【正文】 Qt*k is the totalload transport capacity。黃河灘區(qū)及分滯洪區(qū)風(fēng)險(xiǎn)分析和減災(zāi)對(duì)策。(2)黃河灘區(qū)行洪、滯洪、沉沙作用十分顯著,在減輕河槽淤積、治河防洪保安全方面發(fā)揮了極其重要的作用,它也是維持陶城鋪以下窄河道存在的重要條件。 灘區(qū)淹沒面積分析 在廢除生產(chǎn)堤工況下，由于洪水自然漫灘，大片的灘區(qū)被洪水淹沒，,% ,其次是淹沒水深在1～% ,剩余部分為淹沒水深大于2m的坑塘及堤溝河區(qū)。滿足精度要求。圖315 結(jié)果輸出文件“output 1”設(shè)置 對(duì)于“output2”，點(diǎn)擊“Output specification”項(xiàng)，“Data”參數(shù)區(qū)內(nèi)的“Field type”選擇“2D”，“ Output format”選擇“Point series”，在“Output file”中，設(shè)置輸出文件。點(diǎn)擊“Mesh and Bathymetry”，導(dǎo)入邊界文件()，如圖 38所示：圖 38導(dǎo)入邊界文件為邊界重命名。b）出口邊界條件：出口開邊界有兩類：一類是自然開邊界，主要是經(jīng)下邊界或側(cè)邊界出流的河流，可按實(shí)測(cè)水文資料（水位～流量關(guān)系）確定。節(jié)點(diǎn)之間的近似解一般可以認(rèn)為光滑變化，原則上可以應(yīng)用插值方法確定，從而得到定解問題在整個(gè)計(jì)算區(qū)域上的近似解。 有限體積法（FVM）又稱為控制體積法。 （3）可以進(jìn)行熱啟動(dòng)，當(dāng)用戶因各種原因需暫時(shí)中斷MIKE21模型時(shí)，只要在上次計(jì)算時(shí)設(shè)置了熱啟動(dòng)文件，再次開始計(jì)算時(shí)將熱啟動(dòng)文件調(diào)入便可繼續(xù)計(jì)算，極大地方便了計(jì)算時(shí)間有限制的用戶。堤河、串溝比較多，在防洪方面，還存在著大洪水時(shí)奪流滾河，順堤行洪的危險(xiǎn)。目前此河段灘地面積約519km2，有村莊58個(gè)。 研究工作流程見圖2圖2 研究工作流程圖第二章 河段的基本情況 20世紀(jì)50年代黃河下游河道基本屬于天然情況，60年代以后灘區(qū)農(nóng)民自發(fā)性地逐漸修建生產(chǎn)堤，對(duì)灘地農(nóng)田有一定保護(hù)作用，故屢禁屢建。同時(shí)，生產(chǎn)堤加劇了二級(jí)懸河的發(fā)展，使平灘流量減小，增大了河道整治的難度。如果沒有生產(chǎn)堤，也存在堤防沖決的可能，但由于灘區(qū)漫水早、灘區(qū)水位隨大河水位的上漲而近乎同步抬升，對(duì)大堤的沖擊強(qiáng)度相對(duì)較弱。對(duì)于高含沙中常洪水情況較為復(fù)雜，一般情況下不漫灘雖有利于輸沙入海，但易加重主槽淤積。近年來受經(jīng)濟(jì)利益的驅(qū)動(dòng)，灘區(qū)生產(chǎn)堤不斷向主河槽外延，其區(qū)域擴(kuò)大、防御標(biāo)準(zhǔn)提高，～5m，甚至有些地方修筑的生產(chǎn)堤可以防御5000m3/s以上的洪水。 關(guān)鍵詞：生產(chǎn)堤；防洪；洪水演進(jìn)；數(shù)值模擬；MIKE21模型中圖分類號(hào)：TV871INFLUENCE OF THE YELLOW RIVER DOWNSTREAM PRODUCTION OFBEACH DISTINGUISH FLOOD EMBANKMENTABSTRACT：The production dike which is built on the both sides of the lower reaches of the Yellow River main channel has some impact on the flood control. Retention or abolition, bees the focal point of flood control and decision of the disaster reduction once again. In this paper, choosing Jiahetan to high village river as study area, a twodimensional numerical model was established to simulate the evolution of the typical flood frequency on two conditions of production dykes and demolishing, using the DHI MIKE21 software. The main research contents: 1) According to the research,collecting the basic data of the Yellow River then getting the source and the significance of the research. 2) organizing the related material of production dykes between Jiahetan and high village, getting the production levee reason, standards of construction and its existing stakes.3) learning MIKE software, establishing a twodimensional numerical model of Jiahetan to high village river. Simulating and calculating the flood evolution process, river flow, river flood water level under the two different kinds of working conditions of the existing production dike and demolishing. 4) analysis the water surface elevation, the flow field and the flooded area of the peak flow on Buddhist temple, Dongba head, the stone village, Qing Zhuang and Yulin .Comprehensive analysis of the advantages and disadvantages of the production dykes, considering the need of production and life, besides the effect of the production of embankment on the flood control, unified planning for it .In order to maintain the vitality of the Yellow River channel, coordinator, inhibition of two levels of elevated development, the control plan of the production dykes in the lower reaches of the Yellow River is feasible.Key Words: Production dykes。經(jīng)整理分析得到該課題題目的來源及研究的意義。所以本文就對(duì)生產(chǎn)堤存在的利弊，研究它對(duì)防洪的影響，在確保群眾利益的同時(shí)，減小防洪難度。(2)增加了大水來臨前群眾外遷的時(shí)間。天然條件下的中小漫灘洪水，入灘水流少、含沙量低、灘槽水沙交換較弱，生產(chǎn)堤存在與否對(duì)河道沖淤及灘地橫比降的影響不大。由于河槽過洪能力明顯降低，局部河段2000m3/s左右流量就可漫灘，小水就能造成大災(zāi)。 研究的意義 現(xiàn)狀生產(chǎn)堤嚴(yán)重影響防洪和灘槽淤積分布，但廢除生產(chǎn)堤影響灘區(qū)180余萬人的生存與發(fā)展，地方政府阻力很大。陶城鋪以下河道的河勢(shì)已得到控制；高村至陶城鋪河段，主流已趨于穩(wěn)定，河勢(shì)得到了基本控制；高村以上游蕩性河段也已修建了一批布點(diǎn)工程，縮小了游蕩擺動(dòng)范圍。該河段長227m，是銅瓦廂決口改道后形成的河段。第三章 模型的建立與率定 MIKE 21軟件的介紹 MIKE21數(shù)值計(jì)算與分析軟件是國際上比較成熟的DHI軟件系列中關(guān)于水動(dòng)力、波浪和泥沙輸運(yùn)等模型進(jìn)行潮流場(chǎng)、代表波要素的波浪場(chǎng)和泥沙輸運(yùn)的數(shù)值模擬工具。 控制方程1)控制方程特點(diǎn) 對(duì)于河口、海岸、湖泊、寬淺河道與坡面流等廣闊的寬淺型水域，水平尺度遠(yuǎn)大于垂向尺度，水力要素（流速、水深等）在垂直方向的變化要遠(yuǎn)小于水平方向的變化，沿水深分布比較均勻，其流態(tài)、水力要素可用沿水深平均值來表示。 有限體積法的基本思路易于理解，并能得出直接的物理解釋。擴(kuò)散項(xiàng)：同樣根據(jù)Gauss散度定理，將體積分轉(zhuǎn)變?yōu)槊娣e分后，有： （329）在得到（325）各項(xiàng)的單獨(dú)表達(dá)式后，還要做兩方面的工作：1）在對(duì)流項(xiàng)中需要引入特定的離散格式（328）中界面物理量、和用節(jié)點(diǎn)物理量來表示，可用一階迎風(fēng)格式。在生成的模擬區(qū)域的進(jìn)口和出口添加弧形來定義進(jìn)口邊界和出口邊界。圖312 初始水位的設(shè)置 模型進(jìn)口邊界條件設(shè)置。為了消除這些偏差使模型達(dá)到所需要的精度需要對(duì)糙率文件進(jìn)行多次的修改和驗(yàn)證。為此，本論文將主要從上述兩方面著手，研究生產(chǎn)堤防洪效果。把生產(chǎn)堤的建設(shè)與管理納人河道主管部門的常態(tài)化管理。水土保持研究，1998,5（5）：8590[3]山東黃河河務(wù)局。最后感謝我的父母，沒有你們默默無聞的在后面支持我，我將不會(huì)有現(xiàn)在的今天，謝謝你們給了我無私的愛，為我求學(xué)所付出的巨大犧牲和努力。 p*bk is pbk of the mixing layer when ?Am/ ? t ? ? Ab/?t≤0 , and p*bk is the percentage of the kth size class of bed material in subsurface layer (under mixing layer) when ?Am/ ? t ? ? Ab/?t 0. Eq. (1) is discretized using the Preissmann implicit scheme, with its source term being discretized by the same formulation as that for the righthand term of Eq. (3) in order to satisfy the sediment continuity. Eq. (4) is discretized by a difference scheme that satisfies mass conservation. A coupled method for the calculations of sediment transport, bed change and bed material sorting is established by implicitly treating the pbk in Eq. (2) as pbkn+1and simultaneously solving the set of algebraic equations corresponding to Eqs. (1)(4) by using the direct method proposed by Wu and Li (1992). This coupled method is more stable and can more easily eliminate the occurrence of the puted negative bed material gradation, when pared to the decoupled method, in which the pbk in Eq. (2) is treated explicitly. However, the aforementioned coupling procedure for sediment transport, bed change and bed material sorting putations is still decoupled from the flow calculation. Model Parameters to be Analyzed The parameters in numerical models of flow and sediment transport in rivers can be classified into two groups: numerical parameters and physical parameters. The numerical parameters result from the discretization and solution procedures, while the physical parameters represent the physical properties of flow and sediment, or the quantities derived from the modeling of flow and sediment transport. In the CCHE1D channel network model, the numerical parameters include putation time step and grid length, and the physical parameters are the Manning’s roughness coefficient, nonequilibrium adaptation length of sediment transport, mixing layer thickness, bed material porosit