| By analyzing the historical evolving regular pattern of drought in the period of 500 years and after the establishment of our couitry in Shandong province,the paper defines that drought in Shandong province is a historical problem . Drought have seasonal and area characteristics ,and badly restrict the development of agricultural economy. The different definition of drought are discussed in the article .Integral humidity index is used to comprehensi ve reflect the problem of agricultural drought because it can reflect the objective ru:e of practical water support in one area . Calculating and analyzing the integral humidity indices of spring,summer,autumn and year in Shandong piovince,the result indicated that , in general , the supporting ability of precipitation to agriculture is relatively weak . Integral humidity index show a trend that it is descending from southeast to northwest in any season , and it is also show that the digress of natural precipitation support to agriculture needs is descending in this direction . The differences of water support digress in agriculture needs are big among seasons . Supporting degrees of summer precipitation in agriculture is the highest ,and the lowest is in spring . Annual variances of Integral humidity index are big du; to the annual variance of climate factor, and therefore drought often occur in summer.Using the main crops as example, the climate fragility in agriculture production is analyzed in all aspects . By the five point linear glide average method yield of crops is divided as trend yield and climate yield , as a rule , the anural variations of trend yield are smooth , but it is big for the climate yield .Consequently annual variance of agricultural yield in Shandong province mainly result from the variation of climate yield . It show that climate factor , among ecolc gical factors , is main factor which impact climate yield . Comparing the difference between potential productivity of light and temperature and potential product vity of light , temperature and precipitation precipitation condition restrict the potential productivity severely .In this paper the path analysis method is used :o match statistical analysis for crop yield with light, temperature , precipitation . The results show that precipitation is the leading affecting factor for yield . Then by analyzing the relationship between crop climatic yield and precipitation we obtained the water requirement index in different growth durations.This paper analysed the relation between rainfall and main crops yield in Shandong. The dynamic quantity contribution of rainfall for crops yield are obtained. Thus, direct economic effects of drough: for crops can be assessed . |
