水文变异诊断系统

Hydrological alteration diagnosis system

本文构建的水文变异诊断系统考虑了趋势和跳跃两种变异形式,由初步诊断、详细诊断和综合诊断三个部分组成。其基本思路是首先采用Hurst系数法等对序列进行初步检验,判断序列是否可能存在变异;如果可能存在变异,再利用多种变异检验方法对水文序列进行详细诊断;然后分别对趋势和跳跃诊断结论进行综合,并根据效率系数评价水文序列与跳跃成分或趋势成分的拟合程度,以效率系数较大者作为变异形式判断的结果;最后结合实际水文调查分析,对变异形式和结论进行确认,从而得到最终的变异诊断结果。该系统可以解决单一方法有时检验结果不合理,多种方法常常检验结果不一致的问题。用该系统对海河流域五座大型水库入库年径流系列进行变异分析,结果表明官厅水库呈现显著下降趋势,密云水库、西大洋、王快、黄壁庄四大水库跳跃变异显著,且为均值向下跳跃,不利于区域供水安全。

Hydrological series may vary with time in the form of obvious trend or exhibited jump owing to the influence of human activities or weather changes. This is the case of hydrological alteration in the series. This paper presents a diagnosis system, a tool for hydrological alteration analysis presented, composed of three components, namely primary diagnosis, detailed diagnosis and comprehensive diagnosis. Firstly it adopts the Hurst coefficient method etc. to make a primary diagnosis and judges whether or not the series contains alteration. If it does, then various examination methods may be used to conduct a detailed diagnosis, including three trend diagnosis methods and eleven jump up diagnosis methods. The diagnosis results are also classified into two types, trend results and jump results, for which the trend comprehensive and jump comprehensive are used respectively. Nash efficiency coefficients are calculated to identify alteration form of the series, and the alteration form may be judged if the coefficient is bigger than the other one, but a hydrological survey analysis is often needed before making the final conclusion to confirm the diagnosis results. This system can overcome the shortcoming of either a single-method examination in producing unreliable results on occasion or a multiple- methods examination in producing a conflict among the results. A test case of 45 years inflow series of five reservoirs in Haihe Basin shows that the series of Guanting reservoir contains a declining trend, and the other reservoirs jump down against the water-supply security.