Analysis on Agricultural Drought Degree in Crop Growth Season in Recent 50 Years in Xinmin,Liaoning Province

By means of the analysis methods of linear regression,climate tendency rate,integral humidity index and dry-wet index,precipitation,agricultural water demand and drought degree were analyzed systematically.The results showed that precipitation tendency rate in crop growing season was-19.983 mm/10 a in recent 50 years,and precipitation reduced by around 100 mm.60%-70% years had basically satisfactory precipitation and the satisfaction degree of natural precipitation towards agricultural water demand decreased by 23%.Due to precipitation decrease,climatic type changed from semi-humid and relative drought to moderate drought.The average water deficit was 56 mm in growth season and 36% years were affected by drought.Spring drought was the most serious with the probability of 64%,followed by autumn drought with the probability of 58%,and summer drought was the lightest with the probability of 24%.The drought probability from planting to seedling emergence in May was 70%,which had the greatest effect on agriculture production.