| At first, the influencing factors which had great relevance with groundwater table were determined by the principal component analysis (PCA) method, then established the groundwater table forecast model by using the multivariate time series CAR model, according to the information as rainfall, evapovation, groundwater exploitation and groundwater tables and so on from 2000 to 2009 in Da'an City. Also the model was validated and applied to forecast the groundwater tables. The result shown that: The correlation coefficients of agricultural water consumption, precipitation and evaporation with the groundwater table were 0.56, 0.46 and -0.13, respectively. The contributions of the three factors with the groundwater table were 43.09%, 27.45% and 21.39%, respectively. The total contribution rate was 91.93% and they were the major factors affecting the groundwater table. The relative error between forecasting value and measured value for confined and unconfined water tables was less than 5%. According to the forecast scheme, when the rainfall was reduced 10% and evaporation was increased 9%, and the agricultural water consumption was increased 11%, the confined water table will be reached 8.70 m, and the unconfined water table will be reached 4.55 m. So in drought period, the agricultural exploitation should be reduced properly, the surface water irrigation should be increased, to reduce the possibility of soil desertification. |