Bequeathing a Clean Lake Biwa to Future Generations Lake Biwa Comprehensive Preservation Initiatives ― Seeking Harmonious Coexistence with the Lake's Ecosystem ― Lake Biwa Comprehensive Preservation Liaison Coordination Council Lake Biwa Comprehensive Preservation Promotion Council Contents 1 Overview of Lake Biwa and the Yodo River Basin ○ Overview of the Yodo River Basin 1 ○ Water Use in Lake Biwa and the Yodo River Basin ○ Land Use in Lake Biwa and the Yodo River Basin 2 Overview of Lake Biwa ○ Lake Biwa, an Ancient Lake 2 ○ Dimensions of Lake Biwa 3 Development of Lake Biwa and the Yodo River Basin ○ Early History 3 ○ Expanded Farmlands, Increased Rice Production and Subsequent Development of Commerce ○ A Political Center and Cradle of Culture and Tradition ○ Industrial and Economic Development after the Meiji Restoration ○ Changing Lifestyles 4 Background of Lake Biwa Comprehensive ○ Farmland Development and Flooding in the Edo Period (1603 - 1868) 5 Development Program ○ Flood Control During the Meiji Period (1868 - 1912) ○ Modern Projects for Using Water of Lake Biwa ○ Increasing Demand for Water in the Showa Period (1926 - 1989) 5 Lake Biwa Comprehensive Development Program ○ Program System 7 ○ Breakdown of the Program Expenses ○ Environmental Preservation ○ Flood Control ○ Promotion Effective Water Use 6 Outcomes of the Lake Biwa ○ Effects of Flood Control Projects 9 Comprehensive Development Program ○ Effects of Projects Promoting Effective Use of Water ○ Effects of Environmental Preservation Projects 7 Current Situation of Lake Biwa ○ Land Use around the Lake 11 ○ Water Quality of Lake Biwa ○ Lake Biwa Water Quality Map ○ Eutrophication of Lake Biwa ○ Reed Colonies ○ Attached Lakes (naikos) ○ Lake's Ecosystems 8 History of Lake Conservation Efforts ○ Freshwater Red Tides 15 ○ Water Quality Conservation Campaigns Initiated by Local Residents ○ Shiga Prefectural Ordinance Concerning the Prevention of the Eutrophication in Lake Biwa (Eutrophication Prevention Ordinance) ○ International Conference on the Conservation and Management of Lakes (World Lake Conferences) ○ Establishment of Lake Biwa - Yodo River Water Quality Preservation Organization 9 Survey for Preparing Lake Biwa ○ Background 17 Comprehensive Conservation Plan ○ Guiding Principle and Key Concepts of the Comprehensive Conservation Plan ○ Objectives and Period of the Comprehensive Conservation Plan ○ Promoting Partnerships 10 Comprehensive Environmental Preservation ○ Protecting Water Quality 19 Efforts and Specific Measures ○ Increasing Soil's Recharge Capacity ○ Preserving the Natural Environment and Scenic Landscapes ○ Citizen Participation and Activities ○ Information Sharing and Staff Exchange Promotion ○ Research and Survey ○ 9th International Conference on the Conservation and Management of Lake (World Lake Conferences) 11 Future Progress of Comprehensive ○ Continuous Improvement 30 Lake Preservation Initiatives ○ Coordinating System 12 Chronological Table of Lake Biwa 31 ①The Grandeur of Mt.Shizugatake ②The Granite Cliffs at Kaizuosaki ③Subtle Reflection of Chikubu Island ⑤The White Beach of Omatsuzaki ① ② ③ ④The Old Castle in Hikone ④ ⑤ ⑥ ⑦⑦ForestForest on Mt.Hiei ⑦ ⑧ ⑥A Water District with a Tiny Inlet in Azuchi-Hachiman ⑧The Crystal-clear Water in Seta, Ishiyama Biwako Hakkei (Eight Scenic Places in Omi) selected in 1949. 1 Overview of Lake Biwa and the Yodo River Basin 1 Overview of Lake Biwa and the Yodo River Basin Overview of the Yodo River Basin Fukui The Yodo River, flowing into Osaka Bay, originates in Lake Yogo mountains in and around Shiga Prefecture. After flowing Ado River out of Lake Biwa, the river travels southward down to the TakatokiAne River River Sonobe Shiga Osaka Plain, combining several branches of various sizes River Lake Biwa including the Kizu and the Katsura rivers. The Yodo River Okinoshima Island Seri River Hyogo Hitokuraoroji Kyoto Uso River Echi River changes names during its long travel: the upper and middle River Katsura River Kamo River Kyoto City Gifu Kusatsu Hino River reaches are called the Seta and the Uji rivers, respectively. River Ina River Otsu City Yasu River The Yodo River basin constitutes an extensive area of Seta River Araizeki Weir Uji River 2 Daito River approximately 8,240 km , covering the six prefectures Mie, Kanzaki River Kizu River Yodo River Yodo River Shiga, Kyoto, Osaka, Hyogo and Nara. Ozeki Weir Osaka Bay Osaka City Old Yodo River Nabari River Mie Nara Osaka Nunome River Uda River Shorenji River Water Use in Lake Biwa and the Yodo River Basin Legend Lake Biwa supplies water for various uses: domestic, Lake Biwa Basin industrial and agricultural uses, and for power generation. Yodo River Basin Water of Lake Biwa and the Yodo River supports social and River economic activities not only in their respective basins, but Urban Area also in extensive areas in the Kinki region. Notably, tap Lake Biwa and Yodo River Basin water from the lake/river serves some 14 million people, the largest population in Japan benefiting from a single water source. The water is taken and used throughout the water source. In the upper reaches, water taken from Lake Biwa and Shiga 10.1 dams is mainly used in Shiga Prefecture; in the middle Prefecture Kyoto 17.9 reaches, water is taken from Biwako Canals and the Uji Prefecture Osaka 85.3 River primarily for use in Kyoto City; in the lower reaches, Prefecture water from the Yodo River serves the huge population of Hyogo 26.1 Prefecture Osaka and other cities on the Osaka Plain. 020 40 60 80 100 ［million people］ Population Using Tap Water from Lake Biwa/Yodo River (Water service in fiscal 1994) Land Use in Lake Biwa and the Yodo River Basin Since ancient times, many cities have been developed on the flat lands in Lake Biwa and the Yodo River Basin. During Japan's high economic growth period after World War II, industrialization and urbanization progressed remarkably, particularly in Kyoto, Osaka, Kobe and their suburbs; many forests and farmlands around large cities were converted into residential zones during that period. Today, the Lake Biwa Basin and the upper reaches of the Yodo River have a relatively greater proportion of farmland; the lower reaches contain more residential, commercial and industrial districts. 1992 1955 1895 0 10 20 30 40km Legend Municipality Forests Farm Land Urban Areas Unidentified Areas (Source: Lake Biwa Museum) Water Areas Changes in Land Use in Lake Biwa and Yodo River Basin 1 Overview of Lake Biwa 2 2 Overview of Lake Biwa Lake Biwa, an Ancient Lake Lake Biwa is the only ancient lake in Japan. In terms of surface area, despite being the largest lake in Japan, Lake Biwa is ranked 130th among the world's freshwater lakes. In terms of age, however, the lake is the world's third oldest, with a history of some four million years. The term "ancient lake" is generally defined as an extant lake that was created more than 100,000 years ago. Because they have such long histories, ancient lakes feature a great many endemic species that have evolved within the respective lake. Lake Biwa possesses abundant biodiversity, offering habitats to over 1,000 species, including at least 50 endemic species, such as Biwa trout (onchorhynchus masou rhodurus) and Seta corbiculid clam (corbicular sandai). Lake Baikal Lake Tanganyika Lake Biwa Age Approx. 30 million Approx. 20 million Approx. 4 million years old years old years old Lake Baikal Lake Surface 2 2 2 Area 31,500km 32,600km 674km Maximum Depth 1,637m 1,471m 104m Lake Biwa Lake Tanganyika The Equator Average Depth 740m 572m 41m Water Storage 3 3 3 Capacity 23,000km 18,880km 27.3km No. of Species Approx. 2,500 Approx. 1,300 Approx. 600 Lake Malawi Living in Lake Rate of Endemic Approx. 50% Approx. 50% Approx. 10% Species (Source: "Ancient Lakes" in Lake Biwa Museum) Location and Characteristics of Three Oldest Lakes in the World Dimensions of Lake Biwa Ground Plan The surface area of Lake Biwa, Japan's largest lake, is Ibuki Mountains 674 km2, 17,000 times the area of Koshien Ball Park one of the largest baseball fields in Japan and one-sixth the total area of Shiga Prefecture where the lake lies. At the lake's Mt. Kanekuso narrowest point, it is spanned by Biwako Ohashi Bridge. 1,271m The lake's section north of the bridge is called "Hokko" (northern lake) and that south of the bridge is called Ado River Ane River "Nanko" (southern lake); Hokko and Nanko differ in Mt. Ibuki 1,377m character in various aspects. Mt. Buna Amano River Lake Biwa There are approximately 460 rivers of various sizes flowing 1,214m into the lake. There is, however, only one outflow from the Mt. Ryosen Inukami River 1,084m lake (the Seta River), apart from canals constructed during Echi River early modern times. It is estimated that approximately Hira Mountains Suzuka Mountains Mt. Mikuni 815m Mt. Hiei Hino River 19 years are required to change all water in the lake. 848m Yasu River Shiga Prefecture Land Area 4,017km2 Seta River 2 Lake Biwa Catchment Area 3,174km Araizeki Weir Mt. Gozaisho Lake Surface Area 2 674km Daito River 1,210m (Northern Lake:Southern Lake = 11:1) Shoreline 235km 3 Mountain Storage Capacity 27.3km Average Depth 41.2m Hill Maximum Depth 103.6m Flatland Length (North - South) 63.5km Maximum Width 22.8km Minimum Width 1.35km Seta River Araizeki Weir Cross Section Amagase Dam Biwako Ohashi Bridge Lake Biwa Osaka Bay (Source: The House of Water Benevolence “Aqua-BIWA”) 2 3 Development of Lake Biwa and the Yodo River Basin Early History It is believed that ancient people began living around Lake Biwa over 20,000 years ago. During the Yayoi Period (ca 300 BC - ca 300 AD), rice cultivation was introduced to the fertile wetland around the lake, where increasing numbers of agricultural communities developed, protected by the natural embankment from seasonal changes in the lake's water levels. ●Dainaka-no-ko lake ruin During the reclamation of Dainaka-no-ko inland lake, many artifacts produced between the Jomon (ca6,000BC-ca300 BC) and Heian (794AD-1192AD) periods were discovered on the lake bottom.