During the period from 1998 to 2000, revegetation was carried out at solid rock slopes (quarry sites, etc.). The sites investigated were 15 dams, 4 to 36 years after their construction, managed by Water Resources Development Public Corporation. The grasses which had been introduced dominated in all ten plots where the seeds of mainly exotic grasses had been sown for revegetation. Succession to native plant vegetation was not observed. The species diversity indices were lower in the plots with revegetation by exotic grasses than in the plots without such revegetation. The diversity indices were relatively high in the areas of revegetation near the existing vegetation. In the plots without revegetation, pioneer tree species including Rhus succedanea L., Rhus javanica L.var. roxburgii (DC.) Rehder et Wils., Mallotus japonicus (Thumb. ex Murray) Muell. Arg., Clethra barvinervis Sieb. et Zucc., and Pinus densiflora Sieb. et Zucc. were recorded. Among those, Rhus javanica var. roxburgii, Mallotus japonicus, Clethra barbinervis, and Pinus densiflora grew relatively well even on solid rock.

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The effect of water level lowering for flood control on the reproduction of largemouth bass, Micropterus salmoides, was studied in Miharu Dam Reservoir, Fukushima Japan. The capture investigation was continued from the year of the first filling of water in the dam. The results indicated that largemouth bass increased immediately after invasion, especially in the Pre-Reservoir where water level was fixed. The increased largemouth bass then decreased in the next year, however the tendency in which fishes eaten by largemouth bass decreased was continued. Maturating and hatching season of largemouth bass was surveyed in the Pre-Reservoirs. The hatching date was analyzed by the number of otolith rings, and maturity of gonads were determined by histological analyses. These analyses suggested that their spawning season was from early May to late June when water temperature rose from 15°C to 21°C. Analyses of otolith rings of juveniles indicated that hatching did not occur during the water level lowering period. Furthermore, it was observed that juveniles were dead at the edge of the water during the period. These results suggested that the water level lowering over 2.5m and at the speed over 0.27m/day, water temperature risen from 15°C to 21°C, suppressed the reproduction of largemouth bass.

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Belowground dynamics and strategies were analyzed with respect to three species of Typha spp. in Japan. Root and shoot ratio (R/S) and root and rhizome ratio of them were closely related to the order of their maximum penetrating water depth. More rhizome were developed with deeper water depth, accordingly, biomass allocation for roots became smaller. Bioenergetic model of T. orientalis was formulated for analyzing their belowground strategy and indicated that nutrient flux from below to aboveground organs in heterotrophic season were smaller than T. angustifolia. T. latifolia, T. angustifolia and T. orientalis has each different strategy, enlargement, deep water penetration and preemption, respectively. Typha orientalis increases their density before flowering and the flowering season was the last among three species. Preemption of belowground space was the important strategy for T. orientalis.

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The shrubby willow Salix gracilistyla Miq. is one of the dominant plants in the riparian vegetation of the upper-middle reaches of rivers in Japan and has been used in river restoration practice in Japan. In this study, we measured the biomass and production of a S. gracilistyla stand on a fluvial bar in the Ohtagawa River, Hiroshima Prefecture. Allometric relationships between the stem diameter and the dry weights of plants were determined every month from May to October and in December 2000. To determine the thickening growth, we measured the diameters at ground level of randomly selected shoots. From May to October, the stem diameter at ground level increased by 30%, showing considerable thickening growth. The aboveground biomass, estimated from the stem diameter by using the allometric relationship, increased from May (0.9 kg m^-2) to September (2.2 kg mm^-2) and decreased thereafter because of leaf shedding. In September, leaf and current branch biomass reached 0.6 and 0.3 kg mm^-2 respectively. The biomass increment of old branches and stems from May to December was 0.4 kg mm^-2. The underground biomass determined by digging in the following February was 1.6 kg mm^-2. The aboveground production of S. gracilistyla was estimated to be 1.3 kg mm^-2 yr^-1. This value is comparable to those of other pioneer trees and temperate forests. Our results suggest that S. gracilistyla has a high potential for production despite its small aboveground biomass.

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In the catchment basins of the Nagara River, Gifu Prefecture, Central Japan, many skiing grounds have been developed since the 1970s. Ammonium sulfate ((NH₄)₂SO₄) is used as snow cement on these skiing grounds, and nitrogen pollution in the upper streams has become an issue. Inorganic nitrogen concentration and loading in a stream, where skiing ground occupies 50% of its catchments basin, showed remarkable increases in winter; the concentration being as high as 1.2 mg L_-1 in winter, while 0.2 mg L_-1 in other seasons without snow. Winter nitrogen loading was assumed to contribute to the annual loading by about 70%. No such specific increase in nitrogen concentration and loading has been observed in the streams of the catchment basin without skiing grounds. Over 90% of the inorganic nitrogen in the stream water was in nitrate form. It is quite likely that a great part of the ammonium is nitrified in low temperature conditions.

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On the downstream of the dam, the effect of the erosion of the river bed caused by a decrease in sediment supply from the upper reaches is known. It is considered that a decrease in sediment supply cause armoring of the stream bed, and the fish which spawn at gravel bed can't spawn eggs at the river bed. On the Urayama Dam, as a countermeasure against armoring of the stream bed, sediment at tail of reservoir was put into downstream the dam. In this study, we examined the spawning condition of the dace at the river bed where the sediment was placed, and verified the effect of sediment supply on keeping the spawning-environment. After supplying sediment, the dace was able to spawn there, and we recognized the countermeasure is effective on keeping the spawning-environment of the dace.

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Ecological engineering is at a beginning stage in Korea, with its concept first introduced only in the early 1990s. A rebirth of the concept of ESSD (Environmentally Sound and Sustainable Development) by the Rio Summit in 1992 and surprisingly rapid dissemination of its concept into the major sectors of development activities would give the most profound impact on the ecological consideration in large-scale development projects as well as land and river plans. Basic knowledge and experience of the ecological engineering, mostly adapted from Germany, U. S. A. and Japan, have been applied in the several fields of civil engineering practice, such as stream and river management, highway construction and land and new-town planing. Since the mid-1990s, the Korean government has sponsored various research and development programs of ecological engineering and techniques-the third generation of environmental technology-in order to develop and disseminate the ecological engineering and techniques to conserve and restore the fragile national ecosystem. Academia is trying to make those knowledge and experience, still fragmented and crude, to be systematic and analytic. Ecological engineering, then, will be established as an important discipline in both academia and engineering-practicing societies.

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The importance of a resource and forest management system integrated with land use management is widely recognized in the world. New Zealand (NZ) was the country took the lead to establish the integrated resource management system by dividing the role of natural forests and plantation forests clearly and by establishing the Resource Management Act 1991 (RMA). This review aims to introduce NZ's forest management system, their developing processes and the effectiveness or problems of the system. Comparison to Japan's forest management system was also stated.
The dichotomous management system, which manages indigenous forest for environmental conservation and plantation forest for timber production, allowed the indigenous forests to be free from harvesting. New Zealand was able to conduct this system because of (1) the small area of indigenous forest remaining on the hill countries, (2) the development of plantation forestry to a promising industry and (3) the pressure of rationalization and the conservation movement. The dichotomous forest management system itself is not likely to apply for Japan because of the difference of forest distribution pattern and the profitability of forestry. Nonetheless, the process for clarifying the role of administration bodies and the legislation related to forests might be able to introduce because forest legislations and their administration bodies are still fragmented in Japan.
The establishment of the RMA accompanied by the central government reform, local government reform, and the integration of environmental legislations. These processes enabled the RMA to provide the platform to implement integrated resource management. Although some problems are still remaining, the RMA is an advanced comprehensive environmental law that put every effort to minimize contradiction among legislations and conflicts among the administration bodies. In order to establish an integrated resource or forest management system in Japan, reviewing processes of the administration system and legislations as conducted in NZ might be important.

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Vegetation on the streambed increases the total resistance but decreases the bed shear stress. However, when the drag force term is not separated from the resistance term in the momentum equation, increasing the roughness coefficient due to vegetation may result in increasing the bed shear stress. This is not realistic and crucial to the accurate assessment of sediment transported in the vegetated zone. This paper presents a 1D model for the simulation of flow and sediment transport in the emerging vegetated zone. The model consists of depth-averaged equations of continuity, momentum, turbulent kinetic energy, and its dissipation rate. The suspended load and bedload are estimated, and the bed elevation change is computed by solving the Exner's equation. The model is validated through comparisons with experimental observations. Then, the model is applied to predict the morphological change of the emerging vegetated zone in response to the flood. The developed model can be used to the management of vegetated islands within watercourse made naturally which are important to river restoration projects nowadays.

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Human activities in the Pinang River watershed have dramatically changed landuse and land cover characteristics, and have subsequently altered hydrological and watershed processes. Pinang River water quality in downstream areas is badly polluted, based on the Malaysian Department of Environment-Water quality index (DOE-WQI) classification. In order to assess the past and present water quality and the possible uses of the Pinang River, a water quality index was applied to a data set collected for this study, which is based on the Malaysia DOE-WQI standards. This study investigated the land-use and land cover changes, which are the main contributors to the water quality and hydrological problems in this watershed. With some information derived from Landsat images, Geographic Information System (GIS) application and land-use/land cover map, we identified the land-use changes and landscape patterns in the Pinang River watershed. The results showed that forested and scrub areas decreased rapidly within the sub-watersheds as well as the entire watershed, in contrast to the urban or built-up areas. Statistical analysis indicates that impervious land parcels are increasing, which contribute to water pollution and watershed degradation. Based on land-use fragmentation and diversity indices, it was revealed that these indices are reliable tools for measuring and evaluating land-use and land cover changes for the general guideline for watershed management. This study revealed that integration of GIS and remote sensing (RS) data to quantify landscape structure is a feasible and efficient method for evaluating the temporal effect of land-use activities in the river basin for watershed planning and future development.

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