Effects of climate change on water resources availability have been studied extensively; however, few studies have explored the sensitivity of water to several factors of change. This study aimed to explore the sensitive of water balance in water resources systems due to future changes of climate, land use and water use. Dynamical and statistical downscaling were applied to four global climate models for the projections of precipitation and temperature of two climate scenarios RCP 4.5 and RCP 8.5. Land use projections were carried out through a combination of Markov chains and cellular automata methods. These projections were introduced in a hydrologic model for future water supply evaluation, and its interactions with water use projections derived from a statistical analysis which served to assessment deficits and surplus in water to 2050. This approach was applied in the Machángara river basin located in the Ecuadorian southern Andes. Results showed that the water supply exceeds the water demand in most scenarios; however, taking into account the seasonality, there were months like August and January that would have significant water deficit in joint scenarios in the future. These results could be useful for planners formulating actions to achieve water security for future generations.

气候变化对水资源可利用性的影响已得到广泛研究；但是，很少有研究探索水对多种变化因素的敏感性。这项研究旨在探讨由于气候，土地利用和用水的未来变化而导致水资源系统中水平衡的敏感性。将动态和统计降尺度应用于四种全球气候模型，以预测两种气候情景RCP 4.5和RCP 8.5的降水和温度。通过结合马尔可夫链和元胞自动机方法进行土地利用预测。这些预测被引入水文模型中以用于未来的供水评估，其与用水预测之间的相互作用来自统计分析，该统计分析用于评估到2050年的水短缺和过剩。这种方法在厄瓜多尔南部安第斯山脉的马查加拉河流域中得到了应用。结果表明，在大多数情况下，供水都超过了用水需求。但是，考虑到季节性因素，在未来的联合情景中，像8月和1月这样的月份会出现严重的缺水情况。这些结果对于计划者制定行动以实现子孙后代的水安全可能是有用的。