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本論文は，高度に市街化が進行した都市中小河川における実時間洪水予測に適した集中型概念モデルの精度向上に向けて，合流式下水道による流域外への排水など都市特有の流出機構を考慮し，また全流出成分を概念的に組み込むことで有効雨量の算定や流出成分の分離作業が不要となる新たな都市貯留関数モデルを提案したものである．本提案モデルを，東京都の代表的都市中小河川である神田川上流域を対象に，近年観測された豪雨9イベントに適用し，観測ハイドログラフに対する再現性を検証した．その結果，従来の貯留関数モデルと比べパラメータ数は2つ多くなるものの，流出ハイドログラフの予測精度が格段に向上し，ピーク流量や総流出量を的確に捉えられること，他降雨イベントに対するパラメータの安定性や適応性が向上することを確認した．

本論文では，近年頻発する都市型洪水被害低減を目的に，人工的に形成された非常に複雑な都市型洪水流出過程のモデル化として，既往の土地利用情報のモデル化とは異なり，個々の建物，駐車場，道路等の実際の不浸透域を抽出できる地物データGISを活用し，さらに街区，道路，雨水・下水道管路，河道の情報を付加することにより，雨水の物理的な流出経路を忠実に表現する都市型洪水流出モデルの提案を行っている．東京都内中小河川を対象流域とし，地物データGISを用いて具体的に流域のモデル化を行い，実降雨と仮想豪雨を用いて流出解析を行った．その結果，本モデルにより河川水位を精度良く再現し，また排水不良や河川水位上昇に伴う浸水現象などを含めた洪水流出過程を詳細に表現出来ることを確認した．

The objective of this study is to improve a distributed hydrologic model using SMPT (Soil Moisture Parameter Tank) model by applying kinematic wave model to river flow routing changing time step of day to an hour. The watershed basin is divided into a grid cell of 50m. This model is composed of three structure; surfaces division, river division, and groundwater division. In surface division, evapotranspiration, infiltration, percolation, interflow, and surface outflow were computed in each cell. Kinematic wave model was applied to river flow components. Groundwater component computes the groundwater levels and the flows in the saturated zone of an unconfined aquifer, stream interactions, and groundwater seepage at the ground water surface. The model is applied to simulate water cycle in the Azuma Upper Experimental basin (1.81km2) with a time step of an hour. The model parameter is calibrated through comparison of the simulated river discharge, groundwater levels with the observed value.

In recent years, the practice of environmental impact assessment (EIA) has created significant awareness on the role of environmentally sound projects in sustainable development. In view of the recent studies on the effects of climate change, the Philippine government has given high priority to the construction of flood control structures to alleviate the destructive effects of unmitigated floods, especially in highly urbanized areas like Metro Manila. EIA thus, should be carefully and effectively carried out to maximize or optimize the potential benefits that can be derived from structural flood mitigation measures (SFMMs). A utility-based environmental assessment approach may significantly aid flood managers and decision-makers in planning for effective and environmentally sound SFMM projects. This study proposes a utility-based assessment approach using the rapid impact assessment matrix (RIAM) technique, coupled with the evidential reasoning approach, to rationally and systematically evaluate the ecological and socio-economic impacts of 4 planned SFMM projects (i.e. 2 river channel improvements and 2 new open channels) in Metro Manila. Results show that the overall environmental effects of each of the planned SFMM projects are positive, which indicate that the utility of the positive impacts would generally outweigh the negative impacts. The results also imply that the planned river channel improvements will yield higher environmental benefits over the planned open channels. This study was able to present a clear and rational approach in the examination of overall environmental effects of SFMMs, which provides valuable insights that can be used by decision-makers and policy makers to improve the EIA practice and evaluation of projects in the Philippines.

In recent decades, the practice of environmental impact assessment (EIA) in the planning processes of infrastructure projects has created significant awareness on the benefits of environmentally sound and sustainable urban development around the world. In the highly urbanized megacities in the Philippines, like Metro Manila, high priority is given by the national government to structural flood mitigation measures (SFMM) due to the persistently high frequency of flood-related disasters, which are exacerbated by the on-going effects of climate change. EIA thus, should be carefully and effectively executed to maximize the potential benefits of the SFMM. The common practice of EIA in the Philippines is generally qualitative and lacks clear methodology in evaluating multi-criteria systems. Thus, this study proposes the use of the rapid impact assessment matrix (RIAM) technique to provide a method that would systematically and quantitatively evaluate the socio-economic and environmental impacts of planned SFMM in Metro Manila. The RIAM technique was slightly modified to fit the requirements of this study. The scale of impact was determined for each perceived impact, and based on the results, the planned SFMM for Metro Manila will likely bring significant benefits; however, significant negative impacts may also likely occur. The proposed modifications were found to be highly compatible with RIAM, and the results of the RIAM analysis provided a clear view of the impacts associated with the implementation of SFMM projects. This may prove to be valuable in the practice of EIA in the Philippines.

In this study, the reduction on the environmental load by the replacement of conventional toilets with low environmental load toilets such as water recycling urine-diverting toilet newly developed at highway service areas in Japan was quantified and a cost-benefit analysis concerning introducing low environmental load toilets were performed. Moriya service area which is one of the large–scale service areas and Minori service area which is the middle–scale one were selected for the case study. As for the results, the pollution load, especially, total nitrogen and phosphorous were expected to be reduced by 94% and 79 % from existed system, respectively, in the Minori service area. Concerning the burden of energy and cost, the payback periods by introducing the urine diversion system were 0.3 and 0.8 years for energy, and 2.8 and 12.6 years for cost at Moriya and Minori service area, respectively.

Understanding the interactions between surface water and groundwater is critical for effective water management and conjunctive water use planning as these are intimately linked in the hydrologic cycle. This study is the first attempt to determine the spatio-temporal patterns of the interactions between the surface water of the Red River in Hanoi, Vietnam and the groundwater of two main adjacent aquifers, the Holocene unconfined aquifer (HUA) and Pleistocene confined aquifer (PCA). In this study, an integrated surface-groundwater model was developed by coupling two commercial modeling packages: the river flow routing model (MIKE 11) and the ground flow model (MODFLOW). As for the results, this study revealed that there was very high correlation between the river water levels and HUA groundwater levels. The correlation was found decreasing not only with the distance from the river, but also from the upstream to downstream along the river. Upper parts of the river exhibited seasonal interactions of recharge and discharge between the river and aquifer, while the lower parts of the river recharged groundwater almost throughout the year.

This study investigates the water quality of the Pasig River in Metro Manila during the construction of river improvements through channel alteration. Statistical and trend analysis of surface water have been performed using the records (20082011) of 5 water quality parameters (pH, dissolved oxygen, biochemical oxygen demand, total suspended solids and EC) at 4 observation sites along the Pasig River. The trend analyses were performed using a moving average approach and nonparametric Spearman’s rho technique. The results indicate that most of the water quality parameters do not show significant trend; except for BOD and EC where these were found to significantly increasing in some of the observation sites. TSS was significantly decreasing in one site. Apart from these analyses, 14 other water quality parameters, collected annually, were assessed by comparing the values with the Philippine water quality standards. The findings of this study provide useful references for the monitoring of river water quality in Metro Manila.

Monitoring and interpreting changes in groundwater levels are essential for groundwater management. However, a fairly wide groundwater monitoring network over the Red River Delta, Vietnam was not set up until 1995. This paper investigated trends and their slopes in groundwater level series (19952009) in 63 observation wells for confined aquifer by the non-parametric Mann-Kendall trend test and Sen’s slope estimator. The analyses revealed that groundwater levels experienced significant downward trends almost all wells and time series. Spatial distribution of different trend slope was clarified over the delta in which central and coastal areas showed more serious downward trend slopes than other areas. Trend results for 18 different time series (e.g. monthly, seasonal, annual means and so on) were quite similar regardless to time series to be studied. While annual cycle in groundwater levels were strongly associated with those in rainfall and river water levels, long-term downward trends could result from increasing groundwater withdrawal.

Using the longest records (1995–2009) at a dense network of 21 observation wells available for Holocene unconfined aquifer (HUA) in Hanoi, this paper explored trends and their slopes in groundwater levels by utilizing the non-parametric Mann-Kendall trend test and Sen's slope estimator. At each well, 18 time series encompassing important groundwater level components (e.g. monthly, seasonal, annual means and so on) were analyzed to provide insights into the trends. This study highlighted that nonparametric approach is particularly suited to hydrological series in general and to groundwater level series in particular. Analyses for monthly data revealed that 12 out of 21 wells showed downward trends, while 4 wells showed upward trends. The spatial patterns of different trend slopes were also identified over HUA area. Although the trend results for other time series at a given well were quite similar, different trend patterns were detected in several time series. The findings provide useful references to sustainable groundwater development in Hanoi.