Research On Optimal Allocation Of Water Conservation Forests In Typical Small Watersheds In Hilly Regions Of Daqing River Basin

The construction of water conservation forests in the hilly areas of the upper Xiong'an New Area-upstream of the Daqing River Basin has important practical and far-reaching historical significance for increasing the water resources reserves of Baiyangdian,improving water quality,and supporting the construction of ecological space in the new area.At present,the spatial layout and structural configuration of water conservation forests in the hilly areas of the upper reaches of the Daqing River Basin are unreasonable,which seriously affects the ecological function of water source forests.In order to optimize the spatial configuration of water source forests,at the small watershed scale,this study focuses on the relationship between the water conservation function of forest vegetation,the proportion of stand types,and the relationship between spatial configuration and water conservation function.The relationship between the spatial distribution of water resource forests in the watershed and the runoff of the watershed was studied in depth,and the spatial optimal distribution model of water resources forest in typical small watersheds was proposed.This paper evaluates the water conservation capacity of typical forest types in the study area,and selects the forest types with excellent water conservation capabilities.Taking the Angezhuang watershed of the Dalan small watershed as the research scope,the SWAT model was established and operated,and the applicability of the SWAT model in the Angezhuang watershed was evaluated.On the basis of site type division and quality evaluation,different scenarios were set up in terms of stand type ratio and spatial configuration,and the watershed runoff was simulated to obtain an optimized plan for spatial distribution of water source forests in the Angezhuang watershed.The main research results are as follows:(1)The soil layer plays a major role in the forest water conservation function.Through the analytic hierarchy process,the water conservation capacity of water resources forests of different forest types is comprehensively evaluated,and the following conclusions are obtained: the water conservation capacity of mixed forests in each water source forest is strong In Yu Chunlin,the water conservation capacity scores are from Platycladus orientalis × Pinus tabulaeformis mixed forest (1.5218),Robinia pseudoacacia forest(1.4092),Poplar pure forest(0.9362),Platycladus orientalis forest(0.7601),Pinus tabulaeformis forest.(0.7377),Luanshu Pure Forest(0.6349).Pinus tabulaeformis × Pinus platyphylla mixed forest and thorn.Pure locust forest is the culvert of various types of water source forests.It has the best ability to maintain water resources.It should be the best in the local afforestation planning.(2)Through the sensitivity analysis of the SWAT model and the automatic calibration of the parameters,it is obtained that the simulated values of the model are well matched with the measured values,indicating that the SWAT model has good applicability in the Angezhuang watershed.And the simulation of hydrological and ecological effects in the study area from 2016 to 2017 further verified the applicability of the model.(3)Select the four factors of landform,slope,aspect and soil type,divide the site conditions in Angezhuang watershed into 63 site types,and use the SWAT model to simulate the spatial allocation scheme of different water conservation forests on the basis of site quality evaluation To determine its function of regulating runoff.The simulation results show that under the scenario of scenario 4,that is,the water conservation forest area is 71.15%,the forest type ratio is 30.24% in broad-leaved forest,14.70% in coniferous forest,22.89% in mixed forest,and 32.17% in shrub forest.The production flow in the wet season is reduced by 15.79% compared with the measured value in 2015,and the production flow in the dry season is increased by 15.83% compared with the measured value in 2015.Water source forests play the best role in water conservation and will not affect the lives of local residents.At present,the area of arbors and shrubs in the study area has reached 61.2%,which can be increased by about 10%,but its internal structure is not very reasonable.The focus of future work should be on adjusting the structure of the woodland.