东北黑土区水土资源配置及其空间格局优化

Allocation of water and land resources and ecological security in the black soil area of Northeast China

在水资源刚性约束条件下,如何综合考虑多个目标实现东北黑土区水土资源优化配置仍是有待解决的国际前沿问题.因此,本研究首先分析了该地区水土资源演变规律,然后研发了基于水-碳-经济-生态耦合的水土资源优化配置模型,通过NSGAⅢ智能算法对模型进行求解,最终在4种情景下对黑土区40个城市水土资源进行优化配置和生态安全保障分析.结果表明:(1)在气候变化和人类活动的影响下,1980年之后水田和旱田面积分别增加了91%和14%,林地、草地和湿地分别减少了2%、27%和10%.(2)2001~2020年东北黑土区平均水资源总量为1972亿m^(3),大部分城市的地表水资源量、地下水资源量以及水资源总量呈现增加趋势.(3)4种情景下,东北黑土区主要粮食作物的毛灌溉需水量在491~722亿m^(3)之间.通过优化配置后,在平水年通过增强节水,水稻种植面积仍可增加13.7%;其余水平年通过调整种植结构和增强节水也可大幅度提高粮食产量、农民收入、固碳量和生态效益,减少水资源开发利用,保障东北黑土区粮食安全和生态安全.针对目前水土资源存在的问题,提出了相关对策建议,为东北黑土区粮食增产工程和生态安全提供策略支撑.

In the context of rigid water resource constraints,realizing the rational allocation of water and land resources in the black soil area of Northeast China is of great significance in guaranteeing sustainable food production and ecological security.A continuing international frontier problem is how to integrate water resources,planting structure,food production,economic efficiency,carbon sequestration and ecosystem pattern in the optimal allocation of soil and water resources.Therefore,this study firstly analyzed the evolution of water and land resources in the black soil area of Northeast China,and then developed a water and land resource optimization model based on water-carbon-economy-ecology coupling.The model was solved with the NSGAⅢintelligent algorithm.Finally,the developed model was used to analyze the optimal allocation of water and land resources and ecological security of 40 cities under four scenarios:conventional irrigation in a normal water year,water-saving irrigation in a normal water year,conventional irrigation in a dry water year,and watersaving irrigation in a dry water year.The results show the following:(1)Land-use types have changed considerably under the influence of climate change and human activities over the past 40 years,with the areas of paddy fields and dry fields increasing by 91%and 14%,and the areas of woodlands,grasslands and wetlands decreasing by 2%,27%and 10%,respectively.During the 10-year period from 2000 to 2010,land-use transformation was the most intense.(2)From 2001 to 2020,the total water resources in the black soil area of Northeast China fluctuated between 1267×10^(8) and 2929×10^(8) m^(3),with average total water resources of 1972×10^(8) m^(3).With a few exceptions,most of the cities showed an increasing trend in terms of surface water resources,groundwater resources and total water resources.(3)Under the four scenarios,the gross irrigation water requirements for four crops are 588×10^(8),491×10^(8),722×10^(8),and 600×10^(8) m^(3),respectively.Climatic conditions in different hydrological years directly affect the balance between supply and demand of agricultural water resources,resulting in some areas not being able to satisfy the current irrigation requirements.After optimizing the allocation,the area under rice cultivation can still be increased by 13.7%in normal hydrological years by enhancing agricultural water-saving.Moreover,adjusting the crop planting structure and enhancing water conservation can also significantly increase the grain yield,farmers′income,carbon sequestration and ecological benefits in other hydrological years,save water resources by reducing the exploitation and utilization of water resources,and guarantee food security and ecological safety.The ecological benefits are only slightly reduced under conventional irrigation conditions in a dry hydrological year,which are related to the indirect constraints of limited water resources.In response to the current problems of water and land resources,we suggest that the government should actively carry out agricultural water-saving in the field and process,and adjust the agricultural planting structure based on limited water resources.At the same time,based on the existing spatial distribution pattern of forest,grass and wetland and arable land,adjust the planting structure and the area of forest,grass and wetland.In water-scarce areas(e.g.,Chifeng City,Tongliao City,etc.),the area of corn and woodland can be appropriately increased to improve the carbon sequestration capacity of ecosystems and agricultural systems.This study will provide strategic support for the project of increasing grain yield and ecological security in the black soil area of Northeast China.