River Improvement Works Research Articles

J. de Rijke and Joganji River Improvement Works Early in the Meiji Era

J. de Rijke and Joganji River Improvement Works Early in the Meiji Era

The prospect on accuracy and universality of the river ecology environmental assessment method in IFIM

Recently, the purposes of river improvement works have became not only the protection for flood but also the improvement of ecosystem quality. In this context, habitat evaluation procedures are becoming important. The Instream Flow Incremental Methodology (IFIM) is one of the most popular habitat evaluation method, but still there is little application experience in Japan. In this paper, we study the accuracy and applicability of fish habitat evaluation method by IFIM. At first, we surveyed habitat variables, such as velocity, depth, substrate and cover, to derive suitability-of-use curves, which are the core technique in IFIM, during the summer and the autumn in 1997 in the Furukou River, Yamaguchi prefecture. Then, we compare the observed fish distribution with calculated habitat distribution by using the suitabilityof-use curves obtained from the same river, which showed a good accordance. Next, we compare the observed fish distribution with calculated habitat distribution by using the suitability-of-use curves obtained from literature, which showed a bad accordance. Those results imply that the suitabilityof-use curves obtained from a river will show a good accordance when it is used in the same river, but cannot apply to other rivers.

The characteristics of sound from Flowing water in the river and the experiment of open channel by FFT analysis

The purpose of this study is to find the characteristics of sound of flowing water in the river and in the channel of experiment from frequency analysis by FFT. In the area of river improvement and river conservation works have tended to put importance to landscape from visual approach. But, in the future, it is necessary that the basic idea of acoustic approach called soundscape compared with visual approach is disscused in the river design.

The Characteristics of Fluctuation of Sound of Flowing Water in the River from the Viewpoint of Soundscape

The purpose of this study is to find the characteristics of sound environment from point of view of OM fluctuations in the river space, that is, the physiolbgical effect of environmental sound on man. In the area of river improvement and river conservation work have tended to put importance to landscape from visual approach. But, in the future, it is necessary that the basic idea of acoustic approached called soundscape compared with visual approach is discussed in the river design.

治水事業の費用負担と地域社会の対応 水害予防組合の賦課方式を例として

Japanese flood control was rapidly developed in Modern Ages when regular flood protection works began onnationwide scale. It is flood prevention cooperatives that promoted those public works by bearing a part of the expenses in Modern ages.Flood prevention cooperatives are classified into 3 types according to functions. They are the one that takes a share in the expenses of flood protection works and irrigation-drainage works (type I), the one that practices flood defense activities (type II), and the one that petitions to realize and promote river improvement works and acts a part of the works as an agent of prefecture (type III). The author conducted research on cooperative dues that support activities of cooperatives. The results are as follows.Amount of share in the expenses taken by flood prevention cooperatives much differs in compliance with their functions. In type I cooperative dues were very high, in type II they were less and in type la they were much less. In all types cooperative dues were imposed by standards that based on the degree of flood damages. Especially in type I, much amount of cooperative dues were levied according to many grades, but type II and type III had a few grades. Their objects of imposition were land and houses, and in urban areas they included fabrics such as railroads.Flood prevention cooperatives dissolve when they accomplished their purposes in each function. But the cooperatives of type II shift to public flood defense corporations that consist of municipalities and act by budgets of municipalities.Flood prevention cooperatives fully understood natural features of geomorphology, hydrology and so on, and social features of land use, land ownership, and so on of their areas. On the basis of these recognition they contrived their unique imposition system in consideration of benefit by public flood prevention works. In consequence they promoted public flood prevention works by taking a share in expenses.

地域社会における治水事業進展の活動と費用負担 兵庫県佐治川水害予防組合を例として

Sajigawa Flood Prevention Cooperative is one of the few cases that work actively even at present. The author intended to clarify its characteristic activities to promote prefectural river improvement works and its pecuniary mechanism to support its activities.Sajigawa Flood Prevention Cooperative was originally organized to bear a considerable portion of outlay for river improvement works allocated its area. But prefectural works were stopped, because the cooperative failed in settling disputes with the lower reaches on burden of expenditure. After the failure, the flood prevention works were eventually realized with national financial aid by its active and continuous petitions to Hyogo Prefecture and national government. Thus active petitions became one of the most important and main works of the cooperative hereafter.The other important activity of Sajigawa Flood Prevention Cooperative was to substitute partially for prefectural government as land expropriation agent. Hyogo Prefectural Government easily bought up the land for river improvement works and promoted its works through the agency of cooperative.Financial source of the cooperative consisted of cooperative dues, contributions from adjoining municipalities and land expropriation payment. Cooperative dues consisted of those imposed on land and house individually in proportion to flood damage and those allocated equally to municipalities consisiting the cooperative.After 1969 when adjoining municipalities entered the cooperative, cooperative dues changed into those imposed to four towns consisting the cooperative in proportion of river length. Hence individual dues were abolished after 1969.Contributions from adjoining municipalities aimed to expand prefectural flood prevention works into adjoining area through active petitions of the cooperative. But these contributions stopped, because adjoining municipalities incorporated into two towns consisting the cooperative.Land expropriation payment was that land owner payed one percent of selling price to the cooperative in case of land expropriation substituted by the cooperative. This system abolished because of complication derived from land expropriation payment of adjoining municipalities.As mentioned above, characteristics of Sajigawa Flood Prevention Cooperative are unique. These characteristics were formed by some causes as follows.1. Sajigawa Flood Prevention Cooperative did not need to bear large amount of cost allocated by prefecture, because prefectural flood prevention works were realized with national aid.2. Another financial sources except cooperative dues were avail able: contributions from adjoining municipalities and land expropriation payment.3. Most members of the cooperative were sma llholders, especially of cultivated field. They could not pay large amount of dues, because they could not earn large profits from their field.

A Geographical Analysis of Flood Control Work and Local Share in Expenses

Sharing expenses by the residents of localities where public flood control works are to be undertaken is indispensable for the materialization of flood control works of medium and small-sized rivers in modern times. Flood prevention cooperatives organized by inhabitants in frequently-inundated areas have played an important role in bearing the expenses allotted to localities. But some of the cooperatives could not bear their share of the expenses and flood control work failed consequently.The author analyzed the causes of failure of a flood prevention cooperative in sharing expenses and clarified the problems of local share in expenses taking the case of the Kokufu River Flood Prevention Cooperative on Sado Island.The results are as follows: The most decisive reason that the Kokufu River Flood Prevention Cooperative could not bear its allotment is the impossibility of payment by the inhabitants of the upper basin, because extremely high rates of allotment in the upper basin were decided without adjusting the conflict between upper basin residents and lower basin residents. Hence prefectural river improvement work of the Kokufu River was halfed.Futhermore the following situation contributed to default in payment. In the Kokufu River basin advanced mining techniques were applied to flood control works in the Edo Period, and these works were carried out several times in connection with the prosperity and decline of the Sado Gold Mine. Some rational features in the works, imposition and repayment system, and so on can be seen. But after the Meiji Restoration small landownership in the island society prescribed repayment of much of the expenses of river improvement, and work was stopped.Therefore consideration must be given to relative flood damage between the upper basin and lower basin so as not to produce outstanding inequality between the two districts when making allotment rates.Generally, in frequently-inundated areas, we can see conflict between the uper basin and lower basin. But in that case flood control work cannot be realized without adjustment of advantages and disadvantages between the two districts. Also realization of flood control work requires the intervention of the prefectural goverment with large funds.

YODO RIVER IMPROVEMENT PROJECT FOR FLOOD PREVENTION IN THE MEIJI ERA

The national government has carried out projects for flood control since “the River Act” was enacted in 1896, when Yodo River improvement work started. The civil engineer, who mainly made the plan and led the work was Dr. Tadao Okino. But Mr Johannis de Rijke, who was a Dutchman engaged by the national government of Japan, had already investigated Yodo River to make the plan. In this report, the comparison between the idea of Okino and that of de Rijke was studied. Okino adopted the peak flood discharge proposed by de Rijke as design flood discharge. Besides the floodway plan in the lower part of the basin in Osaka Prefecture was laid by de Rijke. However we found the large difference between the two plans. That was how to deal with the retarding basin in the middle part and Biwa Lake in the upper part of the basin. Okino constructed the intake weir in the channel out of Biwa Lake and changed the retarding basin into the protected lowland.

Ddrop down the water level by the deck-mount accelerator in open-channel

Temporary cofferdam used in river improvement work causes the backwater. In flood time, this backwater increases the risk of overflow over the bank. To diminishthis backwater there are two method. One is kinematic method which is to diminish the flow resistance by using smooth shutterings in shape and rough-ness. The other is dynamic method which is to diminish this backwater by adding momentum ofaccelerator. We carried the mock-up test of dynamic method using the propellers of work-ship as accelerator, and as the result the water level fall down 10 cm. The result exhibited good agreement with the momen-tum principle. This paper presents the result of mockup test.

A Study on Flood Control Techniques on the Sakawa River in the Tokugawa Era

Flood control techniques of the Tokugawa era have not been clear until today. Some preceding relational studies have described that river improvements during the Tokugawa era were conducted by two largest river improvement schools, namely, “Kantouryu ” and “Kisyuryu ” which, accordingly, had directed flood control techniques of the Tokugawa Shogunate.Recent studies have gradually clarified the improvement works in each river in Japan during the Tokugawa era. The results are that “Kantouryu ” and “Kisyuryu ” might not have directed flood control techniques of the Tokugawa Shogunate. To find out these results, more investigation must be done on the river improvement works of the Tokugawa era in each Japanese river. As one of the studies in this new standpoint, this study is aimed at making clear the flood control techniques during the Tokugawa era in Sakawa river running in west Kanagawa Prefecture.

Nest Site Selection of the Brown Dipper Cinclus pallasii

A study on the nesting behavior and nest site selection of the Brown Dipper Cinclus pallasii was carried out in Yabe, Kumamoto Prefecture, central Kyushu, from 1982 to 1985.1) Nest building occurred from August to April, with a peak in December and January. Nest building observed in August to October was not completed.2) Male and female contributed equally in nest building. Any division of labor was not observed.3) Of 53 nests found, 26 (49%) were built under the bridges, 13 (25%) on the overhanging banks or stone walls, and the remainder in the culverts, behind a water fall, in the disused drainage, on the rock, and so on. The use of bridges increased from 1982 to 1985. Nests built on the artificial structures were 64% of all.4) Re-use of a nest over two successive breeding seasons was rare (only one case), but some nest sites were used for several years.5) There was not significant difference in the breeding success between the cavity or covered nest sites and exposed ones.6) The number of breeding pairs increased from six in 1982 to 13 in 1985. Available nest sites did not increase during the study period, but the area of shallows preferred as a foraging site by dippers increased due to the river improvement works, which may have caused the increase of breeding pairs.

PREDICTION OF FLOW RESISTANCE IN COMPOUND CHANNELS AND ITS APPLICATION TO DESIGN OF RIVER COURSES

Laboratory tests were performed to evaluate the interaction of the flow between a main channel and floodplains. In the tests, prismatic channels similar to actual river courses were used. The experimental results showed that the increase in Manning's roughness coefficient due to the interaction could be predicted by estimating an apparent shear stress acting on a vertical plane along a interface between a main channel and flood plain. The mixing coefficient at the interface f can be almost constant and its value is around 0.17. On the basis of the prediction method obtained, the classification diagram for the estimation of the flow resistance in the compound channel was proposed, by which discharge capacity is calculated well in accordance with characteristics of river course, compared with the existing method. Further more, it becomes known how the resistance to flow varies with the change in the cross-section by river improvement works.

Overview of rivers and water resources in Japan

This paper describes the climatic and topographical characteristics of Japan. Derived from these conditions, Japan's rivers tend to be short and precipitate, and severe flooding has been common since early times. Since the end of the last century widescale river improvement works have been undertaken for various reasons. There has been a rapid increase in the productivity of farm land as a result of improved irrigation, and the industrialization and urbanization of Japan have been facilitated. Problems have arisen, however, particularly in regard to pollution and landscape degradation.

CHANGES OP SEA BED DUE TO DETACHED BEEAKWATEES

Since most of the coast lines of Japanese Islands are faced on the open sea and are always attacked by severe waves, beach erosion is one of serious problems in the coastal engineering field. Although Japan has all types of coastal land-forms except the glacial shoreline, remarkable recessions of coast line have been observed at sea cliffs and sandy beaches. The recession of sea cliffs has been found at several districts in Japan since old times. But, beach erosion has become increasingly severe since the early 1950's. The main causes of beach erosion are the reduction in sediment supply from rivers and the interception of the longshore paths of sediment. The former is caused by the river improvement works and by the construction of dams and debris barriers or Sabo works. The later is caused by the coastal structures, such as jetties, groins, breakwaters, and flood-control outlets. In addition a new type of beach erosion has been observed at the coast where coast protection works such as seawalls and bulkheads exist. The beach erosion defence works are being executed at more than 300 sites in Japan. Considerable number of the works were commenced in the 1960's.