Classification of catchments by hydrologic regimes.

Kuzuha, Yasuhisa; Tomosugi, Kunio; Kishii, Tokuo; Hayano, Michiko

doi:10.3178/jjshwr.14.131

Cited by 6 publications

(5 citation statements)

References 5 publications

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“…They classified river basins in Japan according to hydrological regimes, as did Kresser (1981). Kuzuha et al (2001) studied the relationship between CV and MAF and catchment area, thereby showing that the behaviours of CV and MAF in Japan ( Figure 1 in this paper, which is updated) resemble those of figures from Austria (Blöschl and Sivapalan, 1997) and of the central Appalachian region (Smith, 1992): CV decreases with increasing catchment area for relatively large catchment areas. This observation forms the foundation of the analysis in this study.…”

Section: Introductionmentioning

confidence: 53%

“…What are the previously unidentified important and dominant hydrological processes that play a salient role in reproducing the tendency for CV to decrease with increasing catchment area? We believe that improving the Kuzuha et al (2000;2001) classical model to reproduce this tendency can lead to a better understanding of the precipitation-runoff process. We present this improvement and explore important hydrological flood-control processes while deriving a valid model.…”

Section: Introductionmentioning

confidence: 98%

“…They concluded that the tendency of the CV (which shows a decreasing tendency in many cases) and the scatter in the data result from the complex interplay of numerous processes that invites various alternative interpretations. Kuzuha et al (2001) analysed flood data in Japan. They classified river basins in Japan according to hydrological regimes, as did Kresser (1981).…”

Section: Introductionmentioning

confidence: 99%

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Role of spatial variability of rainfall intensity: improve‐ ment of Eagleson's classical model to explain the rela‐ tionship between the coefficient of variation of annual maximum discharge and catchment size

Kuzuha

Sivapalan

Tomosugi

et al. 2006

Hydrological Processes

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Abstract:Eagleson's classical regional flood frequency model is investigated. Our intention was not to improve the model, but to reveal previously unidentified important and dominant hydrological processes in it. The change of the coefficient of variation (CV) of annual maximum discharge with catchment area can be viewed as representing the spatial variance of floods in a homogeneous region. Several researchers have reported that the CV decreases as the catchment area increases, at least for large areas. On the other hand, Eagleson's classical studies have been known as pioneer efforts that combine the concept of similarity analysis (scaling) with the derived flood frequency approach. As we have shown, the classical model can reproduce the empirical relationship between the mean annual maximum discharge and catchment area, but it cannot reproduce the empirical decreasing CV-catchment area curve. Therefore, we postulate that previously unidentified hydrological processes would be revealed if the classical model were improved to reproduce the decreasing of CV with catchment area. First, we attempted to improve the classical model by introducing a channel network, but this was ineffective. However, the classical model was improved by introducing a two-parameter gamma distribution for rainfall intensity. What is important is not the gamma distribution itself, but those characteristics of spatial variability of rainfall intensity whose CV decreases with increasing catchment area. Introducing the variability of rainfall intensity into the hydrological simulations explains how the CV of rainfall intensity decreases with increasing catchment area. It is difficult to reflect the rainfall-runoff processes in the model while neglecting the characteristics of rainfall intensity from the viewpoint of annual flood discharge variances.

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Section: Introductionmentioning

confidence: 53%

Section: Introductionmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

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Role of spatial variability of rainfall intensity: improve‐ ment of Eagleson's classical model to explain the rela‐ tionship between the coefficient of variation of annual maximum discharge and catchment size

Kuzuha

Sivapalan

Tomosugi

et al. 2006

Hydrological Processes

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“…wrote that CV remains constant over a region if simple scaling holds. Indeed, Gupta and Dawdy (1995) and Kuzuha et al (2001) show several regions where simple scaling holds; we have shown in this paper that two kinds of CV-plateau exist, that is A c − A cr and A c × A cr . The mechanisms for these plateaus must be separated, as described above.…”

mentioning

confidence: 65%

“…Simple scaling is valid; therefore, the assumption of the index flood method is also valid if CV is constant with increasing catchment area. However, as described by many researchers (Smith, 1992;Blöschl and Sivapalan, 1997;Kuzuha et al, 2001), CV is not constant for most catchments. Specifically, CV decreases with increasing catchment scale.…”

Section: Introductionmentioning

confidence: 93%

Coefficient of variation of annual flood peaks: variability of flood peak and rainfall intensity

Kuzuha

Tomosugi

Kishii

et al. 2008

Hydrological Processes

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Abstract:Scaling can be a powerful solution for predictions in ungauged basins (PUB). Since becoming a principal scaling tool, the theory concerning the index flood method has been criticized because it requires some scaling conditions that are satisfied in few river basins. In that method, precipitation and flood discharge variability play key roles. Consequently, the coefficient of variation (CV) of annual flood peaks came to be considered after the 1990s. In this paper, we have attempted to clarify true CV characteristics of flood discharges.Using numerical simulations, we attempt to reproduce the empirical characteristics of an increase in CV with increasing catchment area for a small basin (i.e. less than 30-100 km 2 ) and decrease in CV with increasing catchment area for a large basin. First, as a preliminary test, we developed a simple model, which is on the basis of the unit hydrograph. Results obtained using this simple model show that the CV of annual flood peaks shows a constant-increasing-constant pattern, but this model cannot reproduce the empirical characteristics. Secondly, we used an idealized channel network to find the cause of decreasing CV. However, results show that the ability to reproduce the empirical characteristics is unrelated to the presence or absence of a network. This was confirmed using a distributed rainfall-runoff (DRR) model comprising a channel network. The most important cause is decreased CV of rainfall intensity with increasing catchment area.Furthermore, increasing CV of the peak discharge response (PDR) function increases the CV of annual flood peaks. However, the CV of PDR of a partial duration series does not affect the CV of annual flood peaks for smaller basins (0Ð1 km 2 in our simulation condition); hence CV is constant for small basins.

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