基于多目标决策的关中天水经济区水资源时空优化配置研究

Water is the source of life, the key of production, the foundation of ecology. Guan-tian Economic Zone, one of the three key economic Zones clearly defined in the 'Eleventh Five-year Plan of China's Western Development Program', lies in the strategic point, serving as a link between the Eastern and Western parts of China, connecting north and south. However, the rapid development of regional population and economy will definitely intensify the contradictions between supplements and requirements about water resources. Therefore, the optimal allocation of limited water resources and the increase of comprehensive utilization rate have become a major subject urgent to be resolved for the sustainable development. Due to the differences among regions and diversities of methods, some problems still have existed in the current researches. For example, few researches, especially aimed at Guan-tian Economic Zone, have been done on the spatio-temporal optimal allocations of water resources based on multi-objective decisions. Thus, project is proposed, taking the dynamic data in Guan-tian Economic Zone (including Tianshui and Guanzhong areas in the Wei River Basin) concerning water, soil, weather condition, and the RS and GIS spatial analysis technologies as supports, and using neural network methods and hydrological ecological models assessing the eco-environmental water requirements and the social-economical water demands; on this basis, being coupled with grey linear programming and CA-Markov models, establishing the spatial optimal allocation of limited water resources models based on pixel micro-units, proposing multi-objective allocation schemes based on the different levels of water consumption demands, different guarantee rates, as well as different water sources (surface water, ground water and transferring water).

水是生命之源、生产之要、生态之基。关中天水经济区是《国家西部大开发"十一五"规划》中明确的三大重点经济区之一，处于承东启西、连接南北的战略要地。然而区域人口和经济的快速发展，势必导致水资源供需矛盾日趋尖锐。因此，优化配置有限的水资源，提高综合利用率，已经成为可持续发展亟待解决的重大课题。由于区域差异性和方法多样性，目前的研究仍存在一些问题。例如基于多目标决策的水资源时空综合配置研究较少，特别是针对关天经济区的研究更是少闻。鉴于此，项目拟以关天经济区（包括渭河流域天水和关中段）的自然和社会经济等因素的动态资料为数据支持，以RS和GIS空间分析为技术支持，分别采用神经网络法、生态水文模型法、长系列分析法测评区域社会经济需水、生态环境需水和可供水总量；在此基础上，耦合灰色线性规划和CA-Markov方法，构建基于像元微单元的水资源时空优化模型，提出多目标、多水源、多约束和多保证率的综合配置方案。

研究系统分析了区域水资源供需状况、质量特点及存在问题，明确了未来规划年为丰水年、平水年和枯水年的满足不同生态环境需水等级的多情景模式水资源利用数量，并通过以水定土的方式实现了水土资源利用的最佳生态环境效益和社会经济效益。结果表明：①关中北部地区水资源负载指数较高，人口密集，经济需水很大，水资源开发利用水平很高，开发潜力很小。关中南部地区水资源负载指数较低，降水量丰沛，水资源总量丰富，开发潜力较大。依据水资源承载指数和人水平衡关系，大多数区县属于水资源超载地区，以区县为单元，进行级别划分，严重超载地区占了34%，过载地区占了31%，处于临界状态以下的区县仅占19%。②植被生态需水主要集中在每年的夏季，约占生长期生态需水总量的41.43%。高度生态需水的区域主要位于北部的黄土丘陵沟壑区和南部的秦岭山区；低度生态需水的区域主要位于中部的河谷阶地。渭河流域（泾河张家山以上）、嘉陵江流域、褒河流域和伊洛河流域的单位面积生态需水相对较高，渭河流域（宝鸡峡以上）、渭河流域（龙门至三门峡）和渭河流域（咸阳至潼关段）的单位面积生态需水相对较低。③现状年水资源丰度为平水年的低配方案，即水资源满足了区域最小生态环境需水等级下，土地资源的生态服务价值为11.73亿元，经济收益为418.04亿元；2030规划年水资源丰度为平水年的低配方案，土地资源的生态服务价值为11.76亿元，经济收益为487.38亿元。优化结果，未来区域耕地和草地面积仍然会有一定程度的减少，而建设用地面积则会有所增加，主要以城市扩展为主；林地面积有所增加，主要分布在国家级子午岭森林保护区、国家级六盘山森林保护区、省级秦岭-关山森林保护区以及渭河整治绿化区等；水域面积略有增加，表明区域在不断完善引水工程、流域综合治理和建设工程、人工湿地工程以及农业灌溉工程等；未利用地面积有所减少，表明区域土地的节约集约利用程度有所提高。研究对于促进区域人口、资源环境、社会经济的协调和可持续发展具有重要意义。