【作者】 翟禄新；

【导师】 冯起；

【作者基本信息】 兰州大学 ， 自然地理学， 2008， 博士

【摘要】 水资源是西北地区经济、社会和生态环境发展演化的主要影响因子,而气候变化又强烈地影响着水资源系统的变化趋势。本文以水问题为纽带来研究气候变化对西北地区水文水资源的影响,研究成果有望能为流域的综合治理规划、生产力合理布局、水资源开发与保护、防灾减灾和制定全球变化背景下区域社会经济可持续发展模式供科学依据,同时为有关部门制定有关政策和决策,提供可供选择参考的对策措施,以便更好地为国民经济建设与可持续发展服务。本文以西北地区近50a来常规气象资料作为输入,利用Morton CRAE模型计算了区域潜在蒸发、实际蒸散发、地表湿润指数和计算径流深,以标准化降水指数(SPI)分析不同时段的干旱频次来反映区域气候干湿变化,最后应用Mann-Kendall秩次检验法对各水文要素的变化趋势进行了分析,并对气候变化对水文要素的影响进行了较为深入的研究,得到以下结论:1.水文气象要素空间分布现状(1)西北地区降水量自东南向西北呈递减趋势,但祁连山和天山西段是西北地区内陆的两大湿岛,对内陆干旱区的水分供给具有特殊意义;(2)年均气温分布呈东西两端高,中部特别是青藏高原北缘低的特征;(3)区域潜在蒸发能力受气温和降水的控制,西北地区西北部和东南部因低温或较多的降水,蒸发能力相对较小,而塔里木盆地和内蒙古西部为蒸发能力高值区;(4)水分条件决定了西北地区实际蒸散量的大小,因此,实际蒸散发量的分布与降水量的分布格局基本一致:(5)地表湿润指数的分布呈南北高,中间塔里木盆地至甘肃西部至内蒙古西部一线为低值的特征;(6)西北地区计算径流深为南高北低分布,同时计算径流深的分布格局也反映了人类活动在不同地区的影响程度。2.气温和降水量变化趋势(1)近50a来西北地区年平均气温除陕西南部极小部分外,绝大部分地区呈显著或极显著上升趋势。(2)2月、10月极显著升温区域明显较大,而3、4月和7、8、9月增温区域较小,内蒙古河套以北区域除8月份外表现为全年各月均极显著增温态势,西北地区东南陕西南部则表现为全年不显著变化;(3)西北地区5、6、7、8月份降水量变化趋势不明显,年降水量变化趋势主要受此4个月降水量变化的影响。东南部降水量变化为不显著下降趋势,气候变化对该地区降水的影响小于西部地区。3.水文要素计算与变化趋势(1)CRAE模型经修正后可用于西北地区实际蒸散发量的估算,计算结果不仅反映区域水文特征,而且一定程度上反映了人类活动对水文循环的影响程度;(2)受气候变化影响,近50a来西北地区潜在蒸发量仅在2、4、10月呈小范围的显著增加趋势;7、8、9、10、12月份在新疆中部和甘肃河西走廊西部出现显著下降趋势,其余月份和区域无显著变化趋势反映;(3)西北地区各月实际蒸散发量没有显著增加的趋势,但显著下降和极显著下降区域分布面积较大,新疆中南部、青海中西部和内蒙古西部为剧烈下降区域,甘肃东南部和陕西南部部分地区也表现为实际蒸散发量的显著下降。对于年实际蒸散发的变化变趋势,则是年降水量和年潜在蒸发量变化趋势共同作用的结果;(4)近50a来,西北地区东部地表有变干的趋势,这一趋势与降水量的减少和潜在蒸发量的增加有关;(5)西北地区计算径流深变化主要影响区域为内蒙古河套以北地区和陕西南部地区,可能对未来这些地区引水工程的建设和运行造成影响。4.气候干湿变化分析(1)标准化降水指数(SPI)作为一种干旱重建指标,适用于西北地区,也可以作为气候变化的监测指标;(2)降水量的西增东减趋势与干旱频次的西北减少东南增加相对应,亦即气候变化在某种程度上缓解了新疆北部和青海西部的干旱发生频率,但增加了甘肃东南部和陕西中南部的干旱发生频次;(3)与气候变化相对应,全西北地区干旱频次有总体下降的趋势,尽管干旱发生的地域持续在改变。5.水文要素对气候变化的响应分析(1)西北地区东北部计算径流深对气候变化的敏感性最强,其次是青海西部和新疆天山东段,亦即气候变化最易引起这些地区计算径流深的大幅变化。(2)气温与降水共同作用并对计算径流深产生作用,以单纯的气温变化或降水变化来分析水文要素的响应是不全面的。(3)西北地区不同气候区气温和降水对水文要素的影响程度不同,在干旱内陆区、沙漠边缘和大型灌区内,气温为水文要素变化的主要影响因子;而在半干旱地区,降水成为影响水文要素的主要因子;在海拔较高的地区,气温对水文要素的影响相对较强,在相对湿润的西北地区东南部,气温对水文要素的影响不明显。降水是西北地区计算径流深的主要影响因素。(4)年平均气温和降水对同期水文要素的影响中,气温的影响小于降水的影响。降水对计算径流深的影响大于气温对计算径流深的影响,未来降水量的变化是西北地区水资源系统变化的关键因素。(5)经对洮河流域和黑河流域上游气温和降水对地表径流的敏感性分析表明,近50a来西北地区降水对径流的影响远大于气温对径流的影响,且表现为气温的升高导致地表径流的减少,而降水的变化显著地改变了地表径流。气候变化对地下水的影响主要体现在气温升高,引起地下水蒸发加强而造成水位的下降。更多还原

【Abstract】 Water resources is the major factor acting on the development of the local economy, society and evolves of the eco-environment in Northwestern China. The variety of water resources system was always impacted intensely by climatic change. Taking the water problems as the link, this dissertation studies the impacts of climatic change on water resources system in Northwest China. The research results can be used to provide the scientific basis for the basin comprehensive planning, the productive forces rational distribution, the water resources development and protection, the disaster mitigation, and formulating the sustainable development pattern of the social economy under the global climate change background. Moreover, it may supply the choice reference to the relative departments for formulating the policy and the decision-making to serve for the national economy construction and the sustainable development.This dissertation, taking the climatic change in Northwest China in recent 50 year and the hydrological factors, monthly or annual temperature (T), precipitation (P), actual areal evapotranspiration (ETa), potential evapotranspiration (ETp), Surface Wetness Index (SWI), and net precipitation/runoff depth (NP) as an object, has conducted more thorough research to the impacts of climatic change to the hydrological components with the methods of Mann-Kendall, Standardized Precipitatin Index (SPI) and Morton CRAE. The main results show as follow:1. The patterns of hydro-meteorological factors status quo: (1) The trend of mean annual P is descending from the southeast to the northwest of Northwest China. There are two "wet island" in Qilian Mountain and weast Tianshan Mountain in the northwestern interior region. They has the special significance to the supplies of the moisture content in the interior arid region; (2) The mean annual T of the southeasten of Northwest China and west part of Tarim Basin is high, and middle part, especially north edge of the Qinghai-Tibet Plain, is low; (3) The ETp is dominated by the temperature and precipitation. Because of the low temperature or rich rainfall, the ETp is relatively small in the northwest and southeast area of Northwest China. On the other hand, there is high ETp in the Tarim Basin and the west part of Inner Mongolia; (4) Decided by the moisture content condition, the ETa has the consistent distributed pattern with that of the precipitation in Northwest China; (5) The distribution of SWI presents the pattern which that of the north and south part is high, southwesten, northeast and middle part (Tarim basin, west part of Gansu, and western Inner Mongolian) low; (6) The NP is distributed with the pattern of high value in the south part and low in the north part of Northwest China. The pattern of the distribution of NP has also reflected the human activity in the different location.2. The trend of temperature and precipitation: (1) The area of presenting upward trend of T is bigger than other months in Northwest China in February and October, but in March, April and July through September, it is small. The increasing trend of T is significant in the north part of Hetao district in Inner Mongolian in all of months except August. On the other hand, the trend of T is not significant in south part of Shan’xi Province; (2) The trend of P is not significant in May through August in Northwest China, which dominated the trend of the annual precipitation. The trend of P is downward but not significant in the southeast part of Northwest China, and climate change has a limited affection to this region than west part.3. Calculation of hydrological factors and trend analysis: (1) It was show that the modified CRAE can be used for estimating the ETa in the Northwest China. The results of CRAE not only reflect the characteristic of the regional hydrology, and to some extent reflect the impact of human activities on the local hydrological circulation; (2) Affected by climate change, ETp is increasing in a small area only in February and April. The trend of ETp is downward significantly in July through October and December in centre part of Xinjiang and the west part of Hexi Corridor. There is no significant trend in other months and regions in Northwest China.; (3) For every month’s ETa, there are no significant upward trend in Northwest Chnia, but there are some extremely significant decreasing area, which include the centre and south part of Xinjiang, the centre and west of Qinghai, and west of Inner Mongolian. There also have significant downward trend in some region, such as southeast of Gansu and southwest of Shanxi. The trend of ETa is resulted from the annual P and ETp; (4) Related to the change of the local P and ETp, there is a dryer trend in eastrn part of Northwest China in the recent 50 years; (5) The region affected by the change of NP include the north of Hetao in Inner Mongolian and the south area of Shanxi, where this situation will have the influence to the future diversion works’ construction and its operation. 4. Analysis of wetness and dryness of the climate: (1) As a reconstruction method of drought indicators, Standardized Precipitation Index (SPI) is applicable as indicators of climate change monitoring in Northwest China; (2) The change of drought frequency is corresponding to the trend of precipitation. That is, to some extent, climate change mitigate the frequency of drought in the northern part of Xinjiang and western Qinghai, but increase the drought frequency in the central and southern region of Shaanxi and southeasten part of Gansu; (3) Relative to the climate change, Frequency of drought has a general downward trend in the whole region of Northwest China, despite the location is continuing to change.5. Analysis of the responses of hydrological elements to climate change: (1) The NP in northeast part of Northwest China is more vulnerable to climate change than that in west part of Qinghai and the eastern section of the Tianshan Mountains in Xinjiang, and this situation caused the NP increase in these region in future. The NP is not as vulnerable as that in other district of Northwest China; (2) Mean monthly T and P have a synergetic effect to the contemporaneous NP, so it is not comprehensive to analyze the response of temperature or precipitation to water resources system; (3) In different climatic zones, the extent of impact of mean monthly temperature and precipitation to the hydrological factors is different. T is a main impact factor to hydrological factors in the arid inland regions, desert margins and large irrigation district, and precipitation plays an important role in the semi-arid areas. P becomes to a relatively strong factors to hydrological factors in the higher elevation areas. Temperature’s impact to hydrological factors is not obvious in the relatively moist regions in the southeast part of Northwest China. For the NP, Precipitation is the main factor in Northwest China. (4) The impact of mean annual T is weaker than tnat of P on hydrological factors. The NP is affected by P more than T. The trend of precipitation is a main factor to the impact on water resources system in the future. (5) After analysis of sensentivity of runoff in the Taohe River Basin and upstream of Heihe River, the result show that the T has small effect on surface runoff than P. The increase of T results in decrease of runoff and P affects the runoff singnificantly. The effect of climate change on groundwater table is due to the increase of evaporation after T increasing.更多还原