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洪水是我国主要的自然灾害之一,城市洪水更是影响一个地区政治经济的重要因素.目前,城市上游水库调节工程和城市河道整治工程是用来调蓄城市洪水的主要工程手段,但它改变了洪水的下垫面条件,再加上气候变化的加剧,洪水的物理形成和演变机制发生了变化,从而影响了河道的防洪能力.结合非一致性水文频率计算的原理和跳跃分析方法,推求宣恩城区变化环境下的洪水频率分布,进而结合水位流量关系对其防洪能力进行分析.结果发现:雨量序列发生了跳跃向下的中变异,说明气候变化影响下降雨呈减少趋势,年最大日流量序列发生了跳跃向下的中变异,其洪峰流量呈减少趋势,且受气候变化和人类活动双重影响;考虑安全超高0.5m,宣恩站防洪能力不到10年一遇,与过去相比有明显提高,但仍达不到防洪规划20年一遇的要求,为此需将设防高程提高到499.29m以上.宣恩城区河道受到整治工程的影响较大,其防洪预警预案需要适应环境变化进行调整.
Floods are one of the major natural disasters in our country, and urban floods are also an important factor affecting the political economy in a region. Up to now, urban upstream reservoir regulation projects and urban river regulation works are the main engineering measures used to regulate urban floods. However, The underlying surface conditions of floods, coupled with the aggravating of climate change, the physical formation and evolution mechanism of floods have changed, thus affecting the river flood control capability.Combined with the principle of non-uniform hydrological frequency calculation and jump analysis method, The results show that the mid-level variability of rainfall series has a downward jump, which shows that the rainfall shows a decreasing trend under the influence of climate change, and the maximum annual maximum The flow sequence has a downward jump in the middle of the variation, the peak flow shows a decreasing trend, and is subject to climate change and human activities double impact; Considering the safety of ultra-high 0.5m, Xuan’en station flood control capacity of less than 10 years, with the past phase Than the obvious increase, but still can not reach the requirement of flood control planning once every 20 years, so the fortification elevation should be raised to 499.29m above. The river courses in urban areas are greatly affected by remediation works. The flood control and early warning plan needs to be adjusted according to the changes of the environment.