III. Water Environment Preservation and Sustainable Water Resource Management in Urban Areas

Dr. Takeshi Hata
Faculty of Agriculture,  Kobe University, Japan

There are three well-known incidents involving water quality problems in Japan. In 1883, there was pollution of the River Watarase from the Ashio copper mine; in 1955 there was an outbreak of Itai-itai disease (which affects bones and joints), caused by cadmium poisoning at areas along the River Jinzu; and, perhaps best known, the mercury poisoning incident at Minamata in 1956.

Lake Biwa and Lake Kasumigaura are the two largest lakes in Japan. The former serves the water needs of the Kansai region and the latter does the same for the

Toxic chemicals

Polychlorinated Biphenyl (PCB), a carcinogen, was banned in 1972. In 1994, research showed that large concentrations of the chemical could be found in various species of raptor (hawk, eagle, falcon) and certain mammals, including the Japanese monkey. (The problem is similar to the well-documented one of DDT.) As one goes further up the food chain, the higher the concentration.

Another problem concerns nitrogen, which in high concentrations can lead to nitrogen poisoning, also known as cyanosis. Nitrates absorbed by the body are converted to nitrites, which interfere with the oxygen-carrying capacity of blood. Though Japan is 40 percent self-sufficient in terms of calories, it is only 28 percent self-sufficient in cereals. Forty million tons of cereals are imported each year. In order to maximize yields from farmland in Japan, nitrogen fertilizers are used; on average in 1987, 142kg/hectare, more than twice the world average of 52kg/hectare.

Nitrogen contamination is also caused by the release of nitrogen oxides into the atmosphere from imported oils. This nitrogen returns to earth in the form of acid rain and dust. Dioxins are another big problem. The tolerable daily intake (TDI) is just 10 picograms (pg) /day. Contaminated soil found to have an excess of 1,000pg/gram of soil has to be covered up or removed.

Preservation of the water environment

The main points to consider here are:

The need for the water environment to be preserved and developed by all citizens, and it is here that women have a very important role to play.

The need to conduct biological surveys and a national census of river environments.

Participatory planning by citizens in discussion of water issues.

The role of children and water, specifically, the role water resources can play in an educational sense.

"Virtual Water" - water used to produce foods which are then imported to Japan. As Japan is a big importer of foods, this is a very important issue, and one where increasing awareness is necessary.

The role played by forested areas in the preservation of the water environment also needs to be considered. Forested areas are able to serve in a number of different ways, as a water resource by forests' ability to store water or to delay the time of runoff; as a way to help control soil erosion; for health and leisure activities; as locations to preserve wildlife; and as sources of oxygen and the related ability to improve air quality. There is a direct, proportional relation between forested areas and water quality. Smaller forests lead to a corresponding decline in the quality of water.

When considering the multi-functional roles of forested areas, it is worth bearing in mind the following issues: the creation of artificial wetland systems and associated biodiversity; the promotion of perennial vegetation and microclimatic amelioration; and the protection of downstream areas from floods.

One example of water management at the local, community level can be found on Awaji Island in Hyogo Prefecture. The Tazu System, as it is known, is one where citizens themselves look after the water in the community. After the Great Hanshin Earthquake in 1995, the system was quickly restored as citizens were able to utilize their knowledge of the system's operation to immediate effect. In Japan, waterfronts previously had a negative image and citizens avoided them after advanced water pollution. Now, however, that has changed and waterfront areas are popular.

Nature-oriented river works are part of the efforts being made by the authorities to preserve water environment areas. Levees, which act as flood barriers, are made of concrete, but then covered with a top layer of soil and grass to preserve the illusion of nature.

Paddy fields can also be enlisted in the management of sustainable water resources. The multi-objective functions of paddy fields extend to their role in helping determine water quality, especially regarding pollution by chemicals commonly used in agriculture. A significant amount of chemicals like nitrogen and phosphorus are absorbed in paddy fields. Farmers in some areas, however, still over-use chemicals, so further education remains a priority.

Sustainability of water resources

It is important to not overuse or waste water resources. Restoring the natural flow rate and developing new water resources are priorities, thus the continuing need for dams and reservoirs, especially in developing countries. Dam construction has become a very difficult issue, however, because of their impact on the environment.

Using less water, or using water more efficiently, are important goals. One issue which needs to be considered is what to do in times of drought. Who should be allowed to take advantage of water resources, upstream people or downstream ones? If upstream areas are able to use water more efficiently, then this becomes an easier issue to solve. Related issues include ensuring both upstream and downstream areas benefit from development; considering how to store excess water at times of flooding - and how to use it during times of drought; and the control of rivers' flow-rate. Underground "rivers" (actually, enormous pipes, some with a diameter of six meters) and reservoirs have been constructed, though such public works are very costly. Some means like fish ladders will be needed when dams are built on rivers so that fish can bypass dams. A problem here though relates to the quality of water trapped behind dams in reservoirs. Artificial aeration of this water is sometimes necessary in order to approximate the condition of natural water. Hydro-structural developments should not alter the fundamental fact that river water is a resource.

Figure 1. Desire for the multi-objective use of irrigation reservoir

Climate change

Carbon dioxide levels are forecast to reach 700 ppm by the year 2100, along with an associated rise in the average worldwide temperature of 2C and a higher worldwide sea level (increase of 50cm). Some of the effects of global warming include less rainfall forecast, so countries already suffering from water shortages will find their situations worsening. One-third of the world's forests are expected to be affected , and there will be more flooding due to the increased sea level.

Flood management in urban areas

Flooding is an issue in Japan, especially at times of concentrated rainfall in big cities, and more levees are being built to counter potential threats. Historically, however, people have lived with floods - in ancient Europe some houses are built on artificial mounds. International Flood Network (IFNet) has been established to decrease flooding and increase public awareness. Between 1988 and 1997, over half the fatalities from natural disasters worldwide were caused by flooding. Flooding is a particular problem in Asia, where rapid population growth has seen the development of river basins without proper precautions. Developments in river areas modify the frequency of floods elsewhere. Similarly, illegal, large scale commercial logging causes a lot of problems.

IFNet is promoting a satellite-based Global Flood Alert System which will inform affected countries when floods are thought to be about to occur. To this end, a database is currently being compiled, and a current research project on the River Nile is providing monthly streamflow data and forecasts. The introduction of an integrated management system is
vital here.

Flood mitigation and other functions of agricultural land

Over the past decades many people around the world, and particularly in Asia, have moved to high-risk flood areas, where river basins and flood plains have been thoughtlessly developed. Rice paddies play a very big role in flood management. Protected by 30cm-high levees, they can withstand 300mm of rainfall, allowing for vast amounts of rain water to be stored and to recharge the groundwater. Well planed urban development with restored paddy and farm lands is possible in the developing countries for the preservation of water environment. Conjunctive use of surface and ground water is one of the key issues for the case. There are many irrigation reservoirs in Japan, especially in Hyogo prefecture. These are also used effectively in an emergency from natural disaster and for restoration of local communities. In the farmland areas in Kobe, city people are now trying to plan their future village with active use of their natural resources.

Figure 2. Utilization of agricultural reservoirs by pumping up groundwater

Figure 3. Total Number of Small Irrigation Reservoirs and Its Decrease
(in Hyogo Prefecture)

Water Environment Preservation - conclusion:

i ) Protect water, protect people
ii) If there's no water, there's no life
iii) Don't waste water
iv) Encourage participation and involvement of citizens
v ) Pay more attention to local community usage and the need to reform society to be more appreciative and aware of water resources

Q & A

Q: (Mr. Syed Ghias Ud Din) What are the visible symptoms of Minamata disease? What measures are taken to prevent it? What measures are taken to cure it?

A: Methyl mercury poisoning causes physical paralyses in hands, legs, mouth, eyes and ears. The substances accumulate in fishes and shellfishes, which are then eaten. There is no real cure for the illnesses - the best solution is to remove the toxic substances from the water by not introducing them in the first place.

Q: (Mr. Syed Ghias Ud Din) Excessive nitrogen fertilizer use leads to stunted growth, an early onset of puberty and an increased incidence of obesity. We have this problem in Pakistan and are worried about the long-term effects of nitrogen use. What information can you provide about this?

A: We haven't long experience after finding out about this problem in Japan. Awareness in the U.S. and Europe is much higher and policies to counter the effects of nitrogen over-use against methemoglobinemia and cancer are in place there. It's a very difficult problem, and one we expect to do a lot more research into in the future.

Editor's Note: This article is a summary of a lecture delivered by Dr. Takeshi Hata at the 2003 Seminar. AUICK takes full editorial responsibility for the content, while Dr. Hata checked and partly rewrote.