scholarly journals Towards an increase of flash flood geomorphic effects due to gravel mining and ground subsidence in Nogalte stream (Murcia, SE Spain)

2016 ◽  
Vol 16 (10) ◽  
pp. 2273-2286 ◽  
Author(s):  
Jose Antonio Ortega-Becerril ◽  
Guillermina Garzón ◽  
Marta Béjar-Pizarro ◽  
Jose Jesús Martínez-Díaz
Keyword(s):  
Flash Flood ◽  
Time Lag ◽  
Alluvial Fan ◽  
Ground Subsidence ◽  
Flood Event ◽  
Stream Power ◽  
Base Level ◽  
Gravel Mining ◽  
Collateral Effects ◽  
Aquifer Overexploitation

Abstract. Transition from endorheic alluvial fan environments to well-channelized fluvial systems in natural conditions may occur in response to base-level fluctuations. However, human-induced changes in semi-arid regions can also be responsible for similar unforeseen modifications. Our results confirm that in-channel gravel mining and aquifer overexploitation over the last 50 years in the case study area have changed the natural stability of the Nogalte stream and, as a result, its geomorphic parameters including channel depth and longitudinal profile have begun to adapt to the new situation. Using interferometric synthetic aperture radar (InSAR) data we obtain maximum values for ground subsidence in the Upper Guadalentín Basin of  ∼ 10 cm yr−1 for the period 2003–2010. In this context of a lowered base level, the river is changing its natural flood model to a more powerful one. A comparison of the 1973 flood event, the most dramatic flood event ever recorded in the area, with the 2012 event, where there was a similar discharge but a sediment load deficit, reveals greater changes and a new flooding pattern and extension. In-channel gravel mining may be responsible for significant local changes in channel incision and profile. This, together with the collateral effects of aquifer overexploitation, can favour increased river velocity and stream power, which intensify the consequences of the flooding. The results obtained here clearly demonstrate an existing transition from the former alluvial pattern to a confined fluvial trend, which may become more pronounced in the future due to the time lag between the drop in aquifer level and ground subsidence, and introduce a new scenario to be taken into consideration in future natural hazard planning in this area.

scholarly journals Towards an increase of flash-flood geomorphic effects due to gravel mining and ground subsidence in Nogalte stream (SE Spain, Murcia)

2016 ◽  
Author(s):  
Jose A. Ortega-Becerril ◽  
Guillermina Garzón ◽  
Marta Béjar-Pizarro ◽  
Jose Jesús Martínez-Díaz
Keyword(s):  
Flash Flood ◽  
Time Lag ◽  
Alluvial Fan ◽  
Ground Subsidence ◽  
Stream Power ◽  
Fluvial Systems ◽  
Base Level ◽  
Gravel Mining ◽  
Collateral Effects ◽  
Aquifer Overexploitation

Abstract. Transition from endorheic alluvial fan environments to well-channelized fluvial systems in natural conditions may occur in response to base-level fluctuations. However, human-induced changes in semi-arid regions can also be responsible for similar unforeseen modifications. Our results confirm that in-channel gravel mining and aquifer overexploitation over the last 50 years in the case study area have changed the natural stability of the Nogalte stream and, as a result, its geomorphic parameters including channel depth and longitudinal profile have begun to adapt to the new situation. Using interferometric synthetic aperture radar (InSAR) data we obtain maximum values for ground subsidence in the Upper Guadalentín basin of ~ 10 cm yr−1 for the period 2003–2010. In this context of a lowered base level, the river is changing its natural flood model to a more energetic one. A comparison of the 1973 flood event, the most dramatic ever recorded in the area, with the 2012 event, where there was a similar discharge but a sediment load deficit, reveals greater changes and a new flooding pattern and extension. In-channel gravel mining may be responsible for significant local changes in channel incision and profile. This, together with the collateral effects of aquifer overexploitation, can favor increased river velocity and stream power, which intensify the consequences of the flooding. The results obtained here clearly demonstrate an existing transition from the former alluvial pattern to a confined fluvial trend, which may become more pronounced in the future due to the time-lag between the drop in aquifer level and ground subsidence, and introduce a new scenario to be taken into consideration in future natural hazard planning in this area.

scholarly journals Recent human impacts and change in dynamics and morphology of ephemeral rivers

2013 ◽  
Vol 1 (2) ◽  
pp. 917-956 ◽  
Author(s):  
J. A. Ortega ◽  
L. Razola ◽  
G. Garzón
Keyword(s):  
Flash Flood ◽  
Human Impacts ◽  
Morphological Changes ◽  
Flood Event ◽  
Stream Power ◽  
Fluvial Systems ◽  
Before And After ◽  
Ephemeral Rivers ◽  
Natural Dynamics ◽  
Channel Patterns

Abstract. Ephemeral streams induce flash-flood events which cause dramatic morphological changes and impacts on population, due the intermittent activity of these fluvial systems. Human pressure changes the fluvial environment and so enhances the effects of natural dynamics. Local human-induced modifications can be latent over long periods of time. These changes can be studied after the flood event, to quantify their effects and detect which are most harmful. In this paper we study flash-flood effects at two sites in Spain and compare the results before and after a~flood event. Erosion is associated with areas where there have been more anthropogenic changes in floodplains and channels. Deposition is related to erosional processes in the watershed and to the tributaries. Disruption of river channel patterns changes connectivity and scouring appears due to energy excess. This excess tends to concentrate at weak points downstream produced by anthropic disturbances. Riparian vegetation is an energy sink and reaches with more cover show less erosion than those with deforestation. Infrastructures perpendicular to the direction of flow increase stream power, but peaks of erosion on the floodplain appear displaced downstream. It is important to detect human changes by analysis of hydraulic variables before the occurrence of an extraordinary event in order to anticipate catastrophic consequences resulting from inappropriate fluvial management.

scholarly journals Reconstructing the Tropical Storm Ketsana flood event in Marikina River, Philippines

2011 ◽  
Vol 15 (4) ◽  
pp. 1283-1289 ◽  
Author(s):  
C. C. Abon ◽  
C. P. C. David ◽  
N. E. B. Pellejera
Keyword(s):  
Metropolitan Area ◽  
Hydrologic Modeling ◽  
Time Lag ◽  
The Philippines ◽  
Tropical Storm ◽  
Flood Event ◽  
Flood Peak ◽  
Gauge Data ◽  
Metro Manila ◽  
Peak Runoff

Abstract. In September 2009, Tropical Storm Ketsana (local name: TS Ondoy) hit the Manila metropolitan area (Metro Manila) and brought an anomalous volume of rain that exceeded the Philippines' forty-year meteorological record. The storm caused exceptionally high and extensive flooding. Part of this study was a survey conducted along the stretch of the Marikina River, one of the major rivers that flooded. Post-event resident interviews were used to reconstruct the flooding in the absence of stream gauge data. Hydraulic and hydrologic modeling were carried out to understand the mechanism that brought the flood. Peak floods occurred at different hours along the river resulting from the transmission of water from the main watershed to the downstream areas. Modeled peak flood and flood timing coincided well with actual observations except for downstream stations where actual peak floods were observed to have occurred at a later time. Compounding factors such as other flood sources and stream backflow could have caused this discrepancy. Nevertheless, prediction of flood heights and the use of the known time lag between the peak rainfall and the peak runoff could be utilized to issue timely flood forecasts to allow people to prepare for future flooding.

Synoptic analysis and mesoscale numerical modelling of heavy precipitation: a case study of flash flood event in Kota Kinabalu, Malaysia

2019 ◽  
Vol 132 (2) ◽  
pp. 181-201
Author(s):  
Jackson Hian-Wui Chang ◽  
S. S. K. Kong ◽  
Justin Sentian ◽  
Jedol Dayou ◽  
Fuei-Pien Chee
Keyword(s):  
Numerical Modelling ◽  
Flash Flood ◽  
Heavy Precipitation ◽  
Flood Event ◽  
Synoptic Analysis

A Hydrometeorological Modeling Study of a Flash-Flood Event over Catalonia, Spain

2007 ◽  
Vol 8 (3) ◽  
pp. 282-303 ◽  
Author(s):  
A. Amengual ◽  
R. Romero ◽  
M. Gómez ◽  
A. Martín ◽  
S. Alonso
Keyword(s):  
Hydrological Modeling ◽  
Mesoscale Model ◽  
Flash Flood ◽  
Flood Event ◽  
Forecast Errors ◽  
Hydrological Response ◽  
Runoff Simulation ◽  
Management Procedures ◽  
Runoff Model ◽  
Modeling Study

Abstract During the early morning of 10 June 2000, the Catalonia region was affected by a hazardous convective rainfall episode that produced a large increase on flow regimes in many internal catchments of the region. The present modeling study is focused upon the Llobregat basin, the biggest internal catchment with a drainage area of 5040 km2. The first objective of the study is the characterization of the watershed hydrological response to this flash-flood event based on rain gauge data and the Hydrologic Engineering Center’s Hydrological Modeling System (HEC-HMS) runoff model. The HEC-HMS model has been calibrated using five episodes of similar torrential characteristics, and the effects of the spatial segmentation of the basin and of the temporal scale of the input rainfall field have been examined. These kinds of episodes present short recurrence intervals in Mediterranean Spain, and the use of mesoscale forecast driven runoff simulation systems for increasing the lead times of the emergency management procedures is a valuable issue to explore. The second objective uses NCEP and ECMWF analyses to initialize the nonhydrostatic fifth-generation Pennsylvania State University–NCAR Mesoscale Model (MM5) in order to simulate the 10 June 2000 flash-flood episode with appropriate space and time scales to force the runoff model. The final objective analyzes the sensitivity of the catchment’s response to the spatial and temporal uncertainty of the rainfall pattern based on an ensemble of perturbed MM5 simulations. MM5 perturbations are introduced through small shifts and changes in intensity of the precursor upper-level synoptic-scale trough. Main results indicate that 1) an optimum configuration of the runoff model can be clearly defined that best adjusts the simulated basin’s hydrological response to observed peak discharges, their timing, and total volume; 2) the MM5-control driven runoff simulation shows a reasonable reproduction of the observed discharge at the basin’s outlet and appears to be a suitable tool for the hydrometeorological forecasting of flash floods in the Llobregat basin as a whole; and 3) the ensemble of perturbed runoff simulations does not exhibit any relevant degradation of the forecast skill, and some of the members even outperform the control experiment at different stream gauge locations. That is, the catchment is relatively insensitive to rainfall forecast errors of a few tenths of kilometers and no more than 1–2 h.

Evaluating the effect of variable lithologies on rates of knickpoint migration in the Wutach catchment, southern Germany

2020 ◽  
Author(s):  
Andreas Ludwig ◽  
Wolfgang Schwanghart ◽  
Florian Kober ◽  
Angela Landgraf
Keyword(s):  
Transient Response ◽  
Stream Power ◽  
Main Trunk ◽  
Southern Germany ◽  
Level Change ◽  
Base Level ◽  
Bulk Parameter ◽  
River Profiles ◽  
Topographic Evolution ◽  
Headward Erosion

<p>The topographic evolution of landscapes strongly depends on the resistance of bedrock to erosion. Detachment-limited fluvial landscapes are commonly analyzed and modelled with the stream power incision model (SPIM) which parametrizes erosional efficiency by the bulk parameter K whose value is largely determined by bedrock erodibility. Inversion of the SPIM using longitudinal river profiles enables resolving values of K if histories of rock-uplift or base level change are known. Here, we present an approach to estimate K-values for the Wutach catchment, southern Germany. The catchment is a prominent example of river piracy that occurred ~18 ka ago as response to headward erosion of a tributary to the Rhine. Base level fall of up to 170 m triggered a wave of upstream migrating knickpoints that represent markers for the transient response of the landscape. Knickpoint migration along the main trunk stream and its tributaries passed different lithological settings, which allows us to estimate K for crystalline and sedimentary bedrock units of variable erodibility.</p>

Reconstruction of a flash flood event through a multi-hazard approach: focus on the Rwenzori Mountains, Uganda

2016 ◽  
Vol 84 (2) ◽  
pp. 851-876 ◽  
Author(s):  
Liesbet Jacobs ◽  
Jan Maes ◽  
Kewan Mertens ◽  
John Sekajugo ◽  
Wim Thiery ◽  
...  
Keyword(s):  
Flash Flood ◽  
Flood Event ◽  
Rwenzori Mountains
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