Because the pattern of climate and thus water demand varies rapidly, an accurate assessment of available water (AW) must be determined in order to manage water resources sustainable. This study investigated the components of basin AW using a comprehensive water balance framework based on the SWAT model. It consists of a system of relationships describing different components of water balance to estimate diverse forms of AW. The resulting modelling system is capable of displaying current status and past trends in the components of AW, highlight links between blue and green water components, assess AW at farm and basin scales, and forecast spatial and temporal variations of AW components under different water policies and climate scenarios as well as evaluating potential water shortage. To explore this methodology, the system was applied to the Tashk-Bakhtegan basin (Iran). The results for the historical period showed wide changes in the blue water components, which was very lower for the green water ones. For instance, it was between 63% and − 56% for renewable BW and 11% and − 24% for renewable GW with respect to their long term means. Similarly, blue water was more sensitive than green water to future annual precipitation variations. Evaluation of the construction of the basin’s major dam showed that it has drastic impact on the spatial blue AW components; such that they are increased in the adjacent subbasin up to 97% and reduced to half the status quo in the downstream subbasins. The basin has also experienced 30% increase in cropped areas, resulting in 1500 million meter cubic (MCM) water shortage in the current condition. Considering the framework as a relatively easy-to-use tools with readily available data, is strongly recommended for other regions.

由于气候模式和用水需求变化迅速，因此必须准确评估可用水 (AW)，以便可持续地管理水资源。本研究使用基于 SWAT 模型的综合水平衡框架调查了流域 AW 的组成部分。它由描述水平衡不同组成部分的关系系统组成，以估计不同形式的 AW。由此产生的建模系统能够显示 AW 成分的当前状态和过去趋势，突出蓝色和绿色水成分之间的联系，评估农场和流域尺度的 AW，并预测不同水政策下 AW 成分的时空变化和气候情景以及评估潜在的水资源短缺。为了探索这种方法，该系统被应用于 Tashk-Bakhtegan 盆地（伊朗）。历史时期的结果表明，蓝水成分的变化很大，绿水成分的变化非常小。例如，就其长期平均值而言，可再生能源 BW 为 63% 至 - 56%，可再生能源 GW 为 11% 至 - 24%。同样，蓝水比绿水对未来年降水量变化更敏感。流域大坝建设评价表明，对空间蓝色AW分量影响较大；因此，它们在相邻子流域中增加了 97%，而在下游子流域中减少到现状的一半。该流域的种植面积也增加了 30%，导致目前情况下缺水 15 亿立方米。