With many countries facing water scarcity and the demand for water ever-increasing, more people are turning to rainwater harvesting (RWH) as a feasible way of supplementing supply. However, the success of RWH systems depends on several factors, including rainfall, catchment characteristics and socio-economic factors. Hence it is essential to carry out location-specific studies to evaluate the potential of RWH in a particular area. This study sought to assess the influence of seasonal rainfall and climate change, and socio-economic constraints on RWH in the City of Johannesburg. A GIS-based MCDA was run to estimate RWH suitable sites as influenced by various socio-economic factors. The RWH suitability map shows that at least 50% of the city is suitable for RWH. These, together with climate data was embedded into a rainfall-runoff model developed in HEC-HMS to simulate runoff volumes up to the year 2050. The Deficit and Constant loss method was employed to calculate infiltration losses. After calibration, the model results were within acceptable limits (R² = 0.68 and 0.79). The rainfall-runoff simulation results show that high runoff volumes are received during the wet season, which is more than double the non-potable water demand. These results indicate that, with ample storage, RWH systems are feasible despite the rainfall seasonality. Therefore, it is recommended to invest in diverse and multipurpose storage to improve RWH reliability.

随着许多国家面临水资源短缺和对水的需求不断增加，越来越多的人将雨水收集 (RWH) 作为一种可行的补充供应方式。然而，RWH 系统的成功取决于几个因素，包括降雨量、流域特征和社会经济因素。因此，必须进行特定地点的研究以评估特定区域的 RWH 潜力。本研究旨在评估季节性降雨和气候变化以及社会经济限制对约翰内斯堡市 RWH 的影响。运行基于 GIS 的 MCDA 以估计受各种社会经济因素影响的 RWH 合适地点。RWH 适宜性地图显示，至少 50% 的城市适合 RWH。这些，与气候数据一起被嵌入到 HEC-HMS 开发的降雨径流模型中，以模拟到 2050 年的径流量。采用赤字和恒定损失方法来计算渗透损失。校准后，模型结果在可接受的范围内（R²  = 0.68 和 0.79）。降雨-径流模拟结果表明，雨季接收到大量径流，是非饮用水需求的两倍多。这些结果表明，尽管存在降雨季节性，但只要有充足的存储空间，RWH 系统是可行的。因此，建议投资多样化和多用途的存储，以提高 RWH 的可靠性。