The Simulation Study On Eco-hydrological Effects Of Planning Vegetation Types In Nanning Qingxiu Mountain

The water content of urban green space has important influences on urban temperature. Qingxiu mountain is one ofe the largest green space ecosystem in nanning city. It is also called the "green lung", because it is the main source of fresh air which determined by the unique geographical location. In order to understand water conservation properties of planning vegetation, the experiment on simulating the eco-hydrology effet about vegetation type is conducted, which non only can strengthen the scientific nature of planning vegetation, but also provide the oretical basis for reasonable irrigation, and offer technical support for easing the urban heat island effect.Through investigating the mountain field and collecting soil samples, the nature of soil particles is determined, soil hydraulic parameters are estimated with the aid of Rosetta application of artificial neural network. The vegetation is divided into five categories:coniferous, broad-leaved, bamboo, bushes and grass, Pinus massoniana, Metasequoia glyptostroboides, Osmanthus fragrans, Punica granatum, Chimonobambusa quadrangularis, Bougainvillea spectabilis, Musa nana, Zoysia matrella are selected as the representatives of the experiment. Based on the collected meteorological data and the various parameters, Hydrus-1D is used to simulate the soil water movement when the slop is0°,15°,30°,45°, and the infiltration, evaporanspiration, soil water storage,water content with no vegetation and different vegetation are separately analyzed.When there’s no vegetation, the infiltration of different slop is67.72cm, the root water uptake is0cm; The soil evaporation respectively are69.01cm,69.92cm,70.24cm,70.98cm; the soil water storage respectively are26.56cm,26.60cm,26.65cm,26.51cm; the water content respectively are95.66cm,96.22cm,96.79cm,97.49cm.When there’s different vegetation, the infiltration of each vegetation in different slop are the same; the order of infiltration quantity is Bougainvillea spectabilis(65.86), Osmanthus fragrans(63.34), Pinus massoniana(61.34), Musa nana(60.81), Metasequoia glyptostroboides (60.35), Punica granatum(59.19), Chimonobambusa quadrangularis(50.73), Zoysia matrella (18.98).When the slop is0°, the soil evaporation in order is Bougainvillea spectabilis (72.54), Osmanthus fragrans(70.82), Musa nana(68.20), Punica granatum(65.13), Metasequoia glyptostroboides (63.70), Pinus massoniana (62.45), Chimonobambusa quadrangularis (56.91), Zoysia matrella (34.02).The order of soil water storage is Pinus massoniana (28.52), Metasequoia glyptostroboides (26.50), Zoysia matrella (25.18), Chimonobambusa quadrangularis(23.21), Punica granatum (23.20), Bougainvillea spectabilis(22.58), Musa nana(21.20), Osmanthus fragrans(21.06).The soil water content in order is Bougainvillea spectabilis(95.12), Osmanthus fragrans (91.88), Pinus massoniana(90.97), Metasequoia glyptostroboides (90.20), Musa nana(89.40), Punica granatum (88.33), Chimonobambusa quadrangularis(80.18), Zoysia matrella (59.20).From the analysis of the results, the author concludes:(1)The coniferous plants’water-holding capacity is the largest, the grass followed, then are the bamboo, deciduous broad-leaved, thickets, the worst is evergreen broad-leaved.(2) The best eco-hydrological effect is evergreen thickets class, followed by evergreen broad-leaved evergreen conifers, deciduous conifers, deciduous shrubs, deciduous broad-leaved, bamboo, the smallest is the grass.