GIS approach to scale issues of perimeter-based shape indices for drainage basins

Abstract

Shape indices have been in use for several decades to describe the characteristics and hydrological properties of drainage basins. Due to the fractal behaviour of the basin boundary, perimeter-based shape indices depend on the scale at which they are determined. Therefore, these indices cannot objectively compare drainage basins across a range of scales and basin sizes. This paper presents an objective GIS-based methodology for determining scale-dependent shape indices from gridded drainage basin representations. The scale effect is addressed by defining a representative scale at which the indices should be determined, based on a threshold symmetric difference between two grids representing the drainage basin at different resolutions.     

Assessing soil erosion in a small Sicilian basin by caesium-137 measurements and a simplified mass balance model

Abstract

The caesium-137 technique affords both an alternative to conventional measurement methods and an effective quantitative estimate of soil redistribution at the basin scale. Among the available calibration relationships which link the degree of increase or depletion of the ¹³⁷Cs activity relative to the baseline ¹³⁷Cs input and sediment yield, the mass balance approach has received increased application for its physical basis. First, the applicability of the refined simplified point-based mass balance (RSPMB) model of Zhang et al. (1999) at the scale of the morphological unit is proposed herein. The ¹³⁷Cs spatial distribution measured in a small Sicilian basin and the spatial distribution of the sediment yield calculated by a sediment delivery distributed approach are used to estimate values of the two key parameters of the RSPMB model, φ₁ and φ₂, the fraction of ¹³⁷Cs fallout incorporated into soil and a particle size correction factor, respectively. Finally, the best procedure for experimental testing of a distributed sediment yield model by using caesium-137 measurements is investigated.     

Spatial scale effects on sediment concentration in runoff during flood events for hilly areas of the Loess Plateau,China

The spatial scale effect on sediment concentration in runoff has received little attention despite numerous studies on sediment yield or sediment delivery ratio in the context of multiple spatial scales. We have addressed this issue for hilly areas of the Loess Plateau, north China where fluvial processes are mainly dominated by hyperconcentrated flows. The data on 717 flow events observed at 17 gauging stations and two runoff experimental plots, all located in the 3906 km² Dalihe watershed, are presented. The combination of the downstream scour of hyperconcentrated flows and the downstream dilution, which is mainly caused by the base flow and is strengthened as a result of the strong patchy storms, determines the spatial change of sediment concentration in runoff during flood events. At the watershed scale, the scouring effect takes predominance first but is subordinate to the downstream dilution with a further increase in spatial scale. As a result, the event mean sediment concentration first increases following a power function with drainage basin area and then declines at the drainage basin area of about 700 km². The power function in combination with the proportional model of the runoff‐sediment yield relationship we proposed before was used to establish the sediment‐yield model, which is neither the physical‐based model nor the regression model. This model, with only two variables (runoff depth and drainage basin area) and two parameters, can provide fairly accurate prediction of event sediment yield with model efficiency over 0·95 if small events with runoff depth lower than 1 mm are excluded. Copyright © 2011 John Wiley & Sons, Ltd.     

Spatially varied soil erosion under different climates

Abstract

The spatial variability of the factors of the universal soil loss equation is examined on the mediterranean basin of Conca de Tremp covering 43.1 km² in Spain. The evaluation of the rainfall erosivity R and the soil erodibility K is relatively straightforward and spatially-averaged values of these parameters can be applied to the entire basin. Conversely, the spatial variability of annual soil erosion losses on large basins depends primarily on the factors L, S and C describing topographic, vegetation and land use parameters. A grid size analysis of soil erosion losses from the Conca de Tremp basin under mediterranean climatic conditions in Spain shows excellent agreement with the earlier results on the Chaudière basin in Canada. It is concluded for both basins that unbiassed estimates of soil erosion losses are obtained for grid sizes less than about 0.125 km². The analysis of the Conca de Tremp basin validates the use of the grid size factor proposed by Julien & Frenette (1987). It is also found that the grid size factor primarily depends on the average slope gradient which decreases with increasing grid size or drainage area. On the other hand, the grid size factor does not depend on the spatial variability of the factors R, K, L and C.     

Sediment delivery processes and chemical transport in a small forested basin/Processus de production sédimentaire et transport chimique dans un petit bassin versant forestier

Abstract

Because the properties of eroded soil affect the deposition phenomena and transport capacity of chemical materials by eroded particles, recent research is trying to link the grain-size distribution of the eroded sediment to that of the original soil in order to explain the enrichment of chemical content of the sediment with the respect to the parent soil. In this study, the spatial distribution of nitrogen, phosphorus and total organic carbon was firstly deduced using the measurements carried out in 47 soil samples distributed over a forested basin together with a kriging interpolation method. Then the load of each chemical was calculated at morphological unit and basin scales using the above-mentioned spatial distributions and sediment yield values calculated by the SEDD (SEdiment Delivery Distributed) model, which couples the universal soil loss equation with a spatial disaggregation criterion of sediment delivery processes. Finally, at basin scale, a new expression of the enrichment ratio of a given chemical was applied.     

Catchment-scale storm velocity: quantification,scale dependence and effect on flood response

Abstract

The concept of “catchment-scale storm velocity” quantifies the rate of storm motion up and down the basin accounting for the interaction between the rainfall space–time variability and the structure of the drainage network. It provides an assessment of the impact of storm motion on flood shape. We evaluate the catchment-scale storm velocity for the 29 August 2003 extreme storm that occurred on the 700 km²-wide Fella River basin in the eastern Italian Alps. The storm was characterized by the high rate of motion of convective cells across the basin. Analysis is carried out for a set of basins that range in area from 8 to 623 km² to: (a) determine velocity magnitudes for different sub-basins; (b) examine the relationship of velocity with basin scale and (c) assess the impact of storm motion on simulated flood response. Two spatially distributed hydrological models of varying degree of complexity in the representation of the runoff generation processes are used to evaluate the effects of the storm velocity on flood modelling and investigate model dependencies of the results. It is shown that catchment-scale storm velocity has a non-linear dependence on basin scale and generally exhibits rather moderate values, in spite of the strong kinematic characteristics of individual storm elements. Consistently with these observations and for both models, hydrological simulations show that storm motion has an almost negligible effect on the flood response modelling.

Editor Z.W. Kundzewicz; Guest editor R.J. Moore

Citation Nikolopoulos, E.I., Borga, M., Zoccatelli, D., and Anagnostou, E.N., 2014. Catchment-scale storm velocity: quantification, scale dependence and effect on flood response. Hydrological Sciences Journal, 59 (7), 1363–1376. http://dx.doi.org/10.1080/02626667.2014.923889     

Radar rainfall estimation for flash flood forecasting in small urban watersheds

Radar rainfall estimation for flash flood forecasting in small, urban catchments is examined through analyses of radar, rain gage and discharge observations from the 14.3 km² Dead Run drainage basin in Baltimore County, Maryland. The flash flood forecasting problem pushes the envelope of rainfall estimation to time and space scales that are commensurate with the scales at which the fundamental governing laws of land surface processes are derived. Analyses of radar rainfall estimates are based on volume scan WSR-88D reflectivity observations for 36 storms during the period 2003–2005. Gage-radar analyses show large spatial variability of storm total rainfall over the 14.3 km² basin for flash flood producing storms. The ability to capture the detailed spatial variation of rainfall for flash flood producing storms by WSR-88D rainfall estimates varies markedly from event to event. As spatial scale decreases from the 14.3 km² scale of the Dead Run watershed to 1 km² (and the characteristic time scale of flash flood producing rainfall decreases from 1 h to 15 min) the predictability of flash flood response from WSR-88D rainfall estimates decreases sharply. Storm to storm variability of multiplicative bias in storm total rainfall estimates is a dominant element of the error structure of radar rainfall estimates, and it varies systematically over the warm season and with flood magnitude. Analyses of the 7 July 2004 and 28 June 2005 storms illustrate microphysical and dynamical controls on radar estimation error for extreme flash flood producing storms.     

LE CINQUANTIÈME ANNIVERSAIRE DE L'AISH / THE FIFTHIETH ANNIVERSARY OF THE IAHS

Abstract

One of the scale problems in hydrology is to relate nonlinearity in basin response to size and other factors. On the Sputka basin (103.4 km²), three groups of unit hydrographs were identified, each group having a common shape parameter, N, of the Nash model and each, therefore, representing one dimensionless response. The existence of the three dimensionless responses can be explained in the first place by there being different spatial rainfall patterns for the events from which they were derived. The time parameter, K, within the individual groups depends primarily on the initial flow and on the skewness of the rainfall time pattern. However, when the conditions of rainfall uniformity and of a minimum depth are strictly met, and the initial flow is in a certain range, the basin behaves in a linear fashion.     

Hydrological Sciences Journal Countents 1994

Abstract

Since eroded sediments are produced from different sources distributed throughout a basin, sediment delivery processes at basin scale have to be modelled by a spatially distributed approach. In this paper a new theoretically based relationship is proposed for evaluating the sediment delivery ratio, SDR_i, of each morphological unit, i, into which a basin is divided. Then, using the sediment balance equation written for the basin outlet, a relationship between the basin sediment delivery ratio, SDR_W and the SDR_i is deduced. This relationship is shown to be independent of the soil erosion model used. Finally, a morphological criterion for estimating a coefficient, β, is proposed.     

Assessing strategic water availability using remote sensing,GIS and a spatial water budget model: case study of the Upper Ing Basin,Thailand

Abstract

This paper assesses strategic water availability and use under different development pathways on a basin scale using remote sensing (RS), geographical information systems (GIS) and a spatial water budget model (SWBM). The SWBM was applied to the Upper Ing Basin in northern Thailand to investigate the spatial and temporal variations in the location of streams and water yields from different parts of the basin. The base simulation was carried out for the years 1998–2007 using a DEM and actual land-use data at 100-m resolution. The simulated stream network was compared with topographic maps under different flow conditions, which were successfully represented. The 10-year average simulated river flow rate was 1300 L/s, but it more than doubled during periods of heavy rainfall and decreased below 600 L/s in dry seasons. The total length of the streams (based on flow threshold of 25 L/s) on a typical day in the dry season differed by a factor of approx. 1.5. Agricultural water needs and possible extraction were assessed and presented by dividing the basin into 10 different zones based on the stream network. The results show that there is the potential for harvesting significant quantities of water at different spatial gradients with no initial water supply for irrigation. Monthly water yields for each zone were computed; the results varied from less than 50% to over 137% of the per hectare water yield for the entire basin. This variation was due to differences in topography and land cover. The impact of land use and climate change on streamwater availability was also studied. The basin shows very different hydrological responses. The changes in average river flow relative to the base simulation were +27.6%,??32.1%, +94% and +52.9% under deforestation, changing land use from paddy field to orchard, bare soil and increased rainfall scenarios, respectively.

Citation Bahadur KC, K. (2011) Assessing strategic water availability using remote sensing, GIS and a spatial water budget model: case study of the Upper Ing Basin, Thailand. Hydrol. Sci. J. 56(6), 994–1014.     

On the ability of large-scale hydrological models to simulate land use and land cover change impacts in Amazonian basins

ABSTRACT

The MHD-INPE model was applied in the Ji-Parana Basin, a 30 000 km² catchment located in the southwest of the Amazon Basin which has lost more than 50% of its forest since the 1980s, to simulate land use and land cover change impacts on runoff generation process and how they are related to basin topography. Simulation results agree with observational studies in the sense that fast response processes are significant in sub-basins with steep slopes while in basins with gentle topography, the impacts are most visible in slow-response hydrological processes. On the other hand, the model is not able to capture the dependence of LUCC impacts on spatial scales. These discrepancies are probably associated with limitations in the spatial representation of heterogeneities within the model, which become more relevant at larger scales. We also tested the hypothesis that secondary forest growth should be able to compensate the decrease in evapotranspiration due to forest–cropland or forest–grassland conversion at a regional scale. Results showed that despite the small fraction of secondary forest estimated on the basin, the higher evapotranspiration efficiency of this type of forest counterbalances a large fraction of the LUCC impacts on evapotranspiration. This result suggests that enhanced transpiration due to secondary forest could explain, at least in part, the lack of clear LUCC signals in discharge series at larger scales.

EDITOR D. Koutsoyiannis; ASSOCIATE EDITOR T. Wagener     

SUR LES PROJECTS FUTURS DE L'AISH / ON THE FUTURE PLANS OF IAHS

Abstract

The baseflow characteristics of some of the numerous small basins in southeastern Nigeria have been analysed to estimate the developable groundwater in the basins. It is shown that from 5.62 × 10⁴ to 1.59 × 10⁶ m³ of groundwater can be developed per square kilometre of basin per annum. The relationship between the baseflow characteristics and other attributes of the basins, such as geology and stream density, were studied statistically, leading to the development of empirical equations for predicting the hydrological features of the several ungauged streams in the region. It is shown, for example, that the basin geology (represented as the percentage of sands), the drainage density, the basin area, the baseflow depletion rate and the total groundwater stored in the basin, Q_tp, are related by the equation:

Q_tp = ?1.85 × 10⁹?7.96 × 10⁸ dd+4.18 × 10⁷ gf?2.01 × 10⁶ df+6.25 × 10⁵ wa

where dd is drainage density; gf geological factor; df depletion factor; and wa basin area.     

THE VARIATION OF DRAINAGE DENSITY WITHIN A CATCHMENT

Abstract

Actual discharges from two experimental catchments are related to the corresponding measurements of the length of channel flow; within a single catchment this is equivalent to drainage density. Drainage densities ranging from less than 1.0 to nearly 10.0 are associated with discharges ranging from 0.15 to nearly 20.0 c.f.s. per square mile. In each catchment all discharge values (Q) and drainage density values (Dd) are related by a function approximately of the form Q ∝ Dd², which is then discussed in relation to studies made of the variation of streamflow and drainage density between catchments. It is suggested that both peak flow and base flow are related to drainage density in the same way. Studies which include drainage density as a basin characteristic and which relate it to water yield should acknowledge that its value varies within any one catchment, and therefore that the drainage density values derived by a particular method can be related only to one type of flow. In Great Britain the watercourses shown on the 1:10,560 maps relate to specific low flow discharges.     

Etude de la dynamique sédimentaire dans le bassin versant de l'Oued Bellah (Algérie)

Abstract

Suspended sediment dynamics influenced by rainstorms and factors controlling changes in suspended sediment concentrations, were investigated during hydrological events in a small scale, since small agricultural drainage basins can be considered as one of the most important sediment sources. Suspended sediment concentrations were measured during discharge waves in the years 1987–1990, 1992, 2000 and 2001. Positive and anti-clockwise hysteresis was observed at Rybárik basin. A procedure of isolating factors controlling suspended sediment concentrations and dynamics has given a more realistic view on production and transport of suspended sediment. It is confirmed that spatial and temporal variability of sediment availability and suspended sediment dilution by the baseflow, mainly in the case of two or more waves immediately following one after another, significantly control suspended sediment concentrations and dynamics.     

Solution of marble in the karst of the Pikikiruna range,Northwest Nelson,New Zealand

The paper reports the first research on karst solution processes and rates in New Zealand. The study area is an IHD representative basin in the northwest corner of the South Island in a mountain range consisting principally of Ordovician marble. The climate is sunny and warm (17°C) in summer and wet and cool (7°C) in winter. Average precipitation is 2,158 mm of which 525 mm evapotranspires, yielding a discharge of 51–75 l/s/km² in the river basin studied. Almost half of the catchment of 45.1 km² consists of karst which occurs mainly as a doline covered plateau at 600–900 m within which most drainage is subterranean. Water tracing is with fluorescein defined drainage patterns. Marble solution was established by estimating inputs, throughputs and outputs of water and dissolved calcium and magnesium in both autogenic and allogenic karst drainage systems. Particular attention was paid to estimating errors. Water samples for chemical analysis were taken irregularly for approximately one year, and a rating curve relating chemical load to discharge was established. The best estimate of solution loss from the basin yields a mean rate of 100 ±M24 m³/km²/a. Of this 80 per cent is derived from solution of marble by autogenic waters, mostly in the top 10–30 m of the marble outcrop. The remaining 20 per cent is accomplished by allogenic stream solution. Approximately 9.9 per cent of the dissolved calcium and magnesium load leaving the basin originates from non-karst rocks and 4.6 per cent is initially introduced by rainfall. River flows that are exceeded only 5 per cent of the time transport approximately 44 per cent of the annual dissolved load, while mean to low flows that occur for 75 per cent of the time transport 35 per cent of the annual solute load. This confirms the importance of low frequency-high magnitude events, but indicates also that in corrosion systems high frequency events of moderate to low magnitude can also accomplish significant work.     

Assessment of the MODIS global evapotranspiration algorithm using eddy covariance measurements and hydrological modelling in the Rio Grande basin

Abstract

Remote sensing is considered the most effective tool for estimating evapotranspiration (ET) over large spatial scales. Global terrestrial ET estimates over vegetated land surfaces are now operationally produced at 1-km spatial resolution using data from the Moderate Resolution Imaging Spectroradiometer (MODIS) and the MOD16 algorithm. To evaluate the accuracy of this product, ground-based measurements of energy fluxes obtained from eddy covariance sites installed in tropical biomes and from a hydrological model (MGB-IPH) were used to validate MOD16 products at local and regional scales. We examined the accuracy of the MOD16 algorithm at two sites in the Rio Grande basin, Brazil, one characterized by a sugar-cane plantation (USE), the other covered by natural savannah vegetation (PDG) for the year 2001. Inter-comparison between 8-day average MOD16 ET estimates and flux tower measurements yielded correlations of 0.78 to 0.81, with root mean square errors (RMSE) of 0.78 and 0.46 mm d^-1, at PDG and USE, respectively. At the PDG site, the annual ET estimate derived by the MOD16 algorithm was 19% higher than the measured amount. For the average annual ET at the basin-wide scale (over an area of 145 000 km²), MOD16 estimates were 21% lower than those from the hydrological model MGB-IPH. Misclassification of land use and land cover was identified as the largest contributor to the error from the MOD16 algorithm. These estimates improve significantly when results are integrated into monthly or annual time intervals, suggesting that the algorithm has a potential for spatial and temporal monitoring of the ET process, continuously and systematically, through the use of remote sensing data.

Editor D. Koutsoyiannis; Associate editor T. Wagener

Citation Ruhoff, A.L., Paz, A.R., Aragao, L.E.O.C., Mu, Q., Malhi, Y., Collischonn, W., Rocha, H.R., and Running, S.W., 2013. Assessment of the MODIS global evapotranspiration algorithm using eddy covariance measurements and hydrological modelling in the Rio Grande basin. Hydrological Sciences Journal, 58 (8), 1658–1676.     

Homogenization of spatial patterns of hydrologic response in artificially drained agricultural catchments

Anthropogenic modifications to the landscape, with agricultural activities being a primary driver, have resulted in significant alterations to the hydrologic cycle. Artificial drainage, including surface and subsurface drainage (tile drains), is one of the most extensive manipulations in agricultural landscapes and thus is expected to provide a distinct signature of anthropogenic modification. This study adopts a data synthesis approach in an effort to characterize the signature of artificial subsurface drainage. Daily discharge data from 24 basins across the state of Iowa, which encapsulate a range of anthropogenic modifications, are assessed using a variety of flow metrics. Results indicate that the presence of artificial subsurface drainage leads to a homogenization of landscape hydrologic response. Non‐tiled watersheds exhibit a decrease in the area‐normalized peak discharge and an increase in the baseflow ratio (baseflow/streamflow) with increases in the spatial scale, while scale invariance is apparent in tiled basins. Within‐basin variability in hydrograph recession coefficients also appears to decrease with increases in the proportion of the catchment that is artificially drained. Finally, the differences between tiled and non‐tiled landscapes disappear at scales greater than approximately 2200 km², indicating that this may be a threshold scale for studying the effects of tile drainage. This decrease in within‐basin variability and the scale invariance of hydrologic metrics in artificially drained watersheds are attributed to the creation of a bypass flow hydrologic pathway that bypasses the complexity of the catchment travel paths. Spatial homogeneity in responses implies that it may be possible to develop more parsimonious hydrologic models for these regions. Copyright © 2013 John Wiley & Sons, Ltd.     

Sediment budgeting: A case study in the Katiorin drainage basin,Kenya

The primary objective of this study was to compute a detailed budget for a small semiarid tropical drainage basin in Kenya. Results indicated that transfer of sediments (‘inputs’) from primary source areas was minor in comparison to changes in storage. The major sediment source area within the Katiorin drainage basin was the colluvial hillslope zone. The net change in storage within this zone was approximately 2100 Mg yr^?1. Surface wash and rilling were the dominant transport processes responsible for the remobilization of colluvial sediments. Sediment storage within the in-channel reservoir increased by 60 Mg yr^?1, which was minor when compared to the total store of sediment in this reservoir. During 1986, the channel network stored only a small fraction ( < 3 per cent) of the sediment delivered from the hillslope subsystem. Therefore, the in-channel reservoir had limited influence on sediment conveyance to the basin outlet. These data indicate that a static equilibrium condition cannot be assumed within the Katiorin drainage basin. Such an assumption would result in erosion estimates of approximately 5.5 mm yr^?1 for the entire basin (based on a sediment output of 7430 Mg km^?2 yr^?1 and a measured bulk density of 1.35 Mg m^?3). However, this masked the actual rates of 1.2 to 7.1 mm yr^?1 in subbasin primary source areas, and rates of 0.6 to 17 mm yr^?1 for colluvial material in the various subbasins. The extreme accelerated erosion rates resulted from minimal ground vegetation, steep slopes, soil crust formation, an erodible substrate, and a well-integrated drainage network for rapid conveyance of sediments from the hillslope subsystem to the basin outlet.     

Intercomparison across scales between remotely-sensed land surface temperature and representative equilibrium temperature from a distributed energy water balance model

Abstract

Quantifying the reliability of distributed hydrological models is an important task in hydrology to understand their ability to estimate energy and water fluxes at the agricultural district scale as well the basin scale for water resources management in drought monitoring and flood forecasting. In this context, the paper presents an intercomparison of simulated representative equilibrium temperature (RET) derived from a distributed energy water balance model and remotely-sensed land surface temperature (LST) at spatial scales from the agricultural field to the river basin. The main objective of the study is to evaluate the use of LST retrieved from operational remote sensing data at different spatial and temporal resolutions for the internal validation of a distributed hydrological model to control its mass balance accuracy as a complementary method to traditional calibration with discharge measurements at control river cross-sections. Modelled and observed LST from different radiometric sensors located on the ground surface, on an aeroplane and a satellite are compared for a maize field in Landriano (Italy), the agricultural district of Barrax (Spain) and the Upper Po River basin (Italy). A good ability of the model in reproducing the observed LST values in terms of mean bias error, root mean square error, relative error and Nash-Sutcliffe index is shown.

Editor Z.W. Kundzewicz; Associate editor D. Gerten