用灰色系统预测模型预测三峡工程对洞庭湖区洲滩面积的影响

Influence of the Three Gorge Project on Marshland in Dongting-Lake Area by Grey System Theory

以灰数的白色函数生成为基础，建立白化形式的微分方程，来预测坝址每年丰水期、枯水期平均流量，结合三峡工程建库前后不同时空边界条件的分析计算，从而预测出三峡工程对洞庭湖区洲滩面积变化趋势的影响．灰色系统的预测简称灰色预测，它的特点是基于灰色系统的模型进行未来系统变化的预估．本文对洞庭湖洲滩面积的预测，采用灰色拓扑预测．其基本思路是将样本信息作成曲线，在曲线上按某个定值找出许多发生时刻数据，然后用时刻数据分别建立GM（1，1）模型群以预测这些定值未来出现的时刻，将各个未来发生的定值联成曲线。

Based on the grey white function generation of Grey System Theory, a whitened differential equation has been established. It can be applied to forecast the discharge regime at the Three-Gorge Project(TGP) Dam site under flood and dry seasons. According to the variations of discharge with/without building TGP, the corresponding influence upon the marshland around Dongting Lake has been forecasted. In the Grey Syetem Theory, a sample information curve is plotted first. After finding a series of time parameters at the curve on the basis of definite values, the GM (1, 1) model group of the time parameters is set up. Different regimes such as 1974-type and 2000 year are considered. Based on the forecasted discharges before/after building TGP in Chenglinji Hydrological Station, the marshland decreases in East, West, South Dongting Lake areas are predicted respectively. Preliminary results show that there will be a 12.1%-24.9% decrease for the 1974-type, a 17.7.1% - 26.0% decrease for the 2000 year. Further analysis reveals that the decreases of marshland turns out to be greater in West Dongting Lake area than those in East Dongting Lake area.