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旱灾是湖南省最严重的农业自然灾害之一,旱灾几乎年年都有发生,且涉及面广,后续和潜在危害较大。湖南省农业旱灾的受灾率异常指数和成灾率异常指数的变化规律揭示:过去58年,农业旱灾具有明显的波动性与阶段性,大致以5年为尺度,轻重灾期交替出现;受灾率与成灾率具有同步性,在重灾期尤为明显;1980年以来灾情更为严重,成灾率、受灾率都较大。湖南省农业旱灾异常指数周期性变化可以分为2个时段,1990年代初期以前存在4个特征时间尺度,分别为3年、5年1、0和21年4个周期;1990年代初期以后存在3个特征时间尺度,分别为3年、7年和17年年3个周期。根据异常指数的变化,建立了农业旱灾灰色灾变预测模型,进行了重灾预测。结果表明,今后20年湖南省农业旱灾将出现5个重灾年份,分别在2010-2011年、2013—2014年2、016—2018年2、021—2022年、2025—2027年期间,间隔为4年左右。
Drought is one of the most serious agricultural natural disasters in Hunan Province. Droughts have occurred almost year after year with extensive coverage and follow-up and potential hazards. The variation regularity of disaster anomaly index and anomaly index of agricultural drought in Hunan Province revealed that the agricultural drought in the past 58 years had obvious fluctuation and stage, And the disaster rate is synchronous, especially during the disaster; since 1980, the disaster is more serious, the disaster rate and the disaster rate are greater. The periodic change of agricultural drought anomaly index in Hunan Province can be divided into two periods. There are four characteristic time scales before the early 1990’s, which are 3 years, 5 years, 1, 0 and 21 years respectively. After the early 1990s, there are 3 A characteristic time scale, respectively, 3 years, 7 years and 17 years, 3 cycles. According to the change of anomaly index, a gray catastrophe prediction model of agricultural drought was established and a heavy disaster prediction was made. The results show that in the next 20 years, there will be 5 years of heavy losses in agricultural drought in Hunan Province, respectively in 2010-2011, 2013-2014,2,016-208,2,021-2022 and 2025-2027, with intervals of About 4 years.