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1992年上半年,是莒县有气象资料记载以来旱情最严重的一段时间。据气象站资料,1991年10～12月及1992年1～6月共降水102.1mm,是历年同期平均降水量的32.5％,而同期蒸发量达到826.0mm。尤其是杨树进入生长季节后的5～6月份,仅降水22.5mm。全县河水断流,库塘干涸,地下水位平均下降2～5m。许多河滩上的杨树丰产林落叶严重,甚至有的小枝干枯,生长受到严重影响。为了解河滩土壤、水分条件对杨树生长的影响,考察杨
In the first half of 1992, it was the most serious drought in Yixian County since the meteorological data were recorded. According to the weather station data, the total precipitation was 102.1mm from October to December 1991 and from January to June 1992, representing 32.5% of the average precipitation over the same period of the previous year, while the evaporation over the same period reached 826.0mm. In particular, poplar entered the growing season after May to June, only the precipitation 22.5mm. County water cut off, Ku Tang dried up, the average groundwater level decreased 2 ~ 5m. Many poplar trees on the beach yield deciduous leaves, and even some small branches, growth has been severely affected. To understand the river beach soil, water conditions on the impact of poplar growth, study Yang