农业干旱风险评估研究综述

对农业干旱风险致险性、脆弱性及损失模型等方面进行了深入系统的回顾与评述,阐述了农业干旱风险研究的前沿领域和学术问题,展望了农业干旱风险未来的发展趋势:农业干旱致险性评估的关键是构建合适的干旱指标,目前干旱评估指标很多,大致可分为水分变异程度指标、干旱发展过程指标和干旱空间差异指标三类,但多数指标对农业干旱成灾过程反映不足,在评估方法上对农业干旱灾害机理认识不深入,成为了农业致险性评估的瓶颈;农业干旱脆弱性通常决定着农业干旱风险的高低,其中,灌溉能力、技术、资金等是影响农业脆弱性高低的重要因子,而定量刻画农业干旱脆弱性对政策、技术、保险等人文因素的响应是当前研究的薄弱环节;农业干旱风险损失评估模型较多,但由于受区域、人为等因素影响,多数模型普适性较差。因此,未来农业干旱风险评估需要深入认识农业干旱影响的机理和过程,突出研究农业干旱脆弱性对人文因素变化的响应,并通过区间合作来进一步改进风险损失模型。

区域农业干旱风险评估研究——以中国西南地区为例

农业干旱风险评估有助于提升区域灾害风险管理和决策水平,减轻干旱灾害造成的损失。利用历史降水资料、灾情数据和社会经济数据,本文以地级市为评估单元,以各评估单元3种播种面积最大的农作物为评价对象,在发展和完善现有连续无雨日干旱评估指标的基础上,结合作物不同生长阶段对干旱反应的差异,设计了一套农业作物干旱等级判定及其概率研究方法,同时,提出评估单元不同作物干旱等级损失率的计算方法,构建了农业干旱风险损失评估的计算模型。本文以西南区为案例区进行了农业干旱风险评估,结果发现:①采用研究方法求算的各评估单元风险损失结果能有效地表达各评估单元之间的农业干旱风险差异;②根据计算的农业干旱风险指数划分的风险区能比较准确地反映案例区内农业干旱风险的空间分布规律;③西南区农业干旱高度和重度风险区主要分布在该区西部和北部的一些高原、山地之中,而轻度和中度风险区则主要分布在其东部、中部和南部地区。

面板数据下区域农业干旱灾害风险的灰色C型关联分析

正确评估农业旱灾风险可为防灾减灾规划提供辅助决策依据。针对现有旱灾风险评估模型不能充分融合时间元素的问题,以面板数据矩阵表征为出发点,结合样本行为矩阵的位移关联度、速度关联度和加速度关联度,构建了基于面板数据的灰色C型关联模型。对比分析表明,该模型简单有效且不受指标排列顺序的影响。将模型应用于豫北平原5个地区的农业旱灾风险分析中,评估结果与实际相符,进一步证明了模型的合理性。该模型为区域农业干旱灾害风险评估提供了新方法。

基于模糊粗糙集模型的农业旱灾风险评估--以河套灌区为例

为客观评估农业干旱灾害风险的时空变化特征,本文基于区域自然灾害理论,从农业干旱灾害危险性、暴露性、脆弱性和防灾减灾能力四个方面构造农业干旱灾害风险评价指标体系。采用表征气象干旱强度的作物关键生育期的标准化降水蒸散指数(SPEI)作为危险性评价指标之一。基于构建的模糊粗糙集模型和层次分析(AHP)模型,评估了内蒙古河套灌区(2003-2017年)农业干旱灾害风险时空变化特征。研究结果表明,两种方法所得评价结果基本相同。空间分布上,五原县的风险等级最高,磴口县和乌拉特前旗处于中风险区,临河区和杭锦后旗常年稳居低风险区。时间上,临河区、杭锦后旗和乌拉特前旗的风险指数略有增长,而五原县和磴口县的风险指数在2010年后增加明显且波动幅度较大。根据研究区农业旱灾风险评价结果,对研究区五个区县提出了针对性的防治措施以缓解未来的旱灾风险。

Assessment on Agricultural Drought Risk Based on Variable Fuzzy Sets Model

Drought is one of the major natural disasters causing huge agricultural losses annually. Regional agricultural drought risk assessment has great significance for reducing regional disaster and agricultural drought losses. Based on the fuzzy characteristics of agricultural drought risk, variable fuzzy sets model was used for comprehensively assessing agricultural drought risk of Liaoning Province in China. A multi-layers and multi-indices assessment model was estab-lished according to variable fuzzy sets theory, and agricultural drought risk of all 14 prefecture-level cities was respec-tively estimated in terms of dangerousness, vulnerability, exposure and drought-resistibility. By calculating the combi-nation weights of four drought risk factors, agricultural drought risk grade of each city was obtained. Based on the as-sessment results, the spatial distribution maps of agricultural drought risk were drawn. The results shows that eastern cities have lower drought dangerousness than western cities in Liaoning Province totally. Most cities are located in low drought vulnerability region and high drought exposure region. Because of frequent and severe drought since 2000, most cities are located in lower drought-resistibility region. Comprehensive agricultural drought risk presents apparent spatial characteristics, escalating from the east to the west. Drought dangerousness is the most important factor influencing comprehensive agricultural drought risk. Through the spatial distribution maps of drought risk, decision makers could find out drought situation and make decisions on drought resistance conveniently.

Influence Factors and Assessment of Risk Perception for Agricultural Drought Based on Household-scale

This paper describes the basic connotation of risk perception, the influence factors of the risk perception for agricultural drought and the mainstream assess- ment model. Additionally, it summarizes the latest developments of research meth- ods for risk perception for the agricultural drought, and the research status of the risk perception for agricultural drought, and put forward the trends of risk perception for the agricultural drought. Finally, it proposes the research areas of the risk per- ception for agricultural drought should be improved in future.

Risk Assessment and Zoning of Agricultural Drought Disaster in Heilongjiang Province

In this study,we first zoned the drought degree in the years from 1971 to 2000 in Heilongjiang Province by using precipitation anomaly equation as an indicator,and analyzed the temporal distribution characteristics and laws of arid disaster in different periods.Using the method of human being habitat risk assessment,we further studied and zoned the drought disaster risk index(DDRI)of maize cultivated in 74 stations in Heilongjiang Province via GIS software.The results showed that(1)the occurrence frequency of moderate and heavy drought in Heilongjiang Province was 1970s>1990s>1980s,and(2)the high risk area of drought disaster for maize production mainly assembled in Qiqihar and Daqing regions in west Heilongjiang Province,where agricultural drought should be highly concerned,while low risk and slight risk areas mainly distribute in middle areas and east plain areas in Heilongjiang Province.Our study provided basis for the defense of agricultural drought disaster.

Agricultural Drought Resisting and Hydrological-Ecological Changes Taking Hebei Province in North China as an Example

Drought is usually supposed to be a rainfall deficiency problem. Most studies and practices to mitigate drought disaster are focusing on water development and irrigation, while neglecting that the agriculture system is a compounded human-natural system. Drought situation and tendency is also driven by human coping strategies. This paper takes Hebei Province in north China as an example, studing the spirally interact process of drought resisting and hydrological ecological feedback. The result shows that large scale water projects construction facilitated irrigation. With improved irrigation, farmers enhanced multiple crop index and land-use intensity greatly and increased the sowing area of water consuming crop, winter wheat. At the same time, both crop yield and gross output are raising steadily. Water demand and depletion in agricultural system increase year by year. This gradually leads to highly dependent on over exploitation of water resources, especially overdraw of groundwater. The process deteriorated the stability of hydrological-ecological system and made the ecological environment drying up. Drying up environment is breeding greater vulnerability and risk of drought in the long term. For sustainable development, integrated drought risk management should be based on the balance between sustainable water supply and water demand. The key is to improve agricultural system＇s adaptive and resilient capacity to drought.