3-1-1 Structure of water transmission and distribution network in urban areas of Japan

Summary

This chapter explores the development history and structure of Japan's urban water transmission and distribution networks. It discusses the evolution from early, inefficient tree system pipelines to more advanced systems like district metered areas (DMA), which improve water supply reliability and pressure management. Key advancements include the use of electronic data, ICT, and IoT for better network management, as well as the integration of water reservoirs and pumping systems to ensure stable supply and water quality. The chapter also covers design considerations like gravity flow, earthquake-resistant structures, and efficient water distribution in urban areas.

Takeaways

• 😀 Early water supply systems in Japan focused on minimal investment, leading to a disordered pipeline design and lack of proper documentation of pipe locations.
• 😀 The tree system design of early water supply networks led to challenges like fluctuating water pressure, difficulties during pipe repairs, and insufficient capacity for firefighting.
• 😀 Expansion of urban areas prompted the installation of new pipelines, water reservoirs, and distribution plants, improving water pressure, quality, and storage during emergencies.
• 😀 The formation of District Metered Areas (DMA) helped address issues such as water suspension during pipe breaks and enhanced water pressure management, especially in rugged terrains.
• 😀 Recent advancements in ICT and IoT technologies have revolutionized water network management, with systems like SCADA providing real-time monitoring and control over water pressure and quality.
• 😀 Water supply networks in Japan evolved from tree systems to network systems and eventually to DMA systems, which minimized water suspension and improved efficiency during leaks.
• 😀 The water distribution systems in Japan are designed to use gravity flow for energy efficiency, especially in regions with undulating landscapes, while flat cities rely more on pump pressure.
• 😀 Elevated water tanks, once the norm, have been largely replaced by pump pressure systems due to advancements in pump efficiency and earthquake-resistant infrastructure.
• 😀 Key points for efficient water distribution include utilizing gravity for energy savings, ensuring water pressure equalization, preventing leakage, and securing water supply during emergencies.
• 😀 Water works planning in Japan must anticipate future demands like population growth and urban development, with water facilities sometimes being located underground in parks to save land space.

Q & A

What was the main priority during the early development of Japan's water supply system?

The main priority during the early development of Japan's water supply system was to supply water with minimum investment. This led to the use of a disorganized tree system for the pipelines.

What were some common issues observed in early water supply systems in Japan?

Common issues in early systems included fluctuating water pressure due to changes in demand, water suspension during pipe repairs, and insufficient firefighting capacity due to the limitations of the tree system pipelines.

How did the installation of water reservoirs contribute to the improvement of water supply systems?

The installation of water reservoirs helped secure stable water pressure, improve water quality (especially residual chlorine concentration), handle water demand peaks, and provide water storage for emergencies.

What is the significance of the formation of District Metered Areas (DMAs) in Japan's water supply network?

The formation of DMAs was crucial in minimizing water supply disruptions during pipe breaks or disasters, improving water pressure management, and enhancing efficiency in detecting and repairing water leaks.

How has electronic data improved the management of Japan's water distribution networks?

Electronic data, including mapping systems and ICT/IoT technology, has greatly improved the maintenance and renewal planning of pipelines. Additionally, the introduction of SCADA systems enables intensive surveillance and control of the water transmission and distribution networks.

What are the differences between the tree system, network system, and DMA in water supply networks?

In the tree system, water suspension affects large areas, while the network system narrows the suspension range. The DMA system further minimizes the suspension range within the DMA, enabling more precise control and maintenance of water supply.

Why is it important to design water distribution systems with consideration of local geography in Japan?

Due to Japan's undulating landscape, water distribution systems are often designed with reservoirs placed on high ground to take advantage of gravity flow. In large cities on flat land, however, pump pressure systems are more common due to the lack of suitable high ground.

What are some challenges with elevated water tanks in large-scale water supply systems?

Elevated tanks can be costly in terms of earthquake-resistant structures, especially in Japan, which is prone to earthquakes. Furthermore, adjusting water pressure in response to changing water demand is challenging with these tanks.

How can energy-saving measures be implemented in water distribution systems?

Energy-saving measures include utilizing gravity flow distribution systems, implementing water pressure equalization with water distribution plants, and controlling water pressure using SCADA systems. These actions help reduce energy consumption and improve the overall efficiency of the network.

What role does future planning play in the development of water supply networks in Japan?

Future planning is essential for anticipating population growth, urban expansion, and future water demand. Coordination with urban planning departments is crucial to ensure the water supply network can accommodate these changes and that land for waterworks facilities can be secured.