石羊河流域河川径流对气候与土地利用变化的响应

Response of runoff to the climate and land use pattern changes in Shiyang River Basin

应用流域气象和水文过程长期观测数据及四期TM影像数据,在建立基于气候及土地利用两种因素变化的径流过程模拟模型的基础上,分析河川径流对气候与土地利用变化的响应特征,并对其未来可能的变化趋势做出预测。结果表明,(1)1956—2009年,到达石羊河流域下游标志站蔡旗断面的河川径流量,由20世纪50年代的年平均5.392×108m3减少到目前的年平均1.096×108m3;1968年之前蔡旗断面径流量的波动主要是气候变化的结果,而1968之后,蔡旗断面径流量的变化是气候与土地利用变化共同作用的结果;(2)近30年来,气候变化对下游河川径流变化的贡献率平均为4.1%,而土地利用变化,尤其是耕地面积变化的贡献率平均为88.8%;中游灌溉定额平均分别减少5%、10%、15%和20%的情景下,下游河川径流量模拟值分别为1.591×108m3、2.427×108m3、3.262×108m3和4.098×108m3左右。

Shiyang River Basin is one of the inland rivers,which have the highest population density,the highest utilization level of water resources, the most prominent contradiction with water, and the most serious ecological environment problems. Under the background of climate change,the landscape patterns based on desert of Shiyang River Basin have taken place great changes,and thus affected the hydrological processes profoundly,including a decrease in runoff and an increase in conflicts between water demands and water supplies. In this case,the government had made policies on social and economic development,and also enforced a series of the ecological restoration project to slow ecological deterioration down,but the trend was not reversed. In order to achieve sustainable use of soil and water resources,it is very urgent for use to study on the relationship between the evolvement of water resources and the pattern of land use,and to evaluate the role of climate change and the contribution of land use change in the changes of water resources in distribution patterns respectively. In this paper,based on the long-term observed data of meteorological and hydrological process and four periods of TM image data of Shiyang River Basin,the runoff process simulation model was established,which only focusedon the factors of climate and land use change. And the the response characteristic of runoff to the climate and land use change were explored,and also the trend of runoff was predicted. The meteorological data from 1956 to 2009 of Wushaoling and Wuwei weather stations were all from China Meteorological Data Sharing Service System and the remote sensing information was from the Landsat / TM4 image data received by China＇s remote sensing satellite ground station,including the year of 1986,2000,2006 and 2010. The monthly and annual runoff data of upstream six rivers and Caiqi section in Shiyang River basin were partly from electronic material provided by Shiyang river basin administration,and partly from water resources bulletin of it. The results show： Firstly,the annual amount of river runoff arriving at Caiqi section were decreased to 1. 096 × 10^8m^3 at present from 5. 392 × 10^8m^3 of the 1950＇ s during the period of 1956 to 2009,and before1968,the runoff fluctuation of Caiqi section was mainly caused by climate change. However,after 1968 it was affected by the interaction of climate and land use change. Secondly,the average contribution rate of climate to the change of downstream river runoff was 4. 1 percent,while the contribution rate of land use change,especially the cultivated land change,was up to 88. 8 percent in recent 30 years. If the midstream irrigation water reduced by 5 percent,10 percent,15 percent and 20 percent respectively,the simulation value of downstream river runoff would be up to 1. 591 × 10^8m^3、2. 427× 10^8m^3、3. 262 × 10^8m^3,and 4. 098 × 10^8m^3,respectively. This suggested that if water-saving facilities and water-saving technology,especially high and new irrigation technology were adopted,the governance goal of increasing the amount of water from 2. 600 × 10^8m^3 to 2. 900 × 10^8m^3 in Caiqi section in 2010 would be achieved early without the irrigated areas decrease. In a word,the fundamental way of ecological restoration lies in water saving in Shiyang River basin.