Water Rock Glaciers and climate change in the dry Andes of Bolivia: implications for future water supplies

该项目旨在调查玻利维亚干旱山区的岩石冰川，并评估它们未来对该地区供水的贡献。山区水文在维持世界许多干旱地区的社会和经济发展方面发挥着至关重要的作用。然而，气候变化正在导致山区冰川的衰退。玻利维亚的山区冰川自20世纪50年代以来经历了显著的融化，预计21世纪的持续变暖将导致冰川进一步衰退和最终消失，特别是在冰川较小的地方。这场冰川衰退威胁到拉巴斯和埃尔阿尔托市未来的供水，对经济发展产生不利影响，并有助于推动社会、政治和生态不稳定。然而，在玻利维亚的几个高干旱山区，相当多的冰被岩石冰川包围，岩石冰川是一种细长的谷底地貌，由岩石碎屑和冰的不同混合物组成。这些地貌是许多山脉系统中水文系统的重要组成部分，将大量粗细沉积物输送到谷底位置，并形成广泛的潜在水库。由于表面覆盖着岩石碎屑，冰含量不受低幅度和高频温度变化的影响，因此，预计岩石冰川对气候变暖的反应比冰川慢。因此，在全球变暖的情况下，它们有可能在未来的水文系统中发挥重要作用，在冰川持续衰退的情况下为山区社区提供水源。尽管如此，在更好地理解岩石冰川在调节山区水文中可能发挥的作用方面，仍存在几个障碍。首先，尽管迫切需要评估岩石冰川对供水的贡献，但对山区岩石冰川的系统清查很少。其次，虽然人们对冰川对气候变化的反应了解很多，但对岩石冰川的反应却知之甚少。第三，对岩石冰川中的冰量，特别是在区域范围内的冰量了解尚不完整，这妨碍了对这些地貌对供水重要性的评估。因此，这项研究提案将解决前两个问题，并旨在提供一个数据库，我们可以从那里开始回答第三个问题。我们将利用遥感数据绘制玻利维亚干安第斯山脉过去50年来岩石冰川的位置、面积范围和形状图，使用精细的空间分辨率(5米)光学卫星数据和20世纪60年代免费提供的退役日冕数据。我们将使用这些结果来评估这段时间内观测到的气候变化对岩石冰川的反应，包括归因研究表明全球温度对温室气体强迫做出反应的时间(IPCC 2007)。

This project aims to investigate rock glaciers in the arid mountains of Bolivia and assess their future contribution to water supplies in the region. Mountain hydrology plays a crucial role in maintaining social and economic development in many arid regions of the world. However, climate change is leading to recession of mountain glaciers. In Bolivia mountain glaciers have undergone significant melting since the 1950s, and continued predicted warming over the 21st century will result in further glacier recession and eventual disappearance, especially where the glaciers are small. This glacier recession threatens the future water supplies for the cities of La Paz and El Alto, adversely affecting economic development and helping to drive social, political and ecological instability. However, in several of the high arid mountain regions in Bolivia considerable ice is enclosed within rock glaciers, elongate valley-bottom landforms comprising a variable mixture of rock debris and ice. These landforms are an important component of hydrological systems in many mountain systems, transporting large amounts of coarse and fine sediments to valley-bottom locations and forming extensive potential reservoirs of water. With a surface cover of rock debris, the ice content is insulated from low amplitude and high frequency temperature changes and, as a result, rock glaciers are predicted to respond more slowly than ice glaciers to climate warming. Consequently, they have the potential to play an important future role in hydrological systems under conditions of global warming, producing water supplies to mountain communities as glaciers undergo continued recession. Despite this, several obstacles stand in the way of a better understanding of the role that rock glaciers may be able to play in regulating mountain hydrology. First, there have been few systematic inventories of rock glaciers in mountain regions, despite the pressing need to assess the potential of rock glaciers to contribute to water supply. Second, while much is known of the recession of ice glaciers in response to climate change, much less is known of the rock glacier response. Third, there is as yet incomplete understanding of the amount of ice contained within rock glaciers, especially at the regional scale, and this hampers assessments of the importance of these landforms to providing water supply. As a result, this research proposal will address the first two of these problems and aims to provide a data base from which we can begin to answer the third. We will use remotely-sensed data to map the location, areal extent, and form of rock glaciers in the dry Andes of Bolivia over the last 50 years using fine spatial resolution (5 m) optical satellite data and freely available decommissioned CORONA data from the 1960s. We will use these results to assess rock glacier responses to observed climate change over this period which encompasses the time when attribution studies indicate global temperatures responded to greenhouse gas forcing (IPCC 2007).