This paper introduces the equivalent frequency response method (EFRM) into runoff analysis. This EFRM originally had been developed to analyze dynamic behavior of nonlinear elements such as threshold and saturation in control engineering. Many runoff models are described by nonlinear ordinary or partial differential equations. This paper presents that these nonlinear differential equations can be converted into semi-linear ones based on EFRM. The word of “a semi-linear equation” means that the coefficients of derived equations depend on average rainfall

A newly developed heuristic algorithm, Harmony Search, is applied to the parameter calibration problem of the nonlinear Muskingum model. The Harmony Search could, mimicking the improvisation of music players, find better parameter values for in the nonlinear Muskingum model than five other methods including another heuristic method, genetic algorithm, in the aspect of SSQ (the sum of the square of the deviations between the observed and routed outflows) as well as in the aspects of SAD (the sum of the absolute value of the deviations), DPO (deviations of peak of routed and actual flows) and DPOT (deviations of peak time of rented and actual outflow). Harmony Search also has the advantage that it does not require the process of assuming the initial values of design parameters. The sensitivity analysis of Harmony Memory Considering Rate showed that relatively large values of Harmony Memory Considering Rate makes the Harmony Search converse to a better solution.

The grid-based KlneMatic wave STOrm Runoff Modei (Kim, 1998; Kim, et al., 1998) which predicts temporal variation and spatial distribution of saturated overland flow, subsurface flow and stream flow was evaluated at two watersheds. This model adopts the single overland flowpath algorithm and simulates surface and/or subsurface water depth at each cell by using water balance of hydrologic components. The model programed by C-language uses ASCII-formatted map data supported by the irregular gridded map of the GRASS (Geographic Resources Analysis Support System) GIS and generates the spatial distribution maps of discharge, flow depth and soil moisture of the watershed.

A TIN, Triangulated Irregular Network, based topographic modeling method and a distributed rainfall-runoff model using the topographic representation is presented. In the TIN based topographic representation, a watershed basin is modeled as a set of contiguous non-overlapping triangular facets: the watershed basin is subdivided according to streamlines to deal with water movement one-dimensionally; and each partitioned catchment is approximated to a slope element having a quasi-three-dimensional shape by using cubic spline functions. On an approximated slope element, water movement is represented by combined surface-subsurface kinematic wave equations considering a change of slope gradient and slope width. By using the distributed rainfall-runoff model, the effects of spatial variability of soil properties on runoff response are examined.

The method of delays is widely used fur reconstructing chaotic attractors from experimental observations. Many studies have used a fixed delay time ${\tau}_d$ as the embedding dimension m is increased, but this is not necessarily the best choice for obtaining good convergence of the correlation dimension. Recently, some researchers have suggested that it is better to fix the delay time window ${\tau}_w$ instead. Unfortunately, ${\tau}_w$ cannot be estimated using either the autocorrelation function or the mutual information, and no standard procedure for estimating ${\tau}_w$has yet emerged. However, a new technique, called the C-C method, can be used to estimate either ${\tau}_d{\;}or{\;}{\tau}_w$. Using this method, we show that, for small data sets, fixing ${\tau}_w$, rather than ${\tau}_d$, does indeed lead to a more rapid convergence of the correlation dimension as the embedding dimension m is increased.

In this paper, properties of hydrologic cycle in three experimental catchments were compared and different types of a lumped parametric model were applied to understand the hydrologic cycle in the catchments. One of them is a forest catchment and another one includes the reclaimed upland fields and last one does terraces paddy fields. The comparison of hydrologic properties showed that the differences in land use have great influences on the soil properties of surface layer, which changes in hydrologic processes such as evapotranspiration and storm runoff et. al. By the runoff analysis models, good agreements between observed and calculated discharge from the catchments were obtained and it was found that the differences in values of optimized model parameters and water budget components reflect those in the hydrologic cycle among them.

$\ulcorner$수변 복원 (水邊 復元), stream restoration)$\lrcorner$은 미 연방정부의 관련 기관들이 공동으로 참여하여 1998년 10월 발간한 하천과 그 연변의 복원을 위한 종합적인 가이드라인이다. 이 책은 “원칙, 과정, 실무”라는 부제가 붙어 있다. 이 책의 제작 취지는 연방 정보의 범 기관 차원에서 전국에 악화 되가는 하천과 그 연변을 복원하는데 있어 실무자들에게 개념적, 방법적, 기술적 가이드라인을 제공하는 것이다. 이 가이드라인의 제작에 참여한 기관은 농무성, 환경청, 상무성, 국방성(공병단), 내무성 등 15개 기관이다. 이를 위하여 각 기관에서 양해 각서를 조인하여 하천 기술자들은 물론, 생물, 생태, 조경, 하천 형태 등 관련 100명 이상의 전문가들이 ‘연방기관 수변복원 실무그룹’을 구성하여 추진하였다. 이 가이드라인 구조는 3부와 9장, 그리고 부록으로 구성되어 있으며, 원색사진과 그림을 강조하며 추후 수정보완을 위해 바인더로 만들어졌다. 이 가이드라인은 기본적으로 손상이 된 하천의 복원 설계보다는 손상이 안된 하천의 구조와 기능 이해에 더 중점을 두었다. 따라서 이 것 하나만으로 하천 복원에 관한 모든 기술적 지식을 얻기는 어렵다. 그럼에도 불구하고 이 가이드라인 제작팀의 규모와 노력 등을 고려할 때 당분간 미국은 물론 세계적으로 하천 복원과 자연형 하천공법등의 실무에 상당한 기여을 할 것으로 보인다.

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