龍首(shou)渠大約(yue)是在(zai)漢(han)武帝元狩到(dao)(dao)元鼎年間(公元前(qian)120- 公元前(qian)111年)根據莊熊(xiong)羆的(de)建(jian)議而修建(jian)的(de)。這是開(kai)發洛河(he)水利的(de)首(shou)次工程(cheng),征(zheng)調了(le)1萬多民工,挖通起自征(zheng)縣(xian)(今(jin)澄城縣(xian))終(zhong)到(dao)(dao)臨晉(今(jin)大荔縣(xian))的(de)渠道(dao)。據說(shuo)渠成后,重(zhong)泉(今(jin)蒲城縣(xian)東南)以東的(de)1萬多頃鹽(yan)堿地得(de)到(dao)(dao)灌溉,每畝能收10石糧(liang)。
大(da)約在(zai)漢武帝(di)元朔到元狩(shou)年間(jian)(公元前(qian)一(yi)(yi)二八(ba)至(zhi)一(yi)(yi)一(yi)(yi)七年)。有一(yi)(yi)個叫莊(zhuang)熊羆(pi)(注(zhu)(zhu):《漢書(shu)(shu)(shu)·溝(gou)洫志》作“嚴熊”,因(yin)避(bi)漢明(ming)帝(di)劉莊(zhuang)的(de)(de)(de)名(ming)諱,改莊(zhuang)為嚴。又省(sheng)去“羆(pi)”字。)的(de)(de)(de)人,他向皇帝(di)上書(shu)(shu)(shu),建議開渠(qu)(qu)(qu)(qu)(qu)(qu)引洛(luo)水(shui)灌田。他說臨(lin)(lin)晉(jin)(jin)(今大(da)荔縣(xian))的(de)(de)(de)百姓愿意開挖——條(tiao)引洛(luo)水(shui)的(de)(de)(de)渠(qu)(qu)(qu)(qu)(qu)(qu)道以(yi)灌溉重泉(今蒲(pu)城縣(xian)東(dong)(dong)南)以(yi)東(dong)(dong)的(de)(de)(de)土地(di)(di)。如果(guo)渠(qu)(qu)(qu)(qu)(qu)(qu)道修成了(le),就可(ke)以(yi)使一(yi)(yi)萬(wan)多頃的(de)(de)(de)鹽堿地(di)(di)得以(yi)灌溉,收到畝(mu)產十(shi)石(shi)的(de)(de)(de)效益。武帝(di)采納了(le)這(zhe)一(yi)(yi)建議,征調(diao)了(le)一(yi)(yi)萬(wan)多人開渠(qu)(qu)(qu)(qu)(qu)(qu)[注(zhu)(zhu):《史(shi)記·河渠(qu)(qu)(qu)(qu)(qu)(qu)書(shu)(shu)(shu)》,《漢書(shu)(shu)(shu)·溝(gou)洫志》。]。引洛(luo)水(shui)灌溉臨(lin)(lin)晉(jin)(jin)平原,就必須在(zai)臨(lin)(lin)晉(jin)(jin)上游的(de)(de)(de)征縣(xian)(今澄城縣(xian))境內(nei)開渠(qu)(qu)(qu)(qu)(qu)(qu)。可(ke)是(shi)(shi)在(zai)臨(lin)(lin)晉(jin)(jin)與征縣(xian)間(jian)卻橫(heng)亙(gen)著(zhu)一(yi)(yi)座東(dong)(dong)西狹長的(de)(de)(de)商顏山(shan)(shan)(即今鐵鐮山(shan)(shan))。渠(qu)(qu)(qu)(qu)(qu)(qu)道穿越商顏山(shan)(shan),給施(shi)(shi)工(gong)(gong)(gong)帶來了(le)新的(de)(de)(de)困(kun)(kun)難(nan)。 最初(chu)渠(qu)(qu)(qu)(qu)(qu)(qu)道穿山(shan)(shan)曾(ceng)采用明(ming)挖的(de)(de)(de)辦法(fa),但由于(yu)山(shan)(shan)高四十(shi)余(yu)丈,均為黃土覆(fu)蓋(gai),開挖深渠(qu)(qu)(qu)(qu)(qu)(qu)容易塌方,于(yu)是(shi)(shi)改用井(jing)渠(qu)(qu)(qu)(qu)(qu)(qu)施(shi)(shi)工(gong)(gong)(gong)法(fa)。《史(shi)記·河渠(qu)(qu)(qu)(qu)(qu)(qu)書(shu)(shu)(shu)》記載當時(shi)井(jing)渠(qu)(qu)(qu)(qu)(qu)(qu)施(shi)(shi)工(gong)(gong)(gong)法(fa)的(de)(de)(de)技術要領(ling)是(shi)(shi):“鑿井(jing),深者四十(shi)余(yu)丈。往(wang)往(wang)為井(jing),井(jing)下(xia)相(xiang)(xiang)通行水(shui),水(shui)頹以(yi)絕商顏,東(dong)(dong)至(zhi)山(shan)(shan)嶺十(shi)余(yu)里(li)間(jian)。井(jing)渠(qu)(qu)(qu)(qu)(qu)(qu)之(zhi)生自此始。”開創了(le)后代隧(sui)洞(dong)豎井(jing)施(shi)(shi)工(gong)(gong)(gong)法(fa)的(de)(de)(de)先(xian)河。在(zai)洛(luo)惠渠(qu)(qu)(qu)(qu)(qu)(qu)擴(kuo)建施(shi)(shi)工(gong)(gong)(gong)時(shi),曾(ceng)發(fa)現在(zai)總干渠(qu)(qu)(qu)(qu)(qu)(qu)五號(hao)洞(dong)附近有許多交叉放置的(de)(de)(de)漢柏,大(da)約是(shi)(shi)當年施(shi)(shi)工(gong)(gong)(gong)的(de)(de)(de)遺存。井(jing)渠(qu)(qu)(qu)(qu)(qu)(qu)施(shi)(shi)工(gong)(gong)(gong)法(fa)的(de)(de)(de)工(gong)(gong)(gong)程布(bu)置大(da)致如圖3-5所示。渠(qu)(qu)(qu)(qu)(qu)(qu)道要穿越十(shi)余(yu)里(li)的(de)(de)(de)商顏山(shan)(shan),如果(guo)只從兩(liang)端相(xiang)(xiang)向開挖,施(shi)(shi)工(gong)(gong)(gong)面較(jiao)少(shao)、洞(dong)內(nei)通風(feng)、照明(ming)也(ye)有困(kun)(kun)難(nan)。若在(zai)渠(qu)(qu)(qu)(qu)(qu)(qu)線中途(tu)多打(da)幾個豎井(jing),這(zhe)樣既可(ke)增加(jia)施(shi)(shi)工(gong)(gong)(gong)工(gong)(gong)(gong)作面,又能(neng)加(jia)快施(shi)(shi)工(gong)(gong)(gong)進度,同時(shi)也(ye)改善了(le)洞(dong)內(nei)通風(feng)和采光的(de)(de)(de)條(tiao)件。井(jing)渠(qu)(qu)(qu)(qu)(qu)(qu)法(fa)無疑是(shi)(shi)隧(sui)洞(dong)施(shi)(shi)工(gong)(gong)(gong)方法(fa)的(de)(de)(de)一(yi)(yi)個新創。同時(shi),龍首渠(qu)(qu)(qu)(qu)(qu)(qu)的(de)(de)(de)施(shi)(shi)工(gong)(gong)(gong)還(huan)表(biao)現了(le)測量(liang)技術的(de)(de)(de)高水(shui)平,它在(zai)兩(liang)端不通視(shi)的(de)(de)(de)情況(kuang)下(xia),準確地(di)(di)確定(ding)渠(qu)(qu)(qu)(qu)(qu)(qu)線方位(wei)和豎井(jing)位(wei)置,這(zhe)也(ye)是(shi)(shi)難(nan)能(neng)可(ke)貴(gui)的(de)(de)(de)。在(zai)施(shi)(shi)工(gong)(gong)(gong)中掘出恐龍化石(shi),因(yin)而(er)渠(qu)(qu)(qu)(qu)(qu)(qu)道叫作龍首渠(qu)(qu)(qu)(qu)(qu)(qu)。
經十余年的(de)施工,龍(long)首渠建成,可(ke)惜并(bing)未實現原定的(de)設想。失(shi)敗的(de)原因可(ke)能是由于當時井渠未加襯砌,井渠通水后,黃土遇水坍塌,因而導(dao)致工程的(de)失(shi)敗。
北周(zhou)保定(ding)二(er)年,(公(gong)元(yuan)五六二(er)年)又曾(ceng)在(zai)今大荔開(kai)龍首渠以(yi)利(li)灌(guan)(guan)溉(gai)[注:《周(zhou)書·武(wu)帝紀(ji)上》]。至(zhi)唐代,著(zhu)名水利(li)家姜(jiang)師(shi)度(du)(du)在(zai)這廣(guang)帶重新興建灌(guan)(guan)溉(gai)工程,“于(yu)朝邑、河(he)西二(er)縣界,就古通(tong)靈陂,擇地引洛(luo)水及堰黃河(he)灌(guan)(guan)之,以(yi)種(zhong)稻田,凡兩千余(yu)頃,內置屯十(shi)余(yu)所(suo),收(shou)獲萬計。”[注:《舊唐書·姜(jiang)師(shi)度(du)(du)傳》]姜(jiang)師(shi)度(du)(du)不僅(jin)引洛(luo),而且引黃河(he)水灌(guan)(guan)溉(gai),效益(yi)更加(jia)顯著(zhu)。此(ci)后引洛(luo)灌(guan)(guan)溉(gai)相沿不斷,解放后洛(luo)惠渠進一步擴展,灌(guan)(guan)溉(gai)面積增長至(zhi)六十(shi)余(yu)萬畝。
此外,漢(han)代在(zai)山西(xi)省(sheng)汾水(shui)(shui)(shui)(shui)下(xia)游,也有開(kai)(kai)渠(qu)之舉。大(da)約在(zai)開(kai)(kai)龍首渠(qu)時,河(he)東(dong)太守番系著眼(yan)于(yu)解決(jue)漕運的困難,建(jian)議開(kai)(kai)發(fa)今(jin)山西(xi)省(sheng)西(xi)南一(yi)帶(dai)荒瘠土地,措施是:一(yi)方面(mian)引汾水(shui)(shui)(shui)(shui)灌溉(gai)(gai)皮(pi)氏(今(jin)山西(xi)省(sheng)河(he)津縣西(xi)),和汾陰(今(jin)榮河(he)縣北(bei))的田地,同時也引黃(huang)(huang)河(he)水(shui)(shui)(shui)(shui)灌溉(gai)(gai)汾陰、蒲坂(今(jin)永濟縣)的田地。他估(gu)計渠(qu)道修成(cheng)后黃(huang)(huang)河(he)可灌田五千頃,得谷二百(bai)萬(wan)石以上。這些谷物可從渭水(shui)(shui)(shui)(shui)運往(wang)長安,從而(er)避開(kai)(kai)了(le)三門(men)峽的危險。他的建(jian)議得到(dao)了(le)漢(han)武(wu)帝的批(pi)準,當時征發(fa)了(le)數萬(wan)人動工(gong)開(kai)(kai)渠(qu)。可是渠(qu)道建(jian)成(cheng)后運用了(le)不(bu)多幾年(nian),黃(huang)(huang)河(he)主溜(liu)擺離渠(qu)口,渠(qu)道無(wu)法引水(shui)(shui)(shui)(shui),這一(yi)帶(dai)田地因而(er)又形荒廢。不(bu)過番系的建(jian)議仍不(bu)失其價值,日后解決(jue)了(le)引水(shui)(shui)(shui)(shui)口的技(ji)術問題,這一(yi)帶(dai)灌溉(gai)(gai)事業(ye)重又發(fa)展起來(lai),其是利用山溪洪水(shui)(shui)(shui)(shui)淤(yu)灌,更是本地水(shui)(shui)(shui)(shui)利的一(yi)個特色(se)。
漢武帝(di)(di)時(shi)期,關中(zhong)(zhong)(zhong)農(nong)田水(shui)利(li)工(gong)程發展(zhan)很快,在中(zhong)(zhong)(zhong)國名列前(qian)茅。當時(shi),曾設(she)專官管(guan)理關中(zhong)(zhong)(zhong)水(shui)利(li)。哀(ai)帝(di)(di)時(shi)任命(ming)息(xi)夫躬(gong)“持節(jie)行護三(san)輔都水(shui)”[注(zhu):《漢書·息(xi)夫躬(gong)傳(chuan)》]。司(si)馬遷(qian)評價當時(shi)關中(zhong)(zhong)(zhong)在中(zhong)(zhong)(zhong)國的(de)(de)經(jing)濟(ji)比(bi)重時(shi)曾說:“關中(zhong)(zhong)(zhong)之(zhi)地于(yu)天(tian)下(xia)三(san)分之(zhi)一,而(er)人(ren)眾不(bu)(bu)(bu)過什三(san),然量其(qi)富,什居其(qi)六。”[注(zhu):《史記·貨(huo)殖(zhi)列傳(chuan)》]在以農(nong)業為(wei)主要經(jing)濟(ji)部(bu)門的(de)(de)社會里,關中(zhong)(zhong)(zhong)經(jing)濟(ji)的(de)(de)高度發展(zhan)與農(nong)田水(shui)利(li)建設(she)是有(you)直(zhi)接關系的(de)(de)。不(bu)(bu)(bu)過,關中(zhong)(zhong)(zhong)水(shui)利(li)的(de)(de)發展(zhan)并不(bu)(bu)(bu)是一帆(fan)風(feng)順的(de)(de),在東晉南北朝(chao)戰亂(luan)中(zhong)(zhong)(zhong),雖(sui)曾有(you)施工(gong),但(dan)《水(shui)經(jing)注(zhu)》所記的(de)(de)鄭(zheng)(zheng)白渠(qu)(qu)各(ge)干(gan)渠(qu)(qu)已全部(bu)斷水(shui)。至(zhi)唐(tang)代,重又恢復,不(bu)(bu)(bu)僅設(she)有(you)關中(zhong)(zhong)(zhong)諸(zhu)渠(qu)(qu)“渠(qu)(qu)堰使”注(zhu):唐(tang)貞元(yuan)十六年(公元(yuan)八零零年)“使徐班兼白渠(qu)(qu),漕渠(qu)(qu)及升原,成國等渠(qu)(qu)堰使”《唐(tang)會要·疏鑿利(li)人(ren)》。而(er)且各(ge)支渠(qu)(qu)上的(de)(de)斗門,也(ye)設(she)有(you)“斗門長”,專司(si)灌溉(gai)用水(shui)的(de)(de)分配[注(zhu):《唐(tang)六典》卷二十三(san)。管(guan)理制度也(ye)較(jiao)為(wei)周密(mi),但(dan)在豪強兼并下(xia),鄭(zheng)(zheng)白渠(qu)(qu)灌溉(gai)面(mian)積日漸縮小。由此可見(jian),社會政治對于(yu)水(shui)利(li)的(de)(de)影響較(jiao)對其(qi)他(ta)技術方面(mian)更為(wei)直(zhi)接。
龍(long)首(shou)渠(qu)(qu)的(de)(de)建(jian)成,使4萬(wan)余公頃的(de)(de)鹽堿地(di)(di)得到(dao)灌溉(gai),并使其變成“畝產(chan)十石(shi)(音但dan,容量(liang)單位(wei),1石(shi)等(deng)(deng)于10斗)”的(de)(de)上等(deng)(deng)田,產(chan)量(liang)增加了(le)10倍多。這(zhe)段穿過商顏山(shan)的(de)(de)地(di)(di)下渠(qu)(qu)道長達5公里多,是(shi)中國歷史(shi)(shi)上的(de)(de)第一條地(di)(di)下渠(qu)(qu),在世界水(shui)利史(shi)(shi)上也(ye)是(shi)一個(ge)偉大的(de)(de)創造。井(jing)渠(qu)(qu)法(fa)在當(dang)時就通(tong)過絲綢之路傳到(dao)了(le)西(xi)域,直到(dao)今天,新(xin)疆人(ren)民(min)在沙漠(mo)地(di)(di)區仍然(ran)用(yong)這(zhe)種(zhong)(zhong)井(jing)渠(qu)(qu)結合的(de)(de)辦法(fa)修(xiu)建(jian)灌溉(gai)渠(qu)(qu)道,叫(jiao)作“坎兒井(jing)”。中亞和西(xi)南亞的(de)(de)干旱地(di)(di)帶也(ye)用(yong)這(zhe)種(zhong)(zhong)辦法(fa)灌溉(gai)農田。西(xi)漢龍(long)首(shou)渠(qu)(qu)的(de)(de)井(jing)渠(qu)(qu)法(fa)是(shi)中國古代漢族勞動(dong)人(ren)民(min)高度智慧的(de)(de)結晶,它(ta)為世界水(shui)利事業提供了(le)寶貴的(de)(de)經驗。
龍首渠(qu)(qu)興(xing)修之后,沒(mei)有(you)延續下來(lai),因時過(guo)境遷,留下的遺址(zhi)據一(yi)些專家調(diao)查,主要有(you)鐵鐮山人(ren)工渠(qu)(qu)槽,遺址(zhi)位(wei)于(yu)今(jin)西(xi)安韓城鐵路遠(yuan)志(zhi)山村(cun)鐵路線(xian)北(bei)側(ce)。陽泉(quan)溝深挖方渠(qu)(qu)段,位(wei)于(yu)陽泉(quan)溝口(kou)向(xiang)上(shang)至洛(luo)惠渠(qu)(qu)4號隧洞(dong)(dong)下口(kou)。洛(luo)惠渠(qu)(qu)修5號隧洞(dong)(dong)時,采用了漢(han)龍首渠(qu)(qu)創始的“井(jing)(jing)渠(qu)(qu)”施工法,即在洞(dong)(dong)線(xian)的山坡上(shang),每(mei)隔300米打(da)一(yi)眼豎(shu)井(jing)(jing)。1944年4月,興(xing)建(jian)洛(luo)惠渠(qu)(qu)時,在5號洞(dong)(dong)隧洞(dong)(dong)13、16、18號工作井(jing)(jing)處(chu),挖出(chu)松柏(bo)木(mu)板(ban)及(ji)人(ren)字支架(jia)等,經考(kao)證(zheng)為西(xi)漢(han)時龍首渠(qu)(qu)遺跡,在今(jin)大(da)荔縣城西(xi)北(bei)13.5公(gong)里義井(jing)(jing)村(cun)村(cun)北(bei)。
在龍(long)首(shou)渠(qu)(qu)遺跡(ji)重點調查的(de)(de)(de)一(yi)段于2600米(mi)間發現(xian)豎井7個,相(xiang)鄰井的(de)(de)(de)間距(ju)為11米(mi)、160米(mi)、224米(mi),井口直(zhi)徑1. 24米(mi)一(yi)1. 26米(mi)不等,已探明的(de)(de)(de)井的(de)(de)(de)深度27. 80米(mi),深及黃沙土層,井內發現(xian)漢代常(chang)見的(de)(de)(de)繩紋板瓦、筒瓦及陶罐、甕、盆(pen)、釜等殘片。調查報告沒有(you)提及地下(xia)暗渠(qu)(qu)的(de)(de)(de)結構情(qing)況,也未發現(xian)后來北周(zhou)重加開浚時留下(xia)的(de)(de)(de)痕跡(ji)。
1944年(nian)鑿(zao)洛惠渠(qu)五號隧洞(dong)時,曾在(zai)八號豎井(jing)以北,十八、十六、十三號豎井(jing)的工作(zuo)井(jing)中(zhong)發現有西漢時期的柏木(mu)板(ban)和柏木(mu)作(zuo)成的支撐框架。木(mu)頭材(cai)質堅(jian)硬,長2米,均呈(cheng)“人”字形交(jiao)叉排列,顯系(xi)渠(qu)洞(dong)的支護材(cai)料。
陜西古代引(yin)北洛(luo)水的灌(guan)溉工(gong)(gong)程,洛(luo)惠渠(qu)(qu)(qu)的前身(shen)。位于(yu)今蒲城、大(da)荔(li)一帶,創建于(yu)漢武帝(di)元狩三(san)年至元鼎(ding)六年(公(gong)元前120-前111)。當時征(zheng)調1萬多人開渠(qu)(qu)(qu),干(gan)渠(qu)(qu)(qu)自征(zheng)縣(今澄城縣南(nan))引(yin)洛(luo)水,向南(nan)至臨(lin)晉境,再回注洛(luo)水,灌(guan)溉1萬多頃(qing)鹽堿地(di)。施(shi)工(gong)(gong)中(zhong)最艱(jian)巨的一段穿越(yue)商顏山(shan)。商顏山(shan)高40余丈(zhang),明挖(wa)(wa)時渠(qu)(qu)(qu)岸易崩坍,于(yu)是改用隧(sui)洞。隧(sui)洞全長10多里,為了增(zeng)加施(shi)工(gong)(gong)工(gong)(gong)作面(mian) 和滿足若干(gan)豎井。這種隧(sui)道(dao)稱井渠(qu)(qu)(qu)。由于(yu)施(shi)工(gong)(gong)時挖(wa)(wa)出了龍(long)骨(化石),渠(qu)(qu)(qu)道(dao)遂(sui) 命名為龍(long)首渠(qu)(qu)(qu)。