The Amazon rainforest is a critical ecosystem that plays a significant role in maintaining global climate stability and supporting biodiversity. However, in the Amazonian state of Rondônia, recent urban expansion, agricultural development and rainforest deforestation have exposed topsoil to heavy rainfall, increasing runoff and reducing water infiltration. This has led to soil erosion and the risk of flooding in the urban areas. Given the importance of addressing the water issue in this context, this paper aims to investigate the main causes of deforestation in Rondônia and the city of Cacoal. It also uses integrated analytical methods such as literature reviews, design tools, and case studies to deepen the understanding of Cacoal. By analysing the changing forest cover, altitude, rivers, and transport system, it is shown that the current development of Cacoal faces challenges, risks, and threats. The results look for solutions to these issues, exploring the application of the Sponge City concept in Cacoal. It proposes construction schemes for landscape, roads, vegetation, and buildings, to support the reduction of environmental hazards related to stormwater. In addition, other innovative urban planning technologies can effectively reduce surface runoff and increase water absorption capacity, improving the living standards of residents, and making urban life more sustainable.