渭河流域农业干旱评估与致灾机理研究

Global climate change has significantly changed the spatiotemporal distribution of precipitation and air temperature. Due to the particular physical geographical conditions, drought events in China occurred frequently with a trend of increasing during the past decades. Especially, extreme drought events, that seriously affected agricultural production and food security, have resulted in huge losses in agriculture. In this proposal, a distributed hydrological model including an improved crop growth module will be developed. The crop yield will be estimated at watershed scale, and the spatial-temporal evolution pattern of agricultural drought will be analyzed. The disaster mechanism of agricultural drought will be investigated, and the loss of agricultural drought will be evaluated in the Wei River basin. Firstly, the hydrological cycle of the Wei River basin will be simulated by the distributed hydrological model, and the crop growth module of the model will be modified; Secondly, the proposed drought index based on the concept of blue and green water, combined with existing drought indices will be used to analyze the agricultural droughts in the Wei River basin; Finally, the mechanism of agricultural drought hazard in the Wei River basin will be investigated, and the responses of crop yield to water deficit will be quantitatively analyzed. The crop water production function will be established, and the impact of drought on crop yield will be evaluated. This study will provide theoretical basis and technological support to mitigate the impact of droughts on agriculture.

全球变化显著改变了降水与气温的时空分布特征，加之我国特殊的自然地理条件，使得近年来干旱事件呈广发和频发的态势，严重影响农业生产与粮食安全，造成巨大农业经济损失。本项目拟构建渭河流域分布式水文模型，模拟流域尺度农作物产量，分析农业干旱时空演变规律，剖析农业旱灾致灾机理，从而对渭河流域农业旱灾损失进行综合评估。首先，借助分布式水文模型模拟渭河流域水循环过程，并完善其相对薄弱的作物生长模块以模拟流域尺度农作物产量；其次，提出基于蓝水绿水概念的农业干旱评价指标，并优选已有干旱指标分析流域农业干旱时空演变规律；最后，深入剖析渭河流域农业旱灾致灾机理，定量分析作物产量对水分亏缺的响应关系，建立作物水分生产函数，识别农业旱灾致灾因子，探讨干旱对农作物产量的影响，从而对渭河流域农业旱灾损失进行综合评估，为减轻干旱对渭河流域农业的影响提供理论依据与技术支撑。

干旱是世界上影响最广、造成农业经济损失最大的自然灾害之一，每年给全球农业造成数十亿美元的损失。特殊的自然地理条件加之全球气候变化的影响，决定了我国是一个干旱频发的国家，这对于我国的农业发展和粮食安全来说影响重大。渭河流域是我国西北经济较为发达的地区，也是我国重要的粮棉油产区和工业生产基地之一。因此，该地区农业的稳产和高产对于我国西部地区，甚至全国的粮食安全来说具有重要作用。针对近些年干旱事件频发，科学评估由此产生的粮食损失，提出适宜的抗旱减灾措施，以最大限度地减轻旱灾影响和粮食减产，保障国家的粮食安全，是亟待研究的问题。本研究采用气象干旱指标SPI和SPEI分析渭河流域近五十多年气象干旱年代际、年际和季节变化，评估干旱发生频率、发生强度、影响范围以及持续时间；选用农业干旱指标VHI和CWSI评估渭河流域近十六年农业干旱时空演变规律。构建渭河流域分布式水文模型SWAT，采用SUFI-2算法进行参数敏感性分析、率定、验证及不确定性分析，多尺度估算近五十年渭河流域蓝水绿水资源量，从而进行干旱评估，揭示绿水资源对于农业灌溉用水的替代作用。深入剖析渭河流域农业干旱的致灾机理，识别影响渭河流域农业干旱的关键驱动因子，探讨其对渭河流域农业干旱的影响，并定量分析其对干旱程度的相对贡献；分析农业干旱指标用于估算渭河流域粮食产量的可行性。本研究为减轻干旱灾害对渭河流域乃至我国西北干旱半干旱地区农业生产的影响，保障我国的粮食安全提供理论依据与科技支撑。