Paik, Kyungrock

Abstract Among various deterministic rainfall‐runoff models, the tank model, which is a typical conceptual rainfall‐runoff model, is often preferred for its simple concepts. On the other hand, it requires much time and effort to obtain better results owing to the need to calibrate a large number of parameters in the model. Therefore, the demand for an automatic calibration method has been increasing. In this study, three optimization algorithms were tested for automatic calibration: one nonlinea

Mother Nature has left amazingly regular geomorphic patterns on the Earth's surface. These patterns are often explained as having arisen as a result of some optimal behaviour of natural processes. However, there is little agreement on what is being optimized. As a result, a number of alternatives have been proposed, often with little a priori justification with the argument that successful predictions will lend a posteriori support to the hypothesized optimality principle. Given that maximum ent

Abstract We investigated the scaling and topology of engineered urban drainage networks (UDNs) in two cities, and further examined UDN evolution over decades. UDN scaling was analyzed using two power law scaling characteristics widely employed for river networks: (1) Hack's law of length ( L )‐area ( A ) [ ] and (2) exceedance probability distribution of upstream contributing area ( δ ) [ ]. For the smallest UDNs (<2 km 2 ), length‐area scales linearly ( h ∼ 1), but power law scaling ( h ∼ 0.

A new algorithm is developed to extract flow paths from digital elevation data without planar dispersion on the basis of the concept of global search. Widely used nondispersive algorithms, such as deterministic eight‐neighbor flow direction retrieval algorithms, suffer serious uncertainty in their determined flow paths because of the lack of variability, i.e., only eight allowed flow directions. Although uncertainty at the local level is an inherent problem residing in the domain discretization,

Abstract The self‐similar tree topology in open dissipative systems is formed as a result of self‐organization and found in various examples, such as river networks, blood vessels, vascular organizations in plants, and even lightning. It is generally assumed that the tree organization is a result of a dynamic process that minimizes the dissipation of energy. Here, we argue that inherent randomness is a sufficient condition for the generation of tree patterns under evolutionary dynamics and the d

We postulate that the spatial variability in flow velocity in a basin, arising from the systematic downstream variation of celerity, may explain the observed nonlinear rainfall‐runoff relationships. This is based on the argument that different rainfall excess rates will produce different velocity fields in a basin due to the nonlinear relation between velocity and flow. In particular, we show that if the mean velocity V varies with flow Q as V ∝ Q m , then the time to peak t p and the peak f ( t

Abstract This paper presents improvements to the global D8 (GD8) method for calculating single flow directions in a grid digital elevation model. Flow directions computed from grid digital elevation models serve as the foundation for much of the analysis and modeling of hydrological processes that are driven by topographic gradients. The literature includes both single flow direction methods, where flow goes to only one downslope cell, and multiple flow direction methods that apportion flow amon

Horton’s laws have long served as fundamental principles for fractal organization of a drainage basin. Scaling ratios of stream number, length, area, and side tributary have been proposed but the definitions of these basic variables are inconsistent. The concept of eigenarea can be utilized to resolve this issue. Here, we investigated the relationships among Hortonian scaling ratios using the concept of eigenarea. We found that the eigenarea ratio, likewise other scaling ratios, is invariant wit