【作者】 黄胜晔；

【导师】 王腊春；

【作者基本信息】 南京大学 ， 环境科学， 2011， 硕士

【摘要】 鄱阳湖是我国长江流域重要的通江湖泊,研究鄱阳湖的调蓄规律对认识长江与鄱阳湖的互动过程、认识江湖关系有重要意义。近年来鄱阳湖地区极端干旱、极端洪涝等灾害频繁出现,制约了社会、经济发展和生态环境保护。本文基于洪水频率分析、产汇流机制、水量平衡和洪水演进等理论,分析了鄱阳湖流域、汉口站为代表的长江洪水频率,构建了鄱阳湖湖区半分布式水文模型模拟了湖区降雨径流过程,分别计算了鄱阳湖对鄱阳湖流域洪水、对长江洪水的调蓄作用,分析了鄱阳湖的调蓄特征,最后模拟了极端洪水遭遇下鄱阳湖调蓄的能力。通过以上研究本文得到以下结论：(1)鄱阳湖洪水的形成和水位涨落都受到鄱阳湖流域和长江来水双重影响,鄱阳湖流域洪水引起鄱阳湖水位的上涨,而鄱阳湖洪峰水位的高低则决定于长江洪水,鄱阳湖洪水消退快慢主要由长江洪水维持时间长短控制。(2)在分析鄱阳湖对鄱阳湖流域洪水调蓄过程的基础上,根据水量平衡原理建立了鄱阳湖对鄱阳湖流域洪水调蓄量和调蓄率的计算模型。构建半分布式水文模型对湖区产汇流过程进行模拟,模型效率系数R2在0.58-0.94之间,水量平衡系数RE在0.61-0.79之间,结果都达到使用要求。区间水文模型能较好的模拟降雨径流过程,为基于水量平衡原理的洪水调蓄模型提供了有力的技术支持。按鄱阳湖流域降水经验频率确定五个丰枯代表年份,计算鄱阳湖对鄱阳湖流域洪水调蓄,结果表明：在鄱阳湖流域来水很大而长江水位不高时,鄱阳湖的调蓄作用很大,但是当长江洪水达到高水位时,鄱阳湖已达到最大蓄水量而可能启动负调蓄功能；鄱阳湖调蓄作用规律与流域降水年内分布有密切关系,鄱阳湖流域汛期鄱阳湖表现出强调蓄作用,当鄱阳湖流域来水减少时,鄱阳湖对长江洪水的调蓄作用增强。(3)基于长江汉口-湖口洪水演进的鄱阳湖对长江洪水调蓄作用分析。洪水演进计算得到湖口站曰平均水位,模拟水位能较好拟合实测水位,但是在实测水位峰值处与突变处拟合不是很好,且日平均洪峰水位模拟值均小于实测值。分析鄱阳湖调蓄长江洪水作用时,采用变化鄱阳湖湖盆调蓄容积的方法分析鄱阳湖对长江洪水调蓄的贡献量。结果表明：鄱阳湖对日平均洪峰水位的降低作用在0.37m-0.39m之间(1998年降低了0.37m),减轻了长江下游的部分防洪压力。鄱阳湖调蓄具有“汛前讯后大调,汛中微调”和“大洪水小调,小洪水大调”的特点。从最高洪水位来看1998年>1995年>1996年,但是由鄱阳湖调蓄而降低的水位1996年>1995年>1998年,可以推断在较高水位时鄱阳湖调蓄发挥的作用小于在较低洪水位时的调蓄作用。(4)基于气候是影响鄱阳湖洪水的关键因子,在不考虑短期人类活动对鄱阳湖影响的前提下,假设了四种极端洪水遭遇情景,采用鄱阳湖对长江洪水的调蓄作用的研究方法,研究四种情景下鄱阳湖调蓄能力。输入模型的水文数据通过洪水频率曲线计算得到,湖口站初始水位采用1998年5月1日水位12.64m,模拟时间5月1日～9月30日。模拟结果表明：湖口站日平均洪峰水位均超过1998年洪峰水位；四种极端洪水遭遇情景下鄱阳湖对降低湖口站最高水位能力有限,对最高水位的降低在0.36m～0.37m之间,洪水越大,水位降低能力越小；长江湖口处高水位的形成受长江洪水影响较大。尤其是当鄱阳湖流域已发生较大洪水时,应密切注意长江洪水变化,及时做好防汛工作。更多还原

【Abstract】 Poyang Lake is the largest freshwater lake in China. Located in south-central China, the lake is a tributary of the Yangtze River and directly exchanges and interacts with it. Study on the lake regulation law is crucial to recognize interactions of the Yangtze River flow and hydrologic processes of the Poyang Lake and the relationship of Yangtze River and Poyang Lake. In recent years extreme drought and extreme floods occurred frequently, which restrict the development of the regional society, ecology and environment. This paper used the theoretical foundation:Flood Frequency Analysis, Runoff Generation and Routing Theory, Water Balance Principle and Flood Routing Model. This paper calculated the frequency of flood season precipitation in Poyang Lake Bsain and frequency of maximum 30-day discharges in Hankou station. On the analysis of the Poyang Lake area, this paper built a semi-distributed hydrological model to simulate the runoff. After analysis on the characteristics of the pondage actions of the Poyang Lake to the flood of Poyang Lake Basin and Yangtze River, the pondages of Poyang Lake are calculated. At last this paper simulated the Poyang Lake’s pondage action under extreme flood encountering. The main achievements are shown as follows:(1) The formation and water level of Poyang Lake basin’s flood are controlled by both Poyang Lake and Yangtze River. The flood from Poyang Lake makes the water level rise, and the flood peak level is determined by the flood from Yangtze River. The velocity of Poyang Lake’s flood subsidence is controlled by Yangtze River’s flood.(2) On the basis of the characteristics of the pondage actions of the Poyang Lake to the flood of Poyang Lake Basin, the flood storage capacity and rate of storage capacity are calculated. The semi-distributed hydrological model calculated the runoff of the Poyang Lake area. The modelwas calibrated against daily observed runoff at Zifang station for the period 1982, and the data in 1985 and 1986 were used for model validation. The goodness of fit using the Nash-Sutcliffe(1970) efficiency factor(R2) was from 0.58 to 0.94, and the water balance coefficient(RE) was from 0.61 to 0.79, which illustrates the ablityof the model to simulate the hydrological behavior of the Poyang Lake area. Chosen five typical years by empirical frequency calculation, the pondage of Poyang Lake to the flood of Poyang Lake Basin is calculated:The pondage of Poyang Lake is large as the Yangtze River’s flood is small, but it is limited as the Yangtze River reached peak level. The rule of Poyang Lake’s pondage to Poyang Lake basin is closely related to the distribution of precipitation in the year. The strong pondage effect to Poyang Lake basin acts as Poyang Lake basin’s flood season.(3) Hydrological flood rooting model for Yangtze River (Hankou station to Hukou station) was used to calculate the pondage actions of the Poyang Lake to the flood of Yangtze River. The daily water levels of Hukou station were simulated by flood rooting model. The model was calibrated against daily observed water level at Hukou station from May to September, which showed the overall simulation was attached to observed water levels, but the peak levels were less than observed peak levels. When analyzing the pondage action to the flood of Yangtze River, the lake basin of Poyang Lake was made a differential treatment. The results showed that Poyang Lake’s pandage action subducted peak levels from 0.37m to 0.39m (0.37m for 1998), which relieved flood pressure for the middle and lower reach. The characteristics of pondage action are that pondage is smaller as the Yangtze River’s flood is larger. The peak levels followed the order of 1998>1995>1996, and the Poyang Lake’s pondage action followed the order of 1998<1995<1996.(4) Based on the hypothesis that the key factor effecting Poyang Lake’s flood was the climate and human activity’s effect was ignored, four extreme flood scenes were assumed. The pondage actions to Yangtze River were simulated in four scenes. The initial water level was 12.64m(1st, May,1998). Simulation time was from 1st May to 30th Sep.. The results showed that simulated peak levels in four scenes were higher than peak level in 1998. The pondage actions were less than that in 1998, which were from 0.36m to 0.37m. The Yangtze River’s flood had a larger impact on the peak level in Hukou station. When large floods have occurred in Poyang Lake Basin, close attention should be payed to changes in the Yangtze River flood and flood control work should be ready in time.更多还原