Study On Ecological Water Demand Of Several Types Of Green-land In Zhengzhou City

The city green-land has irreplaceable function in city ecosystem, it has ecological function such as improving local microclimate, cleansing air, reducing noise, providing habitat for biology and sight entertainment and so on. Water is one of the important ecological factors which the city green-land depends on, water resource abundant or not directly influences the ecological function of the city green-land. The eco-environment supply of city green-land system has three methods: rain supply, groundwater supply, manpower supply, and manpower supply is the most important method. The development of the city calls for higher demand about the quantity and the quality of the city green-land , at the same time , it increase the city water resource conjuncture .The contradiction of supply and demand about the city water resource becomes more seriously day by day , which induces the city economy water to impropriate plenty of city ecological water , which leads to many environment problems, for example, the ecological water of the city green-land system can't be ensured , the environment degrades, ecological service function declines. So, it is very necessary to study on ecological water demand of the city green-land, which can reach the purpose of saving water, meanwhile, ensure the water for green-land during its normal growth.This paper adequately recapitulated relational concept of the ecological water demand, as well as its research background, and research significance, summarized the main calculational methods of vegetation ecological water demand, at the same time, relating with Zhengzhou's practice, referred to the thought of quota determination of water demand, evaluated quota determination of water demand through practical survey about main vegetation species in this city. With regard to the methods, quota determination of water demand of arbor, shrub and lawn respectively were TDP method, quick-weighing method and mini-lysimeter method, then according to the green-land acreage of different types , evaluated ecological water demand of the green-land in Zhengzhou, furthermore, according to the average rainfall quantity from 1951—2006, calculated the water shortage monthly and yearly, which provided part support in theory and reference in the strategy of distributing the water scientifically.The main content and results are these:⑴By practical survey, calculated the quota determination of water demand of some kinds of familiar arbor, shrub and lawn in fine and cloudy sky for the first in Zhengzhou. The quota determination of water demand of Chinar is 2.827 L·m-2.d-1 in sunny day as well as 2.144 L·m-2.d-1 cloudy sky, while the Arborvitae is 1.764 L·m-2. d-1 in sunny day as well as 1.413 L·m-2. d-1 in cloudy sky .⑵B ased the area of different kinds green-land, attempted to calculate yearly eco-water demand of arbor, shrub and lawn, which can provide gist and compare for later city green-land research..Eco-water demand per acreage of different kinds of green-land order is arbor