The Delaware River Basin (DRB) supplies water to approximately 15 million people and is essential to agriculture and industry. In this study, a monthly water balance model is used to compute monthly water balance components (i.e., potential evapotranspiration, actual evapotranspiration, and runoff [R]) for the DRB for the 1901 through 2015 period. Water‐year R is used to identify drought periods in the basin and seven drought periods were identified. All but one of the drought periods occurred before about 1970; after this date, precipitation increased in the DRB and droughts were infrequent. The seven droughts were largely driven by precipitation deficits, rather than by unusually warm temperatures. For six of the seven droughts, the precipitation deficits were associated with atmospheric pressure patterns that resulted in northerly wind anomalies (i.e., conditions that deviate from the long‐term mean) over the basin that indicate an anomalous flow of dry air from the North American continent into the DRB. An examination of drought events estimated from a tree ring–based reconstruction of the Palmer Drought Severity Index for the 490 through 2005 time period indicates that although there were some DRB droughts that were longer and more severe during previous centuries, the DRB droughts during 1901 through 2015 were comparable in duration and severity to most drought events during previous centuries.

中文翻译：

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特拉华河流域的水文气候干旱

特拉华河流域（DRB）为大约1500万人供水，对农业和工业至关重要。在本研究中，使用了每月水平衡模型来计算1901年至2015年期间DRB的每月水平衡分量（即潜在的蒸散量，实际的蒸散量和径流量[ R ]）。水年R用于确定流域的干旱时期，并确定了七个干旱时期。除了其中一个干旱时期外，所有干旱时期都发生在1970年之前。在此日期之后，DRB的降水增加，干旱很少发生。七次干旱的主要原因是降水不足，而不是异常温暖的温度。对于七种干旱中的六种，降水不足与大气压力模式有关，导致北部流域出现异常北风（即偏离长期平均值的条件），这表明来自北美的干燥空气异常大陆进入DRB。