A new topographic index to quantify downslope controls on local drainage

Hjerdt, K. N.; McDonnell, Jeffrey J.; Seibert, Jan; Rodhe, Allan

doi:10.1029/2004wr003130

Cited by 203 publications

(173 citation statements)

References 31 publications

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“…The application of our research framework to rain-dominated regions is recommended to investigate how topography controls flow regimes in these areas. The difference between DDG and local or neighbor gradients (Hjerdt et al, 2004). 4 FLD Downstream flow length The downslope distance of a pixel along the flow path to the outlet of a watershed (Greenlee, 1987 (Burrough et al, 2015).…”

Section: Resultsmentioning

confidence: 99%

“…However, Panagos et al, (2015) indicated that the resolution of 25 meters is adequate for calculation of slope factor at the European scale. Similarly, DEM resolutions were not found to significantly affect the calculation of DDG (Hjerdt et al, 2004). Thus, considering the same DEM data with the resolution of 25-meter, we assume the error caused by the DEM resolution would also be minor.…”

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confidence: 99%

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Topography significantly influencing low flows in snow-dominated watersheds

Li¹,

Wei²,

Yang³

et al. 2017

Preprint

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and other environmental fields. Flow variables include annual mean flow (Qmean), Q10%, Q25%, Q50%, Q75%, Q90%, and annual minimum flow (Qmin), where Qx% is defined as flows that at the percentage (x) occurred in any given year. Factor analysis (FA) was first adopted to exclude some redundant or repetitive TIs. Then, stepwise regression models were employed to quantify the relative contributions of TIs to each flow variable in each year. Our results show that topography plays a more important 30 role in low flows than high flows. However, the effects of TIs on flow variables are not consistent.Our analysis also determines five significant TIs including perimeter, surface area, openness, terrain characterization index, and slope length factor, which can be used to compare watersheds when low flow assessments are conducted, especially in snow-dominated regions. 35

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Section: Resultsmentioning

confidence: 99%

mentioning

confidence: 99%

Topography significantly influencing low flows in snow-dominated watersheds

Li¹,

Wei²,

Yang³

et al. 2017

Preprint

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show abstract

“…On the basis of this flow path, five indices were computed for each pixel: the elevation above the stream, the distance from the stream, the average gradient along the flow pathway to the stream and the ratio of the flow path length and gradients, which is often considered a proxy for travel times, summed along the entire flow pathway. In addition, the downslope index (Hjerdt et al, 2004) was defined as the gradient towards the closest point, which is at least 5 m (in altitude) below the pixel in question. The upslope area and slope were combined into the topographic wetness index (ln[a/tan(ˇ)]) similar to Beven and Kirkby (1979), where a is the upslope area per unit contour length and tan(ˇ) is the local slope with the difference that here tan(ˇ) was defined using the downslope index (Hjerdt et al, 2004).…”

Section: Catchment Characteristics and Structurementioning

confidence: 99%

“…In addition, the downslope index (Hjerdt et al, 2004) was defined as the gradient towards the closest point, which is at least 5 m (in altitude) below the pixel in question. The upslope area and slope were combined into the topographic wetness index (ln[a/tan(ˇ)]) similar to Beven and Kirkby (1979), where a is the upslope area per unit contour length and tan(ˇ) is the local slope with the difference that here tan(ˇ) was defined using the downslope index (Hjerdt et al, 2004). For each of these indices considered, catchment-wide median values were computed to represent each of the catchments.…”

Section: Catchment Characteristics and Structurementioning

confidence: 99%

Controls on snowmelt water mean transit times in northern boreal catchments

Lyon

Laudon

Seibert

et al. 2010

Hydrological Processes

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Abstract:Catchment-scale transit times for water are increasingly being recognized as an important control on geochemical processes. In this study, snowmelt water mean transit times (MTTs) were estimated for the 15 Krycklan research catchments in northern boreal Sweden. The snowmelt water MTTs were assumed to be representative of the catchment-scale hydrologic response during the spring thaw period and, as such, may be considered to be a component of the catchment's overall MTT. These snowmelt water MTTs were empirically related to catchment characteristics and landscape structure represented by using different indices of soil cover, topography and catchment similarity. Mire wetlands were shown to be significantly correlated to snowmelt MTTs for the studied catchments. In these wetlands, shallow ice layers form that have been shown to serve as impervious boundaries to vertical infiltration during snowmelt periods and, thus, alter the flow pathways of water in the landscape. Using a simple thought experiment, we could estimate the potential effect of thawing of ice layers on snowmelt hydrologic response using the empirical relationship between landscape structure (represented using a catchment-scale Pe number) and hydrologic response. The result of this thought experiment was that there could be a potential increase of 20-45% in catchment snowmelt water MTTs for the Krycklan experimental catchments. It is therefore possible that climatic changes present competing influences on the hydrologic response of northern boreal catchments that need to be considered. For example, MTTs may tend to decrease during some times of the year due to an acceleration in the hydrologic cycle, while they tend to increase MTTs during other times of the year due to shifts in hydrologic flow pathways. The balance between the competing influences on a catchment's MTT has consequences on climatic feedbacks as it could influence hydrological and biogeochemical cycles at the catchment scale for northern latitude boreal catchments.

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“…Many terrain indices [19][20][21][22] have been developed in order to build up a stronger connection between water presence and topography. Most of these terrain indices can generally be categorized into two groups, valley bottom based and drainage based.…”

Section: Introductionmentioning

confidence: 99%

A Comparison of Terrain Indices toward Their Ability in Assisting Surface Water Mapping from Sentinel-1 Data

Huang

Nguyen

Zhang

et al. 2017

IJGI

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Abstract:The Sentinel-1 mission provides frequent coverage of global land areas and is hence able to monitor surface water dynamics at a fine spatial resolution better than any other Synthetic Aperture Radar (SAR) mission before. However, SAR data acquired by Sentinel-1 also suffer from terrain effects when being used for mapping surface water, just as other SAR data do. Terrain indices derived from Digital Elevation Models (DEMs) are easy but effective approaches to reduce this kind of interference, considering the close relationship between surface water movement and topography. This study compares two popular terrain indices, namely the Multi-resolution Valley Bottom Flatness (MrVBF) and the Height Above Nearest Drainage (HAND), toward their performance on assisting surface water mapping using Sentinel-1 SAR data. Four study sites with different terrain characteristics were selected to cover a very wide range of topographic conditions. For two of these sites that are floodplain dominated, both normal and flooded scenarios were examined. MrVBF and HAND values for the whole study areas, as well as statistics of these values within water areas were compared. The sensitivity of applying different thresholds for MrVBF and HAND to mask out terrain effect was investigated by adopting quantity disagreement and allocation disagreement as the accuracy indicators. It was found that both indices help improve water mapping, reducing the total disagreement by as much as 1.6%. The HAND index performs slightly better in most of the study cases, with less sensitivity to thresholding. MrVBF classifies low-lying areas with more details, which sometimes makes it more effective in eliminating false water bodies in rugged terrain. It is therefore recommended to use HAND for large scale or global scale water mapping. However, for water detection in complex terrain areas, MrVBF also performs very well.

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A new topographic index to quantify downslope controls on local drainage

Cited by 203 publications

References 31 publications

Topography significantly influencing low flows in snow-dominated watersheds

Topography significantly influencing low flows in snow-dominated watersheds

Controls on snowmelt water mean transit times in northern boreal catchments

A Comparison of Terrain Indices toward Their Ability in Assisting Surface Water Mapping from Sentinel-1 Data

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