城镇化人为扰动下垫面类型影响水源涵养功能的评价.

Great decrease in water retention function of various artificial disturbed landform units (DLU) caused by urbanization activities, when compared with original Landform units (OLU). is the mam reason and factor that not only cause urban water and soil loss but also aggravate urban waterlogging under the certain rainfall and special designed drainage network capability. Field investigations, physical laboratory analyses and analytic hierarchy process composite method were performed comprehensively to analyze the impacts of various DLUs on water retention function of OLU. Results indicated that: 1) >2mm particle content for various DLU was over 45%, and <2 mm particle content of OLU was more than 92%; natural repose angle of soil-sock mixture (34°-38°) in DLU were all higher than OLU; uniformity coefficient and curvature coefficient changed between 11.05-41.30 and 0.32-3.15. in which uniformity- coefficient decreased by 4.51%-80.27% than OLU. 2) The soil bulk density- of various DLU showed the order as construction road (CR, 1.74 g/cm3) >slope greening belt (SGB. 1.54 g/cm3) > 1 year disturbed soil accumulation (DSA1, 1.48g/cm3) > 2 year disturbed soil accumulation (DSA2, 1.34 g/cm3) >3 year disturbed soil accumulation (DSA3, 1.31 g/cm3). which increased by 33.85%, 18.46%, 13.85%, 3.08%, 0.77%, respectively, compared with sloping land; and the soil total porosity, field capacity' and saturated water content presented the contrary trends. 3) Soil infiltration capacity' of various DLU were lower than that of OLU, the soil stable infiltration rate presenting the order as DSA3 (2.89 mm/min) > SGB (2.65 mm/min) > DSA2 (1.89 mm/min) > DSA1 (1.64 nun/nnn) > CR (0.45 mm/min), at same time, the soil stable infiltration rate of OLU ranged between 2.83 and 6.22 mm/min; the conversion from forest to new-DSA had greatest impact on regulating function for rainfall and urban flood, while conversion to CR was the lowest. 4) The soil total reservoir storage, usable storage and flood control storage in various DLU were lower than that in OLU. soil total reservoir storage showing the order as DSA3 > DSA2 > DSA1 > SGB > CR, which presented decreases of 1.08%, 2.27%, 5.63%, 15.41% and 21.96%. respectively, compared with sloping land (453.70 t/hm2); the conversion process from grass to CR caused the greatest damage to storing water and regulating the overhand flow. 5) The water retention functions in DLU were all obviously weaker than that m OLU. and CR was weakest (0.421) while NF was strongest (0.651), the water retention function was influenced by factors such as soil depth, particle-size distribution, soil porosity', soil organic matter content, soil bulk density, and soil permeability', so more attentions should be paid to urban surface water, forest and grassland occupied area and its spatial distribution, short-term disturbed soil accumulation should also be conducted by temporary greening measures at the same time during urbanization process. These results could provide scientific basis for the function recovering of urban soil and water conservation ecological sen-ices, which also help for constructmg urban green belts and alleviating flood waterlogging durmg the urbanization construction process. [ABSTRACT FROM AUTHOR]