基于分布式水文模型的小麦渍害对气候变化响应研究

Response of Wheat Sub-Surface Waterlogging to Climate Changing Using DHSVM Model Simulations

为探讨长江中下游地区小麦渍害对气候变化的反应,以湖北省监利县为研究对象,收集1970-2018年监利气象观测数据和CMIP5(coupled model intercomparison projectphase5)四种情景[RCP(representative concentration pathway)2.6、RCP4.5、RCP6.0和RCP8.5]2020-2069年全球气候模式模拟气象结果数据,通过分布式水文模型(DHSVM模型:distributed hydrology soil vegetation model)模拟了近100年四种情景监利农田土壤表层(0~30cm)土壤体积含水量,并以此来计算小麦受渍指数[sub-surface waterlogging index(SSWI),每年3-4月(小麦拔节至灌浆期)受渍天数比率]。结果表明,监利小麦受渍指数有逐年递减的趋势,但受渍时间的年际间差异会越来越大,四种情景也呈现出相同的变化规律,其中RCP4.5情景规律最明显,其主要原因是全球CO2排放增加。降雨量增加可能会加大渍害的危害程度,但同期辐射量和气温升高会导致农田蒸散和空气中水汽含量提高,降低农田土壤含水量,有利于渍害的危害程度降低。由于农田水平衡建立在高降水、高蒸散的基础上,因此出现极端天气的可能性增加。

In order to explore the response of wheat waterlogging to climate change in the middle and lower reaches of the Yangtze river,Jianli county,Hubei province,was taken as the research object.The meteorological observation data and four scenarios(RCP(representative concentration pathway)2.6、RCP 4.5、RCP 6.0 and RCP8.5)of CMIP5(coupled model intercomparison project phase 5)were collected,and the global climate model from 2020 to 2069 was used to simulate the meteorological results.The distributed hydrological soil vegetation model(DHSVM)was used to simulate the soil volume moisture content(0-30 cm)of four scenarios of monitoring farmland in the past 100 years.The sub-surface waterlogging index(SSWI)of wheat and ratio of waterlogging days from March to April each year(jointing to filling stage of wheat)were calculated.The results showed that the waterlogging index of Jianli wheat had a decreasing trend year by year,but the difference of waterlogging time between years increased.The four scenarios of this trend were the same,and the most obvious scenario was RCP 4.5.The main reason is the increase of global CO2 emissions.The increase of rainfall may increase the severity of waterlogging,but because of the increase of radiation and temperature in the same period,the evapotranspiration of farmland and the moisture content in the air will be increased,and the soil moisture content of farmland will be reduced,which is conducive to the reduction of the severity of waterlogging.Because the water balance of farmland is based on the high precipitation and evapotranspiration,the possibility of extreme weather will increase.