Influence Of Landscape Structures On River Water Quality In The Yuan River Basin

Significant attention has recently been given to understanding the hydrological effects of landscape.Investigation the impact of the interaction between landscape composition and landscape configuration on the water quality;analyze the influence mechanism of the landscape structure on the part of the water nutrients and heavy metals under different spatial division methods;explore the effect of the basin area and mean dendritic stream length on the relationship between landscape structure and water quality.There is significance to the ecological protection of river basins.In this study,water samples were collected at 38 sampling sites in the mainstream and tributaries of the Yuan River in July 2018 and January 2019.Determined water chemical indicators(K⁺,Na⁺,Mg²⁺,HCO₃^-,and SO₄^2-etc.)and nutrient indicators(DO,NO₃^--N,NH₄⁺-N,TP,and DOC,etc.)and heavy metal indicators(Al,Cr,Mn,Fe,Co,Ni,Cu,Zn,As,Cd and Pb,etc.).Based on the much mathematical-statistical methods combination,the results showed that:(1)The interaction between landscape composition and landscape configuration is an important factor that drives water quality.Under the regional division method,the impact of landscape configuration on water quality accounts for 91.5%of the total explanatory rate in the short-distance buffer zone(100m,300m).The impact of landscape composition on water quality at the long-distance buffer scale(3000m)and sub-basin scale accounted for 72.5%of the total interpretation rate,while the water quality change in the transition zone(500m,1000m)was affected by the interaction of landscape composition and spatial configuration.The interaction effect on the water quality in the 1000 m buffer zone has the highest interpretation rate.(2)The ENN?MN of Forestland,the ED of Farmland,and the LPI,LSI of Residential land are the core characteristics that affect river water quality.These factors that affect the water quality proportion of their class type interpretation rate is 37.8%,31.2%,and 53.8%.(3)Farmland PD,COHESION,and IJI indicators are the main indicators that affect the nutrients of the river.The combination of Forestland,Residential,and ENN?MN,LPI is the main indicator that affects the heavy metals.(4)Under different spatial divisions,analysis of the nutrient change mechanism of the water at the 100 m riparian buffer zone scale,and the study of the heavy metal change mechanism at the sub-basin scale will help to understand the relationship between landscape structure and water quality.The 1000 m scale is a key scale that affects water quality changes,and setting up a mixed buffer zone to manage landscape structure is of great significance to basin environmental protection.(5)Under the division method of sub-basin and zone,compared to the division method of the sub-basin the smaller basin area enhances the correlation between landscape composition characteristics and water quality.In addition,the input of external pollutants weakened the influence of the mean dendritic stream length on the relationship between landscape structure and water quality.The above results show that strengthening the management of land use in the buffer zone near the river bank is essential to protect the water quality of the river.In the process of land use management,the relationship between landscape composition and landscape configuration characteristics must be fully considered,and equal emphasis on management and planning is an effective adjustment.An important measure for protecting water quality is that for different pollution types of rivers adopting corresponding division methods and buffer scales can help improve the accuracy of quantitative analysis.Besides,basin area and mean dendritic stream length are important indicators that affect the relationship between landscape structure and water quality.In future studies,based on the targeted arrangement of sampling sites in the selected study area,the appropriate division method is selected,and the area of the sub-basin with sampling sites as the outlet is controlled within a certain range,which reveals the impact of the internal landscape structure of the watershed on the water quality.Based on the Yuan River Basin,this study provides new insight into the relationship between landscape structure and river water quality and can provide a scientific basis for Yuan water environmental protection and management.