Research And Application Of Low-carbon Water Resources Allocation Method

Under the background that climate change is deeply affected by human activities,dealing with the water balance and carbon balance of social-economic system and ecological-environmental system is the key for human society to curb the continuous increase of atmospheric CO2 concentration and cope with the crisis of freshwater resource shortage.According to the main characteristics of the natural-artificial dual water cycle,carbon cycle,and their interaction mechanism,as well as the analysis of the impact of water resources allocation on low-carbon development mode.This study proposed the objectives,principles and tasks of low-carbon model water resources allocation,and constructed a low-carbon water resource allocation framework system of "supply and demand dual control".This study carried out the following studies under the guidance of the above framework system.First,quantitating the relationship between water supply,energy consumption and carbon emissions according to the energy consumption process of water supply system.Calculating and analyzing the energy consumption and carbon emissions of water supply system in Song-Liao River Basin(SLRB).Then,constructing a water resource allocation model based on carbon emission reduction of water supply system(WRAMCERWSS),for achieving a double-win situation between regional water supply and carbon emission reduction.Next,respectively predicting the water demand schemes of low carbon and current model,according to different social development models in SLRB.Finally,using the WRAMCERWSS to generate the water resource allocation scheme set for planning years,recommending the scheme according to the evaluation results,and proposing the scheme safeguard measures.The main research achievements are as follows:(1)Establishing the relation function of water supply-energy consumption-carbon emission in water supply system.The following results are obtained by using the relational function:the annual average energy consumption of water supply system in SLRB was 8.2 billion kW·h,accounting for 1.96%of the regional average power consumption in the past five years(2017-2021),and the energy consumption factor was 0.125 kW·h/m3.The annual average CO2 emission of water supply system was 5.1748 million tons,and the CO2 emission factor was 78.9 g/m3.The CO2 emissions of industrial,agricultural,domestic and ecological water supply accounted for 40.5%,21.5%,23.8%and 14.2%,respectively.The CO2 emissions of surface water,groundwater,external water transfer,reclaimed water and seawater desalination water supply accounted for 55.1%,24.1%,5.0%,13.8%and 2.0%,respectively.There were significant differences in the sensitivity of CO2 emissions to the water supply at both ends of supply and demand in SLRB water supply system,indicating the possibility and necessity of water-carbon collaborative optimization in the basin water supply system.(2)Predicting the water demand for the planning years in SLRB,the water demand of the low-carbon development model(medium plan)and the status quo development model(high plan)in 2035 is 93.785 and 103.666 billion m3,respectively,and the water demand of the two schemes in 2050 is 1 14.060 and 124.242 billion m3,respectively.(3)Constructing a water resource allocation model based on carbon emission reduction of water supply system with a hybrid PSO-GA algorithm,taking the minimum water shortage rate of the basin,and the lowest carbon emission of water supply system as the objective function.The model was used to solve the planned annual water resources allocation scheme in the SLRB.The results showed that:in the medium scheme for 2035,the total water supply in the basin was 90.876 billion m3,the water shortage rate was 3.10%,the carbon emission of the water supply system was 7.84 million t,and the carbon emission factor was 86.27 g/m3.In the high scheme for 2035,the total water supply was 98.794 billion m3,the water shortage rate was 4.70%,the carbon emission of the water supply system was 8.8276 million t,and the carbon emission factor was 89.40 g/m3.In the medium scheme for 2050,the total water supply was 114.06 billion m3,the water shortage rate was 1.95%,the carbon emission of the water supply system was 11.2954 million t,and the carbon emission factor was 101.00 g/m3.In the high scheme for 2050,the total water supply of the high scheme was 118.329 billion m3,the water shortage rate was 4.76%,the carbon emission of the water supply system was 12.642 million t,and the carbon emission factor was 106.84 t/m3.Through the overall objective evaluation and adaptability evaluation,it was recommended that the medium scheme is the water resource allocation scheme for the planning years of SLRB.(4)By comparing the solution results of the WRAMCERWSS(Model Ⅰ)and the model only considering water shortage rate as the target(Model Ⅱ)showed that:under the condition that the water shortage rate of each scheme with a little change,the carbon emission factors of water supply system in ModelⅡ would increase significantly compared with model Ⅰ(In 2035,the medium and high plan increased by 6.75%and 9.28%,respectively.In 2050,the two schemes increased by 8.13%and 11.28%,respectively).Therefore,the Model Ⅰ can reduce the carbon emissions of the water resource allocation system on the premise of ensuring water supply by appropriately changing the water supply combination.In conclusion,the WRAMCERWSS can achieve the double-win goal of water resource allocation system guaranteeing water supply and carbon emission reduction.The results of its application in SLRB can not only serve as the basis for water resource and other related wading-related planning,but also play a positive role in guaranteeing the socio-economic low-carbon development mode of the basin,which has significant practical significance.