Research On Optimal Allocation Of Land And Water Resources Of Cultivated Land In Naoli River Basin

The optimal allocation of soil and water resources of cultivated land aims to ensure the production capacity and sustainable production capacity of cultivated land by adjusting the matching relationship of soil and water resources of cultivated land,so as to guarantee the national food security.The research plays an important role in the efficient utilization of soil and water resources and has a profound impact on the sustainable development of regional society,economy and ecological environment.Naoli River Basin is an important commodity grain production areas of Sanjiang Plain in Heilongjiang province.With the reclamation of cultivated land,the rapid growth of the proportion of paddy field area,the increase demand of farmland irrigation,overexploitation of groundwater resulted in the decrease of the level underground water year after year.ecological environment problems such as water quality deterioration,the contradiction between the irrigation water resources use of cultivated land and the protection of ecological environment had become increasingly prominent.the improvement of cultivated land grain production at the cost of excessive exploitation of groundwater resources was not conducive to the sustainable utilization and development of land and water resources of cultivated land.The existing researches on optimal allocation of soil and water resources had made some achievements.but there were still some deficiencies.Research on optimal allocation of soil and water resources was limited to quantitative optimal allocation of land and water resources.but few studies on spatial optimal allocation of land and water resources.Meanwhile.in the existing studies on the quantitative optimal allocation of land and water resources.only taking water resources as the constraint condition,the optimal allocation of land resources was carried out according to the water demand of different land use types,but water resources were not involved in the optimal allocation,and the optimal allocation of land and water resources is not realized at the same time.To sum up,it was urgent to solve the research on the dual optimal allocation of quantity and space of land and water resources at multi-scale.In view of this,under the constraint of limited water resources,taking it as the goal that ensure the grain production capacity and sustainable production capacity of cultivated land.built the quantitative optimal allocation model of land and water resource at multi-scale based on the multi-interests of cultivated land,multi-spatial scale and multi-types of cultivated land.A scheme of the dual optimal allocation of quantity and space of land and water resources of cultivated land was put forward on the basis of determining the method of spatial optimal allocation of land and water resources in order to provide the important reference for the optimal allocation of land and water resource of cultivated land and the scientific guidance for sustainable development of cultivated land resources,water resources,social economy and ecological environment.This study took Naoli River Basin as the study area to master the spatial-temporal dynamics of the quantity and structure of cultivated land.as well as the spatial-temporal distribution and dynamics of precipitation,surface runoff and groundwater,so as to determine the dynamic change of total water resources.From the perspective of system theory and macroscopic scale,this paper analyzed the cooperative relationship between the subsystem of cultivated land resources and the subsystem of water resources by using the Haken model.Based on the supply and demand perspective of farmland water balance principle,and taking 30m×30m grid as the micro-scale of the research unit.the ratio method of available water supply of cultivated land and water demand of cultivated land was used to calculate the land and water resource matching index of cultivated land during the whole growing stage and each growing stage.On this basis,the comprehensive index of land and water resources matching of cultivated land was calculated after comprehensive consideration of the influence of the available water supply ratio of cultivated land in each growing stage on cultivated land productivity and the difference in the sensitivity of cultivated land yield to water in each growing stage.The potential attenuation method was used to calculate the water productivity of cultivated land,and the water productivity potential of cultivated land between the water productivity of cultivated land and the actual capacity of cultivated land.The water use efficiency of cultivated land was analyzed by using the ratio method between the actual productivity of cultivated land and the available water supply of cultivated land.The response equation between cultivated land productivity and water supply was constructed to analyze the influence of water deficit on crop growth and cultivated land yield.Based on the above.regions and irrigation areas were divided according to the administrative areas and farm boundaries in Naoli River Basin,the threshold value of irrigation quota of cultivated land at watershed scale was determined and the thresholds of available supply of irrigation water resources at regional scale and irrigation area scale were determined.And under the constraint of these thresholds,took 2015 as the present year and 2020-2025 as the planning year.With the methods of multi-objective programming and dynamic programming,the quantitative optimal allocation model of land and water resources of cultivated land was constructed at multi-scale.With the methods of multi-objective programming and dynamic programming,the quantitative optimal allocation model of land and water resources of cultivated land was constructed at multi-scale.Based on the research results of actual productivity,water productivity potential and comprehensive index of soil and water resources matching,the strategy set of spatial optimal allocation of land and water resources of cultivated land was determined after spatial superposition and analysis.By using spatial optimization model of AgentLA.the dual optimal allocation of the quantity and space of land and water resources was realized according to the strategy set of spatial optimal allocation of land and water resources of cultivated land.The optimal allocation scheme of quantity and space of land and water resources in current and planning years was put forward.The research showed that:(1)The present situation of cultivated land and water resources was clarified.The area of cultivated land in the study area continued to grow,and the paddy field gradually increased while the dryland gradually decreased,the increased cultivated land(especially the paddy field)was mainly distributed in the middle and lower reaches of the river basin from 2000 to 2015.During the study period,the average annual precipitation,precipitation in each season(except spring)and precipitation in crop growing stage all showed the characteristics of increasing.However,from a long time series(1957-2015).the precipitation showed a significant decreasing trend in the study area.Influenced by precipitation,temperature,vegetation cover and other factors,the surface runoff and groundwater exploitable volume showed the variation characteristics of increasing from 2000 to 2015.From the perspective of system theory and macroscopic scale,water and land resources was regarded as the subsystem of compound system,by using the Haken model of synergetic theory,it was showed that the relationship between water resources and cultivated land in the study area has not formed an orderly cooperative change,and the subsystem of water resources and cultivated land had shown the characteristics of reduced order and disordered development from 2000 to 2015.(2)The spatial-temporal dynamics of land and water resource matching index of cultivated land during the whole growing stage and each growing stage,and the spatial-temporal dynamics of comprehensive index of soil and water resource matching of cultivated land during the whole growth period were studied.From the perspective of supply and demand at micro-scale,it could be seen that the water demand of cultivated land and the available supply of water resources in the whole growing stage and each growing stage showed an increasing trend.except that the water demand of cultivated land fluctuated around 2.92×109m3 in the early growing stage and the available supply of water resources reduced in the later growing stage.The matching degree of land and water resources of cultivated land during the whole growing stage was generally low,but it showed an increasing trend and increased differentiation.The land and water resource matching index of cultivated land in each growing stage changed complex.with 2010 as the boundary,it showed obvious periodical characteristics.The comprehensive index of land and water resources matching of cultivated land was less than 0.40.it was relatively low.but the comprehensive index of land and water resources matching of dryland and paddy field was gradually increasing.The water demand of cultivated land,the available supply of water resources,the land and water resources matching index of cultivated land and the comprehensive index of land and water resources matching of cultivated land all showed the spatial dynamic characteristics of the high value areas shifting and expanding from the middle reaches to the west of the middle reaches and the lower reaches.(3)The water productivity and its potential of cultivated land were calculated,the spatial-temporal dynamics of the water use efficiency of cultivated land and the response of cultivated land productivity to water were studied.The water productivity of cultivated land increased gradually from 2000 to 2015.The water productivity of dryland showed the characteristics of bimodal distribution and the change characteristics of agglomeration and movement to high value area.The water productivity of paddy field presented approximately normal distribution,and the axis of normal distribution gradually moved to the high value.The spatial distribution of water production of cultivated land was decreasing from the south to the north.Water productivity potential of cultivated land showed a clustering feature.the high-value area of spatial distribution was significantly reduced and the low-value area was significantly expanded,and the spatial difference was gradually reduced from 2000 to 2015.The water use efficiency of cultivated land showed obvious characteristics of stage changes.and showed an obvious trend of increasing and gradually gathering,and the difference of spatial distribution gradually weakened.The area of high-value area continued to expand,and it was mainly distributed in some areas in the middle and upper reaches and scattered areas in the lower reaches.The variation range of dryland productivity decreased with the change of water and the difference was small.while the variation range of paddy field productivity increased with the change of water and the difference was large.The difference in the spatial distribution of the response of cultivated land productivity to water showed a change characteristic of weakening and then strengthening.By 2015.the spatial distribution of the high-value area of the response of cultivated land productivity to water was consistent with the spatial distribution of paddy field.(4)Taking the available supply of irrigation water resources of cultivated land as the constraint,aiming at ensuring cultivated land productivity and sustainable production capacity.an quantitative optimal allocation model of land and water resources of cultivated land was constructed based on multiple stakeholders of cultivated land,multiple spatial scales and multiple types of cultivated land.And then the dual optimal allocation of quantity and space of land and water resources of cultivated land was realized according to the spatial allocation strategy set of land and water resources which was put forward based on the comprehensive analysis of the research results such as the comprehensive index of land and water resources matching of cultivated land,the actual productivity of cultivated land and the water productivity potential of cultivated land.(5)The optimal allocation scheme of land and water resources of cultivated land in 2015 was put forward.After optimal allocation at region scale,the total area of paddy field and dryland was 5.00× 109m2 and 9.31 × 109m2 respectively.The irrigation quota of paddy field was 0.4950m3/m2,and that of dryland was between 0.02m3/m2?0.07m3/m2 in four regions such as Jixian and so on.There was no irrigation in dryland and the irrigation quota of paddy field ranged from 0.2476m3/m2 to 0.3486m3/m2 in three regions such as Baoqing and so on.At the same time.7.28%paddy field were converted to dryland,and the adjusted areas were mainly distributed in Baoqing region.followed by Raohe region.Thongh the optimal allocation at region scale,the total grain production of regions was 7.92 ×109kg.After optimal allocation at irrigation area scale.the total area of paddy field and dryland was 4.70×109m2 and 9.60×109m2 respectively.The irrigation quota of paddy field was 0.4950m3/m2,and that of dryland was between 0.0295m3/m2?0.1014m3/m2 in four irrigation areas such as Raohe and so on.There was no irrigation in dryland and the irrigation quota of paddy field ranged from 0.2476m3/m2 to 0.4052m3/m2 in other thirteen irrigation areas.At the same time.11.95%paddy field were converted to dryland,and the adjusted areas were mainly distributed in the irrigation area of Eighty-three Farm,followed by the irrigation area of Entrepreneurship Farm.Thongh optimal allocation at irrigation area scale.the total grain revenue of irrigation areas was 22.927 billion yuan.(6)The optimal allocation scheme of land and water resources of cultivated land in planning years from 2020 to 2025 was put forward at RCP4.5.After optimal allocation at region scale,the total area of paddy field and dryland was 4.48×109m2 and 9.83 ×109m2 respectively.The irrigation quota of paddy field was 0.4950m3/m2,and that of dryland was between 0.0048m3/m2?0.0811m3/m2 in three regions such as Jixian and so on.There was no irrigation in the dryland and the irrigation quota of paddy field ranged from 0.2476m3/m2 to 0.2891m3/m2 in four regions such as Baoqing and so on.At the same time.16.5%paddy field were converted to dryland,and the adjusted areas were mainly distributed in Fujin region,followed by Baoqin region.Though the optimal allocation at region scale.the total grain production of regions was expected to reach up to 7.39^109kg.After optimal allocation at irrigation area scale,the total area of paddy field and dryland was 4.26×109m2 and 1.0×1010m2 respectively.The irrigation quota of paddy field was 0.4950m3/m2,and that of dryland was between 0.0047m3/m2?0.0811m3/m2 in four irrigation areas such as Raohe and so on.There was no irrigation in dryland and the irrigation quota of paddy field ranged from 0.2476m3/m2 to 0.3275m3/m2 in other thirteen irrigation areas.At the same time,20.05%paddy field were converted to dryland,and the adjusted areas were mainly distributed in fifteen irrigation areas such as Eight-five-three Farm.Thongh the optimal allocation at irrigation area scale.the total productivity of cultivated land was expected to reach up to 7.13×109kg and the total grain revenue of irrigation areas was expected to reach up to 22.018 billion yuan.(7)The optimal allocation scheme of land and water resources of cultivated land in planning years from 2020 to 2025 was put forward at RCP8.5.After optimal allocation at region scale,the total area of paddy fleld and dryland was 5.02×109m2 and 9.30×109m2 respectively.The irrigation quota of paddy field was 0.4950m3/m2.and that of dryland was between 0.0691m3/m2?0.1349m3/m2 in three regions such as Jixian and so on.There was no irrigation in dryland and the irrigation quota of paddy field ranges from 0.3135m3/m2 to 0.4464m3/m2 in four regions such as Baoqing and so on.At the same time.6.55%paddy field were converted to dryland,and the adjusted areas were mainly distributed in Baoqin region.followed by Raohe region.Though the optimal allocation at region scale.the total grain production of regions was expected to reach up to 8.81×109kg.After optimal allocation at irrigation area scale,the total area of paddy field and dryland was 5.05×109m2 and 9.26×109m2 respectively.The irrigation quota of paddy field was 0.4950m3/m2,and that of dryland was between 0.0036m3/m2?0.1349m3/m2 in five irrigation areas such as Raohe and so on.There was no irrigation in the dryland and the irrigation quota of paddy field ranged from 0.2476m3/m2 to 0.4538m3/m2 in other twelve irrigation areas.At the same time,5.77%paddy field were converted to dryland,and the adjusted areas were mainly distributed in thirteen irrigation areas such as Eight-five-three Farm and so on.Though the optimal allocation at irrigation area scale,the total productivity of cultivated land was expected to reach up to 8.55×109kg and the total grain revenue of irrigation areas was expected to reach up to 24.141 billion yuan.