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2.3洪水分析棠兴国光河坝工程位于涓水一级支流桃花港下游处，衡山县白果镇国光村境内，距衡山县城42km，白果镇3km，基本无实测水文资料，因此，本次洪水复核的参数参照《湖南省暴雨洪水查算手册》进行计算，用推理公式法推求设计洪水。（1）洪水标准：设计洪水频率：P＝5％，校核洪水频率：P＝2％（2）设计校核暴雨的查算：根据《衡山县水资源特征值统计及估算成果表》，棠兴国光河坝工程位于涓水一级支流桃花港下游处，衡山县白果镇国光村境内，距衡山县城42km，白果镇3km。桃花港发源于衡山祝融峰北侧，由望峰乡樟树屋场入境，经岭坡至白果紫雾江入涓水，全长约20km。河坝坝址位于桃花港下游，控制流域面积106.0km2，干流长度22.4km，河流坡降43.0‰。（3）工程等级及洪水标准：根据《水闸设计规范》（SL265—2001），对于山区、丘陵区水利水电枢纽中的水闸，其级别可根据所属枢纽工程的等别及水闸自身的重要性确定。根据《水利水电工程等级划分及洪水标准》（SL252－2000）及《水闸设计规范》（SL265—2001），棠兴国光河坝是一处具有灌溉、防洪等综合利用的水利水电枢纽工程。棠兴国光河坝最大过闸流量535.69m3/s,工程规模为中型，其工程等别为Ⅲ等。水闸枢纽中的水工建筑物应根据其所属枢纽工程等别、作用和重要性划分级别，其级别表2.1确定：表2.1水闸枢纽建筑物级别划分工程等级永久性建筑物级别临时性建筑物级别主要建筑物次要建筑物Ⅰ134Ⅱ234Ⅲ345Ⅳ455Ⅴ55－按照上述规范规定，棠兴国光河坝工程属于Ⅲ等工程，其永久性主要建筑物级别为3级，永久性次要建筑物级别为4级，临时性建筑物级别为5级。平原区（Ⅲ等）水闸的防洪标准为：设计洪水重现期为30～20年，校核洪水重现期为100～50年。本工程属于丘陵区水闸，位于白果镇国光村境内，且失事后造成的损失和影响都不大，故本次洪水标准按下限取值。桃花港河坝采用的洪水标准为：设计洪水重现期为20年，校核洪水重现期为50年。该区洪水过程线的计算，由于流域内无实测水文资料，设计洪水采用暴雨资料推求。查1984年湖南省水利厅编《暴雨洪水查算手册》，采用《湖南省暴雨洪水查算系统》计算设计洪水。根据棠兴国光河坝所处地理坐标和集水面积，利用《手册》查得该水库属湖南省暴雨一致区第八区，其流域特性如下表：表2-2流域参数查算成果表参数单位数值集雨面积km2106干流长度km22.4平均坡降‰43流域中心24小时点雨量(mm)mm100产流系数（R上/R总）0.75变异系数0.42降雨初损(mm)mm30偏态系数3.5用图解法求净峰流量Qm及汇流历时τ，成果见下表。表2-3棠兴国光河坝设计洪水成果表设计参数单位P=2%P=5%P=10%模比系数Kp2.151.821.56点面折算系数α0.9350.9350.93524小时点雨量H24点mm21521521524小时面雨量H24面mm201.03170.17145.86暴雨衰减指数n20.6530.6680.678暴雨衰减指数n30.7810.7930.8041小时内暴雨量H1mm79.6970.4562.433小时内暴雨量H3mm116.67101.4688.926小时内暴雨量H6mm148.39127.72111.1612小时内暴雨量H12mm172.71147.42127.33径流比例系数ψ0.750.750.75总径流深R总mm171.03140.17115.86地表径流深R上mm128.269105.12886.895流域地理参数θ19.9319.9319.93流域汇流参数m0.630.630.63汇流历时τh5.8906.2086.564洪峰流量Qmm³/s538.99436.82349.162.4设计洪水过程线该区的洪水过程由地面径流过程与地下径流过程叠加而成。地面径流过程采用径流分配系数法、地下径流过程利用等腰三角形关系推求，由此而得的该区洪水过程线成果见下图。表2-4棠兴国光河坝桃花港流域P=2%洪水过程单位：m3/sP=2%洪水过程计算表Δt(1小时)Qm/ΣQiQiQ0Qi+Q000.0000.001.391.38710.01141.542.7744.31920.02386.874.1691.02830.083313.475.55319.02440.140528.756.94535.68950.113426.788.32435.10260.091343.699.71353.40070.075283.2611.10294.35880.063237.9412.49250.42490.053200.1713.87214.043100.045169.9615.26185.216110.039147.3016.65163.942120.034128.4118.03146.446130.030113.3019.42132.726140.02698.2020.81119.006150.02386.8722.20109.063160.02179.3123.58102.896170.01971.7624.9796.730180.01764.2126.3690.563190.01556.6527.7584.397200.01349.1029.1378.231210.01141.5430.5272.064220.01037.7731.9169.675230.00933.9933.2967.285240.00830.2134.6864.896250.00726.4436.0762.506260.00622.6637.4660.117270.00518.8838.8457.727280.00415.1140.2355.338290.00311.3341.6252.948300.0027.5543.0050.559310.0013.7844.3948.169320.0000.0045.7845.779图2-4棠兴国光河坝桃花港流域P=2%洪水过程线P=2%0.0100.0200.0300.0400.0500.0600.0010203040TQQiQ0Qi+Q0表2-5棠兴国光河坝桃花港流域P=5%洪水过程单位：m3/sP=5%洪水过程计算表Δt(1小时)Qm/ΣQiQiQ0Qi+Q000.0000.001.1371.1410.01134.052.27436.3220.02371.193.41174.6130.083256.924.548261.4740.140433.365.685439.0450.113349.786.822356.6060.092284.787.959292.7470.074229.069.096238.1680.063195.0110.233205.2490.053164.0611.370175.43100.045139.2912.507151.80110.039120.7213.644134.37120.034105.2414.781120.03130.03092.8615.918108.78140.02680.4817.05597.54150.02371.1918.19289.39160.02165.0019.32984.33170.01958.8120.46679.28180.01752.6221.60374.23190.01546.4322.74069.17200.01340.2423.87764.12210.01134.0525.01459.06220.01030.9526.15157.11230.00927.8627.28855.15240.00824.7628.42553.19250.00721.6729.56251.23260.00618.5730.69949.27270.00515.4831.83647.31280.00412.3832.97345.35290.0039.2934.11043.40300.0026.1935.24741.44310.0013.1036.38439.48320.0000.0037.52137.52图2-5棠兴国光河坝桃花港流域P=5%洪水过程线P=5%0.050.0100.0150.0200.0250.0300.0350.0400.0450.0500.0010203040TQQiQ0Qi+Q0表2-6棠兴国光河坝桃花港流域P=10%洪水过程线单位：m3/sP=10%洪水过程计算表Δt(1小时)Qm/ΣQiQiQ0Qi+Q000.0000.000.940.9410.01128.141.8830.0220.02358.852.8261.6730.083212.363.76216.1240.140358.204.70362.9050.113289.125.64294.7660.091232.836.58239.4170.075191.897.52199.4180.063161.198.46169.6590.053135.609.40145.00100.045115.1410.34125.48110.03999.7811.28111.06120.03486.9912.2299.21130.03076.7613.1689.92140.02666.5214.1080.62150.02358.8515.0473.89160.02153.7315.9869.71170.01948.6116.9265.53180.01743.5017.8661.36190.01538.3818.8057.18200.01333.2619.7453.00210.01128.1420.6848.82220.01025.5921.6247.21230.00923.0322.5645.59240.00820.4723.5043.97250.00717.9124.4442.35260.00615.3525.3840.73270.00512.7926.3239.11280.00410.2327.2637.49290.0037.6828.2035.88300.0025.1229.1434.26310.0012.5630.0832.64320.0000.0031.0231.02图2-6棠兴国光河坝桃花港流域P=10%洪水过程线P=10%0.050.0100.0150.0200.0250.0300.0350.0400.0010203040TQQiQ0Qi+Q02.5洪水总量的计算洪水总量Wmp=1000*R总*F，则Wm5%=18129.2万m3，Wm2%=14858.02万m3,Wm10%=12281.16万m3。2.6洪水计算成果根据棠兴国光河坝桃花港流域汇流情况，各相应洪水过程线的最大洪峰流量见下表图2-7频率P(%)P=2P=5P=10最大洪峰流量Qm（m³/S）535.69439.04362.90