The water temperature and nitrogen load were measured at Yasawa stream (YSW) and Ota stream (OTA) to evaluate how construction projects there and the environment in the riparian buffer zone affect the natural water purification and aquatic life of the streams. YSW and OTA flow into the Uchi Marsh in Tsukidate Town situated upstream of the Kitakami River in Kurihara County, Miyagi Prefecture. The riparian buffer zone (R.B.Z) in this study was defined as the area located within 50m of a riverbank. YSW is a stream supported with bank protection works surrounded by few riparian forests. On the other hand, OTA is a natural levee in a woody region. The water temperature was measured every hour from 14 September to 12 October 2001 by an automatic thermometer set at three sites at each stream. We found that the riparian forest suppresses the rise of mean and maximum water temperature and prevents a large diurnal change in the water temperature. The concentrations of NH_<4^->N, NO_<2^->N, NO_<3^->N were measured at 11 sites in YSW and 16 sites in OTA. The nitrogen load of the watershed was 76,814g/day at YSW, and 71,203g/day at OTA. The nitrogen load at the lowest site was 5,444g/day at YSW, 6,207g/day at OTA, or 7.1 %, 8.7 % respectively. Thus, there was not large difference in the factors reducing the nitrogen load at the two watersheds. However, we could not evaluate the purification function by the ratio of riparian forest cover.

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In order to estimate work efficiency (WE) and workload of manual log transportation (log species: Tectona grandis L.f.), factors of log transportation were grasped, and then the possibility of reducing in workload was examined. The research was carried out on 2 workers at Banjarejo Log Yard, East Java, Indonesia in 2002. Parameters, chosen based on 1997's research, were transporting distance [D1(<10m), D2(10-20m), D3(20m<)], and log classification [L1(1 log, 1 worker; log weight 35 kg, diameter 15 cm), L2 (1 log, 2 workers; log weight 95 kg, diameter 30 cm), L3 (1 log, 8 workers; log weight 450 kg, diameter 60 cm)]. Average WE was D1:0.593, D2:0.212, and D3:0.121 m^3/m/hr/man. There was a strong linear (positive) relationship between transporting distance and carrying time, and strong exponential (negative) relationships between transporting distance and WE and also between carrying time and WE. WE at L2 was higher than at L1. The average results of workload to energy expenditure during transportation (EETr) were L1: 0.0797, L2: 0.0711, and L3: 0707 kcal/kg/min; Relative Metabolic Rate (RMR) was L1: 3.2, L2: 2.7, and L3: 2.7; and total energy expended during a day's work (EEWT) was L1: 1356, L2: 1216, and L3: 1222 kcal/day. Workload was heavier at L1 than at L2. According to these results, it is highly probable that transporting L2 will result in higher WE, but also in a lighter workload than that of L1. Therefore, the method applied to transporting L2 is strongly recommended for transporting L1.

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Model tests under plane strain condition were carried out to verify the mechanical characteristics of a reinforced slope with a wooden retaining wall. As a result, the effect of slope reinforcement by wooden retaining wall and its mechanism were significantly influenced by the loading condition. Firstly, under the "front-loading condition", in which the loading weight was given from the upper side of the reinforced area, the wooden retaining wall provided greater slope stability because the slope deformation was restricted by the same mechanical mechanism as general earth reinforcement methods. However, the upper-layer reinforcements may be damaged near the facing by large bending force when they decompose. On the other hand, under the "back-loading condition", in which the weight was applied from the top behind the reinforced area, the wooden structure showed some resistance to the lateral earth pressure just like a quasi-RC wall, though it contributed less toward slope stabilization. But the reinforcements were also subjected to less stress under the back-loading condition. Further more, it appears that the slope stability may be improved by the compaction of back fill during the process of retaining wall construction.

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