)式中：——孔口出流面積；——孔口中心水頭，；——孔口出流系數(shù)，取；——溢洪道凈寬；——堰上水頭，；——流量系數(shù)，取；——側(cè)收縮系數(shù)，?。弧舷掠嗡^差，。給定一個(gè)上游水位，試算水庫下游水位，步驟如下：對(duì)于一個(gè)給定的上游水位，首先假設(shè)一個(gè)水庫下游水位，并計(jì)算對(duì)應(yīng)的通過泄洪孔、溢洪道和水輪機(jī)的下泄流量，進(jìn)而求得總下泄流量，從水庫下游水位流量關(guān)系曲線查取其相應(yīng)的下游水位，若查得的水位值與假設(shè)的數(shù)值相等或者十分接近，則認(rèn)為假設(shè)的下游水位是合適的。否則，重新假設(shè)下游水位進(jìn)行試算。再給定一個(gè)上游水位，重復(fù)上述步驟，可得到水庫上游水位與下泄流量的關(guān)系,見下圖表。根據(jù)以上公式求得水庫水位-下泄流量關(guān)系曲線如下表2-4：表2-4水庫水位-下泄流量關(guān)系曲線表水庫上游水位Z上(m)水庫下游水位Z下(m)水頭h1(m)泄洪底孔流量Q1(m3/s)水頭h2(m)溢洪道流量Q2(m3/s)水頭h3(m)水輪機(jī)流量Q3(m3/s)總下泄流量Q(m3/s)228129.0843544.614991.6198.92428.161965.38229129.5244550.9151387.2199.48425.762363.88230130.0145557.1361823.5499.99423.562804.23231130.5246563.2972297.92100.48421.523281.73232131.0747569.3882807.52100.93419.623796.51233131.6348575.4093350.05101.37417.824343.28234131.2249581.36103923.62101.78416.134921.12235131.8250587.27114526.65101.18414.505528.42236133.4451593.11125157.74101.56411.946163.79237134.0652598.90135815.71101.94411.436826.03238134.6953604.63146499.49103.31409.957514.07239135.3254610.31157208.16103.68408.498226.96240135.9555615.93167940.86104.05407.048963.83庫水位下泄流量關(guān)系曲線如下圖2-6：圖2-6水庫水位-下泄流量關(guān)系曲線1.6.4防洪設(shè)計(jì)成果水庫防洪設(shè)計(jì)成果見表2-5。表2-5特征水位特征水位（m)下泄流量（m3/s)防洪限制水位2