This research quantitatively and qualitatively analyzes the factors responsible for the water level variations in Lake Toba, North Sumatra Province, Indonesia. According to several studies carried out from 1993 to 2020, changes in the water level were associated with climate variability, climate change, and human activities. Furthermore, these studies stated that reduced rainfall during the rainy season due to the El Niño Southern Oscillation (ENSO) and the continuous increase in the maximum and average temperatures were some of the effects of climate change in the Lake Toba catchment area. Additionally, human interventions such as industrial activities, population growth, and damage to the surrounding environment of the Lake Toba watershed had significant impacts in terms of decreasing the water level. However, these studies were unable to determine the factor that had the most significant effect, although studies on other lakes worldwide have shown these factors are the main causes of fluctuations or decreases in water levels. A simulation study of Lake Toba's water balance showed the possibility of having a water surplus until the mid-twenty-first century. The input discharge was predicted to be greater than the output; therefore, Lake Toba could be optimized without affecting the future water level. However, the climate projections depicted a different situation, with scenarios predicting the possibility of extreme climate anomalies, demonstrating drier climatic conditions in the future. This review concludes that it is necessary to conduct an in-depth, comprehensive, and systematic study to identify the most dominant factor among the three that is causing the decrease in the Lake Toba water level and to describe the future projected water level.

中文翻译：

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ENSO，气候变化和人类活动对印度尼西亚多巴湖水位的影响：重要文献综述

这项研究定量和定性地分析了印度尼西亚北苏门答腊省多巴湖水位变化的影响因素。根据1993年至2020年进行的几项研究，水位的变化与气候多变性，气候变化和人类活动有关。此外，这些研究表明，由于厄尔尼诺南部涛动（ENSO）造成的雨季降雨减少，以及最高和平均温度的持续升高是多巴湖集水区气候变化的一些影响。此外，诸如降低工业水平，人口增长以及对多巴湖流域周边环境的破坏等人为干预对降低水位也产生了重大影响。然而，尽管对全世界其他湖泊的研究表明，这些因素是水位波动或下降的主要原因，但这些研究无法确定影响最大的因素。对鸟羽湖的水平衡进行的模拟研究表明，直到二十一世纪中叶之前都有剩余水的可能性。预计输入放电将大于输出。因此，可以在不影响未来水位的情况下优化多巴湖。但是，气候预测描绘了另一种情况，情景预测了极端气候异常的可能性，表明未来的气候条件更干燥。审查得出的结论是，有必要进行深入，全面，