内蒙古草地畜牧业系统旱灾风险评价模型

Drought Risk Assessment Model to Animal Husbandry Systems in Inner Mongolia Pastures

在区域自然条件综合评价中,多指标因子的简化和降维处理是评价的关键问题之一.本文将高维降维技术——投影寻踪评价模型(PPE)应用于草地畜牧业旱灾综合风险评价,利用改进的加速遗传算法(RAGA)优化投影方向,将多维数据指标转换到低维子空间,通过寻求最优投影方向及投影函数值实现对畜牧业旱灾风险的分类与等级评价,克服了常规投影寻踪方法计算量大、编程实现困难的缺点.并采用草地畜牧业旱灾风险评价投影寻踪模型,在"致灾因子危险性分析-承灾体脆弱性分析-恢复性分析"的风险综合评价框架内,对内蒙古草地畜牧业系统旱灾风险进行了评价,评价结果表明20世纪90年代以后,虽然旱灾危险性加大,但是由于恢复性增强,大部分牧区风险都有所降低,但对于有的牧区,由于草地退化沙化严重,从而导致旱灾风险一直偏高.认为在气候暖干化背景下,只有调整草地畜牧业发展战略,从生态效益和经济效益出发,优化牧场整体生产结构,增草增畜,使草地资源得到恢复性演替,才能降低草地畜牧业旱灾风险.

One of the difficulties frequently encountered in regional condition assessment is that not one but all the influencing factors associated with regional condition must be used. A new technique of falling dimension named projection pursuit was applied to animal husbandry drought risk assessment through using the improved real coding based accelerating genetic algorithm to optimize the projection direction. Thus, it could transfer multi-dimension data in to one dimension data, through searching for the optimum projection direction to realize the animal husbandry drought-risk classification and its grade evaluation. The method could overcome the shortcomings of large computation amount and difficulty of computer programming in traditional projection pursuit method. Based on the integrate drought risk assessment frame of ＂hazard- vulnerability -resilience＂, a drought assessment indexes system and model related with animal husbandry systems was constructed, and drought risk of animal husbandry systems in Inner Mongolia was assessed. The results showed that the drought risk decreased after 1990s results from the resilience＇ s increased evidently. It is also suggested that in the context of climate change, the resource allocation should be optimized, and intensive animal husbandry should be developed rapidly. Only by this way, the drought risk of animal husbandry can be reduced.