干旱区城郊种植业水足迹分析与适宜耕地规模测算——以乌鲁木齐市为例

Analysis of the water footprint of suburban planting in arid lands and determination of suitable farmland scale: a case study of urumqi

水足迹方法能够完整、清晰地描述种植业的耗水特征。以干旱区绿洲城市乌鲁木齐市为例,运用水足迹模型分析种植业产品耗水特征,构建水足迹强度系数以探讨种植业耗水对本地水资源的影响度,进而从作物水足迹和水源类型角度建立绿洲耕地规模测度模型测算乌鲁木齐市适宜耕地规模,研究发现:1作物生长期水足迹受土壤水分胁迫和产量损减影响呈现差异化;22005—2011年间,绿水强度系数波动剧烈,蓝水强度系数均值超出容量极限,作物生长期对蓝水资源依赖性较强,从而进一步加剧了蓝水资源的匮乏;3乌鲁木齐市合理耕地规模约为6万hm2,2005—2011年种植业实际耕地规模均处于超载状态,超载量变化呈现先降后升的特征,现状种植业发展模式对绿洲生态系统扰动不断加剧。

Water is the basis for the formation,stability,and development of oasis cities. With the rapid increase in urban population and improvement of economy in arid areas,cropping systems have been developed in the outskirts of oasis cities.This had led to the exploitation of water resources,causing vegetation degradation,soil salinization,and water scarcity for industrial and domestic consumption. Therefore,analyzing the characteristics and influence of water use in cropping systems and determining the suitable farmland scale are urgently required. The water footprint method can be used to completely and clearly describe the characteristics of crop water consumption. Recently,most studies performed using the water footprint method focused on the quantification,influencing factors and implications of water footprints in a region or country.However,research on how the water footprint of crop production affects the water use of natural environment and economic development is scarce. In this study,we selected Urumqi as the typical oasis city in an arid area. We analyzed the water consumption in Urumqi by the water footprint model. Further,a model of water footprint with a water intensity coefficient was developed in order to determine the impacts on local water resources due to crop water use. On the basis of the cropwater footprint and water resource types available,we generated a model for determining the area that can be allocated for farming purposes in the oasis city. This study revealed the following findings：（ 1） soil water stress and yield loss reduction showed differential responses during the crop growth period. Vegetables,corn,and pulses can adapt to water shortage and drought conditions and retain their production capacity. Blue water consumption per area per yield for cotton was higher,whereas that for vegetables was lower. Fruits needed a higher proportion of green water per area per yield,and vegetables,wheat,rice,and potato formed the largest group in the annual water footprint.（ 2） Between 2005 and 2011,the green water intensity coefficient fluctuated remarkably,and the average volume of blue water exceeded its capacity limits. The crops depended more on blue water resources during the growing period; therefore,blue water resources were remarkably affected.（ 3） In Urumqi,farmland occupies about 9 × 10^5mu; the actual area occupied by farmland was in an excess from2005 to 2011,and the situation is speculated to worsen over the coming years. The model of planting development has disturbed the oasis ecosystem. Our findings suggest that ecosystem health needs to be improved and a socioeconomic system needs to be developed in the oasis city.