Identification and Prediction for the Long Range Runoff Systems

In this paper, the runoff simulation method has been discussed in order to obtain effective information for water resource planning. The framework consists of the identification of the long range runoff systems and the simulation for the areal daily precipitation while the runoff data are simulated by their combination. First, for identifying the long range runoff systems, the improved statistical unit hydrograph method is proposed based on the techniques of information theory. Next, the daily precipitation data are simulated over a long period and in a wide area through the successive combination of regional correlation analysis between the base or sub-base and surrounding stations, spatial simulation between the base and sub-base stations, and sequential simulation at the base station. Finally, by the combination of the improved statistical unit hydrograph method and the simulation method for areal daily precipitation, the observed data are shown with sufficient accuracy

Rule-based reservoir operation considering long range forecast

A model for long range and real time reservoir operations is developed, considering the medium and long range weather forecast provided by the meteorological agency. The reasoning employed by the reservoir operator to make the appropriate decision on the reservoir operations, in the presence of uncertainty and inevitable errors in the forecast, is modeled through a rule-based scheme. A fuzzy inference procedure is used to evaluate the rules and produce the control output. The forecast inputs are of medium and long range inflow rates and trends. The operations are conducted according to "control levels" that are related to control actions designed to keep the reservoir state as near as possible to the target one. The simulation of the operation of a single reservoir throughout the year is performed for water utilization, hydropower and river preservation purposes. The focus is on drought management, and the results show that the model behaviour is coherent with the model formulation

An Approach to the Adaptive Flood Control by Multi-Reservoir Systems

The aim of this study is to establish a procedure for the adaptive flood control by multi-reservoir systems. The multi-reservoir systems have several reservoirs located in series, parallel, or mixed type and several flood defence points. The foundamental idea is to combine the typhoon simulation techniques with the optimal operation techniques based on Dynamic Programming. That is to say, at every control time, many typhoons are simulated according to the stochastic structures of a typhoon. And for each simulated typhoon, an optimal release flow at the control time will be decided in a sense of a probability of exceedance, or a safety rate based on the frequency distribution estimated from the set of the above optimal release flow. Of course, the simulated results antecedent to the control time will be compared with the observed ; and through the feedback loop, the characteristic parameters will be corrected. From this point of view, we may consider this procedure as an approach to “the adaptive flood control”

Runoff System Model in Snow Accumulation and Melting Seasons

The model making in the snow accumulation and melting seasons may be dealt with with the series of the following system. Snowfall→Transformation System I→Snowpack→Transformation System II→Snowmelt→Tranformation System III→Streamflow. The snowmelt and runoff system models developed in this study are primarily concerned with considering the above processes on as physical a basis as possible and at the same time best representing those processes in light of practical modelling considerations according to available data. As for the snowfall and the transformation system I, firstly, the observed data of depth of snow are directly introduced into the model. As for the transformation system II, in addition to the temperature index method the heat budget considerations are partly introduced into the model. And moreover the behaviour through the snowpack of the water melted or frozen by the heat transfer is introduced on a physical basis in order to make the model more rational. As for the transformation system III, the statistical unit hydrograph method proposed previously is expanded to the snow accumulation and melting seasons with some modifications. Lastly the above models are applied to the Kuzuryu River, in particular. For the very heavy snowfall of 1981 the sequence of inflow into the dam up the river are estimated

Application of the Manifold Cell Model in Rainfall-Runoff Analysis of a Hydrologic System

The paper aims to modify the newly developed manifold cell model, then to build up adequate rainfall-runoff model for simulating the spatially distributed characteristics of a hydrologic system, and finally, to apply the model for flood forecasting so as to predict accurately and instantaneously the possible flood trend in a river basin during typhoon hitting period. In order to verify the accuracy of the manifold cell model, Tseng-wen River Basin, Taiwan was chosen as a project area for illustration. From the analyzed results, the proposed manifold cell model was found to be proper for applying to the simulation of the deterministic relationship between rainfall and runoff

Optimal Planning of Flood Control Systems Based on Screening, Simulation and Sequential Models

The aim of this study is to establish the optimal flood control system accounted for by the comprehensive criteria on the whole river basin. Especially, we will examine the effects of flood control projects in the system consisting of multi-sub-basin and multi-defense points against flood inundation probability in time and space. We define the planning problem of flood control projects as the minimization problem of the construction cost among all alternatives while satisfying the required safety rate for the prevention of flood inundation. First, the better alternatives are extracted by using the random search method. Second, the optimal system on the exact basin model is determined by appliaction of the simulation method for them. Lastly, the optimal construction order of the final system is gained by Dynamic Programming with the criteria that the expectation of the inundation damage under construction is minimized. So, we call the above three steps i) Screening model, ii) Simulation model and iii) Sequential model in flood control planning, respectively

Distributed Runoff Model Linking Surface with Groundwater Processes

統合的な水文過程を解析するために、Hydro-BEAM(Hydrological River Basin EnvironmentAssessment Model)をベースとした多層メッシュ型流出モデルを提案する。表面流出にはキネマティックウェーブモデルを、不飽和地中流にはリチャーズ式を、地下水流には非圧地下水モデルを用いて時空間的な解析がなされる。ここでは窪地貯留や樹冠遮断に伴う降雨の初期損失が考慮されている。さらに、貯水池操作や人間活動に伴う土地利用変化に対応するために、流域分割や土地利用のダイナミクスが導入されている。ここで提案するモデルは異なる初期条件やパラメータを用いてキャリブレーションされ、地表水と地下水の直接的な結合(dynamic linkage)を検証するために、野洲川流域に適用された。A method with multi-layer and mesh-typed runoff model using Hydro-BEAM(Hydrological River Basin Environment Assessment Model) is proposed to analyze theintegrated hydrological processes. The spatiotemporal simulation is calculated with thekinematic wave model for surface runoff, Richard's equation for unsaturated subsurfaceflow and the unconfined flow for groundwater. The initial loss of rainfall due tointerception by depression storage reprocess is considered here. Moreover the basindivision and land use dynamics are introduced to encounter reservoir operation andland utilization with human activities. The proposed model is calibrated for differentinitial conditions and parameters, and applied into the Yasu River to verify the dynamiclinkage between surface and groundwater.統合的な水文過程を解析するために、Hydro-BEAM(Hydrological River Basin EnvironmentAssessment Model)をベースとした多層メッシュ型流出モデルを提案する。表面流出にはキネマティックウェーブモデルを、不飽和地中流にはリチャーズ式を、地下水流には非圧地下水モデルを用いて時空間的な解析がなされる。ここでは窪地貯留や樹冠遮断に伴う降雨の初期損失が考慮されている。さらに、貯水池操作や人間活動に伴う土地利用変化に対応するために、流域分割や土地利用のダイナミクスが導入されている。ここで提案するモデルは異なる初期条件やパラメータを用いてキャリブレーションされ、地表水と地下水の直接的な結合(dynamic linkage)を検証するために、野洲川流域に適用された。A method with multi-layer and mesh-typed runoff model using Hydro-BEAM(Hydrological River Basin Environment Assessment Model) is proposed to analyze theintegrated hydrological processes. The spatiotemporal simulation is calculated with thekinematic wave model for surface runoff, Richard's equation for unsaturated subsurfaceflow and the unconfined flow for groundwater. The initial loss of rainfall due tointerception by depression storage reprocess is considered here. Moreover the basindivision and land use dynamics are introduced to encounter reservoir operation andland utilization with human activities. The proposed model is calibrated for differentinitial conditions and parameters, and applied into the Yasu River to verify the dynamiclinkage between surface and groundwater