Environment and Our Lives

A Walk around the Lake Biwa Watershed
The entire catchment area of Lake Biwa can been seen on the floor of the circular 'bird's-eye view' room. Here you can walk upon over 2000 aerial photographs at a scale of 1:10 000.

The water leaves Lake Biwa via the Seta River, which changes its name downstream first to the Uji River, and then the Yodo River. Finally the water enters the sea in Osaka Bay. The lake is surrounded by paddy fields, rivers, forests and mountains up to 1,377 m high. Urban centres, such as Otsu and Hikone can also be seen on the shores of the lake. The detail on the map is so fine individual buildings can be distinguished.

Everyday Life during the Past 50 Years
In this gallery is a display of objects, mementos and events related to daily life in Japan over the past 50 years. These include electrical appliances, magazines, toys and posters.

Many Japanese people viewing this display comment on how rapidly things have changed, and how it seems like only yesterday that they were using a certain object or watching a certain event. The progress of technology and the ensuing change from an environmentally-conscious lifestyle to one centred on 'convenience' has been that rapid!

Life and Water Usage in the Countryside
Many traditional houses in rural areas had a kawaya, an old-fashioned kitchen located over a stream. The water in the stream was used for daily chores, such as washing vegetables and a source of cooking water. The water in the stream was kept very clean, as after it left one kawaya, it entered a neighbour's kawaya. Water from the laundry and the family's bathwater and night soil from the outhouse was used on the vegetable garden as fertilizer.

However, by the mid 1960s things had begun to change. Washing machines, for instance, became commonplace and the water used for the laundry was instead just drained into the nearest stream.

A Countryside House
Opposite the kawaya is a countryside house that was built between 1880 and 1890. It was occupied until 1993, after which it was donated to the Museum.

The house is set out like it would have looked during 1964. Items from that time include a barrel shaped bath. Using only 10 buckets of water, this type of bath was very efficient. In the traditional living room is a television set, another item that dramatically changed the Japanese way of life.

Life with Tapwater
With the development of modern water supply systems, even the average household has access to unlimited quantities of cold and hot water for washing dishes and for bathing. Toilets and sinks now collect wastewater loaded with a great variety of chemicals, detergents and food items, which get flushed together down the drain.

Life on the Riverside
About 30 years ago the forests along river banks were well developed, with tall deciduous trees and many evergreens. People used to conserve the trees on the river bank as protection against bank erosion by the water flow, and the trees sheltered a wide assortment of shrubs and herbs and their associated wildlife.

Recently, however, these riverside forests have been disappearing. From the purely mechanical viewpoint of civil engineers, the riverside forests are of no use, and so many trees have been cut down to make way for residential areas and agricultural fields.

Forests and Water
Natural forests play an important role in producing good-quality drinking water. Even during heavy rain, forest soil can absorb water like a sponge, delaying run-off and preventing flash flooding. The soil of the forest filters the rainwater and also contributes to the water's quality through increases in the amount of dissolved minerals and in alkalinity. After penetrating into the soil and percolating down to the water table, the water will eventually become groundwater.

A Look into an Urban Stream
Life in urban streams is not usually diverse, but it is often abundant. In Japan these streams are often polluted by domestic waste and therefore people tend to dislike them. Indeed, in some places, raw sewage is discharged directly into them.

However, from the perspective of some organisms living in these polluted streams, such habitats are a paradise because they are so rich in food. For these organisms polluted urban streams are a good environment. Let's think about the meaning of a 'good environment'.

Life in Harmony with Nature
The countryside called 'satoyama' is characterized by rice fields, irrigation ponds and surrounding woods, and a moderate level of human exploitation.

Until recently, people's life in the countryside had, in many respects, been harmoniously related to Nature. In the past, villages obtained most of what they needed from the countryside surrounding them and, as a result, a diversity of habitats was available for many kinds of organisms.

Display collection
Specimens of various terrestrial fauna and flora from around Shiga Prefecture can be viewed in the draws.

Fisherman's Life
Since the Jomon Period, when hunting and gathering was the norm, fisheries have flourished around Lake Biwa and in its satellite lakes and rivers.

However, since the 1950's the total fish catches have been decreasing, giving rise to concern about the future of lake products in this region. Most fishermen are worried about the reluctance of the younger generation to contemplate a career in Lake Biwa commercial fisheries.

Aquatic Micro-World
Lake Biwa is home to an astounding range of microscopic fauna and flora. 3D images of some of them can be seen in the 'Micro-World' tunnel.

Every morning a fresh plankton sample is taken from Lake Biwa. Visitors can view the sample using the microscope in the gallery.

World of Aquatic Plants and the Function of Reed Beds
The distribution of aquatic plants within Lake Biwa varies in relation to water depth, sediment type and the actions of waves. The lake is home to several endemic species of water plants, such as Biwa tapegrass, but has also been invaded by alien species, such as Canadian pond weed.

Reeds are particularly important in the lake for providing habitats for organisms, such as attached algae, snails and many types of aquatic insect larvae, and also act as spawning sites for fish and nesting sites for birds. Additionally, reed beds absorb excess nutrients and thus help to purify the water, while also stabilizing the lake shore with their roots.

Physical Characteristics of the Lake
The waters of the lake can be classified into two types according to light availability and the potential for photosynthesis. The upper zone where light can penetrate sufficiently for photosynthesis is called the euphotic zone, below that is the decomposition zone.

During the summer Lake Biwa is stratified thermally. The sun heats up the top layer of the lake and this warm water rests on top of the colder water below. During the winter the top layer of water gets colder than the underlying water and because cold water is denser than warmer water, it sinks causing vertical mixing of the water column.

The Environment and our Daily Life
Since the 'Soap Movement' of the early 1970s, the people of Shiga Prefecture have taken a keen interest in the changes to the environment around them. Part of the gallery is dedicated to the various projects that local people are working on in collaboration with museum staff. Examples include surveys of fireflies and the progress of an invasive species of dandelion.

People can also write comments, observations and opinions here and many of them are then displayed in the Opinion Corner.

Water Use of Lake Biwa
On leaving the gallery there are a series of maps showing the areas that have depended on Lake Biwa or its out-flowing river for tapwater at various times.

In 1895 it was just an area in downtown Osaka. As the decades passed this dramatically increased, so that now a staggering 14 million people depend on Lake Biwa for tapwater.

List of Exhibits

Geological History	Human History	Environment & Our Lives	Aquarium	Discovery Room	Outdoor Exhibits