丹江口水库对汉江中下游影响的生态学分析

基于黄家港水文站1954～2000年的日径流量资料，以1967年为节点，将47年水文序列划分为节点前的“近自然状态河流”和节点后的“人工干扰状态河流”两种水文情势。采用Richter提出的变动范围法，基于包含32个水文参数的水文改变指标体系，定量评估了黄家港水文站1967年前后水文情势的变化。根据分析，把1967年之前的各个水文参数的第1至第3四分位数间的数值范围设为管理目标。进一步分析了丹江口水库的修建对汉江中下游生态水文的影响。结果表明，1967年以后，丹江口水库的修建对汉江中下游水文情势的影响较为显著：极大地改变了径流的年内分配，使流量过程均化，使极值流量出现日期提前、历时缩短等等。在此基础上，结合汉江中下游河道生态系统的特点，以鱼类为指示生物，初步探讨了上述水文情势的变化对汉江中下游鱼类的生长、繁殖和越冬等带来的影响，并对如何降低不利影响提出了相应的改进措施.

ECOLOGICAL IMPACTS OF THE DANJIANGKOU RESERVOIR ON THE MIDDLE AND LOWER REACHES OF THE HAN RIVER

Based on the daily flows from 1954 to 2000 in the Huangjiagang Gauge, the 47 year hydrologic regimes were divided into two sequences: one as “near natural state river” before 1967 and another as “man interfered river” after 1967. According to the Range of Variability Approach (RVA) proposed by Richter，a method using Indicators of Hydrologic Alteration (IHA) containing thirty two eco hydrologic parameters, the difference between the flows before and after 1967 was quantitatively evaluated.The value ranging from 25th to 75th for each parameter before 1967 was set as the management target.The impacts of the Danjiangkou Reservoir on ecosystems of the middle and lower reaches of the Han River were further analyzed.The results indicate that，after 1967，most hydrologic parameters have experienced significant alterations.The intra year allocation of run off has been greatly changed and the intra year variations in discharges have been smoothed.Extreme flows are found to occur earlier and the duration has been shortened.Based on these analyses，in combination with the ecosystem characteristics of the middle and lower reaches of the Han River，fish is chosen as the representative biological indicator.The impacts of the above mentioned changes in flow regimes on the growth，reproduction and wintering of fish in the middle and lower reaches of the Han River were then preliminarily discussed. In the end，suggestions on how to reduce the negative impacts were proposed in details.