在美国利亚桑那州,水从表层和地下水库的放出量多于自然更换的水量.由于多年来一直是这样的情况,地下蓄水层的水位不断下降.为了找出使水的供需平衡的方法,进行了各种研究,通过管理天然.植被以减少蒸发或获得更多雪来增加出水量.试图使它作为增加世界缺水地区水的供应量而进行植被管理的实践或研究阶段的指导方针. In Arizona, the United States releases more water from the surface and underground reservoirs than naturally-exchanged water, which has been declining for many years in the aquifer. To find a way to balance the water supply and demand Methodologies, various studies have been conducted to increase water output by managing natural vegetation to reduce evaporation or to obtain more snow.It is attempting to make it a practical or research guide for vegetation management in order to increase the supply of water in the world’s water-scarce areas policy.