美國聯(lián)邦地質(zhì)調(diào)查局（USGS）上有一份關(guān)于全美2005年取用水情況的報(bào)告（http://pubs.usgs.gov/circ/1344/pdf/c1344.pdf），對我們了解美國水資源狀況有一個(gè)總的了解，博主選取其中的摘要部分和熱力發(fā)電部分進(jìn)行了翻譯，未獲授權(quán)翻譯，也未進(jìn)行校對。本人承諾不應(yīng)用于商業(yè)用途。

Abstract

摘要

表1 1950-2005年全美用水量趨勢（單位：十億加侖/天）

Estimates of water use in the United States indicate that about 410 billion gallons per day (Bgal/d) were withdrawn in 2005 for all categories summarized in this report. This total is slightly less than the estimate for 2000, and about 5 percent less than total withdrawals in the peak year of 1980. Freshwater withdrawals in 2005 were 349 Bgal/d, or 85 percent of the total freshwater and saline-water withdrawals. Fresh groundwater withdrawals of 79.6 Bgal/day in 2005 were about 5 percent less than in 2000, and fresh surface-water withdrawals of 270 Bgal/day were about the same as in 2000. Withdrawals for thermoelectric-power generation and irrigation, the two largest uses of water, have stabilized or decreased since 1980. Withdrawals for public-supply and domestic uses have increased steadily since estimates began.

Estimates of water use in the United States indicate that about 410 billion gallons per day (Bgal/d) were withdrawn in 2005 for all categories summarized in this report. This total is slightly less than the estimate for 2000, and about 5 percent less than total withdrawals in the peak year of 1980. Freshwater withdrawals in 2005 were 349 Bgal/d, or 85 percent of the total freshwater and saline-water withdrawals. Fresh groundwater withdrawals of 79.6 Bgal/day in 2005 were about 5 percent less than in 2000, and fresh surface-water withdrawals of 270 Bgal/day were about the same as in 2000. Withdrawals for thermoelectric-power generation and irrigation, the two largest uses of water, have stabilized or decreased since 1980. Withdrawals for public-supply and domestic uses have increased steadily since estimates began.

美國用水預(yù)測表明，本報(bào)告所列全美2005年所有取水約4100億加侖/天（410Bgal／d），略低于2000年估計(jì)數(shù)，比1980年高峰年總?cè)∷陨偌s5%。2005年淡水取水約349Bgal/d，或占淡水和咸水取水總量的85%。2005年地下淡水取水量為 79.6 Bgal／d，比2000年約少5%，同時(shí)地表淡水取水量約270 Bgal／d，約等于2000年。熱力發(fā)電和灌溉用水取水是最大的兩類用水領(lǐng)域，1980年以來已趨于穩(wěn)定或下降。公共供水和家庭用水自開始估算以來已經(jīng)開始穩(wěn)步增長。

Thermoelectric-power generation water withdrawals were an estimated 201 Bgal/d in 2005, about 3 percent more than in 2000. In 2005, thermoelectric freshwater withdrawals accounted for 41 percent of all freshwater withdrawals. Nearly all of the water withdrawn for thermoelectric power was surface water used for once-through cooling at power plants. Twenty-nine percent of thermoelectric-power withdrawals were saline water from oceans and brackish coastal water bodies.

2005年熱力發(fā)電用水預(yù)計(jì)為201Bgal／d，比2000年增長3%。2005年熱力發(fā)電淡水取水量占全部淡水取水量的41%。幾乎所有熱力發(fā)電的取水都是用于電廠開式循環(huán)冷卻的地表水。29%的熱力發(fā)電取水來自從海洋和沿海水域取用的鹽水。

Withdrawals for irrigation in 2005 were 128 Bgal/d, about 8 percent less than in 2000 and approximately equal to estimates of irrigation water use in 1970. In 2005, irrigation withdrawals accounted for 37 percent of all freshwater withdrawals and 62 percent of all freshwater withdrawals excluding thermoelectric withdrawals. Irrigated acreage increased from 25 million acres in 1950 to 58 million acres in 1980, then remained fairly constant before increasing in 2000 and 2005 to more than 60 million acres. The number of acres irrigated using sprinkler and microirrigation systems

has continued to increase and in 2005 accounted for 56 percent of the total irrigated acreage.

2005年灌溉用取水約128Bgal/d，相比2000年低約8%而約相當(dāng)于1970年的灌溉取水量。2005年，灌溉取水量約占全部淡水取水量的37%以及非熱力發(fā)電用淡水的62%。灌溉量從1950年的2500萬英畝增長到1980年的5800萬英畝，而后基本穩(wěn)定到2000年，2005年預(yù)計(jì)將超過6000萬英畝。采用噴灌和微灌技術(shù)灌溉的農(nóng)田持續(xù)增長，2005年預(yù)計(jì)將占到全部灌溉土地的56%。

Water withdrawals for public supply were 44.2 Bgal/d in 2005, which is 2 percent more than in 2000, although the population increased by more than 5 percent during that time. Public supply accounted for 13 percent of all freshwater withdrawals in 2005 and 21 percent of all freshwater withdrawals excluding thermoelectric withdrawals. The percentage of the U.S. population obtaining drinking water from public suppliers has increased steadily from 62 percent in 1950 to 86 percent in 2005. Most of the population providing their own household water obtained their supplies from ground-water sources.

2005年公共供水取水預(yù)計(jì)為44.2Bgal／d，比2000年增長2%，但同期（供應(yīng)）人口增長超過5%。2005年公共淡水取水量占全部淡水取水量的13%以及非熱力發(fā)電用淡水的21%。全美通過公共供水系統(tǒng)獲得飲用水的人口已從1950年的62%穩(wěn)步增長到2005年的86%。采用家庭自供水人口大部分通過地下水源獲得供水。

Self-supplied industrial water withdrawals continued to decline in 2005, as they have since their peak in 1970. Self-supplied industrial withdrawals were an estimated 18.2 Bgal/d in 2005, a 30-percent decrease from 1985. An estimated 4.02 Bgal/d were withdrawn for mining in 2005, which is 11 percent less than in 2000, and 18 percent less than in 1990. Withdrawals for mining were only 58 percent freshwater.

從1970年達(dá)到高峰后，自供水工業(yè)取水量2005年內(nèi)繼續(xù)下降。2005年自供工業(yè)取水量預(yù)計(jì)為18.2Bgal/d，相比1985年下降30%。2005年預(yù)計(jì)有4.02Bgal/d的取水用于采礦業(yè)，相比2000年下降約11%、相比1990年下降約18%。采礦業(yè)取水中只有58%是淡水。

Livestock water use was estimated to be 2.14 Bgal/d in 2005, which is the smallest estimate since 1975, possibly due to the use of standardized coefficients for estimation of animal water needs. Water use for aquaculture was an estimated 8.78 Bgal/d in 2005, nearly four times the amount estimated in 1985. Part of this increase is due to the inclusion of more facilities in the estimates in 2005, and the use of standardized coefficients for estimating aquaculture use from other data.

2005年牲畜用水預(yù)計(jì)為2.14Bgal/d，是1975年以來最小量了，這可能是由于在動(dòng)物需水量方面采取了標(biāo)準(zhǔn)化系數(shù)的原因。2005年水產(chǎn)養(yǎng)殖用水量預(yù)計(jì)為8.78Bgal/d，約為1985年的4倍，這種增長的部分原因是由于2005年有更多的設(shè)施納入技術(shù)并且在從其他數(shù)據(jù)預(yù)測水產(chǎn)養(yǎng)殖用水方面采取了標(biāo)準(zhǔn)化系數(shù)。

Fresh surface water was the source for a majority of the public-supply, irrigation, aquaculture, thermoelectric, and industrial withdrawals. Nearly 30 percent of all fresh surface-water withdrawals in 2005 occurred in five States. In California, Idaho, and Colorado, most of the fresh surface-water withdrawals were for irrigation. In Texas and Illinois, most of the fresh surface-water withdrawals were for thermoelectric power generation.

地表淡水是公共供水、灌溉、水產(chǎn)養(yǎng)殖、熱力發(fā)電和工業(yè)取水的主要來源。2005年有5個(gè)州地表水取水率超過30%。加利福尼亞州、愛達(dá)荷州、科羅拉多州，地表淡水中大部分用于灌溉。德克薩斯州和伊利諾伊州的地表淡水取水大部分用于熱力發(fā)電。

About 67 percent of fresh groundwater withdrawals in 2005 were for irrigation, and 18 percent were for public supply. More than half of fresh groundwater withdrawals in the United States in 2005 occurred in six States. In California, Texas, Nebraska, Arkansas, and Idaho, most of the fresh groundwater withdrawals were for irrigation. In Florida, 52 percent of all fresh groundwater withdrawals were for public supply, and 34 percent were for irrigation.

2005年大約67%的地下淡水用于灌溉、18%用于公共供水。2005年全美有6個(gè)州地下淡水取水率超過50%。在加利福尼亞州、德克薩斯州、內(nèi)布拉斯加州、阿肯色州和愛達(dá)荷州，地下淡水中的大部分用于灌溉；在佛羅里達(dá)州，52%的地下淡水用于公共供水、34%的地下淡水用于灌溉。

（Thermoelectric Power 熱力發(fā)電）

Thermoelectric power has been the category with the largest water withdrawals since 1965, and for 2005 made up 49 percent of total withdrawals. The largest total and fresh and saline surface-water withdrawals were during 1980. Withdrawals by thermoelectric-power plants increased from 40 Bgal/d in 1950 to 210 Bgal/d in 1980, declined to 187 Bgal/d in 1985, and have since increased to 201 Bgal/d in 2005.

自1965年起，熱力發(fā)電就成為最大的取水用戶，2005年達(dá)到了總?cè)∷康?9%以上。1980年（取水）總量、淡水和咸水等達(dá)到最大。熱力發(fā)電廠取水量從1950年的40Bgal/d上升到210Bgal/d，1985年下降至187Bgal/d，之后回升至2005年的201Bgal/d。

Thermoelectric-power water withdrawals have been affected by limited water availability in some areas of the United States, and also by sections of the Clean Water Act (Amendments to the 1972 Federal Water Pollution Control Act) that regulate cooling system thermal discharges and mandate the use of best available technology for minimizing environmental effects of cooling water intakes (Michelletti and Burns, 2002). Consequently, since the 1970s, power plants have increasingly been built with or converted to using wet recirculating cooling systems (using cooling towers or cooling ponds) or dry recirculating (air-cooled) systems instead of using once-through cooling systems. Recent energy industry data indicate that about 43 percent of the generating capacity in the United States is associated with once-through cooling, 42 percent with wet recirculating cooling towers, 14 percent with wet recirculating cooling ponds, and less than 1 percent with dry recirculating systems (Feeley and others, 2008). Records of cooling systems in fossil fuel plants from 1996 to 2004 and a smaller number of nuclear plants from 1996 to 2000 indicate that average use rates for once-through systems ranged between 50 gallons per kilowatt hour (gal/kWh) and 65 gal/kWh; for recirculating-cooling systems with cooling towers, between 1.0 gal/kWh to 2.0 gal/kWh; and for recirculating-cooling systems with ponds or canals, between 14 gal/kWh to 24 gal/kWh. However, consumptive use ranged from a small percentage of total withdrawals at once-through power plants to approximately 70 percent of water withdrawn at recirculation systems with cooling towers (Dziegielewski and others, 2006).

熱力發(fā)電取水在美國的一些地區(qū)受到可用水資源有限和《清潔水法》（1972年《聯(lián)邦水污染控制法》修正案）的影響，該法要求冷卻系統(tǒng)的熱排放和強(qiáng)制要求使用可能的最好技術(shù)以使得冷卻水進(jìn)水口的環(huán)境影響最小化（米切萊蒂和布爾薩，2002年）。因此，自上世紀(jì)70年代以來，電廠已越來越多地在建造時(shí)直接采用或（運(yùn)行電站）轉(zhuǎn)向采用濕式循環(huán)冷卻系統(tǒng)（使用冷卻塔或冷卻水池）或干循環(huán)（風(fēng)冷）系統(tǒng)來而不是使用直流冷卻系統(tǒng)。最近的能源行業(yè)數(shù)據(jù)表明，全美大約43%的發(fā)電裝機(jī)采用直流冷卻（開式循環(huán)冷卻），42%的采用濕式循環(huán)冷卻塔，14%采用濕式循環(huán)冷卻池，采用干式循環(huán)系統(tǒng)的不足1%（菲利等人，2008年）。一項(xiàng)關(guān)于從1996年到2004年的化石燃料電廠以及1996年到2000年少量核電廠的冷卻水系統(tǒng)的記錄表明，直流系統(tǒng)的平均用水量為50-65加侖每千瓦小時(shí)（gal/KW.h）；采用冷卻塔的循環(huán)冷卻系統(tǒng)，（平均用水量）在1-2加侖/千瓦時(shí)，采用水池或水渠的循環(huán)冷卻系統(tǒng)，（平均用水量）在14-24加侖/千瓦時(shí)之間。然而，直流循環(huán)發(fā)電廠總用水量的消耗量大約只有采取冷卻塔的循環(huán)冷卻水系統(tǒng)取水量（消耗）的70%（Dziegielewski等人，2006）。

Use of recirculation water for cooling reduces the intake water requirement at a power plant, resulting in reduced water withdrawals. The increasing influence over time of using technologies that require less water can be observed in the USGS water-use historical record. The trend showing the increase, decline, and subsequent gradual increase of water withdrawals for thermoelectric power generation from 1950 to 2005 (table 14) occurred as the net power generated increased steadily during the same period (U.S. Department of Energy, 2007). The ratio of total water withdrawals to energy produced, in gallons per kilowatt hour, can be calculated using the USGS estimate of thermoelectric water use with the USDOE EIA records of historic net power production. This ratio decreased from an average of 63 gal/kWh during 1950 to 23 gal/kWh during 2005.

發(fā)電廠冷卻水的循環(huán)使用減少了進(jìn)水要求，從而減少了取水量。采取需水量更少的技術(shù)帶來日益增加的影響在聯(lián)邦地質(zhì)調(diào)查局（USGS）的用水記錄中可以看到。趨勢顯示出熱力發(fā)電取水量增長、下降，從1950年到2005年由于凈發(fā)電裝機(jī)的同期持續(xù)增長導(dǎo)致的逐漸增加（美國能源部，2007年）。用于能量生產(chǎn)的取水總量比例，加侖每千瓦小時(shí)，可以使用美國聯(lián)邦地質(zhì)調(diào)查局（USGS）的熱力發(fā)電用水估計(jì)來計(jì)算美國能源部能源信息統(tǒng)計(jì)署歷史凈發(fā)電記錄所需（用水）。這一比率1950年的63加侖/千瓦時(shí)均值下降到2005年的23加侖/千瓦時(shí)。

表2 2005年全美熱力發(fā)電取水量分類統(tǒng)計(jì)表（單位，百萬加侖/天）


表3 2005年全美公共供水取水量（單位，百萬加侖/天）



圖12005年全美公共取水地圖（分水源和分州）

博主譯注：

1、從該報(bào)告可以看到美國1950年到2005年期間用水變化趨勢，尤其是熱力發(fā)電用水的趨勢，盡管節(jié)水技術(shù)有了顯著進(jìn)步，但因熱力發(fā)電總量的增加，熱力發(fā)電用水總量還是增加較快，占到了全美用水的半壁江山。

2、與以往聽一些水利專家介紹的情況不同的是，公共供水系統(tǒng)供應(yīng)了全美86%人口（約2.58億）的家庭用水；公共供水系統(tǒng)中的2/3來自于地表水（如湖和徑流），其余1/3來自于地下水，有38個(gè)州依靠地表水供應(yīng)50%以上的家庭用水。因此研究這些公共供水系統(tǒng)取水點(diǎn)與核電站取排水點(diǎn)的關(guān)系、核電站下游公共取水點(diǎn)應(yīng)急保障措施等對于我們理解美國的有關(guān)法律法規(guī)將是有幫助的，建議國內(nèi)業(yè)界和水資源、環(huán)境保護(hù)主管部門關(guān)注。