| Given that the mounting frequency and magnitude of drought in China recent years and many major grain producing provinces are in drought prone region,agricultural drought has become one of the most important factors restricting agricultural production.Agricultural drought refers to reduction of crop due to lack of rainfall,low soil water content and untimely irrigating,which caused water demand of growing crop cannot be satisfied.Agricultural drought is created by various factors,such as hydrologic situation,meteorological situation,crop distribution,crop type,growth condition,tillage system and tillage level.Thus establishing reasonable agricultural drought evaluation index is of great importance in assessing drought condition accurately,master drought evolution rule and carry out agricultural drought resistance and early warning and forecasting work.Under the above background,analyzed temporal and spatial distribution of agricultural drought systematically,discussed driving mechanism of agricultural drought and proposed targeted drought resistance measures.The main contents and results are listed as follows:(1)Use of annual precipitation data from 1954 to 2013 in Henan province,using precipitation Z index,the spatial and temporal evolution of agricultural drought in nearly 60 years is analyzed.The study found that: The annual precipitation of Henan province from1954 to 2013 is slightly decreasing on the whole.The multi-year average figure is 772.6mm,Xin Yang city ranks the first with 1090.5mm,and Pu Yang city is 565.2mm.The annual Z index is decreasing and drought intensity is increasing.15 out of recent 60 years is suffered from drought,the drought frequency is 25%.Due to uneven inter-annual distribution of precipitation,drought frequency is high during 1990 s,while frequency from 2000 to 2013 decreases,drought intensity rises up,the drought frequency ranges from 25% to 37% all over the Henan province.(2)Using the data from the agricultural drought area based on regional agricultural drought index,specific analysis on agriculture drought situation and evolution characteristics from 1990 to 2013 in Henan province,and combining the precipitation Z index evaluation result,the comprehensive analysis of characteristics of drought.The study found that: The overall variation of agricultural drought area tends to be stable from 1990 to 2013.The disaster areas are relatively large in 1999 and 2011,49272.4 and 48390.4 thousand mu respectively,while in 1990,2005 and 2010,drought areas lessen to 15711.4,17927.5 and17735.4 thousand mu.Slight drought area ratio rises evidently with the year,Ia index show adecreasing trend,and the tendency rate is-0.12/10 a,which means drought degree is alleviated year by year.Drought degree is of medium level in 1991,1992,1994,1997,1999,2000,2001 and 2011,and agricultural drought is more serious due to lack of precipitation in 1992,1995,1997,1999,2001,2012 and 2013.Estimated there's no year scale drought,mild level agricultural drought occurs in 1990,1991,1993,1996,1998,2000 and 2002 to 2010 caused by impacts such as maldistribution of precipitation.(3)Most of the regions would suffer from agricultural drought,while variations still exist in drought degree and crop disaster area.Considering the uneven spatial and temporal distribution of precipitation and different drought resistance capacity,agricultural drought in part of south district is less serious than other parts of Henan province.(4)Precipitation is the number one trigger of climate factors influencing drought.Regional agricultural drought index decreases(or increases)0.06 when precipitation increases(or decreases)100mm.Year-end reservoir storage capacity come the first,as it increases(or decreases)1 billion m3,regional drought index decreases(or increases)0.113.(5)Influenced by climate change and human activities,inter-annual and spatial distribution of precipitation is not uniform,temperature during growing season is commonly high,added the uneven spatial distribution of water resources and limitations and differentiation of hydraulics infrastructure in 18 cities,Henan province is frequently suffered from agricultural drought and has large spatial differences.Based on the characteristics of agricultural drought in Henan province,8 drought resistance measures,such as speeding up reinforcement process of water storage projects and water supply works,are raised to lessen the damage of drought. |
PDF Full Text Request