The Effects Of Land Use On Surface And Groundwter Water Quality In Taizi River Watershed

The influences of land use type and landscape pattern index change on water quality of surface water and groundwater in taizi river basin from landuse type structure and landscape pattern changes two aspects were studied using the GIS spatial analysis and statistical method, The Person related qualitative discriminant analysis and redundancy analysis(RDA) was used to explore the effect of land use types and the change of landscape pattern on the influence of surface water and groundwater. The partial least squares model quantitatively was used to assess the impact of land use type change of water quality parameters. In order to improve the regional water quality, rational planning of land structure, adjust the landscape pattern, the research results can provide effective basis evidence. The results are as follows:(1) In general, water quality in the upstream and middle is better than downstream. The upstream water quality affected by land use type is not obvious. Water quality in the middle was mainly affected by woodland, and the representative hydration parameter is TOC. Downstream water quality is relatively poor, mainly affected by anghropic activities, such as paddy fields, residential land, industrial and mining land and fluvial bog, and the concentration of NO2-, NO3-, SO42- and TDS is high.(2) The Spearman Correlation and Redundancy Analysis(RDA) results showed that the concentration of NO2-, K+, HCO3-, T, ORP, DO, Cl-, EC, NO3-, Br-, Ca2+ and Mg2+ are extinctly influenced by land use type change, such as resident land, canals, dry farmland, built-up land and grassland, The concentration of NO2- is the most significant indicator affected by the change of land use. Percentage of resident land, canals, and dry farmland are positively related to this indicator(r2>0.6, p<0.5), which of them best related is resident land(r2>0.8, p<0.05). The concentration changes of K+ and Cl- mainly reflect the change of residential land and Built-up land area. Percentage of grassland is negatively related to the most of the present water quality parameters, especially the HCO3-, concentration of which is negatively related to the percentage of grassland obviously. The concentration of EC, NO3-, Br-,Ca2+, and Mg2+ are affected by the beach, and showing the positive correlation.(3) Landscape pattern change can affect the water quality. the most obvious impact of all landscape index are concentration(AI), edge density(ED), patch density(PD) as well as shape index(SHAPE_MNDE), Shannon diversity(SHDI), the largest patch area ratio(LPI) and spread index(CONTAG). Among them, AI and ORP is positive correlation. AI and TOC is significant negative correlation, boundary density(ED) shows contrary trends to the correlation of two parameters. SHDI and CONTAG main influence water quality index of NO2-, K+, and DO.of which SHDI and NO2-, K+ was significantly positively related to DO, and was significantly negative correlation. CONTAG is opposite.to SHDI. PD and SHAPE_MN mainly affect Cl- and ORP. PD and Cl- significant showed positive correlation, otherwise ORP showed the negative correlation. The SHAPE_MN shape index is opposite to PD.(4) A multi-liear model was established by using partial least squares(PLS) to quantativeily predict the relationship between land use and surface water quality. Surface water quality parameters, such as DO, K+, NO2-, NO3-, ORP and TDS were affected significantly by land use types. NO3- concentrations in stream are greatly affected by industrial land and paddy, however, grass land has a strong negative relationship with strem nitrate concentrations.