It is commonly thought that eutrophication seldom occurs in water areas, such as rivers and lakes, in snowy cold regions because of the climatic conditions. However, this does not apply to water areas where the nutrient load is high and where the streams have stagnated.
To cope with unusual phenomena in such water areas, such as water bloom, it is necessary to measure water temperatures and observe chlorophyll-a concentrations continuously to make short-term predictions a few day later.
In this report, we try to predict the water quality after a few days using online information about chlorophyll-a concentrations from hourly measurements of the water temperature and by using a fluorescence spectrophotometer. Also, the weather forecast of the week and the Kalman filter are applied to the ecosystem model of water quality.
As a result, we confirm that it is possible to predict changes in chlorophyll-a.

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T-Dam Reservoir, one of the reservoir in Kyushu, Japan has been supplying water for paddy field irrigation. During recent years it has shown serious deterioration of water quality specially in summer. Destruction of thermocline has been prohibited to maintain desirable temperature downstream of the reservoir for paddy field irrigation. As one of the ways of reducing algal blooming in the reservoir, two vertical curtains, having depths to cover the epilimnion thickness, are installed across the reservoir in order to curtail the nutrient supply from nutrient-rich inflow to the downstream epilimnion of the reservoir. Withdrawal level is also regulated to keep the downstream epilimnion off the nutrient supply. The results of this study illustrate the consequences of curtains on algal blooming in the reservoir. The processes in the reservoir ecosystem have been modeled, by assuming stratified layered structure at each zone of the reservoir, to predict the water quality and algal species composition in the reservoir.

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In this paper, SWMM using Runoff Block and Transport Block is applied to stormwater runoff quality analysis for a sewer system at Kobe. Model parameters such as buildup of pollutant, power (or exponent) for runoff rate, are discussed by use of previous researches and then determined through the present studies. The result of computation employing the value of model parameters obtained in this study, shows a good agreement with the observed data except some cases.

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Current control using dispersed aeration is one way to suppress algal blooms by controlling the hydraulic state of the reservoir artificially. We have studied current control method in both the planning stage and the practical stage. This report estimates the effect of measures to improve water quality using a simulation model in the planning stage.
We examined the effect of current control to improve the water quality of reservoirs, by simulation using a modified one-dimensional model for current control using dispersed aeration, the parameters of which were determined by experiments in several reservoirs. The results show that current control is effective but that aeration must be stopped in case of flood and that care must be taken not to upwell dense turbid water when resuming aeration.

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This paper deals with the production and consumption of dissolved oxygen caused by the behavior of algae and bottom mud in the reservoir. The amount of oxygen that produced by algae with photosynthesis and consumed with respiration, were obtained with field experiments. The relation between 0₂ production and water temperature, sunlight intensity were analyzed. The behavior of algae are shown to be characterized by optimal 0₂ production temperature, optimal sunlight intensity etc. Also 0₂ consumption by respiration and bottom mud is evaluated quantitatively. The validity of results was examined using 1-D water quality simulation of DO.

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The flush operation was carried out in the summer of 1995 under the high temperature and very dry weather to improve the water quality in the upstream area of Nagaragawa Estuary Barrage.
The flush operation consists of the overflow operation to wash down phytoplankton, and of the underflow operation to increase DO at the bottom. When the flush operation was introduced, the water quality was reasonably improved, which was due to the change of flow patterns and to the increase of turbulent mixing diffusion caused by seiches and bores.

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Field observation on how the characteristics of pollution load and the conditions of water quality of mountainous Lake Onogawa change as time progresses is investigated. The process of nutrient release from bottom deposit is discussed from the data on batch test of and field observation. In the hypolimnion, nitrogen metabolism is controlled by the process of nutrient elution and'diffusion process. In the epliminion, the water quality of the lake is between olig- and mesotrophic condition because the lake is used for hydropower generation.

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Relation between flow patterns and stratification process is investigated by the observed data in Lake Onogawa. Transition of the time-scale, 7hr., obtained from coherence of temperature-cross-spectrum and retention time estimated from velocimetry has good agreement to the flow patterns in the lake. The flow in the epilimnion has high-rate horizontal circulation because the lake is used hydropower generation. In the hypolimnion, sediment transportation is observed in closing stage of the fluid in 1995, July, in spite of the flow stagnant in the stratification season.

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Groundwater development in small islands often requires management to prevent sea water intrusion into coastal aquifers. In this paper, therefore, a two-dimensional fresh and salt water flow model is studied to increase irrigation water supply to a sugar cane field. Both the groundwater flow rate across the area of a planned subsurface dam and the movement of immiscible fresh-salt water interface are predicted by the present model. A preliminary evaluation for a feasible groundwater development is attempted. The groundwater flow rate across the dam site to the sea is predicted as about 329×10³ m³/year for the precipitation 1267mm in 1991, which is 73% of the average annual precipitation of 1734mm.

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A generalized inference engine which takes charge of application of dam operational regulations is designed for a synthesized reservoir control support system. First, the common expression and logical mechanics of operational regulations established for dam reservoirs in Japan are extracted. Second, an inference engine which can treat these logics such as the mutual reference among the provisions of regulations is explored. The system designed here enables us to accommodate each provision of dam operational regulations into a rule as it is, which will be a useful tool not only for inference itself but for providing support information.

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This paper presents a practical method for estimation of basin-wide snow water equivalant. First, the relation between observed hydro-meteorological data and topographical characteristics of Kawamata-Dam basin at the Upper-Kinu river are made clear. Then, the model for estimating of both snow water equivalant and snowmelt is presented, and parameters of the model are calibrated by the observed snow depth.
Finally, a validity and a practical utilization of the method for estimating of snow water equivalant are discussed.

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A gravel storage-infiltration method, which make a part of the surface rainfall runoff infiltrate into the soil layer with the aid of gravel layer which inserted artificially in the underground, is proposed to reduce the flood discharges and to prepare the environmental water in urbanizing area. The mechanisms of infiltration from the inserted gravel layer are clarified by numerical analysis.
In addition, assuming a case where this facility is settled in the residential area of Uji city, a rainfall runoff analysis is conducted and the practicability of this method is examined.

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Rainwater storage system is one of the effective measures for preventing serious flood dameges in an urbanized area. In this paper, after discussing about the contribution of existence of the water storage to relieving extreme urban climate, a method for provisional assessment of effect of the storage system is presented. In order to get some fundamental information for a future plan of river channel construction and administrative arrangement in an urbanized catchment, a set of systematic simulations of runoff discharge in conditions of various distributed patterns of rainwater storage by using the kinematic-dynamic model are carried out.

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Although a large number of effort has been made on the analysis of water balance in a small basin, little is known about the balance in wider area in detail. Remote sensing technic is useful for the analysis. Recently snow volume and evapotranspiration distribution can be evaluated from satellite data. Therefore water balance in the Tohoku district, 66, 000km², is studied from using these data in this paper. As the result, we obtain the distribution of precipitation and runoff ratio, and discuss these data.

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Japan and China are located in the Asian monsoon region and received its effects. But the hydrological characteristics of the region are not studied enough. The Huai He river in China have determined as the representative basin of GAME-T project, sub project of GEWEX.
This paper shows the difference of yearly water balance between the Huai He river and our experimental basins, that is Urajiro river and Tsukuba experimental basins etc.

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This paper describes the groundwater movement indicated by the results of a long-term investigation of the leakage volume, groundwater level and water quality measured since the initial filling of the reservoir. Main results obtained from this investigation can be summarized as follows: 1) The leakage volume tends to decrease with time. In particular, the leakage volume at measuring points where leakage was considerable at initial filling decreased remarkably. 2) The difference in the ratio of transmissivity of the rock mass showed that the sealing zone built during dam construction was functioning soundly. Furthermore, the variation with time of the ratio of transmissivity showed that a natural sealing zone was formed near the reservoir by siltation. 3) The variation of the water quality of groundwater showed that the seepage water from the reservoir arrived at the downstream side after more than one year from the start of filling.

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Data acquisition, preprocessing, management, manipulation & analysis and product generation are essential parts of any research application. To save researchers and engineers from the enormous efforts, time and money, we should have an open structured hydrologic database containing various types of hydrologic and geographic data, which is independent of any specific project application and could be easily accessed by multiple users. In this paper we are presenting the use of the Relational Data Base Management System (RDBMS) to arrange the hydrologic and meteorologic time series data and the Geographic Information System (GIS) to integrate many different kinds of information for a particular objective about the spatial objects in an area. Our objective is to store and manage large amount of data involved in the rainfall-runoff processes. As a case study we have processed the data for the Yodo River basin and as one of applications we have illustrated a system to estimate hourly evapotranspiration for river basins by using RDBMS and GIS techniques.

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Old concepts in planning, operation and management need to be revised in order to fulfill the purpose of sustainable development. This study proposes to utilize the inflow forecasts as a tool for drawing the maximum use of storage as an aid to sustainable reservoir development and management. The inflow forecasts under different levels of forecast accuracy and lead time are applied to various sizes of reservoir and demand scenarios via optimization techniques. It was found that small reservoirs are vulnerable to forecast error whereas large reservoirs are robust to it. Introduction of inflow forecasts in the planning stage can reduce the unnecessary size of reservoir. Existing reservoirs can function better as if they had virtual capacity expansion and that can also offset the new demands of water supply and reservoir construction.

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Author derived the theoretical equations which provide the first four moments of discharge from storage function model under the assumption that rainfall input belongs to first order auto-regressive process. It is well known that auto-correlation function of first order autoregressive process decreases exponentially or shows damped oscillation according to positive or negative regression coefficient. Consequently, these derived theoretical equations are grouped into two cases according to positive or negative coefficient. Finally, these equations are examined by Monte Carlo simulation method. This paper makes it clear that the above regression coefficient plays an important role in stochastic response.

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In order to improve the flood forcasting accuracy for dam operation, we developed a real-time prediction system. The system is based on the filtering and prediction theory developed by Kalman and others. A lumped runoff model is transformed into a stochastic model by incorporating noise terms. The system takes account of the fact that the optimum values of the model parameters change from flood to flood. Three kinds of parameter are selected through the sensitivity analysis for many runoff data. Discharges are forcasted by use of prediction systems more than one, with different values of parameter respectively. Hence contributions to runoff is evaluated for each predicted discharge stochastically. Then most suitable discharge for flood runoff specified is determined by a weighting average method.

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A gate operation model for the hydro-power plant during a flood is proposed by the use of fuzzy theory. First, three types of empirical equation which decide the target release are extracted from the questionnaire to gate operators. Second, the parameters of these equations are determined throuth fuzzy inference from deviation of water level, change of the deviation and changing rate of inflow discharge. The operation model proposed here is applied to the real hydropower plant and it is verified that the system performance ia almost at the same level of that of skilled operators.

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Recently, fuzzy system and neural networks system are advanced in many engineering field. In this paper, the fuzzy set theory and neural networks system are applied to the reservoir operation to support system for flood control. The author's consider to put the hydrological information, the control rules of reservoir operation and the information obtained by inquires to reservoir operator into the dam supporting system. This system is that neural networks are applied to the decision of the operator line of reservoir operation and fuzzy system is applied to the decision of operational volume (release discharge) of reservoir operation. It is understood that application of fuzzy and neural network systems to the reservoir operation is effective.

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Severe flood damages in the southern region of Thailand caused by torrential rains or typhoons were found every year. Rainfall and water level were observed from a few monitoring stations in the region on daily basis. A real time flood forecasting model was formulated and applied to this region for flood disaster prevention. The model composed of two major components, the rainfall-runoff model and the hydrodynamic model. The rainfall-runoff model, a storage function model, was used to calculate the direct runoff due to rainfall. The hydrodynamic model, a vertically integrated model for mass and momentum conservation, was used to simulate flow in the river network. The model was able to predict water level and discharge at any location in the basin.
Comparison between observed and simulated water levels and discharges from the numerical schemes indicated the applicability of the proposed model with satisfactory results, although time interval of observed data was longer than flood discharge arriving time. However, higher accuracy of the forecasting required more frequency of the observed. rainfall and water level data both in time and space. Telemetering system was also recommended for the implementation of efficient flood forecasting system.

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In the previous study, the neural networks with back-propagation method (BP) were applied to predict the occurrence of debris flow. It was also found that this model is useful to estimate the critical rainfall. In this study, LVQ (Learning Vector Quantization) is introduced to improve the accuracy of the prediction. The LVQ and BP are applied to the debris flow at Unzen and Sakurajima Volcanoes. Comparison between the results by both methods confirms that LVQ has an advantage in prediction. The BP model is used to find the critical condition at Unzen Volcano. Validity of the method is demonstrated by the theory of the occurrence criteria of debris flow.

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The main objectives of this study is to develop utilization criteria of habitat variables in IFIM based on several methods. We utilized habitat variables such as velocity, depth, and substrate for pale chub, dark club, and river lizard goby in Oto River observed in 1994. We measured water temperature during the summer in 1995 to improve the IFIM by introducing the relationship between this and number of captured fishes. The major conclusions are as follows:(1) Utilization criteria of velocity for pale chub in summer is best developed by UPA, and (2) Water temperature (during one day) data are not sufficient at present to explain the relationship between this and number of captured fishes.

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The method of classification of urban river space is investigated for the river front improvement. For a case study, UPGMA clustering method is applied to the data with 42 qualitative and quantitative attributes related to the structural characteristics of the Old-Ota River, flowing through the Hiroshima delta.
The results of cluster analysis shows that the characteristics of each cluster composed of divided sub-reaches are able to be understood quantitatively. Also, through the results for the two different years, it is suggested that the environmental improvement works could be rightly reflected in the classification of river space.

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Recently, the public has become more and more concern of the recovery of a natural environment. Toward this goal, improvement of existing river environments and the building of new rivers and streams in parks have been going on increasing numbers. Traditional Japanese gardens have had man-made streams-or YARIMIZU, as they are called-for centuries. However, there is not much scientific literature dealing with YARIMIZU, and there are no studies that we know of evaluating YARIMIZU from a hydraulical viewpoint. The authors are interested in evaluating the river environment of YARIMIZU to gain a better understanding of the ancient Japanese gardening methods in terms of up-dated hydraulical knowledge.

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When trees in river channels drift during flood, those that are stacked in rivers sometimes cause flooding of river water. In addition, when they lodge against river structures, such as bridge piers, the structures may be destroyed due to an increased pressure of the river flow. Therefore, the plans for felling and planting trees in river channels need to be made so that trees do not lodge or drift during flood. The purpose of this research is to understand how the critical lodging value calculated from the results of the general test on felling trees fluctuates during flood. The results of the examination on relevant factors affecting the critical lodging value are reported in this paper.

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Water resources engineering in Hirai River considering ecology has been put througth two years ago. We investigated phase of fishes, benthos in Hirai River before and after the river improvement.
Summary of results is shown as follows. We found in decreasing two kinds of fishes during one year at most deep stream (=abyss), decreasing fishes was kinds of inhabit river bed, but the same a kinds of fish at rapids stream, and benthos was increasing at rapids stream more than abyss.

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Of elements related to river environment, pools play an important role in habitats of fishes. We investigated the geometrical and hydraulical features of a few pools naturally formed in Sendai River and observed the situation of habitat of fishes. The results indicated that the pool in the channel bend gave the inhabitable place to fishes due to the non-uniform structure of flow and river bed topography. The formation process of pool was also investigated theoretically and observationally with a focus on step-pool formation in mountain rivers. The comparison between theoretical and observational results showed that the pools were formed by the flood occuring once five years and the interval of the pool can be calculated by the presented method.

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River Watarase is the largest tributary of River Tone, and has drainage area of 2, 602km². The range of direct control of the Ministry of Construction is from confluence to 56km upstream. An improvement of flood plain has been in progress around 48km as a water-front development in Kiryu district and another improvement of river channel is also in progress at River Kiryu, a tributary of River Watarase. By the improvement of flood plain, a large area of vegetation has been changed into a park and multi-purpose grounds. The type of improvement of river channel at River Kiryu is flattening of channel bed and carrying out the work of bank protection. The valuation of people for the improvement was investigated using questionnaire.

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It is needed to get fundamental information about vegetation in rivers for developing a future river plan from view points of environment. The authors attempt to understand the relation between horizontal-vertical distribution of vegetation and channel hydraulic characteristics in rivers by using the result of the detail field survey in the Fuji River. At first, area of horizontal distributions of 21 kinds of vegetaion are compared with 5 major hydraulic parameters in lkm length each along the river. In the next, relative height of each vegetation from the standardized water level is also compared with, size of vegetated area at each lkm, then some interesting results are represented.

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Without sediment supply from the upstream, the river is suffered by the so-called rotational degradation during flood. When the river is bordered by vegetation zone, the flow near the vegetated zone is retarded and the bed degradation is limited to the central zone. Then, during the period with small discharge after flood, some part of the width becomes dry, and it often allows the vegetated zone to invade there. On the next flood, the flow concentrates to the center zone more by the growth of vegetated zone and the degradation becomes severer. Such a process is discussed in a simple scheme experimentally and theoretically.

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The purpose of this study is to clarlify the mutual relationship between river vegetation and river conditions. On the basis of a full vegetation survey performed on an alternating bar formed in the Yoshino River, Tokushima, Japan, some findings are presented with regard to the interaction between plant communities and alluvial process of the bar. A regression analysis is carried out to formulate local covering rates of some kinds of plant communities and bare lands with some parameters representing flood properties and morphological process of the bar. Resultant equations show significant correlation with the observations.

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Our fishes research conducted on the Kitatani River found that the fish species have been reduced, compared with those around 1955. To determine the reasons for this decrease, we examined changes in the Form and water of the r i ver. As a result, we could speculate some phenomena. In particular, we recognized that changes in the form of the river caused by improvements could adversely affect the fishes. We also understood that changes in water temperature restricts the fishes inhabiting the river.

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The river bed variation is a natural process. In the master plan, though the river bed and the water surface stage is shown to have a smooth profile and the safety measures are taken accordingly but in reality the case is not exactly so. The natural variation of the bed level from such smoothness in the longitudinal direction in a 13akm reach of Kinu river was analyzed. Through the 1-D steady flow simulation the associated variation in the water surface stage was analyzed. The subsequent probability of water surface to overtop the design levee height is near 1%. Such consequences should also be taken into account in the reliability analysis of flooding.

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Hydrological cycle of the Kokubunji experimental basin in the Musasino upland was studied at the spring in the Kokubunji-manyo garden in relation to the applicability of the hourly concentrated hydrological model and the basin management by means of the houses infiltration facilities. The hydrological model can also be considered the surface infiltration capacity of the pervious area. The analyses were carried out for two years hydrological data in 1992 and 1993, in which the sewer system had been expanded and the inverting wells became scarcely used.
The results indicated that the model generally reproduced observed runoff hydrographs, and the model applicability was confirmed. We also predicted the simulated hydrographs of which the assumption that the houses infiltration facilities were introduced, using the above hydrological model. It is found that the houses infiltration facilities are important for managing a basin in respect of the springs conservation.

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A numerical model which calculates air temperature and wind distributions within single districts of a few square kilometers, was developed by adding the effect of urban building canopies to the previous model. The micro-climate characeristics above and below the canopy were depicted in detail for each of these canopy conditions. In comparison to the roughness parameter treatment of the existing mesoscale model, the urban canopy numerical model achieved more realistic distributions.

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A meteorological and physiological field observation was conducted in summer on Tama River to verify the applicability of'new thermal sensation index to evaluation of outdoor thermal environment. The results and analysis based on human energy budget show that 1) Virtual Thermal Load calculated from meteorological data agree with thermal sensation, 2) nose temperature agree with thermal sensation, 3) Thermal sensation is affected by'physiological effect'such as large gap of meteorological conditions or prejudice for forest. Temporal and spatial characteristics of thermal environment around river are also discussed.

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Meteorological field observations were conducted along Sagami river basin to investigate the characteristics of penetration of sea breeze front along a river (wind channel effect). The meteorological observations based on the ground level show the existence of four types of local wind front. The observed speed and thickness of sea breeze agree well with theories.
The vertical structure of sea breeze are also discussed using captive baroon and Doppler Soder data.

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A turbulent closure model including the vegetation effects was developed to simulate the lower atmospheric layer in the urban areas. The submodels based on the SIB (Simple Biosphere Model) were used to calculate the atmospheric parameters at vegetation areas. These submodels used the variables at referent level and the resistances represented the vegetation to calculate new values for next time step and then feedback to the main model. The turbulent model (Yamada) which already being developed to including the effects of the buildings and pavement on the heat transfer process has been used as mainmodel in this study. The observation and numerical study were carried out for Tama Center on the west of Tokyo.

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Urbanization in coastal areas has been in progress accompanied by the change of land-use, the concentration of population and consumption of lots of energy. In addition, large-scale reclamation projects have been constructed in Japan. There are therefor isolated and higher temperature areas can be appeared. Such areas are called “heat island” on the basis of the shape in the contour map of atmospheric temperature. In the present study, three dimensional atmospheric numerical experiments with high-order turbulence modelling are performed for examining the effects of urbanization and construction of reclaimed islands on the local climate in coastal urban areas.

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Meteorological field ovservations were conducted at an irrigated alfalfa farm in arid area to evaluate the mitigation caused by the farm effect against the intense heat in summer. Atmospheric on the farm was always in stable conditions. The atmospheric temperature decreased 5 degs. from the upwind edge of the farm to its downwind edge. These phenomena were well reproduced by the turblent closure model. Evapotranspiration from the farm was estimeted to be 11mm/day, which was reasonable value in comparison with other estimated value in arid area.

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Sapporo has a heavy snowfall when a cold air flow appears on Ishikari Bay against the monsoon. Predicting a wind field is important to predict a snowfall. First, we study on horizontal convection by numerical analysis which is caused by temparature difference between the sea and the cold air flow which is about 20°C. On the other way, convction on the tip of the cold air flow is confirmed by doppler radar observations. Second, we analyze the wind field and derive a release rate of the latent heat between the convection area and the compensation area by convection model.
As a result, it was found that the horizontal convection is weak on an actual condition and that the vertical profile of the vertical velocity in convection model is similar to actual one. The change from the convection to a little low pressure around Ishikari Bay can be estimated with the release rate of the latent heat.

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It is important to forecast short-term rainfall in a small area located in urban small rivers basins. In this paper, through temporal extrapolaion of the rainfall's migration and of the rainfall strength's variation, short-term rainfall forcasting is carried out. Point rainfall is predicted for a lead time of 10 to 30 minutes with the model presented herein. In this forecasting process, some prediction is not well achieved, the reason for which is investigated, and means for upgrading the forecasting accuracy is then examined.

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A method for estimating the probable 1-hr rainfall based on the time concentration of a heavy rainfall is proposed. The method utilized the Slade type III normal transformation approach, whereby estimates were derived from the frequency analysis of the time concentration of heavy rainfall. By knowing how concentrated the heavy rainfall is, within the range of possible estimates, it would be possible to make a better decision on how much 1-hr rainfall should be used in designing hydraulic structures. Although this work focused on 1-hr rainfall, it presents a potential procedure which can be used for a range of desired rainfall durations.

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It is important to know the probable maximum precipitation (PMP) for a river basin. But unfortunately the PMP is presently not known in Japan. In other countries PMP is generally estimated for a meteorologically homogeneous region, but in geographically complex areas like most of Japan, it is difficult to determine these regions. This is because the wind field is affected by geographical features, and the atmospheric condition can make a large difference in relatively short distances. Therefore in this study, using a 3-D wind field simulation model, the atmospheric condition is estimated for a test case during an actual heavy rainfall. Finally using a 1-D convective cloud model, the regional heavy rainfall potential for a selected area is estimated.

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Rainfall is the most essential for investigating hydrological processes and water balance. However, because it is difficult to get spatial and daily rainfall data using equipments at many observation sites in the field, especially in developing countries, different useful methodologies have been required. Geostationary Meteorological Satellite-Infrared (GMS-IR) data has an excellent characteristic that the data can be collected 8 times every day, and is, therefore, available to obtain spatially-averaged data in a large-scale area. In this study, a regression model for estimating daily rainfall using GMS-IR data is proposed. The model is applied to daily rainfall data obtained in the regions of an area of 0.25°×0.25° in the Shikoku island, and can give satisfactory estimations.

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Purposes of this research are to observe the vertical profile of the rain drop size distribution, and to utilize the results into formulating a new method of estimating rainfall intensity and/or amount by making use of information detected by operational radar observations. Firstly, observations were carried out by the MU Radar, which can detect vertical profiles of the Doppler spectrum that are composed of both the rain drop itself and air movements. Secondly, formulations to correlate the ground surface-based rainfall intensity with the radar reflectivity by taking into account both i) the difference in rainfall intensities between radar beam and rain gage height as well as ii) the width of Doppler spectrum were completed. Finally, the formulation was applied into two case studies using Miyama Radar and NEXRAD.

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A physically-based short-term rainfall prediction method, which uses a volume scanning radar, is extended so that it utilizes grid point values from a numerical weather prediction, namely GPV data, as supplementary information. It is noted that this extended method does not use predicted GPV rainfall data The conceptual rainfall model in the prediction method plays the role of bridging a gap between radar information and the numerical-weather prediction. This extended method is applied to a rainfall event which occurred in the Baiu season, in July of 1994. Results shows that for extended lead time of three and four hours, the prediction of expanding rainfall area was greatly improved.

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