Study On Rainwater Impounnded Capacity Of Different Greenland Types In Campus

The construction of Sponge city has been paid much attention in the grim situation of flood disasters come to the major cities.The effect of green space as a natural sponge on rainwater regulation cannot be ignored,it was found that the effect of greenland on rainwater storage was not paid enough attention when thinking about the management idea of rain flood.This study aims to discuss the construction of vegetation cover types in green space with the combination of landscape planning design and rainwater gathering theory.The soil moisture content of different vegetation types in the campus after rain has been measured and analyzed,through the comparative analysis to get the following conclusion:1.From the total rainfall storage amount of soil,the advantages of rainwater gathering capacity in open arbor forest is: Ginkgo biloba L.forest>Catalpa bungei C.forest>Magnolia denudata Desr.forest;Eriobotrya japonica(Thunb.)Lindl.forest,Armeniaca mume Sieb.forest>Hibiscus syriacus Linn.forest,Punica granatum L.forest,Amygdalus persica L.forest;dense forest is Zelkova serrata(Thunb.)Makino forest,Trachycarpus fortunei(Hook.)H.forest>Sophora japonica Linn.forest.The sparse forest can store more rainwater than the dense forest;Because of the rainwater interception by canopy layer,and the dense forest canopy is high density but not formed humus,so that only a little of water was absorbed into the soil,which is the same as the previous study.In the sparse forest land which covered with green,the type of trees like Ginkgo biloba L.,Catalpa bungei C.,the angle between branches and crown axes is acute,with sparse leaf blade showed strong capacity for rainwater accumulation;Small forest showed more stable water absorbed capacity than big forest;Surface soil moisture variability of dense forest is greater than sparse forest;The Soil moisture content below the surface of the horizontal space of different forest types reaches the remarkable level,and the rainwater storage in the trunk is larger than the middle of the crown projection,the difference of small forest in horizontal space is not remarkable.With the soil layer is deeper,the water content is more obvious in the horizontal space.2.The dgreen of total rainfall retention of bushwood soil is: Spiraea japonica L.,Sorbaria sorbifolia(L.)A.>Nandina domestica Thunb.,compound vegetation of greenbelt is: arbor-bush-grass(Albizia julibrissin Durazz.+ Lonicera fragrantissima Lindl.+ mixed lawn)>arbor-bush(Cercis chinensis Bunge f.+ Spiraea japonica L.),Cynodon dactylon(L.)pers.lawn>Poa pratensis L.+ Cynodon dactylon(L.)pers.lawn;The rainwater storage capacity of bushwood and lawn is greater than compound vegetation,and the bushwood is greater than lawn,moreover,the lawn don't showed obvious advantages of tatal rainwater storage than other vegetation greenland.The horizontal space moisture of Spiraea japonica L.bushwood showed significant difference,but Sorbaria sorbifolia(L.)A.bushwood and Nandina domestica Thunb.bushwood is not.Because of the interception from upper branches,the arbor-bush-grass land and arbor-bush land showed significant effect on horizontal space moisture of soil.The surface moisture of mixed lawn is greater than single lawn,like Cynodon dactylon(L.)pers.and Ophiopogon japonicus(Liliaceae),the Cynodon dactylon(L.)pers.lawn showed advantages of moisture content under the sub-soil layer;The Cynodon dactylon(L.)pers.showed more advantages than Ophiopogon japonicus(Liliaceae)of single lawn.3.The soil moisture content in different plaza forest showed significant difference,maplewood square 1(Acer mono Maxim.+ Ophiopogon japonicus(Liliaceae)),2(Acer mono Maxim.+ Oxalis corymbosa DC.)> catalpa square(Catalpa bungei C.+ Ophiopogon japonicus(Liliaceae))> melia square(Melia azedarach L.+ Ophiopogon japonicus(Liliaceae)),It can found that there is no significant difference in total water holding bwteen square forest which covered different plants.The type of arbor and the vegetation type that cvered square green space will affect the amount of rainwater in the horizontal spaces.4.Through test and analysis find that the form of sparse forest + lawn should be used to forest design,and the species of crown is small,branch less,compact structure is better.Compound vegetation is easy to cause rainfall interception and secondary allocation.The rainwater accumulation of bushwood and lawn is better,and should be designed emphatically on that,soil structure should be optimized under the premise of ensuring vegetation growth habits.Attention should be paid to the reasonable application of litter in green space.It is Should be noticed in design that dense forest is prone to form more litter and its environment is conducive to transforming it into humus.