River System
A river along with its tributaries is known as a river system. It is a network of interconnected rivers and streams that drain into a larger body of water, such as an ocean or a lake. River systems play a vital role in the water cycle and are crucial for the distribution of freshwater across the Earth's surface.

Definition
A river system consists of a main river, also known as the trunk stream or the main stem, and its tributaries. Tributaries are smaller rivers or streams that flow into the main river. They increase the volume of water in the main river and contribute to its overall flow. As water flows downstream, it collects water from various tributaries, forming a complex network of waterways.

Formation
River systems are formed through a combination of factors such as precipitation, topography, and geology. Rainfall and snowmelt contribute to the formation of small streams that gradually merge to form larger rivers. The landscape, including mountains, valleys, and plains, determines the direction and path of the rivers. Over time, erosion and deposition processes shape the river system, creating diverse features such as meanders, waterfalls, and floodplains.

Importance
River systems are of immense importance to both humans and the environment. They serve as a source of freshwater for drinking, irrigation, and industrial purposes. River systems also provide habitats for various plants and animals, supporting biodiversity. They facilitate transportation, trade, and commerce, as rivers have historically been major transportation routes. Furthermore, river systems play a crucial role in shaping the landscape and influencing weather patterns.

Management
Managing river systems is essential to ensure their sustainability and prevent negative impacts such as flooding and pollution. Governments and organizations implement measures to regulate water flow, construct dams for flood control and hydroelectric power generation, and implement pollution control measures to maintain the health of the river systems. Additionally, maintaining the ecological balance of river systems is crucial to preserve the diverse ecosystems they support.

In conclusion, a river along with its tributaries is known as a river system. It is a complex network of interconnected waterways that play a vital role in the water cycle and provide numerous benefits to both humans and the environment. Managing and preserving river systems is crucial for their sustainability and the well-being of all organisms that depend on them.