S.A.
Jan. 10-13, International Conference on Water Resources Engineering, Bangkok, Thailand. Contact: S. Selvalingam, Asian In- stitute of Technology, P.O. Box 2754, Bangkok, Thailand
March 13-17, International Geodynamics Conference, Tokyo. Contact: K. Obayashi, Ocean Research Institute, 1-1 5-1, Minamidai, Nakano-ku, Tokyo 164, Japan
April 11-14, International Conference on Urban Storm Drainage, Southampton, England. Contact: P.R. Helliwell, Dept. of Civil Engineering, University of Southampton, Southampton SO9 5NH, U.K.
April 24-27, Joint Symposium on Aspects of Navigability of Constraint Waterways, including Harbour Entrances, Delft, The Netherlands. Contact: Symposium on Aspects of Navigability, c/o Delft Hydraulics Laboratory, Rotterdamsweg 185, P.O. Box 177, Delft, The Netherlands
May, lpternational Symposium on Hydrogeochemistry of Mineralized Waters, Cieplice, Poland. Contact: Z. Plochniewski, lnstitut Geologiczny, Rakowiecka 4,02-517 Warszawa, Poland
May or June, Tenth Congress on Irrigation and Drainage, Athens, Greece. Contact: In-
ternational Commission on Irrigation and Drainage' 48 Nyaya Marg, Chanakyapuri, New Delhi 1 10021, India
May 22-26, 7th International Harbour Congress, Antwerp, Belgium. Contact: Ingenieurshuis, Jan van Rijswijcklaan 58. B- 2000 Antwerpen, Belgium.
June 29-July 5, THIRD WORLD CONGRESS ON WATER RESOURCES: WATER FOR HUMAN SURVIVAL, Sao Paulo, Brazil. Con- tact: Terceiro Congresso Mundial de Recur- sos Hidricos, Caixa Postal 9721, Sao Paulo, Brazil
June 5-10, International Symposium on Ground-water Pollution by Oil Hydrocar- bons, Praha, Czechoslovakia. Contact: Stavebni geologie, n.p., Gorkeho n.7, Praha 1, Czechoslovakia
June 10-Aug. 10, International Higher Hydrological Course: Scientific Basis of Ground Waters Research and Protection. Contact: International Higher Hydrological Course, Geography Department, Moscow State University, Moscow V-234, 11 7234, U.S.S.R.
June 12-14, Joint Symposium on Design and Operation of Fluid Machinery, Fort Collins, Colorado, U.S.A. Contact: H.T. Falvey, Bureau of Reclamation Code 1532, P.O. Box 25007, Denver, CO 80225, U.S.A.
June 26-28, INTERNATIONAL SYM- POSIUM ON RISK AND RELIABILITY IN WATER RESOURCES, Waterloo, Ontario, Canada. Contact: T. Unny, Department of Civil Engineering, University of Waterloo, Waterloo, Ontario N2L 3C1, Canada
July 9-14, Tenth International Congress on Sedimentology, Jerusalem, Israel. Contact: G. Guirtzman. Geological Survey, 30 Malkhei Israel Street, Jerusalem 95501, Israel
July 10-1 3, Third International Conference on Permafrost, Edmonton, Alta., Canada. Contact: M.K. Ward, National Research Council, Montreal Road, Ottawa, Ont. K1A OR6. Canada
July 10-14, Second International Con- ference on Finite Elements in Water Resources, London, England. Contact: C. Brebbia, Southampton University, Southamp- ton SO9 SNH, U.K.
Aug. 7-12, IAHR Symposium on Ice Problems, Lulea, Sweden. Contact: Division of Water Resources Engineering, University of Lulea, Lulea, S-95187 Sweden
DROUGHT (continued from page 6)
bleak. The sole solution to the drought is prolonged and copious amounts of precipitation. For some water users, a drought can be considered broken with the first major rainfall that provides some relief to- the native vegetation but, for others, particularly water managers concerned with reservoir storage or well-field operations, the effects of the drought may linger for a year or longer after a period of normal precipitation begins. Even though a few areas of the United States have had some relief from the drought, other regions continue to be severely affected. Most citizens will feel the sting of the drought this summer as they watch food prices climb.
The full effects of the extremely deficient snowpack in the West are yet to be felt. Runoff from this usually dependable source is expected to be well below normal this spring and summer. Thus, the timing of the ad- ditional precipitation needed is also a critical factor. Rain must come in quantity before the onset of next winter; even if greater than average amounts of snow fall, streamflow and reservoir storage may not be replenished until a year from now. By then, the situation
with respect to both the quantity and quality of water resources could be at a desperate level.
To minimize the effects of future drought, the United States needs to develop a better understanding of its existing water supply, its anticipated water needs, and its current water use. And more efficient use must be made of the existing water resources. Using this back- ground, decisions on agricultural, industrial, and municipal developments may be made with a fuller awareness than at present of the potential effects of droughts on society and its economy. Skillful planning and persuasive management will be needed to evaluate and arrange trade-offs among competitive users.
In contrast to energy, the world's water supply is not being consumed, but learning to adjust to the changes in its quantity, quality, and distribution in time and space is every bit as crucial as developing new fuel sources.
REFERENCE
Nace, R. L., 1967, Are we running out of water?: U.S. Geol. Survey Cir. 536,7 p.
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