Projected hydrologic changes in monsoon-dominated Himalaya Mountain basins with changing climate and deforestation
Projected hydrologic changes in monsoon-dominated Himalaya Mountain basins with changing climate and deforestation
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DOI：
10.1016/j.jhydrol.2015.03.048
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发表时间：
2015-06
影响因子：
6.4
通讯作者：
R. Neupane;J. White;S. Alexander
中科院分区：
文献类型：
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作者：
R. Neupane;J. White;S. Alexander
在山区源头，气候和土地利用变化会影响短期和长期的场地水收支，从而对滑坡风险、水力发电和可持续农业产生影响。为了预测喜马拉雅山脉与气候和土地利用变化相关的水文变化，我们使用了针对尼泊尔东部和西部边缘的塔莫尔河和塞提河流域校准的水土评估工具（SWAT）。利用16个全球环流模式（GCMs）的排放情景特别报告（SRES） （B1、A1B和A2）得出的2080年平均温度和降水模拟了未来气候变化。土地利用变化在空间上进行了模拟，包括(1)农业用地、(2)草地和(3)人类住区面积的扩展，这些扩展是通过考虑现有土地利用以及与能够支持不同土地利用类型的流域高程和坡度特征的可行性相关的预估变化而产生的。从这些模拟中发现，与基线模拟相比，所有基于gcm的情景的年流量都更高，其中SRES-A2和SRES-A1B在Tamor和Seti盆地分别最大增加了13%和8%。在季节基础上，我们评估了季风季节在所有情景下的高降水量，对应于Tamor和Seti流域分别为72%和68%的高流量。这种影响在地理上似乎很重要，在塔莫尔盆地东部的影响较大，可能是由于该地区的季风期更长、更强。然而，我们预测，在土地利用情景中，河流流量的变化很小，这可能是由于喜马拉雅山脉断裂导致的地下水水库输水量增加，而不是地表径流的变化。然而，当气候和土地利用变化的综合影响下，流量适度增加，这表明了这些山区水文产量的抵消机制。更好地了解这些流域对气候和土地利用变化的潜在水文反应可能对国家和跨国水管理至关重要。
In mountain headwaters, climate and land use changes affect short and long term site water budgets with resultant impacts on landslide risk, hydropower generation, and sustainable agriculture. To project hydrologic change associated with climate and land use changes in the Himalaya Mountains, we used the Soil and Water Assessment Tool (SWAT) calibrated for the Tamor and Seti River basins located at eastern and western margins of Nepal. Future climate change was modeled using averaged temperature and precipitation for 2080 derived from Special Report on Emission Scenarios (SRES) (B1, A1B and A2) of 16 global circulation models (GCMs). Land use change was modeled spatially and included expansion of (1) agricultural land, (2) grassland, and (3) human settlement area that were produced by considering existing land use with projected changes associated with viability of elevation and slope characteristics of the basins capable of supporting different land use type. From these simulations, higher annual stream discharge was found for all GCM-derived scenarios compared to a baseline simulation with maximum increases of 13 and 8% in SRES-A2 and SRES-A1B for the Tamor and Seti basins, respectively. On seasonal basis, we assessed higher precipitation during monsoon season in all scenarios that corresponded with higher stream discharge of 72 and 68% for Tamor and Seti basins, respectively. This effect appears to be geographically important with higher influence in the eastern Tamor basin potentially due to longer and stronger monsoonal period of that region. However, we projected minimal changes in stream discharge for the land use scenarios potentially due to higher water transmission to groundwater reservoirs associated with fractures of the Himalaya Mountains rather than changes in surface runoff. However, when combined the effects of climate and land use changes, discharge was moderately increased indicating counteracting mechanisms of hydrologic yield in these mountains. Better understanding of potential hydrologic response to climate and land use changes in these basins might be crucial for national and transnational water management.