Study On The Optimal Allocation Of Agricultural Water And Land Resources Based On Water-carbon-economy Coupling Model

Rational optimisation of the allocation of agricultural water and land resources is of great importance to safeguard agricultural production and maintain food security.Water and land resources are the basic elements to ensure the development of agricultural production in China.Affected by economic development,climate change and human activities,land and water resources are often unevenly distributed and unreasonably used.At the same time,farmland ecosystems are both an important carbon source and a huge carbon sink system.Carrying out carbon footprint analysis of farmland can provide an important basis for research on the optimal allocation of land and water resources,which is a key step in maintaining ecological balance and has practical significance for sustainable agricultural development.This study takes Youyi Farm in the Sanjiang Plain as a typical study area.Firstly,the single-crop coefficient method combined with remote sensing technology was applied to analyse the changes in net irrigation water requiretment for each crop growth period from 2010 to 2019,and the response of net irrigation water requiretment to meteorological factors was explored through the generalised additive model(GAM).Secondly,the ecological footprint method was used to assess the ecological carrying capacity of local land and water resources.Finally,a water-carbon-economy coupled agricultural water and land resource optimisation model was constructed using the local surface water and groundwater availability as the source of water for crop irrigation,and the optimal solution was selected through the evaluation model to obtain the most suitable results for local agricultural development.The main results achieved in this study are as follows:(1)The actual average net irrigation water requiretment from 2010 to 2019 is Rice>Maize>Soybean.As meteorological factors change dynamically from year to year,irrigation water requiretments vary considerably.For Rice,the largest proportion of irrigation water(34%)is used in the early stages of growth for the whole reproductive period.For Maize and Soybean,the highest proportions of net irrigation water requiretments are found at mid-growth(45%and 52%).In addition,the three main meteorological factors that had the greatest impact on net irrigation water requiretments were precipitation,relative humidity and sunshine duration.(2)The ecological footprint of agricultural water resources per capita in the study area is 5.26hm~2/person,while the ecological carrying capacity is 1.97hm~2/person on average for many years.The ecological footprint of water resources per capita far exceeds the ecological carrying capacity.The ecological footprint of per capita arable land resources is less than the ecological carrying capacity;the coupling coordination degree between the ecological footprint of agricultural land and water resources and the ecological carrying capacity of land and water resources of Youyi Farm is in a barely coordinated and primary coordinated state.(3)The multi-objective optimisation model was used to obtain a more suitable crop cultivation structure and the allocation ratio of surface water and groundwater use in this study area,so as to achieve coupled water-carbon-economy optimisation.The ratio of rice area,maize area and soybean area is 3:6:1;the water consumption is under control,with an average annual water consumption of 1.77×10~8m~3,and the target of increasing carbon sequestration is achieved,with an average annual increase of8×10~8kg.The optimisation results are of great significance to the conservation of black land and the sustainable development of agricultural land and water resources.