The response of annual runoff to the height change of the summertime 0°C level over Xinjiang

According to climate features and river runoff conditions, Xinjiang could be divided into three research areas: The Altay-Tacheng region, the Tianshan Mountain region and the northern slope of the Kunlun Mountains. Utilizing daily observations from 12 sounding stations and the annual runoff dataset from 34 hydrographical stations in Xinjiang for the period 1960–2002, the variance of the summertime 0°C level height and the changing trends of river runoff are analyzed both qualitatively and quantitatively, through trend contrast of curves processed by a 5-point smoothing procedure and linear correlation. The variance of the summertime 0°C level height in Xinjiang correlates well with that of the annual river runoff, especially since the early 1990s, but it differs from region to region, with both the average height of the 0°C level and runoff quantity significantly increasing over time in the Altay-Tacheng and Tianshan Mountain regions but decreasing on the northern slope of the Kunlun Mountains. The correlation holds for the whole of Xinjiang as well as the three individual regions, with a 0.01 significance level. This indicates that in recent years, climate change in Xinjiang has affected not only the surface layer but also the upper levels of the atmosphere, and this raising and lowering of the summertime 0°C level has a direct impact on the warming and wetting process in Xinjiang and the amount of river runoff. Warming due to climate change increases the height of the 0°C level, but also speeds up, ice-snow melting in mountain regions, which in turn increases river runoff, leading to a season of plentiful water instead of the more normal low flow period.     

流域主体功能区划方法与指标体系构建——以长江流域为例

在对国内外空间区划与流域规划研究成果评析、主体功能区划与流域规划关系梳理的基础上,针对目前自然单元主体功能区划不足与流域协调发展实践需要,以长江流域为例,开展流域主体功能区划理论与方法研究。阐述了流域主体功能区划的内涵与特征,提出其本质是主体功能区划与流域规划的有机结合体,进而构建区划逻辑思路与方法路线。基于科学性、系...     

南极地区大陆架划界引发的法律制度碰撞

自《南极条约》1961年生效以来,南极地区一直处于以《南极条约》为核心的南极条约体系的约束之下.1982年《联合国海洋法公约》(以下简称《公约》)建立了大陆架制度,要求沿海国应在批准《公约》生效10年内完成200海里以外大陆架外部界限的划定①.1994年《公约》生效后,澳大利亚、挪威、阿根廷和英国在提交各国200海里以...     

青海共和盆地风况及风沙地貌

利用共和盆地茶卡、共和、贵南站2012-2015年的风资料,分析盆地风向、风速和输沙势的变化特征,并结合Google Earth高清影像,对盆地风能环境与风沙地貌进行探讨。结果表明：（1）盆地年平均风速1.6～2.7 m·s^-1,西北部、中部和东南部年起沙风出现的频率分别为7.7%、3.5%、0.9%,起沙风主要发生在冬、春季,风向以WNW和W为主。（2）盆地属于低风能环境,风沙活动自西北部向东南部减弱,方向变率指数0.7～0.96,风况为窄单峰或宽单峰风况,西北部和中部风向变率属于低变率,东南部属于中等变率,合成输沙方向较一致,为281.0°～286.7°。（3）盆地沙丘类型有新月形沙丘（链）、格状沙丘、复合型链状沙丘、沙山、沙垄、抛物线沙丘等,沙丘类型和风况较吻合。     

内陆河流域生态环境的空间分异特征

分析研究了内陆河流域气候条件,植被生态,土壤环境及水环境质量等生态环境要素的空间变异特征,探讨了流域不同地带的生态环境功能。结果表明：干旱内陆河流域气候条件,尤其是水热条件和地貌特征是植被生态,土壤环境及水环境形成与分异最主要的控制性因素,几大环境要素之间相互联系,相互制经久形成内陆流域生态环境空间带规律和生态系统功能在空间不同地带上的显著差异性,认识这种分带规律与不同区域的生态功能,是合理开发的     

网状河流体系的基本特征及其影响因素

网状河流近年来受到较多关注,无论从沉积特征还是从地貌及水力学特征看,网状河流都是一种典型的河型,但目前对网状河流的认识还存在一定的局限性,从沉积特征,地貌及沉积微环境特征及形成条件等方面的对网状河流进行了系统的论述和总结。     

塔里木河中游土地沙漠化与环境因子关系研究

根据已有的和大量的调查地贡巴扎地区沙漠化与主导环境因子之间的关系进行了研究,结果表明：沙漠化形成主要因子的重要性依次为地下水位,植被,微地貌类型、土壤质地。以沙漠化研究为基础的维护合理的生态水位应为４．４米左右。     

西北干旱区水资源转化与开发利用模型

干旱地区的内陆河发源于山区,在山前平原地区受干旱气候、地质地貌结构和岩性的影响,地表水与地下水之间具有大数量转化的特点。根据水量平衡原理,通过对西北干旱区内陆河流域山前平原地区河水、地下水、泉水相互转化机制的研究和分析,建立了模拟与计算相结合,兼有预测性质的水资源转化与开发利用模型。模型概念明确,形式简单,所需资料容易获得。在新疆乌鲁木齐河流域实际应用结果表明,模拟的流域最大可能引水量和水资源净可利用量,都远比现状实际引水量和水资源净利用量小得多,水资源开发利用明显过度,每年超采地下水１．２×１０８ｍ３,与当地水文地质部门计算结果非常一致,效果较好。另外,模型预测结果还表明,对于处在完成地表水与地下水联合开发利用阶段的,类似乌鲁木齐河流域的内陆河流域来说,可用水资源的开发已达到极限,再采用传统的提高地表渠系利用率的方法,已不可能增加流域的可用水资源量。这不仅从理论上解决了,水利和水文地质部门长期以来有关地表水和地下水到底如何开发才算合理的争论;也证实了,这样做的结果不但在经济上得不偿失,而且将破坏流域已建有的地下水开采和供水系统,有可能造成更大的经济、社会和生态损失。     

Groundwater control on the suspended sediment load in the Na Borges River, Mallorca, Spain

Groundwater dominance has important effects on the hydrological and geomorphological characteristics of river systems. Low suspended sediment concentrations and high water clarity are expected because significant inputs of sediment-free spring water dilute the suspended sediment generated by storms. However, in many Mediterranean rivers, groundwater dominance is characterised by seasonal alternations of influent and effluent discharge involving significant variability on the sediment transport regimes. Such areas are often subject to soil and water conservation practices over the centuries that have reduced the sediment contribution from agricultural fields and favour subsurface flow to rivers. Moreover, urbanisation during the twentieth century has changed the catchment hydrology and altered basic river processes due to its ‘flashy’ regime. In this context, we monitored suspended sediment fluxes during a two-year period in the Na Borges River, a lowland agricultural catchment (319 km²) on the island of Mallorca (Balearic Islands). The suspended sediment concentration (SSC) was lower when the base flow index (i.e., relative proportion of baseflow compared to stormflow, BFI) was higher. Therefore, strong seasonal contrasts explain the high SSC coefficient of variation, which is clearly related to dilution effects associated with different groundwater and surface water seasonal interactions. A lack of correlation in the Q-SSC rating curves shows that factors other than discharge control sediment transport. As a result, at the event scale, multiple regressions illustrate that groundwater and surface water interactions are involved in the sedimentary response of flood events. In the winter, the stability of baseflow driven by groundwater contributions and agricultural and urban spills causes hydraulic variables (i.e., maximum discharge) to exert the most important control on events, whereas in the summer, it is necessary to accumulate important volumes of rainfall, creating a minimum of wet conditions in the catchment to activate hydrological pathways and deliver sediment to the drainage network. The BFI is also related to sediment delivery processes, as the loads are higher with lower BFI, corroborating the fact that most sediment movement is caused by stormflow and its related factors. Overall, suspended sediment yields were very low (i.e., < 1 t km^− 2 yr^− 1) at all measuring sites. Such values are the consequence of the limited sediment delivery attributable to soil conservation practices, low surface runoff coefficients and specific geomorphic features of groundwater-dominated rivers, such as low drainage density, low gradient, steep valley walls and flat valley floors.     

气候转暖及人类活动对北疆中小河流降水-径流关系的影响

利用近40 a来的水文气象资料,分析北疆20世纪80~90年代气候转暖及人类活动对北疆不同地区的中小河流降水-径流关系的影响,主要结论如下:①北疆西部的哈拉依灭勒河、卡琅古尔河,在1980年以后气候转暖的背景下,它们的自然降水-径流关系并无明显改变。②北部额尔齐斯河流域东部产流区平均高程较高的大青河,在90年代气候显著转暖的背景下,其自然降水-径流关系并无明显改变;而位于大青河东侧、流域平均高程较低、山区流域降水量较小的小青河,在90年代气候明显转暖的背景下,其自然降水径流关系发生了变化,所形成的自然地表径流量明显减少。③天山中部北坡的乌鲁木齐河,在80~90年代气候转暖的背景下,其自然降水-径流关系发生了变化,产流量明显偏多。④天山东部北坡的开垦河,在80~90年代气候转暖及人类活动影响的背景下,其自然降水-径流关系发生了变化,产流量减少。⑤乌鲁木齐近郊低山丘陵区的水磨河,在近40 a来的增温及人类活动影响的背景下,其自然降水-径流关系发生了变化,尽管乌鲁木齐年降水量有增加趋势,而其径流却是减少的。