Threshold Runoff Computation for Flash flood forecast on Small Catchment Scale

Abstract. Variational methods are widely used for the analysis and control of computationally intensive spatially distributed systems. In particular, the adjoint state method enables a very efficient calculation of the derivatives of an objective function (response function to be analysed or cost function to be optimised) with respect to model inputs. In this contribution, it is shown that the potential of variational methods for distributed catchment scale hydrology should be considered. A distributed flash flood model, coupling kinematic wave overland flow and Green Ampt infiltration, is applied to a small catchment of the Thoré basin and used as a relatively simple (synthetic observations) but didactic application case. It is shown that forward and adjoint sensitivity analysis provide a local but extensive insight on the relation between the assigned model parameters and the simulated hydrological response. Spatially distributed parameter sensitivities can be obtained for a very modest calculation effort (~6 times the computing time of a single model run) and the singular value decomposition (SVD) of the Jacobian matrix provides an interesting perspective for the analysis of the rainfall-runoff relation. For the estimation of model parameters, adjoint-based derivatives were found exceedingly efficient in driving a bound-constrained quasi-Newton algorithm. The reference parameter set is retrieved independently from the optimization initial condition when the very common dimension reduction strategy (i.e. scalar multipliers) is adopted. Furthermore, the sensitivity analysis results suggest that most of the variability in this high-dimensional parameter space can be captured with a few orthogonal directions. A parametrization based on the SVD leading singular vectors was found very promising but should be combined with another regularization strategy in order to prevent overfitting.

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Extending the Predictability of Hydrometeorological Flood Events Using Radar Rainfall Nowcasting

Journal of Hydrometeorology ◽

10.1175/jhm514.1 ◽

2006 ◽

Vol 7 (4) ◽

pp. 660-677 ◽

Cited By ~ 55

Author(s):

Enrique R. Vivoni ◽

Dara Entekhabi ◽

Rafael L. Bras ◽

Valeriy Y. Ivanov ◽

Matthew P. Van Horne ◽

...

Keyword(s):

Lead Time ◽

Flash Flood ◽

Spatial Scales ◽

Surface Characteristics ◽

Hydrologic Model ◽

Flood Events ◽

Catchment Scale ◽

Radar Rainfall ◽

Time Operation ◽

Forecast Lead Time

Abstract The predictability of hydrometeorological flood events is investigated through the combined use of radar nowcasting and distributed hydrologic modeling. Nowcasting of radar-derived rainfall fields can extend the lead time for issuing flood and flash flood forecasts based on a physically based hydrologic model that explicitly accounts for spatial variations in topography, surface characteristics, and meteorological forcing. Through comparisons to discharge observations at multiple gauges (at the basin outlet and interior points), flood predictability is assessed as a function of forecast lead time, catchment scale, and rainfall spatial variability in a simulated real-time operation. The forecast experiments are carried out at temporal and spatial scales relevant for operational hydrologic forecasting. Two modes for temporal coupling of the radar nowcasting and distributed hydrologic models (interpolation and extended-lead forecasting) are proposed and evaluated for flood events within a set of nested basins in Oklahoma. Comparisons of the radar-based forecasts to persistence show the advantages of utilizing radar nowcasting for predicting near-future rainfall during flood event evolution.

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Evaluation of olive grove management on various soils at the micro-catchment scale with the AnnAGNPS model to quantify their impacts on organic carbon

10.5194/egusphere-egu2020-13427 ◽

2020 ◽

Author(s):

Encarnación Taguas ◽

Ronald L. Bingner ◽

Henrique Momm ◽

Robert R. Wells ◽

Martin Locke

Keyword(s):

Organic Carbon ◽

Sandy Loam ◽

Experimental Studies ◽

Life Time ◽

Conventional Tillage ◽

Catchment Scale ◽

Maximum Increase ◽

Small Catchment ◽

Silty Loam ◽

The Impact

Soil organic carbon (SOC) stock changes are crucial to identify the risk of desertification in fragile areas such as the Mediterranean Basin and to fulfill environmental protection global conventions. In Spain, 48% of the world&#8217;s olive oil is produced with 2.6 Mha dedicated to the crop and there is clear concern over the carbon balance in the context of climate change and the resulting loss of productivity. In this work, 108 scenarios were prepared with the model AnnAGNPS in a small catchment of extensive olive groves by considering the impact of soil type and management using 6 different soil types (with textures sandy, S; sandy loam, Slo; loam, L; clay loam, Clo; silty loam clay, SiLoC; clay, C), 3 different managements (no till, NT; conventional tillage, CT, and cover crop, SC), 3 types of fertilization (two organic with different rates, F2 and F3,&#160; and another inorganic F1) and 2 contrasting reach organic carbon half-life time (0.1 day-730 days). The consistency of the simulated values of annual OC attached to the sediments and of variations of ground SOC (h=200 mm) were evaluated and compared in the context of the region of Andalusia.There were significant differences of annual values of the sediment OC for the scenarios of soil and management with a range variation between 0.0 kg.ha-1 and 368.9 kg.ha-1. In addition, S and SC showed the lowest variability intervals while Clo and NT had the highest sediment OC and variation ranges. For the SOC pools, the effects of soil and fertilization types were more evident than of the management. The combination C-SC-F3 presented the maximum increase of SOC (0.150 mg OC.g-1soil.y-1) while the combination Slo-NT-F1 presented the minimum (0.080 mg OC.g-1soil.y-1). Despite specific calibrations needed to quantify OC balances, the consistency of the hydrological and erosive parameterization based on the abundance of experimental studies supports the use of AnnAGNPS for simulating the OC loss in agricultural catchments.

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Hydrological response of a small catchment burned by experimental fire

Hydrology and Earth System Sciences ◽

10.5194/hess-16-267-2012 ◽

2012 ◽

Vol 16 (2) ◽

pp. 267-285 ◽

Cited By ~ 70

Author(s):

C. R. Stoof ◽

R. W. Vervoort ◽

J. Iwema ◽

E. van den Elsen ◽

A. J. D. Ferreira ◽

...

Keyword(s):

Hydrological Processes ◽

Canopy Interception ◽

Catchment Scale ◽

Small Catchment ◽

Hydrological Impact ◽

Central Portugal ◽

Extreme Flooding ◽

Rain Events ◽

Physical Changes ◽

Fire Impact

Abstract. Fire can considerably change hydrological processes, increasing the risk of extreme flooding and erosion events. Although hydrological processes are largely affected by scale, catchment-scale studies on the hydrological impact of fire in Europe are scarce, and nested approaches are rarely used. We performed a catchment-scale experimental fire to improve insight into the drivers of fire impact on hydrology. In north-central Portugal, rainfall, canopy interception, streamflow and soil moisture were monitored in small shrub-covered paired catchments pre- and post-fire. The shrub cover was medium dense to dense (44 to 84%) and pre-fire canopy interception was on average 48.7% of total rainfall. Fire increased streamflow volumes 1.6 times more than predicted, resulting in increased runoff coefficients and changed rainfall-streamflow relationships – although the increase in streamflow per unit rainfall was only significant at the subcatchment-scale. Fire also fastened the response of topsoil moisture to rainfall from 2.7 to 2.1 h (p = 0.058), and caused more rapid drying of topsoils after rain events. Since soil physical changes due to fire were not apparent, we suggest that changes resulting from vegetation removal played an important role in increasing streamflow after fire. Results stress that fire impact on hydrology is largely affected by scale, highlight the hydrological impact of fire on small scales, and emphasize the risk of overestimating fire impact when upscaling plot-scale studies to the catchment-scale. Finally, they increase understanding of the processes contributing to post-fire flooding and erosion events.

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Hydrological response of a small catchment burned by experimental fire

Hydrology and Earth System Sciences Discussions ◽

10.5194/hessd-8-4053-2011 ◽

2011 ◽

Vol 8 (2) ◽

pp. 4053-4098 ◽

Cited By ~ 3

Author(s):

C. R. Stoof ◽

R. W. Vervoort ◽

J. Iwema ◽

E. van den Elsen ◽

A. J. D. Ferreira ◽

...

Keyword(s):

Soil Water ◽

Water Repellency ◽

Hydrological Processes ◽

Canopy Interception ◽

Soil Water Repellency ◽

Catchment Scale ◽

Small Catchment ◽

Hydrological Impact ◽

Rain Events ◽

Fire Impact

Abstract. Fire can considerably change hydrological processes, increasing the risk of extreme flooding and erosion events. Although hydrological processes are largely affected by scale, catchment-scale studies on the hydrological impact of fire are scarce, and nested approaches are rarely used. Taking a unique approach, we performed a catchment-scale experimental fire to improve insight into the drivers of fire impact on hydrology. In north-central Portugal, rainfall, canopy interception, streamflow and soil moisture were monitored in shrub-covered paired catchments pre- and post-fire. Post-fire runoff coefficients were higher than pre-fire, and fire changed the rainfall-streamflow relationship – although the increase in streamflow was only significant at the subcatchment-scale. Fire also increased the response of topsoil moisture to rainfall, and caused more rapid drying of topsoils after rain events. Since soil physical changes due to fire were not apparent, we suggest that changes resulting from vegetation removal played an important role in increasing streamflow after fire, namely: (1) increased effective rainfall and decreased transpiration – increasing the amount of water available for (sub)surface runoff, (2) more rapid development of soil water repellency and decreased surface water storage – increasing overland flow risk, (3) more rapid breakdown of post-fire soil water repellency – increasing infiltration during extended rain events. Results stress that fire impact on hydrology is largely affected by scale, highlight the hydrological impact of fire on small scales, and emphasize the risk of overestimating fire impact when upscaling plot-scale studies to the catchment-scale. Finally, they increase understanding of the processes contributing to post-fire flooding and erosion events.

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Towards a webcam-based snow cover monitoring network: methodology and evaluation

10.5194/tc-2019-142 ◽

2019 ◽

Cited By ~ 1

Author(s):

Céline Portenier ◽

Fabia Hüsler ◽

Stefan Härer ◽

Stefan Wunderle

Keyword(s):

Snow Cover ◽

Monitoring Network ◽

Grid Cell ◽

Swiss Alps ◽

European Alps ◽

Catchment Scale ◽

Small Catchment ◽

Point Field ◽

Camera Orientation ◽

Elevation Model

Abstract. Snow cover variability has a significant impact on climate and environment and is of great socio-economic importance for the European Alps. Terrestrial photography offers a high potential to monitor snow cover variability, but its application is often limited to the small catchment scale. Here, we present a semi-automatic procedure to derive snow cover maps from arbitrary webcam images. We use freely available webcam images of the Swiss Alps and propose a procedure for the georectification and snow classification of such images. In order to avoid the effort of manually setting ground control points (GCPs) for each webcam, we implement a new registration approach that automatically resolves camera parameters (camera orientation, principal point, field of view (FOV)) by using an estimate of the webcams position and a high-resolution digital elevation model (DEM). Furthermore, two recent snow classification methods are compared and analyzed. The resulting snow cover maps have the same spatial resolution as the DEM and indicate whether a grid cell is snow-covered, snow-free, or not visible from webcams' positions. GCPs were used to evaluate our novel automatic image registration approach. The evaluation reveals in a root mean square error (RMSE) of 14.1 m for standard lens webcams (FOV

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Soil Erosion and Sediment Deposition Modelling at the Small Catchment Scale

Geografie ◽

10.37040/geografie2012117020170 ◽

2012 ◽

Vol 117 (2) ◽

pp. 170-191 ◽

Cited By ~ 1

Author(s):

Barbora Vysloužilová ◽

Zdeněk Kliment

Keyword(s):

Soil Erosion ◽

River Sediment ◽

Agricultural Land ◽

Catchment Scale ◽

Erosion And Deposition ◽

Small Catchment ◽

Erosion Processes ◽

Erosion Models ◽

Deposition Processes ◽

Gis Environment

Water erosion is considered to be the most important factor behind the degradation of agricultural land. Many methods of measuring soil erosion processes, using mathematical models, have been developed in recent years. The most widespread of these, USLE, and its modifications have been used as the basis for new erosion models. Two such models, USPED (Mitášová et al. 1996) and WaTEM/SEDEM (Van Rompaey et al. 2001; Van Oost et al. 2000; Verstraeten et al. 2002), have been utilized to study erosion and deposition processes in the experimental rural catchment of Černičí. River sediment transport is also calculated using the WaTEM/ SEDEM model. The results are discussed with results from USLE and a field survey. The article also presents brief instructions for implementing the models in a GIS environment.

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