| Agriculture is the most vulnerable industry to weather effect,especially the effect of drought and waterlogging.Studying on the influence to agriculture from drought and waterlogging is necessary under the background of strengthened climatic change.The essay has made comparative researchat small scale based on analyzing the drought andwaterlogging dynamics of Dongxing District and Pujiang County in recent 55 years,as well as the relationship among drought and waterlogging dynamics,meteorological yields,yield reduction rate,reduction variable coefficient,according to the monthly rainfall data of Dongxing District and Pujiang County in recent 55 years(1961-2015),and their per unit yield of major crops(rice?corn?sweet potato?wheat and rape)in recent 33 years(1983-2015).The following conclusions were made through the study:(1)The precipitation of two areas both had the following features in the recent 55 years:(1)The amount of precipitation(annual mean value,seasonal mean value and monthly mean value)of Pujiang County was larger than that of Dongxing District;the precipitation of the two areas at each statistic period(annual,seasonal,monthly)showed a fluctuated declining trend.(2)The precipitations of Pujiang County at the growth periods of its five major crops respectively were all greater than that of Dongxing District.Affected by climate change,the precipitation during the growth period of crops(rice,corn,sweet potato)in the spring crops of the two areas showed a fluctuated declining trend;The precipitation during the growth period of wheat in the autumnspring was relatively stable,but the precipitation of Dongxing District during the growth period of rape showed fluctuated rising while it showed a fluctuated declining trend in Pujiang County.(2)In the recent 55 years,drought and waterlogging of the two areas had the flowing features:(1)Drought frequency and waterlogging frequency of Pujiang County were both 29.09%,and the total frequency of drought and waterlogging was 58.18%,which were higher than that of Dongxing District(23.64%,18.18%,41.82%).Drought and waterlogging dynamics of Dongxing District showed an alternate turn of drought and waterlogging while the state of Pujiang County was changed from waterlogging to drought.(2)The drought frequency of Pujiang County was 20% in spring,27.27% in summer and autumn respectively;the waterloggingfrequency was 23.64% in the three seasons;the total frequency of drought and waterlogging was 40% in spring,50.91% in summer and autumn respectively,which were higher than that of Dongxnig District(drought frequency: 14.29%,23.64%,23.64%;waterloggingfrequency: 18.44%,18.44%,20%;total frequency of drought and waterlogging: 32.73%,41.82%,43.64%);the drought frequency,waterlogging frequency,total frequency of drought and waterlogging of Pujiang County were 18.18%,14.55%,and 32.73% respectively,which were lower than that of Dongxing District(25.45%,23.65%,and 49.1% respectively).The drought and waterlogging turn of Dongxing District was changedfrom waterlogging to drought during the four seasons,while it was complicated in Dongxing District.(3)The months of partial drought,partial waterlogging,and drought and flood of the two areas were almost the same.Partial drought months were concentrated in July and August,partial waterloggingmonths were centered on February and December,and the drought and waterlogging state of other months were close.The drought and waterlogging dynamics of the two areas were complicate in the recent 55 years.(3)The drought and waterlogging of the two areas during growth period of major crops in the recent 55 years showed the following features:(1)total frequency of drought and waterlogging of Dongxing District was 44.10%,which was higher than that of Pujiang County(40.15%),in which,the drought frequency value of Dongxing District(23.03%)was higher than that of Pujiang County(18.49%);while the waterlogging frequency mean value(20.10%)was lower than Pujiang County(21.67%).(2)The drought frequency of the spring cropsof the two areas was close(24.24%);the waterlogging frequency of Pujiang County was 27.88%,which was higher than that of Dongxing District(21.22%).The total drought and waterloggingfrequency of Pujiang County(52.12%)was higher than that of Dongxing District(45.46%).The drought and waterlogging turned alternately in Dongxing District during spring crops,while the situation in Pujiang County showed the trend of changing from waterlogging to drought.(3)The drought frequency,waterlogging frequency and the total frequency of drought and waterlogging were 21.82%,20.77%,and 42.73% respectively during autumn spring in Dongxing District,which were higher than that of Pujiang County(12.73%,16.36%,and 28.19%).The drought and waterlogging of the crops in autumn springof both areas showed the feature of alternated change.(4)The orders of drought frequency of the major crops in the two areas were: Dongxing District was rice>sweet potato>wheat,rape>corn;Pujiang County was corn,sweet potato> rice> rape.The orders of waterlogging frequency of the major crops in the two areas were:Dongxing Districtwas rice>corn,rape> sweet potato,wheat;Pujiang County was sweet potato> rice,corn> wheat> rape.The orders of total drought and waterlogging frequency of the major crops in the two areas were:Dongxing District is rice>rape>corn,sweet potato>wheat;Pujiang County is rice,sweet potato>corn> wheat> rape.(4)The relationship between crop yield and drought and waterlogging in the two areasin the recent 33 years has the following characteristics:(1)There was a significant correlation between the meteorological yield and drought and waterloggingforriceof Dongxing District and for wheat of Pujiang County.(2)There was a significant correlation between the yield reduction and drought andwaterloggingfor rice,wheat of Dongxing District and for wheat of Pujiang County.(3)There was a significant correlation between the coefficient of variation of rice,wheat and rapeseed in Dongxing District and drought and waterlogging.(4)As the crop yield was affected by many factors,the meteorological yield,yieldreduction rate and coefficient of variation of the remaining crops in the two areas were not significantly correlated with drought and waterlogging. |
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