Chu-Hui Chen

Application to Reservoir Operation Rule-Curves

Researches in reservoir operation rules had already been studied more than half a century but much still remains to be done. Besides, as a result of global climate change and many nature or human causes, make the frequency and intensity of a lot of hydrological events such as drought and flood change, the existing reservoir operation rules need to change. This paper aims at reservoir operation rule -curves in detail, and applies to the newly rising evolution alg orithms to optimize reservoir operation systematically. Furthermore, the study detects the drought events by the prediction data and water resource system model, optimizes the double -group rule-curves and makes the water resources more effectively. The LiYuTan reservoir in Taiwan, for example, establish, the up -to-date operation rule.

Estimation of effective hydrogeological parameters by considering varying heterogeneity and pumping rates

Darcy’s law and pumping tests, Tabu searches (TS) integrated with the Adjoint State Method (ASM), are two upscaling approaches used to transform local hydrogeological parameters at the scale of measurement into effective parameters on larger scales. This study proposed the above methods in order to estimate the effective parameters of heterogeneous and anisotropic aquifers at different degrees of heterogeneity (variances and correlation lengths). The results revealed three important principles: (1) the means of the effective transmissivities by Darcy’s law under different Dirichlet boundary conditions are used as the real ones in this study, because the optimal values under different Dirichlet boundary conditions are very close to each other at the same level of heterogeneity; (2) the estimations by TS integrated with ASM at low degrees of heterogeneity are much closer to the means of optimums by Darcy’s law than the estimations at high degrees of heterogeneity. Regardless of the pumping rate, the optimum at high degrees of heterogeneity is not good enough to represent the total study field. In considering the estimations at low degrees of heterogeneity, the drawdown caused by a low pumping rate is not sufficient to identify the effective parameters, while the drawdown caused by a higher pumping rate is useful for estimating the effective parameters. This suggests that the range of pumping rates influences the results estimated by TS and ASM, and the effective parameters identified using the effective range of pumping drawdown are more than enough to represent the whole study aquifer. With a larger variance of heterogeneity, the range of the pumping rate becomes smaller, leading to results closest to those estimated by Darcy’s law; (3) the estimations are influenced by the variances of heterogeneity more than the correlation lengths of heterogeneity.

Effect of hysteresis and infiltration rate on finger dynamics

A process was development for researching the finger dynamics using digital image analysis and the soil water content concept model. Nonuniform wetting front profile expanded vertically under the equalized potential head horizontally. Experimental data and the present concept model matched adequately. For extending the application of concept model, hysteresis models (Hogarth in 1988 and Huang in 2005) are compared. The initial temporal and spatial fingered velocity was faster with time under the same rainfall intensity, as well as fingered width. Besides, the mean fingered velocity also increase with rainfall intensity. The present concept model expounded the evolution of lingered flow and the hydraulic properties of linger dynamics successfully.

The Relationship between Boussinesq Equation and Non-Linear Storage of Baseflow Simulation

There are several approaches for the analysis of baseflow which include different kind of conceptual models and theoretical analysis. The concepts of linear and nonlinear storage are often used in modeling the baseflow and the nonlinear relationship between baseflow (Q) and moisture storage (S) can be described as S = aQ b . Boussinesq equation is used to predict the baseflow, and the results are as good as the estimation by nonlinear storage. The purpose of this paper is to discuss the relationship between nonlinear storage concept and the Boussinesq Equation. The parameters a in nonlinear storage modeling will be discussed. By using the observed streamflow data in Taiwan, the physical properties of parameter a will be identified. The present study concentrated on the structure of baseflow modeling and their parameters.