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基于遥感数据的解译分析,从1987年到2007年敦煌市自然植被面积下降543.69 km2,自然生态系统面积缩小17.62%,土地荒漠化趋势明显。根据实际测定的样方生物量与对应的土地利用类型面积拟合曲线,估算这一时期自然植被的生物量从102.42×104t下降到72.33×104t。敦煌市自然植被和人类活动的用水量此消彼长,总用水规模在6.3×108m3左右。自然植被用水量从1987年的3.072 7×108m3减少到2007年的2.17×108m3,净减少达30%。人类活动用水量从1987年的3.315 7×108m3增加到2007年的4.093×108m3。疏勒河干流及其支流党河都因为人类活动用水大量增加,挤占了自然植被的用水。特别是农业灌溉占用了绝大部分水资源,成为敦煌生态环境退化的主要原因。恢复和保护敦煌的生态问题,不仅需要调控党河流域的人类活动,也要调控疏勒河干流地区的人类活动。
Based on the interpretation and analysis of remote sensing data, the area of natural vegetation in Dunhuang City decreased by 543.69 km2 from 1987 to 2007, the area of natural ecosystems was reduced by 17.62%, and the trend of land desertification was obvious. According to the curve of actual area measured by quadrats, the biomass of natural vegetation was estimated to decrease from 102.42 × 104t to 72.33 × 104t in this period. The water consumption of natural vegetation and human activities in Dunhuang City has been exacerbated. The total water consumption is about 6.3 × 108m3. Natural vegetation water consumption decreased from 3.072 7 × 108 m3 in 1987 to 2.17 × 108 m3 in 2007, a net decrease of 30%. Human activity water consumption increased from 3.315 7 × 108 m3 in 1987 to 4.093 × 108 m3 in 2007. The main Shulehe River and its tributaries, the rivers of the rivers, have largely consumed water for natural vegetation because of the massive increase in human activities. In particular, agricultural irrigation takes up most of the water resources and has become the main reason for the deterioration of the ecological environment in Dunhuang. To restore and protect the ecological problems of Dunhuang not only needs to regulate and control human activities in the party’s river basin, but also human activities in the areas along the Shule River.