The effects of inter-basin transfers (IBTs) on watershed hydrological balances and associated ecosystem processes remain poorly understood in arid regions because of data scarcity and the complexity of ecosystem responses to water management in many parts of the world. To fill this gap, the objective of this study was to quantify the effect of IBTs on watershed hydrological regimes and the associated vegetation dynamics. We conducted a case study on the Shiyang River Basin, a typical mountain-oasis-desert inland river basin in northwestern China, using water balance and wavelet analysis methods. Long-term (1980–2020) monitoring data from river discharge and groundwater tables were used to construct the water balances and quantify the periodicity of the surface water and groundwater. We observed that over 2.90 billion m of transferred water during 2003–2020 mitigated the declining trend in groundwater, resulting in a change in water storage trend from –91.9 mm/y to –53.7 mm/y. IBTs contributed approximately 230 % of the increase in observed river runoff, 21 %–60 % (42 % on average) of the increase in total water storage, and 1 %–32 % (12 % on average) of the evapotranspiration deficit (i.e., the portion of actual evapotranspiration beyond climate-driven evapotranspiration). IBTs also significantly altered the seasonal fluctuation and periodicity of river flows and groundwater. Increased water availability promoted vegetation recovery and resulted in multiscale resonance periodicities with vegetation, ranging from monthly to interannual scales. Our results indicate that IBTs markedly modified the water cycle, hydrological regimes, and ecosystem processes in the study basin. Thus, we call for long-term monitoring of the timing, frequency, and magnitude of ecohydrological modifications from IBTs to provide critical information for effective watershed management policies to achieve long-term sustainable development in water-stressed regions.

中文翻译：

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跨流域转移对大型内陆河流域流域水文及植被绿化的影响

在干旱地区，由于数据匮乏以及世界许多地区生态系统对水管理响应的复杂性，人们对流域水文平衡和相关生态系统过程的影响仍然知之甚少。为了填补这一空白，本研究的目的是量化 IBT 对流域水文状况和相关植被动态的影响。我们以石羊河流域这一西北地区典型的山地-绿洲-荒漠内陆河流域为例，采用水平衡和小波分析方法进行了案例研究。利用河流流量和地下水位的长期（1980-2020）监测数据来构建水平衡并量化地表水和地下水的周期性。我们观察到，2003年至2020年间，超过29亿立方米的调水缓解了地下水的下降趋势，导致储水趋势从–91.9毫米/年变为–53.7毫米/年。 IBT 对观测到的河流径流增量贡献了约 230%，对总蓄水增量贡献了 21%–60%（平均 42%），对蒸散亏缺贡献了 1%–32%（平均 12%）（即，实际蒸散量超出气候驱动的蒸散量的部分）。 IBT 还显着改变了河流和地下水的季节性波动和周期性。可用水量的增加促进了植被恢复，并导致与植被的多尺度共振周期，从月尺度到年际尺度。我们的结果表明，IBT 显着改变了研究流域的水循环、水文状况和生态系统过程。因此，我们呼吁对IBTs生态水文改变的时间、频率和幅度进行长期监测，为有效的流域管理政策提供关键信息，从而实现缺水地区的长期可持续发展。