The Seventh Meeting of the PWRI-NILIM-USGS
Committee on Hydrology and Water Resources

14-16 July 2003, Sapporo

Mr. Nakamura (NILIM) and Mr. Nagayama (PWRI) welcomed the meeting participants to Sapporo and to the Seventh meeting of the Japan-U.S Committee on Hydrology and Water Resources. Dr. Harry Lins (USGS) expressed his gratitude to Messrs. Nakamura and Nagayama and to their staffs for organizing the meeting and for their assistance in making arrangements for the U.S. delegation.

The meeting began with a presentation by Harry Lins on current directions in water resources research in the United States. Lins summarized the contents of a recent report by the U.S. National Research Council's Water Science and Technology Board (WSTB) entitled Envisioning the Agenda for Water Resources Research in the Twenty-First Century. The WSTB noted that a substantial commitment of new funds is needed for expanded research three topical areas: water availability, water use, and water institutions. The specific functions recommended by the Board for each of the three areas can be obtained from the U.S. National Academy of Sciences website at http://search.nap.edu/books/0309075661/html/.

Junichi Yoshitani presented an overview of the reorganization of the former PWRI and new organizational schemes and missions of the present PWRI and NILIM, approval process of the Japanese government's initiative on global water variability, and reality of the low visibility in hydrologic science to the public. His presentation meant the assessment of the present PWRI's position in the international arena for further discussion on future collaboration between NILIM/PWRI and USGS.

Lins then reviewed of the history of the PWRI-USGS collaboration, beginning with the circumstances leading up to the signing of the original Memorandum of Understanding Concerning Cooperation in the Field of Hydrology, Water Resources and Global Climate Change on February 3, 1992, and the sequence of six workshops that preceded the present meeting in Sapporo. His presentation included the rationale and justification for the various research projects undertaken during the past decade.

<Technologies for Modeling and Analysis of Hydrologic Systems>

Kazuhiko Fukami overviewed the objective of this topic, i.e. the improvement of accuracy and reliability of hydrologic analysis and forecasting even under the change of climatic/hydrologic environments. Then he explained the PWRI's activities on this topic as follows:

1. Application of efficient monitoring of basin environment using remote sensing from satellites and/or aircrafts
1.1 Snow water equivalent (SWE) mapping with Synthetic Aperture Radar (SAR) aboard satellite
In order to estimate water resources due to snow in a river or dam watershed, PWRI made a study on snowcover-extent & SWE monitoring with RADARSAT-SAR (active remote sensor in the microwave region). The study area was the Chuetsu district of the Niigata Prefecture of Japan. An algorithm to retrieve the spatial distribution of SWE from SAR images was developed. On the basis of ground-based snow surveys, it was verified that the algorithm was applicable to classifying SWE into four ranks irrespective of the variation of the snowpack's physical condition in plains of wet-snow region.
1.2 Monitoring basin-wide hydrologic / hydraulic conditions using remote sensing
PWRI investigated the applicability of high-res. remote sensing data to river channel & its physical environment. The IKONOS image was effective monitoring the temporal change of stream channels, although the 1m-resolution was not still enough to monitor the conditions of river structures. The applicability of three-line-sensor (TLS) aboard a helicopter was also investigated. The TLS was applicable to 1) topographic mapping including riverbed beneath clear water, 2) the detection of targets in river area, 3) monitoring river-bed materials (size distribution of river-bed sands & gravels), etc.
PWRI is now conducting a research also on the estimation of water budget of the Tonle Sap Lake in Cambodia with remote sensing, sponsored by the Japanese Ministry of Education, Culture, Sports, Science and Technology (MEXT).

2. Development of GIS-based distributed-parameter models
Two types of GIS-based distributed-parameter model were developed. One is a conceptual distributed-parameter hydrologic model, "Modified PWRI-Distributed Model," developed for long-term precipitation-runoff simulations. The model utilizes a physically-based scheme for land-atmosphere interactions (evapotranspiration & infiltration) the parameters of which are correlated to the physical properties of soil and vegetation. The other parts are conceptual and based on the former PWRI-distributed model. The other is fully physically-based distributed-parameter hydrologic model, "Watershed Environmental Hydrology (WEHY) Model," which was developed by the cooperative research with Dr. M.L.Kavvas of the University of California at Davis, as a flood analyzing and forecasting tool. The latter model is based on areally-averaged conservation equations. Both the models was applied and verified at two mountainous forested watersheds. These two models are expected to be useful to evaluate the effect of the change of climate and watershed environment (forest, land-use, urbanization, etc.) on hydrologic regime.

3. Relations Between Flow Regime and Regional Climatic and Geophysical Conditions
The DAD characteristics of the Tokai Storm (Year 2000) was investigated and clarified quantitatively. As a result, the effectiveness of DAD analyses was confirmed to understand and compare the storm characteristics among various rainfall events in Japan and to improve a geographic zoning in terms of DAD characteristics to estimate the largest-level storms and floods.

Lastly, he supplemented a study on the development of low-flow management system at the Yasu River in Japan.

George Leavesley reviewed USGS activities related to modeling and analysis of watershed systems, including:

(1) Coupling of surface-water and ground-water models- The watershed model PRMS, the 1-D channel hydraulics model DAFLOW, and the ground-water model MODFLOW have been coupled for fully integrated applications.
(2) Objective parameter estimation- The USGS is participating in the Model Parameter Estimation Experiment (MOPEX) program to investigate a priori parameter estimation methodologies for a variety of hydrologic process conceptualizations. MOPEX is also a component of the Prediction of Ungauged Basins (PUBS) program of the IAHS.
(3) Water management decision-support systems- Work is continuing under the joint USGS-Bureau of Reclamation Watershed and River System Management Program. The focus remains the research and development of decision support systems and their application to achieve an equitable balance among water resource issues.
(4) Incorporation of remotely sensed data- The USGS is a collaborator with the University of Arizona, University of Colorado, and Lawrence Berkeley Laboratory in the NASA Southwest Regional Earth Science Research Center. The purpose is to investigate the integration of remotely sensed data into resource-management applications. The first work is to explore the use of remotely sensed snow-covered area and snowpack water equivalent data in river basin management.
(5) Forecast methodologies- The coupling of atmospheric and hydrologic models is being investigated at several spatial scales. Downscaling from the MRF weather forecast model is being used to make 15-day hydrological forecasts on the upper Colorado River basin. Dynamical downscaling from the MM5 local scale atmospheric model is being investigated on the Yampa River basin.
(6) Improved hydrologic and ecosystem process simulation- The Water, Energy, and Biogeochemical Budgets (WEBB) program of the USGS is investigating these processes and their interactions to better define and model the flow paths and residence times of water in a basin. The use of isotopes as tracers is one aspect of the WEBB program to help identify flow paths and residence times. Interest in this approach and the use of a modular modeling framework has facilitated the development of new research activities with the International Atomic Energy Agency to explore the use of isotopes in river basin management.
(7) Integrated analysis and support tools- The USGS is collaboratively working with the U.S. Agricultural Research Service, U.S. Natural Resources Conservation Service, and the Friedrich Schiller University in Germany to integrate the Modular Modeling System (MMS) with the fully object-oriented Object Modeling System (OMS). A larger integrated program has also been initiated among eight U.S. government agencies to facilitate the development and sharing of models, analysis tools, and databases. These participating agencies are the USGS, Nuclear Regulatory Commission, Department of Energy, Environmental Protection Agency, Army Corps of Engineers, National Oceanic and Atmospheric Administration, Agricultural Research Service, and Natural Resources Conservation Service.

Both organizations share common interests in hydrologic modeling and analysis for the purpose of water resources management. Through discussions conducted during the meeting, the following research topics were identified as areas of possible collaboration over the next 12-24 months.

1) Establish basin-wide hydrologic modeling tools and methodologies utilizing GIS analyses. A major need is to avoid being dependent on existing hydrologic databases, in order to be able to predict and/or evaluate the effects of changes in land use and climate on water resources. (PWRI - development of GIS-based hydrologic model such as PWRI distributed model; USGS - development of the OMS-MMS-GIS Weasel system and the multi-media environmental model, and MOPEX)

2) Promote technical support for basins facing water conflicts caused by water shortage. (PWRI -Yasugawa-river project; USGS - Water2025)

3) To propose suitable methodologies for the investigation, analysis, and solution of problems related to the water resources of international rivers. (PWRI - Mekong-river study; USGS - tracer applications to international rivers)

Fukami and Leavesley agreed that both organizations would promote cooperative activities in common areas of interest, particularly on the above three items. Cooperation will be accomplished through information and personnel exchanges. For example, the PWRI plans to incorporate the OMS-MMS-GIS Weasel system into the PWRI distributed model.

<Hydrologic Measurements and Data Systems>

Masayuki Oote reviewed PWRI's research into hydrologic observations of flood flows using floats, as well as PWRI's interests in new observation technologies to replace the present float observation (or to compensate for the disadvantages of float measurements). PWRI is doing field research on the influence of bridge pier disturbance on flood flow measurement; 3-dimential structure of parallel spiral flow and its impact on the use of floats; and conversion factors to obtain vertically-averaged velocity by using non-contact surface velocity measurement methods, pressure-type Flood Current Meter, and ADCP.

Ralph Cheng described how streamgaging data are used for resource appraisal and allocation, design of water infrastructure, flood hazard planning, and flood forecasting. A large percentage of the over 7000 gaging stations operated by the USGS posts river discharge on WWW at near real-time. However, the river discharge is not directly measured; rather it is derived from a stage-discharge relation. There is a need to improve streamgaging technologies to allow river discharge measured directly at near real-time for delivery to users. Systematic research and development efforts at the USGS have shown that it is possible to determine river discharge using non-contact radar systems. The present state-of-the-technology allows reliable measurement of river surface velocity from a riverbank, but the channel cross-section must be determined using ground-penetrating radar (GPR) with the radar beam pointing normal to river water surface. The USGS plans to continue this pursuit with the emphasis on a better understanding of the river hydraulics. The advances achieved from bank-side mounted radar system for river discharge leads to the concept of an air-borne radar system that measures river discharge from a helicopter. The helicopter system is suitable for emergency responses in regional floods and for applications to regions that are difficult to gain access.

Cheng also described how, as part of an urban geologic and hydrologic natural hazards initiative, the USGS attempts to build a near-real time flood simulation and warning system to complement streamgaging in flood prone river basins. The proposed system consists of the integration of an atmospheric forecast model, a regional hydrologic model that sets the appropriate boundary conditions for a hydraulic model to simulate normal and flooding river conditions. The unstructured grid UnTRIM model has been shown to be robust and efficient for simulating flood inundation in urban areas. Models in the integrated system will be running concurrently and interactively. When this system is successfully built and proven valid, the system will be used for flood forecast and for issuing flood warning at near real-time via the internet. In summary, the USGS is attempting to advance technologies in streamgaging, flood hazard studies, and flood warning for near real-time operations.

<Aquatic Ecology and Water Quality Investigations>

Kunihiko Amano described activities conducted in conjunction with Jim Sartoris of USGS related to the function of wetlands in terms of water quality change (water treatment) and mutual relationship with aquatic ecosystems. USGS is pursuing studies focused on water quality changes and the effect of macrophytes in constructed wetlands in Hemet, CA. PWRI is conducting studies focused on water quality changes driven by aquatic ecosystems in Watarase reservoir. Amano also presented the results of field measurements aimed at analyzing the phenomenon of inorganic nutrients increase accompanying the cessation of phytoplankton blooms in Watarase reservoir in early June, and its analysis using numerical simulation.

<Coastal Processes and Coastal Systems>

Kenichi Torii of NILIM described the natural setting of the Japanese coast resulting in large sediment volumes delivered to the coast; with the historic and current sedimentary system heavily influenced by river modification, sand & gravel removal, and coastal structures. NILIM analyses provided an overview of the scale and location of erosion problems around the Japanese coast. This set the background for describing coastal systems in terms of sedimentary cells that extend from the river basin to the coastal limits of transport - with the river mouth as a critical area for understanding processes. Two NILIM projects were described:

1) Efforts to understand the processes of sediment transport and sedimentation in the Abe river sediment cell. Significant changes in the rates of removal of gravel from the river were related to coastal response. The project sets the stage for providing scientific guidance to linked, and potentially conflicting, issues related to flood hazard control and coastal erosion.

2) Mouth area - where river and coastal processes interact. Research approaches to describe the sedimentary system and the processes by which it responds were described.

These projects provide a broad framework (the sediment cell) for research on coastal systems and identify a critical segment (the river mouth) and critical issues (storm processes, sediment availability) for research.

John Haines introduced the efforts of USGS coastal geologists and oceanographers to understand the relationship of geology to coastal response with the goal of forecasting coastal change. Though USGS programs are broad, addressing many issues and many environments, the focus here was on the erosion and evolution of sandy beach systems. The talk had three primary sections:

4) describing the development of a conceptual (partly quantitative) "sediment budget" model for regional coastal systems by mapping (sidescan, ground penetrating radar, seismics) and interpreting the geology,
5) outlining efforts to monitor (LIDAR, GPS topography and bathymetry) and model the coastal response at and near the shoreline at a variety of time scales, and
6) based on the geologic framework and shoreline response apply field experiments and a variety of models to refine and test our understanding of coastal change.

The elements described above provide the science and information base needed to forecast coastal change given realistic scenarios for future natural and human influences. Finally the presentation indicated some of the many ways efforts to forecast coastal change in sedimentary systems supports broader environmental and resource management issues.
There is much in common between the interests and approaches of the two agencies. Both are approaching coastal issues as systems defined by the regional sediment budget, and both are striving to enhance process understanding so as to better understand coastal change. Both agencies recognize that understanding the processes of sediment transport and sedimentation has application to a wide range of environmental issues. NILIM has, naturally, an approach that is reflective of their engineering mission to improve the activities of their parent Ministry. This is reflected in the close connection between their research and the past and potential future human alterations of coastal systems. This reflection of engineered systems, and the responsiveness to complex and conflicting uses of coastal resources, may inform the USGS as it strives to link its science to decision-making in much the way that NILIM already does.

The particulars of Japanese and U.S. coastal systems have some similarities - and some differences. In striving to better understand coastal systems, as research colleagues, we can learn from efforts where systems are similar (processes at river mouths, storm impacts on sandy shores) and where systems differ (sediment starved versus sediment rich systems). There may be opportunities to share data that, for both agencies, enhance the data available to address fundamental research questions. There is, as with all scientific pursuits, much to be gained by sharing knowledge of capabilities and technologies that have application to shared interests.

< Geomorphology and Sediment Transport>

Tadashi Suetsugi presented material describing how, in Japan, vegetation encroachment has been occurring in many rivers. NILIM is studying on a restoration method of the fluvial system by widening the river channel and supplying gravels at upper reaches focusing on the Nagata district of the Tama River. And it is verified that this restoration technique has been effective through the observation in 2001-2002. USGS started the restoration by vegetation clearing in the Platte River in 2002. Both Institutes will continue the collaboration on these issues.