Water is exposed to various types of stressors. There are environmental stressors or anthropogenic stressors, which have direct and/or indirect impacts on climate change. The overall objective of this paper is to develop a pioneer simple tool that can measure the water resources vulnerability due to environmental and anthropogenic factors. The tool is developed under six stages. Stage-1: A list of 28 indicators pertinent to the present work are generated; Stage-2: The indicators are assorted into two main categories, namely, environmental and anthropogenic indicators; Stage-3: Indicator weights are suggested using expert elicitation procedure; Stage-4: Index formulation is performed consecutively; Stage-5: The proposed index is applied; Stage-6: An appropriate adaptation strategy is proposed to each specific country. The developed tool is applied to the Limpopo River basin using 28 indicators. Results show that both the environmentally and anthropogenically driven vulnerability of the four riparian countries are moderate ranging from 41.98% in Mozambique to 47.69% in South Africa. The value of indicators ranges from 0.93% to 98.81% in environmentally driven vulnerability and ranges from 0.00% to 97.66% in anthropogenically driven vulnerability. Climate change is thought to increase the vulnerability of water resources by 9.47% in Mozambique to 13.56% in South Africa. The developed tool can be applied to other river basins and countries elsewhere considering indicator weight.