陆地生态系统绿水资源开发与雨水集流技术潜力分析

绿水是源于降水、存储于土壤并通过土壤蒸发和植被蒸腾消耗掉的水资源,是一种在传统水资源评价体系中被忽视了的水资源。本文分析了中国绿水资源的空间分布特征,探讨了中国内陆河流域、腾格里沙漠和黄土高原等地区的绿水分配特征,以及雨水集流技术在绿水开发利用中的潜力。中国绿水资源总量约3.4万亿m3,约占降水资源总量的54%;其分布很不均衡,西北地区的绿水占降水比例的70%以上,而南方地区的平均比例为48%,说明中国西北干旱半干旱地区绿水资源的开发潜力较大。在半干旱地区的黄土高原雨养农业区,绿水占有量超过90%,其中非生产性绿水占45%～50%;在干旱地区内陆河黑河流域,绿水占有量达77%,其中非生产性绿水占52.4%。雨水集流结合地表覆盖等水保措施可以显著提高绿水生产力,在绿水资源开发利用方面具有较大的潜力。

Assessment of the Green Water Resource and Its Exploitation by Rainwater Harvesting Techniques in the Terrestrial Ecosystem

Green water is the fraction of rainfall that infiltrates into the soil and is available to plants, through evapotranspiration. It is often neglected in the conventional water-resource assessment. This paper analyzes the spatial distribution of green water in China and the relation between green water and blue water in the inland river basin, Tengger desert and the Loess Plateau, and discusses potentiality of rainwater harvesting techniques in green-water exploitation. It may be estimated that the total amount of green water is approximately 3 400 km3/a in China, about 54% of the total precipitation. Green water covers over 70% of the precipitation in northwestern regions and about 48% in southern regions and its distribution is highly heterogeneous. In the rain-fed Loess Plateau, the proportion of green water to the precipitation is more than 90%, of which non-productive green water accounts for 45%~50%; and in the inland Heihe river basin, the proportion of green water to the precipitation is about 77%, of which non-productive green water accounts for 52.4%. Combined use of rainwater harvesting and mulching could increase green-water productivity, and is promising for green-water exploitation.