珠三角門戶城市惠州和端州“山—湖—城—江”格局的形成機(jī)制

趙茜瑤 林箐

中國(guó)傳統(tǒng)山水城市中，形成“山—湖—城—江”結(jié)構(gòu)的城市不在少數(shù)，并且以優(yōu)美的湖山風(fēng)光聞名于世。它們有的位于濱海沖積平原，有的位于深厚的堆積平原，在不同的自然地理?xiàng)l件中形成了相似的城市山水結(jié)構(gòu)。其背后是順應(yīng)自然資源、因地制宜的城市營(yíng)建傳統(tǒng)的在地實(shí)踐。同時(shí)也形成了獨(dú)特的城市景觀特色和完整的城市環(huán)境韌性系統(tǒng)。然而在當(dāng)代中國(guó)的城市化進(jìn)程中，自古以來形成的“十里不同風(fēng)，百里不同俗”的獨(dú)特城市風(fēng)貌正逐漸淹沒在全球化浪潮之中，趨同的城市建設(shè)方式和景觀導(dǎo)致富有本土特色的城市生活無法有效開展而逐漸消失，自然環(huán)境遭到破壞，極端災(zāi)害頻發(fā)。在這樣的背景下，研究山水范式的地方實(shí)踐，探索城市內(nèi)外的自然系統(tǒng)如何通過山水營(yíng)建聯(lián)系起來，將為避免城市特色危機(jī)、保護(hù)城市生態(tài)環(huán)境、提升現(xiàn)代城市韌性帶來一定的啟發(fā)和指導(dǎo)。

不同于北方地區(qū)由于下游河流的頻繁改道，城市往往選擇在與大江大河有一定距離的地方建設(shè)，中國(guó)南方的城市與水系的關(guān)系往往更為親近，城市常常直接臨江而建[1]。珠江流域位于中國(guó)大陸南陲，由于特殊的地理、氣候因素，在古代社會(huì)發(fā)展較晚?；葜菖c端州（現(xiàn)肇慶）作為古代珠江地區(qū)的重要府城，是珠江的主要支流東江和西江進(jìn)入珠江三角洲的門戶城市，具有分領(lǐng)廣東東西二翼的重要戰(zhàn)略位置。兩座城市在古代開展城市建設(shè)的時(shí)間相對(duì)較早，并持續(xù)千年在相同城址進(jìn)行城市建設(shè)，均形成了“山—湖—城—江”的山水結(jié)構(gòu)，成為珠江三角洲地區(qū)重要的風(fēng)景城市，具有較強(qiáng)的相似性（圖1）。以往的研究往往從單一城市造景手法、審美意趣、水利和園林建設(shè)等角度出發(fā)，忽視了城市以及湖泊能夠得以留存的原因和規(guī)律。通過分析研究歷史上惠州與端州在城市選址和城市山水格局的建設(shè)過程，從珠三角區(qū)域的角度可以更深入地發(fā)掘古人在人居環(huán)境體系建設(shè)方面的創(chuàng)造性智慧。

1 區(qū)域條件與城市

1.1 珠三角地區(qū)的自然基底

惠州和端州所處的珠三角地區(qū)，處于地殼構(gòu)造的沉降區(qū)，是海陸之間的過渡地帶。其外圍山丘環(huán)繞、眾水匯流，堆積作用旺盛，形成了高度發(fā)育的三角洲景觀。珠三角屬南亞熱帶海洋性氣候，雨量集中，降雨強(qiáng)度大，加之河流本身徑流量大，洪水泛濫時(shí)有發(fā)生。自然條件下河流易發(fā)生決口，形成汊流，甚至使干流改道，形成河、涌綜合交錯(cuò)的水域景觀。洪水泛濫還造成自然堤；泥沙堆積，堤身加高，又可形成排水不良的堤后沼澤。因此防洪排澇成為泛濫平原生產(chǎn)生活的重要問題，也成為后期該地區(qū)人類生產(chǎn)建設(shè)活動(dòng)的基礎(chǔ)[2]。

1.2 區(qū)域地理?xiàng)l件與城市選址

惠州和端州城市建設(shè)的必要性主要是由區(qū)域自然地理?xiàng)l件影響下形成的門戶地位所決定的。惠州“東距潮，西連廣，比接贛，南極于?！保鳌ぜ尉浮痘葜莞尽罚『锰幱趶闹榻侵尥ㄏ蚧洊|蓮花山脈南北兩側(cè)地區(qū)的“丫”字形路線的交叉點(diǎn)，可以聯(lián)系廣州和江西、福建，扼守廣東東部[3]。這促使了惠州城的產(chǎn)生興起以及長(zhǎng)期處于地區(qū)行政中心的地位，并使之發(fā)展為粵東地區(qū)與珠江三角洲地區(qū)之間最為重要的人流、物流集散地。而顧祖禹在《方輿紀(jì)要》一書的肇慶府條目中之記述：“府帶山控江，袤數(shù)千里，據(jù)廣州之上游，當(dāng)賀、梧之津要?！倍酥莸靥幹榻侵尬骶?，扼西江的總口，北面可溯西江支流桂江、賀江等，越過南嶺可接瀟湘，通達(dá)長(zhǎng)江流域，南有新興江及陸道可至高州、雷州等地[4]。實(shí)為兩廣之間的咽喉，廣州西面之屏障。不僅為政治、軍事重鎮(zhèn)，而且是西江流域水運(yùn)樞紐和經(jīng)濟(jì)中心（圖2）。

惠州和端州城市的自身選址則體現(xiàn)了對(duì)區(qū)域自然環(huán)境和門戶城市需求的準(zhǔn)確判斷，具體體現(xiàn)在以下幾方面。

1）河流改道。依水而建的城市，河流的變遷將直接影響城址的選擇。據(jù)學(xué)者考證[5]，宋代以前，惠州地區(qū)的東江及其支流西枝江周邊尚有明顯的河流三角洲地貌景觀，東江河道發(fā)生過數(shù)次擺動(dòng)，惠州古城的位置也隨之發(fā)生了4次移動(dòng)。宋代以后，隨著對(duì)東江地區(qū)的開發(fā)程度增大，“圍堤興筑”帶來農(nóng)業(yè)的繁榮。人工圍墾促使東江下游三角洲放射狀的水道系統(tǒng)成為單一正干流道，直接限制了東江河道的自然擺動(dòng)，府城的選址也自此沒有再發(fā)生過改變（圖3）。端州城址處于西江故道和西江之間的高地上，同樣也是應(yīng)對(duì)水流量極大的西江水患風(fēng)險(xiǎn)的選擇。

2）交通商貿(mào)需求。河流走廊往往是天然的水陸交通廊道。唐宋時(shí)期，由于廣州在全國(guó)中外貿(mào)易中的地位不斷上升，由廣州輸入的商品需要向北運(yùn)輸，加之國(guó)家政治中心向南移動(dòng)，廣東地區(qū)的交通線地位更顯重要?；葜荨⒍酥莘謩e扼守進(jìn)出廣州的東、西要道，出于對(duì)往來的船舶和陸上商隊(duì)的管理以及進(jìn)出口貨物的轉(zhuǎn)運(yùn)等方面的需求，沿江設(shè)置具備政治、經(jīng)濟(jì)中心性質(zhì)的州城十分必要。

3）城市安全。由于遠(yuǎn)離中央政權(quán)又瀕臨大江，軍事防御和防洪是城市安全重點(diǎn)考慮的方面?；葜莞沁x址在兩江交匯處，于此地設(shè)城，便于扼控水陸交通的要沖之地。在城西的山前湖泊（后演變?yōu)槲骱?，水面浩大，與兩江一道將城環(huán)抱，易守難攻。經(jīng)過人工筑堤攔水和疏浚改造，湖泊也發(fā)揮著水柜作用，承接山前匯水的同時(shí)也起著調(diào)蓄東江水量、排水排洪的功用，保護(hù)城市安全[6]。在端州，古人卻未似惠州一般選擇距端州不遠(yuǎn)的北江和西江匯流之處建城。原因是此地雖有交通之利，但周邊毫無屏障且兩江匯合，水患威脅嚴(yán)重。而端州所在之處三榕峽、大鼎峽、羚羊峽由西至東把守西江咽喉，北有水澤和高山為障，這使端州成為天然易守難攻之地，又能借西江之便。

1.3 區(qū)域條件對(duì)“山—湖—城—江”格局形成的影響

優(yōu)良的區(qū)域地理位置使得城市具備優(yōu)先發(fā)展物質(zhì)經(jīng)濟(jì)，進(jìn)行城市營(yíng)建的可能。兩城分扼東江、西江總口，是珠三角腹地進(jìn)入粵東地區(qū)和粵西地區(qū)的門戶，戰(zhàn)略位置重要，在歷史上均長(zhǎng)期被統(tǒng)治階級(jí)當(dāng)作地方中心[7]，在發(fā)展上處于區(qū)域的前列。此外出于戰(zhàn)略防御目的對(duì)要塞城市的建設(shè)傾斜和士大夫官員的派遣等，也推動(dòng)了城市發(fā)展和風(fēng)景營(yíng)建。

而城市自身選址，則受中國(guó)古代建城勘察相地的“形勝”思想影響，使之具備了各個(gè)山水要素和營(yíng)建山水城市的便利條件。兩城選址周邊均具備背山面水的自然山水格局，并且在山與城之間均有大片水澤作為后期形成湖泊的基礎(chǔ)自然條件。惠州和端州均緊靠江水，表現(xiàn)出極強(qiáng)的親水性，這一現(xiàn)象在中國(guó)其他的大江大河是不多見的，形成了珠江流域傳統(tǒng)山水城市的特色。選址一方面充分利用了江、湖作為城市的防御屏障和基礎(chǔ)設(shè)施，另一方面也面臨著較高的洪水風(fēng)險(xiǎn)，因此城市營(yíng)建需要通過整理水系、發(fā)展湖泊和防洪堤防措施提升城市安全，在天然的山水結(jié)構(gòu)上最終形成城湖相依的山水城市環(huán)境。

2 “山—湖—城—江”格局的形成

2.1 城湖一體的惠州府城

1 現(xiàn)代惠州和端州的城市山水風(fēng)景Urban landscape of modern Huizhou and Duanzhou

2 惠州和端州的區(qū)域地理?xiàng)l件Regional geographical conditions of Huizhou and Duanzhou

3 惠州城市選址變遷Change process of Huizhou city site selection

惠州西湖因位于城西而得名，其形成是自然和人工共同作用的結(jié)果。據(jù)《惠州西湖志》記載，大約于東晉年間，受東江自然堤的阻攔，東江泛濫的洪水、西面山地的匯水和山中涌泉在東江之南和西枝江之西的低洼地匯聚形成湖面。由于自然堤時(shí)決時(shí)成，湖泊難以常年保持穩(wěn)定水位，常常處于一時(shí)豐盈一時(shí)干涸的狀態(tài)，直到宋時(shí)筑堤攔蓄湖水，才成為經(jīng)常性湖泊。西湖能維持至今，離不開歷代的修堤蓄水。建造與維護(hù)惠州西湖的活動(dòng)與惠州城市的韌性發(fā)展息息相關(guān)，主要體現(xiàn)在以下幾個(gè)方面。

1）保障城市安全是西湖進(jìn)行水利開發(fā)的首要?jiǎng)右??；葜葑怨攀潜冶貭?zhēng)之地，西湖和東江、西枝江一起讓城市幾乎四面環(huán)水，易守難攻。為了守住這道防衛(wèi)屏障，歷朝歷代的地方官員均很重視西湖湖水的集蓄?；葜莞墙ㄓ谏健⒔g，春夏汛期會(huì)受到山洪和江水暴漲的威脅。西湖的存在，可對(duì)洪水起到調(diào)節(jié)作用，保護(hù)府城安全。西湖主要通過拱北堤、碧水關(guān)、南隱堤3處水利設(shè)施進(jìn)行洪水的調(diào)節(jié)，并與堤、閘、城墻、渠道等工程構(gòu)筑物一起形成一個(gè)可蓄可泄且具有防洪效益的城市水利工程系統(tǒng)，維護(hù)城市韌性發(fā)展。

2）惠州府城城市的營(yíng)建和西湖的開發(fā)是相互推進(jìn)的，城市發(fā)展加速了對(duì)西湖的開發(fā)利用，西湖的存在也深刻影響了惠州府城的空間形態(tài)發(fā)展。西湖水量豐沛，水域廣闊，“溉田數(shù)百頃，葦藕蒲漁之利，歲數(shù)萬”（民國(guó) 《惠州西湖志》），促進(jìn)了惠州小農(nóng)經(jīng)濟(jì)的發(fā)展，城市人口不斷增加。隨著淡水需求加大，明初時(shí)在擴(kuò)建城池時(shí)將一部分西湖水引入城內(nèi)，又因筑城開鑿了一些地方，共同形成百官池（鵝湖）。西湖水在此池經(jīng)過停蓄澄清后作為水源供官民使用，再通過碧水關(guān)排入江內(nèi)，并與城內(nèi)其他排水溝渠一道為城市泄洪排水和防火功能服務(wù)。

3）宋時(shí)的惠州府城面積尚小，城市與湖并未直接接壤。但此時(shí)惠州經(jīng)濟(jì)發(fā)展迅速，在規(guī)模開發(fā)下，西湖已成為承擔(dān)惠州府城水利、游賞與文化的一處重要水體。在明清時(shí)期由于城市進(jìn)一步發(fā)展擴(kuò)張，逐漸形成與江湖水岸形態(tài)緊密貼合的城市形態(tài)。這一形態(tài)還讓惠州得名鵝城，沿用至今。但隨著人口不斷增長(zhǎng)，府城附近用地緊張，大約自明代起，出現(xiàn)了與湖爭(zhēng)地的情況，占湖為屋為田的現(xiàn)象時(shí)有發(fā)生。為了維護(hù)西湖，當(dāng)?shù)毓賳T自宋至民國(guó)時(shí)期組織了多次修繕和疏浚，重視對(duì)改造、化育后的“人工自然”精心照顧，制定相應(yīng)禁令和管理制度。這才使得西湖不至于堙廢成田，鵝湖不致淤為平地，才能歷經(jīng)千年持續(xù)發(fā)揮多種效益（圖4）。

4）古代惠州的歷代官員和居民在對(duì)西湖進(jìn)行水利和農(nóng)業(yè)生產(chǎn)開發(fā)的同時(shí)，也發(fā)掘了其風(fēng)景資源價(jià)值。西湖周邊最早的風(fēng)景建設(shè)可以追溯到傳說中東漢的伏虎臺(tái)和晉代的龍興寺、唐代的泗州塔等佛教建筑的興筑。宋代開始通過筑堤攔湖形成常年湖泊后，風(fēng)景建設(shè)的理水通過水利、交通和城防工程的建設(shè)形成的堤網(wǎng)系統(tǒng)得以完成[8]，形成水面豐盈、湖山相映、水光接天、幽深曠朗的自然格局。宋以后文人士大夫或直接參與西湖的建設(shè)或游歷題詠，帶來文人寫意的內(nèi)涵與風(fēng)格，“苧蘿西子”的景觀逐漸形成。

惠州是目前有文獻(xiàn)可考的珠三角地區(qū)最早具有城市“八景”的州府城市。北宋惠州郡守陳稱“筑堤捍江，以全西湖”（明·《明一統(tǒng)志》），使西湖得以成湖，惠州的漁業(yè)、農(nóng)業(yè)得到極大發(fā)展。西湖的整治工程經(jīng)驗(yàn)和官員本身的審美文化修養(yǎng)，使郡守具備高度概括惠州景觀的能力。他題寫的北宋八景囊括東江、西湖以及西湖水源地的關(guān)鍵之處，一半集中于西湖，一半集中在外部的江山勝景，將西湖與府城圈定其中，呈現(xiàn)出田園湖山城市的特色。此后，府城的品題數(shù)量不斷增加，至民國(guó)時(shí)期張友任撰寫《惠州西湖志》時(shí)擴(kuò)展為十七景，并始終保持以湖山風(fēng)光為主的特色。通過不斷的人工建設(shè)和詩詞唱詠，共同將湖山與詩文關(guān)聯(lián)化，使惠州始終保持著湖城交融的城市特色（圖5）[9]。

2.2 端州府城與星湖

星湖舊稱瀝水，原是西江故道旱峽在北嶺山下形成的一片水鄉(xiāng)澤國(guó)。古代西江發(fā)洪水的時(shí)候，當(dāng)上游洪峰到達(dá)肇慶段時(shí)，由于羚羊峽處西江河道突然收窄，使得西江分流一支在龜頂山北面進(jìn)入旱峽，后在羚山附近分3支匯入西江。隨著嶺南地區(qū)在宋代的大發(fā)展，出于保護(hù)生產(chǎn)生活安全和獲取可利用土地的目的，人們對(duì)這一地區(qū)開始進(jìn)行人工整理，最終在城市以北形成大型湖泊。

星湖所處的這片水域最初對(duì)于端州府城的作用主要在于行洪排澇，影響城址的選擇。根據(jù)文獻(xiàn)記載“兩水夾州，則西江勢(shì)分，無泛濫之患，形勢(shì)更宜”（清·李調(diào)元《南越筆記》）。因此端州府城建設(shè)在一小山岡之上，利用二水分流減輕城市排洪壓力，減少洪澇災(zāi)害發(fā)生。但是“端郡東北附郭，田數(shù)百頃，諸水匯于瀝湖，春夏水溢，則田胥沒?！保ㄇ濉缎y(tǒng)高要縣治》）為了保障城市周邊農(nóng)業(yè)生產(chǎn)的安全，歷代官民對(duì)瀝水進(jìn)行多次治理，修后瀝水、躍龍竇、新瀝等水道引導(dǎo)瀝水入西江。并在城外自三榕峽至羚羊峽修筑堤圍，防止西江重新進(jìn)入舊河道引發(fā)洪澇[10]。積水基本排走的同時(shí)，西江也被固定在南邊的水道，進(jìn)而出現(xiàn)大片適宜耕種的土地。

4 惠州府城和惠州西湖的營(yíng)建過程The construction process of Huizhou city and the West Lake

古代肇慶地區(qū)山民、疍民及少數(shù)民族較多，動(dòng)亂頻繁。平原風(fēng)貌的變化和維持社會(huì)穩(wěn)定的需要促使府城城池開始建設(shè)，自宋起經(jīng)過歷代的不斷修葺，形成尤為高大堅(jiān)固的城墻，在軍事防御和抵御洪水方面多次發(fā)揮重要作用，并因其防洪方面的突出功用被保留至今。端州府城城池呈較為規(guī)整的長(zhǎng)方形，沿西江方向?yàn)殚L(zhǎng)軸，順應(yīng)河流的形態(tài)。城外沿城墻在城的東、西、北三側(cè)挖掘城濠，并通過水門與城內(nèi)的上下濠相連通。城濠體系通過與西江水系及瀝湖聯(lián)通，形成一套具有調(diào)蓄功能的城市水系。城內(nèi)水面的分布與城內(nèi)的功能布置相聯(lián)系，發(fā)揮著軍隊(duì)官船停泊、生活用水供應(yīng)、防火等多方面的功能[11]。

西江流域魚類資源豐富，端州地區(qū)自唐代起利用近水之便，開始塘魚生產(chǎn)，并經(jīng)西江水運(yùn)對(duì)外銷售。宋代隨著廣東地區(qū)的大開發(fā)，此地開始興修水利，開渠筑池，排水造田。通過將洼地?田筑成魚塘，種植蒲草等水生經(jīng)濟(jì)作物，肇慶平原的自然風(fēng)貌逐步發(fā)生改變。明清時(shí)期延續(xù)了農(nóng)耕的傳統(tǒng)，瀝湖周邊始終一片田園景象。魚塘水田的格局為日后瀝湖擴(kuò)大，提供了便利條件。但到清晚期和民國(guó)時(shí)期，瀝湖逐漸失修，淤積為田塘，水面急劇縮小，“僅一渠流經(jīng)巖前，強(qiáng)名為湖”（《民國(guó)高要縣志》），排水的渠涌淤塞，致使?jié)碁?zāi)嚴(yán)重。新中國(guó)成立以后通過水庫工程將原來澇患嚴(yán)重的部分低產(chǎn)田和?塘聯(lián)成互相連通的6個(gè)湖面，用于蓄納徑流、消納洪水和灌溉，最終形成星湖（圖6）。

星湖附近最重要的景觀是七星巖，因7座形態(tài)各異的石灰?guī)r山峰立于湖中而聞名。七星巖雖距離端州府城數(shù)里，但秀美的風(fēng)光使人們很早就認(rèn)識(shí)到這幾座孤峰的風(fēng)景價(jià)值，將之比作嵩臺(tái)蓬萊。早在晉代七星巖便見于文字記錄，歷代文人騷客留下不少詩句文章。對(duì)于七星巖的開發(fā)建設(shè)，除了石刻較早出現(xiàn)，整體基本以保持自然天成的景色為主。歷代官員均十分重視對(duì)七星巖的保護(hù)，多次頒布禁止開發(fā)采石的禁令。隨著肇慶地區(qū)宗教文化的興盛，七星巖內(nèi)開始建設(shè)寺廟以及若干園林建筑，以明代最盛。在民國(guó)時(shí)期曾成立“七星巖公園會(huì)”主持公園建設(shè)工作，但工程中輟[12]。新中國(guó)后建成星湖后，成立廣東地區(qū)首個(gè)國(guó)家級(jí)風(fēng)景名勝區(qū)。

端州四面環(huán)山，地理位置險(xiǎn)要，明初出現(xiàn)的初版八景以四周山體景致為主，反映了端州作為區(qū)域重鎮(zhèn)注重選址布局的整體意識(shí)。在洪水威脅和軍事防御的需求下，城防工程和水利設(shè)施的建設(shè)成為歷代城市管理者的重點(diǎn)事務(wù)，因此后續(xù)的八景中出現(xiàn)水利和城防景觀?！鞍濉薄盀r湖返棹”等被列入端州八景。此后隨著佛教的興盛以及七星巖和鼎湖山等的陸續(xù)發(fā)現(xiàn)和整理，人工構(gòu)筑的占比逐漸加大（圖7）。

2.3 兩城 “山—湖—城—江”格局的形成特色

2.3.1 “山—湖—城—江”的山水格局

惠州和端州的山水格局均是在天然山水結(jié)構(gòu)下經(jīng)過人工修繕形成的，天然山水結(jié)構(gòu)的特點(diǎn)是湖泊形成和城市營(yíng)建選址的前提，決定惠州自西向東形成了“山—湖—城—江”的景觀序列，而在端州這一序列轉(zhuǎn)變?yōu)樽员毕蚰?，進(jìn)而影響了城市的空間形態(tài)?；葜莞鞘苤朴谒虬毒€和有限的土地，形成了紡錘形、南北為長(zhǎng)軸的城市形態(tài)，城市與自然山水之間貼合緊密。而端州由于西江北岸土地面積大，城市形態(tài)受制于自然條件的情況少，可以形成規(guī)整的城池，但仍呈現(xiàn)沿江發(fā)展的特點(diǎn)（圖8）。

2.3.2 人工與自然結(jié)合的湖泊發(fā)展歷程

古代中國(guó)的城市離不開農(nóng)耕和水利建設(shè)的基礎(chǔ)，西湖始于蓄水，瀝湖始于排水，但其本質(zhì)均是為了整理土地以用于農(nóng)業(yè)和城市開發(fā)。兩城均建設(shè)了以城內(nèi)濠池與城外湖泊為主，與江相連的城市水系。對(duì)于濱水城市的城市安全和可持續(xù)發(fā)展具有重要的作用，促進(jìn)了山、水、城一體的空間結(jié)構(gòu)形成。作為城市的支撐系統(tǒng)，一定程度上保證了惠州和端州在中國(guó)古代能夠在水文條件復(fù)雜多變的珠江三角洲地帶長(zhǎng)期穩(wěn)定發(fā)展。兩座城市將水系建設(shè)與城市風(fēng)景開發(fā)融為一體，經(jīng)過歷代的疏浚整治和修建整理，在滿足水利需求的同時(shí)創(chuàng)造出聞名天下的湖光勝景，風(fēng)景建設(shè)過程在時(shí)空分布上雖然存在較大差異，但是其背后營(yíng)建山水城市的思路是一致的。

2.3.3 城市景觀特色的塑造

惠州和端州作為古代珠江三角洲區(qū)域除廣州外的2個(gè)區(qū)域文化的核心城市，較早出現(xiàn)了“城市八景”。2個(gè)府城均有大型江湖山水濕地相伴，八景的變化可以反映城鄉(xiāng)物理環(huán)境的變化和審美訴求的變遷。通過對(duì)比兩城的八景內(nèi)容可見，兩城雖具有相似的湖山結(jié)構(gòu)，但是基于兩地不同的自然地理特色和人文底蘊(yùn)，形成的八景具有不同的特色?；葜莅司爸谐呛惑w的特色始終如一，而端州則經(jīng)歷了由展現(xiàn)地方形勝向關(guān)注人工構(gòu)筑轉(zhuǎn)變的過程。兩城在風(fēng)景集稱上的差異，反映出地方文化在城市山水體系建設(shè)中的作用。

3 結(jié)語

惠州和端州兩座府城在歷史長(zhǎng)河中逐漸形成具備湖山結(jié)構(gòu)的臨江山水城市，城市的人工環(huán)境和自然環(huán)境通過古人傳統(tǒng)的空間規(guī)劃策略和工程建設(shè)緊密地結(jié)合在一起。其本質(zhì)是基于城市所在區(qū)域的地理?xiàng)l件進(jìn)行的人工干預(yù)和水文梳理的過程[13]。通過改造自然、發(fā)展農(nóng)業(yè)培育土地、建設(shè)抵御災(zāi)害的安全支撐體系等方式形成了山、湖、城、江一體的景觀系統(tǒng)，滿足了古人的生存需要，也承載了古人對(duì)生活的藝術(shù)追求[14]。時(shí)至今日，惠州和肇慶均面臨著老城區(qū)建設(shè)飽和、山體破壞、水系統(tǒng)失衡的問題，原本和諧的山水城市面臨嚴(yán)峻挑戰(zhàn)。作為著名的山水城市，湖山范式在珠江流域的代表實(shí)踐，雖然這兩座城市的傳統(tǒng)城湖關(guān)系早已發(fā)生改變，但在珠江三角洲地區(qū)快速城市化的今天，兩城所代表的傳統(tǒng)城市設(shè)計(jì)，對(duì)于提升三角洲城市韌性，增強(qiáng)城市的可持續(xù)發(fā)展依然有較為重要的現(xiàn)實(shí)意義。可以得到以下3方面的啟示。

1）空間上，對(duì)于三角洲地區(qū)的城市來說，水系是城市空間的重要組成部分，是聯(lián)系城市內(nèi)外的自然系統(tǒng)的重要結(jié)構(gòu)。城市空間發(fā)展應(yīng)該注意保障對(duì)城市具有重要功能價(jià)值的藍(lán)綠系統(tǒng)，與河流、湖泊的動(dòng)態(tài)水文過程相協(xié)調(diào)，才能增強(qiáng)城市自然系統(tǒng)的承災(zāi)韌性。

2）時(shí)間上，三角洲城市往往具有很強(qiáng)的親水性，在濱水空間積累了深厚的城市歷史文脈信息。城水之間的互動(dòng)關(guān)系應(yīng)該得到合理的引導(dǎo)發(fā)展，通過整合濱水空間的自然和人文價(jià)值來適應(yīng)城市未來的發(fā)展方向。

3）功能上，對(duì)于具有優(yōu)美山水結(jié)構(gòu)的城市，山水環(huán)境的生態(tài)功能和美學(xué)功能目標(biāo)應(yīng)轉(zhuǎn)化為城市發(fā)展的空間約束，制定合理的土地開發(fā)計(jì)劃。充分發(fā)揮城市山水格局系統(tǒng)的環(huán)境、經(jīng)濟(jì)和社會(huì)等綜合效益。

圖片來源：

圖1中端州照片引自http://www.chinadaily.com.cn/m/guang dong/zhaoqing/2011-06/14/content_12689952.htm，惠州照片由暖木先生提供；圖2根據(jù)谷歌地圖繪制；圖3根據(jù)參考文獻(xiàn)[5]繪制；圖4據(jù)《惠州西湖志》《惠州市城市建設(shè)志》相關(guān)圖紙推測(cè)改繪；圖 5、7 據(jù)參考文獻(xiàn)[9]繪制；圖6據(jù)《高要縣志》《肇慶府屬基圍圖》《端州區(qū)水利志》相關(guān)圖紙推測(cè)改繪。

Among traditional Chinese landscape cities,there are a great deal that have developed under the structure of “mountain-lake-city-river”, and become world-renowned for the beautiful scenery of lakes and mountains, some of which are located in the coastal alluvial plains, some of which are located in the thick accumulational plains. These cities take shape of a similar urban landscape structure, as a result of adjusting to the nature law and following the local conditions, gradually developing a unique urban landscape feature and a complete urban environmental resilience system,however, the tide of globalization is gradually encroaching on the unique urban style featured in ancient times. The local characteristics of urban life can not be effectively carried out and are gradually disappearing in the convergence of urban construction methods and landscapes. A series of problems such as frequent extreme disasters and damaged natural environment, has made the further research on realization of landscape model and the exploration on how to build the natural system by connecting the water and mountain inside and outside city more significant, for avoiding the city crisis, protecting the ecological environment and increasing the city resilience.

Different from the frequent diversion of downstream rivers in northern areas, cities in southern China often have a closer relationship with the water systems so that cities are often built directly by rivers[1]. Huizhou and Duanzhou (now called Zhaoqing) are significant capital cities in the ancient Pearl River region, and the gateway cities of the main tributaries of the Pearl River,taking a significant strategic position to separate the east and west wings of Guangdong. The two cities have formed a “mountain-lake-city-river”landscape structure, becoming an important scenic city in the Pearl River Delta region, with strong similarity (Fig. 1). Previous studies often start from the perspective of single-city landscape-making,aesthetic interest, water conservancy and garden construction, ignoring the reasons and laws that cities and lakes can be preserved. Through the analysis of Huizhou and Duanzhou’s historical urban site selection and construction process of urban landscape pattern, it can deeply explore the creative wisdom of the ancients in the construction of the human settlements environment system from the perspective of special regions.

1 Regional Conditions and Cities

1.1 Natural Bases of Pearl River Delta Region

Huizhou and Duanzhou in the Pearl River Delta region are located in a subsidence area of crustal structure, which is a transitional zone between land and sea. Its peripheral hills surround, the flow of water, the accumulation of strong help to form a highly developed delta landscape. Under natural conditions, rivers are prone to burst, forming branch flows, even diverting the main stream, forming a water landscape with integrated crisscross of rivers and streams. Flooding also caused natural dikes, the accumulation of the sediment and the heightening of embankment formed the poorly drained embankment marshes, all which make flood control and drainage raise become a significant issue of production and life in the region, also turning into the foundation of human production and construction activities in the area in the later period[2].

1.2 Regional Geographical Conditions and Urban Location

The necessity of urban construction in Huizhou and Duanzhou is mainly decided by the gateway status formed under the influence of regional natural geographical conditions. Huizhou is just in the “Ya”glyph route intersection from the Pearl River Delta to the north and south sides of the Lianhua Mountains,which can contact Guangzhou and Jiangxi, Fujian,holding the eastern of Guangdong[3], Duanzhou is located in the western edge of the Pearl River Delta,the main mouth of the Xijiang River. In the north,it can be connected to Hunan across the Nanling to the Yangtze River basin. In the south it can go to Gaozhou, Leizhou and other places (Fig. 2)[4].

The location of Huizhou and Duanzhou cities shows the precise judgment of the requirements of the natural environment and gateway cities in the region,reflecting in the following aspects.

1) river diversion. For cities built on water,the change of river will directly affect the choice of city site. Based on the research by scholars, before the Song Dynasty, the Dongjiang River in Huizhou region had several swings, while the position of Huizhou ancient city also changed four times. After the Song Dynasty, with the increase exploitation of Dongjiang area, artificial reclamation has changed delta radial delta waterway system of the lower reaches of the Dongjiang River into a single positive main flow channel, directly limiting the natural swing of Dongjiang River. Since then, the location of the capital city has not changed (Fig. 3)[5]. Located in the highland between the old road of Xijiang River and the Xijiang River, the Duanzhou site is also the good choice to deal with the risk of flooding in the Xijiang River with great water flow.

5 惠州歷代“城市八景”的空間分布The spatial distribution of “Huizhou Eight Scenes” in past dynasties

2) traffic trade needs. In general, river corridors are natural land and water corridors. During the Tang and Song Dynasties, Guangdong’s traffic line position became even more significant as trade activities in Guangzhou was flourishing and the political center moved to the south. Huizhou and Duanzhou respectively hold the east and west routes in and out of Guangzhou, for the sake of requirements in the aspects of the management of transport ships and land caravans to import and export of goods, it is necessary to set up state towns with the political and economic center along the river.

3) city safety. Since it is far away from the central government and on the verge of the great river, military defense and flood control are the key considerations for urban safety. The capital of Huizhou is located at the junction of the two rivers, convenient to control the land and water transportation. In the lake front of mountain (later becoming the West Lake), the water is huge with the two rivers together around the city, which is easy to defend and difficult to attack. While receiving water from the front of the mountain after the artificial embanking and dredging, it also plays a role of regulating the quantity of Dongjiang River water and discharging water to protect the city’s safety[6].Different with Huizhou, the ancients in Duanzhou didn’t choose the Beijiang River and Xijiang River flow to build the city near to Duanzhou. The reason is that though this place has the traffic advantages,there is no barrier around it and the two rivers meet,leading to the serious threat of flooding. Sanrong Gorge, Dading Gorge, Lingyang Gorge, where Duanzhou located in, could guard the throat of the Xijiang River from west to east, with waters and high mountains in the north as barriers. It not only makes Duanzhou a natural place which is easy to defend and difficult to attack, but also takes advantage of the Xijiang River.

1.3 The Influence of Regional Conditions on the Formation of the “Mountain-Lake-City-River” Pattern

With excellent regional geographical location,cities have the possibilities to give priority to the development of material economy and construction of the urban. The two cities are the gateway to the eastern and western regions of the Pearl River Delta,occupying an important strategic[4,7]. Moreover,strategic defense of the fortress city’s construction tilt and the dispatch of literati and officials also promoted urban development and scenic construction.

Huizhou and Duanzhou are close to the river water and strongly water-friendly, and both of them have the advantages of fronting water and with hills on their back, a large scale of water to develop the lakes between the mountains and cities, which is rare in other large rivers in China, taking the shape of the Pearl River basin traditional landscape city characteristics. On the opposite of these advantages,the site selection also faces high flood risks, therefore,the city construction needs to improve the city’s safety through arranging water systems, developing lakes and flood control embankments, which finally forms a mountain-water city environment with city-lake dependency on the natural landscape structure.

6 端州府城和端州星湖的營(yíng)建過程The construction process of Duanzhou city and the Star Lake

2 The Formation of the “Mountain-Lake-City-River” Pattern

2.1 The Capital of Huizhou with City and Lake

According to theHuizhou records of the West Lake, around the East Jin Dynasty, the natural embankment, the flood of the Dongjiang River, the gathering water in the western mountain and the mountain surge spring converged to form a lake.The lake is difficult to maintain a stable water level all year round, which is often in a timely abundance or dry hole state. It is not become a regular lake until building the embankment to block the lake in the Song Dynasty. The construction and maintenance of Huizhou West Lake is closely related to the development of resilience in Huizhou city, mainly reflected in the following aspects.

1) ensuring the safety of the city is the primary motivation for water conservancy development in West Lake. For the sake of keeping this defensive barrier, local officials of all dynasties laid stress on the water storage of the West Lake. Huizhou was built between mountains and rivers, which will be threatened by flash floods and surging river water in spring and summer. The West Lake can play a role in regulating the flood and protecting the safety of the city. West Lake has considerable flood control benefits together with engineering structures such as dikes,gates, city walls and channels, and thus maintaining the toughness of urban development.

2) mutual promotion of the construction of Huizhou’s capital and the development of the West Lake. The development of the city speeds up the utilization of the West Lake, while the West Lake also profoundly affects the development of the space form of Huizhou’s capital. As the demand for fresh water increased, part of the West Lake water was introduced into the city during the expansion of the city at the beginning of the Ming Dynasty. Some places were excavated in the shape of the Baiguan Pool (Goose Lake). West Lake water is used as a water source for government officials and citizens and serving for the city’s flood discharge, drainage and fire prevention functions together with other drainage ditches in the city.

3) During the Song Dynasty, Huizhou was still a small region that was not directly adjacent to the lake,however, the rapid economy increase prompted the large development, and the West Lake has become an important water body for water conservancy,sightseeing and culture of Huizhou’s capital. During the Ming and Qing Dynasties, it gradually formed a city closely suited to the coastal pattern of the river and lake for the sake of the further development and expansion of the city. For the sake of maintaining the West Lake, local officials organized a number of repair and dredging from the Song Dynasty to the Republic of China, putting stress on the transformation, education after the “artificial nature” of careful care, formulating the development of the corresponding prohibition and management system (Fig. 4).

4) Officials and residents of ancient Huizhou discovered the value of scenic resources while developing water conservancy and agricultural production in the West Lake. Since the Song Dynasty, the water management system for landscape construction has been completed through the dike network system formed by the construction of water conservancy,transportation and urban defense projects. Scholars and officialdom either directly took part in the construction of the West Lake or the theme of traveling, bringing the connotation and style of scholar free brushwork[8].

Huizhou is the earliest capital city in the Pearl River Delta region with “eight scenic” reputation,which is currently available for examination. The eight scenic spots in the Northern Song Dynasty included the key points: half in the West Lake, half in the scenic outdoors of Dongjiang River, the West Lake and the West Lake’s water sources, expressing the characteristics of pastoral lake and mountain city. Since then, the number of titles in capital city has been increasing. By the time of the Republic of China,Huizhou records of the West Lakewritten by Zhang Youren, expanded to 17 scenes, which has always maintained its feature with lake and mountain scenery as the main parts (Fig. 5)[9].

2.2 Duanzhou’s Capital and Star Lake

Star Lake, formerly known as Lishui, was originally a land of rivers and lakes formed under Beiling Mountain by Hanxia, the old route of Xijiang River. With the great development of Lingnan areas in the Song Dynasty, people began to organize manually the waters for the sake of protecting production and living safety and acquiring usable land, eventually forming a large lake to the north of the city.

7 端州歷代景觀集稱的空間分布The spatial distribution of Duanzhou landscape in past dynaties

The water area where Star Lake is located in,was initially served as flood discharge, drainage and site selection for Duanzhou’s capital. For the sake of keeping the safety of agricultural production around the city, officials and people of the past dynasties governed the drain water many times. After the repairment, the Lishui River was led into the Xijiang River through the Houlishui River, the Yuelong Dou River, the Xinli River and other waterways. In addition, a causeway was built outside the city from Sanrong Gorge to Lingyang Gorge to prevent the Xijiang River from re-entering the old river channel and causing flooding[10].

The change of plain style and the need to maintain social stability prompted the construction of the capital city pool. Since the Song Dynasty, through the continuous repair of the past generations, it has formed the particularly tall and strong wall, which played a significant role in the military defense and flood protection. The city wall system was connected with Li Lake by the Xijiang River water system, forming a set of urban water system with storage function, which plays a role in the parking of military official ships, water for life,fire prevention and other functions[11].

With the development of Guangdong in the Song Dynasty, the area began to build water conservancy, open canals to build ponds, drain water to build fields. The pattern of fish pond water fields are conducive to for the expansion of the Li Lake in the future, however, the lake gradually fell into disrepair in the late Qing Dynasty and the Republic of China. The silt was derelict into a field pond, and the water surface narrowed sharply. After the establishment of the People’s Republic of China, the original flood-stricken parts of the low-yielding fields and Tongtang were connected to six lake surfaces through the reservoir project for storing runoff, reducing flooding and irrigation, which finally formed the Star Lake (Fig. 6).

The most significant landscape near Star Lake is the Seven Star Cave, which is well-known for its seven limestone peaks with various shapes. With the prosperity of religious culture in Zhaoqing area, Seven Star Cave began to construct temples and several garden buildings, most prosperous in Ming Dynasty.During the Republic of China, the “Seven Star Cave Park Club” was set up to preside over the construction of the park, but the project was interrupted[12]. After the founding of the People’s Republic of China,Xinghu Lake was completed, and it is famous as the first national scenic spot in Guangdong Province.

The first eight scenes in the early Ming Dynasty were mainly surrounded by mountain scenery, reflecting that Duanzhou lays stress on the overall awareness of site selection and layout as an important regional city. With the threat of flood and the demand of military defense, the construction of the city defense project and water conservancy facilities were the key affairs of city managers in past dynasties, which appeared in the following eight scenes. Since then, with the prosperity of Buddhism and the discovery and arrangement of Seven Star Cave and Dinghushan Mt, the proportion of artificial constructions is gradually increasing (Fig. 7).

2.3 The Formation Features of the “Mountain-Lake-City-River” Pattern in the Two Cities

2.3.1 The Formation of the “Mountain-Lake-City-River” Pattern

The natural landscape structure in Duanzhou and Huizhou is characterized by the premise of lake formation and urban construction site selection,determining that Huizhou has formed a landscape sequence of “mountain-lake-city-river” from west to east. However, this sequence has changed to from north to south in Duanzhou and further has affected the spatial form of the city. Under the control of the water shore line and limited land, the capital of Huizhou takes the shape of the city form with spindleshaped, north-south long axis, leaving the water and mountain close to the city. Due to the large land area on the north bank of the Xijiang River, the urban form is not strictly affected by the natural conditions,which can form a well-regulated city pool, however,Duanzhou still presents the characteristics of the development along the river (Fig. 8).

2.3.2 The Combination of Man-made and Nature Lake Development

8 惠州和端州的“山—湖—城—江”格局Huizhou and Duanzhou’s “mountain - lake - city - river” pattern

Cities in ancient China could not be separated from the foundation of farming and water conservancy construction. The West Lake began to store water and the Li Lake started to drain water, however, its essence is to organize land for agricultural and urban development. Both cities have built urban water systems that are mainly connected to the city’s puddly and out-of-town lakes, which plays a significant role in the urban safety and sustainable development of waterfront cities, promotes the formation of a spatial structure integrating mountain, water and city. As the support system of the city, it guarantees the long-term stable development of Huizhou and Duanzhou in ancient China in the Pearl delta with complex and variable hydrological conditions to some extent.Through dredging, renovation and construction of past dynasties, they have created world-famous lake scenery while conforming to water demand. Though there are huge differences in time and space during the scenery construction, it shares the thinking mode of building landscape city.

2.3.3 Shaping the Unique Urban Landscape

Duanzhou and Huizhou are considered as the key cultural cities in ancient Pearl Delta Region apart from Guangzhou, where and the eight scenery appeared early. The changes of the eight scenery can reflect the changes in the physical environment and aesthetic demands of urban and rural areas.Compared with the eight scenery of the two cities,it can be seen that although there are similar lake and mountain structure, the eight scenery has own unique characteristics on the basis of the different natural geographical characteristics and humanistic background of the two places. The city-lake integration of Huizhou eight scenery has been consistent from beginning to end. However,Zhaoqing has experienced from the display of local success to the artificial construction process.

3 Conclusions

Huizhou and Duanzhou have become the landscape cities alongside the river, and the artificial environment and natural environment of the city are closely connected through the traditional spatial planning strategy and engineering construction of the ancients, as a result of nature transformation, a safe supportive system building to resist disasters,agriculture development to cultivate land, formation of the humanized nature[13]. Although the traditional city-lake relationship between the two cities has changed for a long time, the traditional urban design represented by the two cities is still of great practical significance for improving the resilience of the delta cities and enhancing the sustainable development of the cities in today’s rapid urbanization in the Pearl River Delta region.

In terms of space, water system is an important part of urban space for cities in the delta region, a significant structure of natural systems connecting with inside and outside the city. The development of urban space should lay stress on the protection of the blue-green system which has significant functional value to the city, coordinating with the dynamic hydrological process of rivers and lakes, and thus enhancing the disaster resilience of urban natural system.

In terms of time, delta cities often have a strong hydrophilic character, and have accumulated a profound historical context of the city information in the waterfront space. The interaction between the city and the water should be reasonably guided and developed to adapt to the future development direction of the city by integrating the natural and human values of the waterfront space.

In terms of function, the ecological function and aesthetic function objectives of the landscape environment should be transformed into spatial constraints of urban development for cities with beautiful landscape structure to formulate a reasonable land development plan. It will take full advantages of the comprehensive benefits of environmental, economic and social benefits of urban landscape pattern system.

Sources of Figures:

Fig.1 city of Huizhou is quoted from Mr. Nuanmu, city of Duizhou is quoted from http://www.chinadaily.com.cn/m/guangdong/zhaoqing/2011-06/14/content_12689952.htm; Fig. 2 is based on Google Maps; Fig.3 is based on reference [5]; Fig.4 is based onHui Zhou Xi Hu ZhiandHui Zhou Cheng Shi Jian She Zhi;Fig. 5, 7 is based on reference [9]; Fig.6 is based onGao Yao Xian Zhi, Zhao Qing Fu Shu JiWei Tu, Duan Zhou Qu Shui Li Zhi.