干旱缺水地区缓解水危机的途径: 水资源需求管理的政策效应

水资源短缺是制约干旱区经济发展的瓶颈因素,缓解水资源供需矛盾必须引入水资源需求管理政策。基于市场机制的价格调整和基于行政管理的数量控制是水资源需求管理的两种重要手段。论文基于分布式水资源-经济模型,在用水需求零增长、用水结构升级调整的情景下,研究了水价调整和水量控制在抑制农业用水需求中的政策效应。结果表明,因现行灌溉水价过低,农户对水价上涨不敏感,水量控制比水价调整更加有效。如果要达到相同的节水效果,水价调整政策下农户收入损失比水量控制要更大。水价调整政策下农户收入损失由于成本上涨和作物结构转换导致,水量控制政策下农户收入损失主要是作物种植规模压缩所致,两种政策均需考虑一定的利益补偿。水价调整和水量控制都会导致种植结构转换,但对区域粮食安全影响不大,对经济作物的影响较大,水价上涨会减少用水量多的作物种植,水量控制会使作物种植结构由单方水效益低的作物转向单方水效益高的作物。

Solutions to Water Scarcity in Arid Regions: Effectiveness of Water Demand Management Policy

Water scarcity is the most severe constraint to socio-economic development in arid regions. It calls for water demand management to control rapid increase of water demand and to alleviate conflicts between water demand and supply. There are two kinds of water demand management policies, i.e., price control which is based on market mechanism and quota control which is based on administrative management. This paper assumes that the water structure changed along with the upgrading of industrial structure under the zero growth of total water requirement and examines the effectiveness of price control and quota control measure for reducing water demand based on a distributed water-economic model (GBEM). The results show that quota control measure is more effective than price control in curbing water demand. The current price of irrigation water is too low compared with shadow price of water resource so that farmers will not respond to water price change unless water price was raised at the level of shadow price of water resource. To save same amount of irrigation water, farm income under water price control will loss much more than that under quota control. The farm income loss under water price control consists of increased irrigation cost and change of cropping system. The farmer income loss under quota control is caused by decrease of sown areas. Both of the two kinds of policy instruments need to consider benefit compensation to farmers. The two kinds of water demand management policies have less impact on food security. However, cash crops production will change while water demand management policies are implemented. The crops which need more irrigation water will decrease if water price is raised, while quota control measure is implemented, cropping system will shift from the crops with low water efficiency to the crops with high water efficiency.