Fluvial Processes in Dryland Rivers

Graf, William L.

doi:10.1007/978-3-642-83048-8

Cited by 393 publications

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“…1). The Avelós stream is an ephemeral river of 2 nd order (Graff, 1987), ca. 8 km extension, medium steepness of 9.7 m/km and a drainage area of 42 km 2 .…”

Section: Study Areamentioning

confidence: 99%

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Hydrologic cycle and dynamics of aquatic macrophytes in two intermittent rivers of the semi-arid region of Brazil

2006

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The dynamics of aquatic macrophytes in intermittent rivers is generally related to the characteristics of the resistance and resilience of plants to hydrologic disturbances of flood and drought. In the semi-arid region of Brazil, intermittent rivers and streams are affected by disturbances with variable intensity, frequency, and duration throughout their hydrologic cycles. The aim of the present study is to determine the occurrence and variation of biomass of aquatic macrophyte species in two intermittent rivers of distinct hydrologic regimes. Their dynamics were determined with respect to resistance and resilience responses of macrophytes to flood and drought events by estimating the variation of biomass and productivity throughout two hydrologic cycles. Twenty-one visits were undertaken in the rewetting, drying, and drought phases in a permanent puddle in the Avelós stream and two temporary puddles in the Taperoá river, state of Paraíba, Northeast Brazil. The sampling was carried out by using the square method. Floods of different magnitudes occurred during the present study in the river and in the stream. The results showed that floods and droughts are determining factors in the occurrence of macrophytes and in the structure of their aquatic communities. The species richness of the aquatic macrophyte communities was lower in the puddles of the river and stream subject to flood events, when compared to areas where the runoff water is retained. At the beginning of the recolonization process, the intensity of the floods was decisive in the productivity and biomass of the aquatic macrophytes in the Taperoá river and the Avelós stream. In intermediate levels of disturbance, the largest values of productivity and biomass and the shortest time for starting the recolonization process occurred.Keywords: stream, disturbance, flood, drought, aquatic macrophyte. RESUMO Ciclo hidrológico e dinâmica de macrófitas aquáticas em dois rios intermitentes da região semi-árida do BrasilA dinâmica de macrófitas aquáticas em rios intermitentes está relacionada com as características de resistência e resiliência das plantas as perturbações hidrológicas da cheia e da seca. A região semi-árida do Brasil apresenta rios e riachos intermitentes, com ocorrência de eventos de perturbação em diferentes graus de intensidade, freqüência e duração ao longo de um ciclo hidrológico. O objetivo deste estudo foi determinar a ocorrência e variação de biomassa de espécies de macrófitas aquáticas em dois rios intermitentes de regime hidrológico distintos. A dinâmica foi determinada pelas respostas de resistência e resiliência das plantas aos eventos de cheia e de seca, através da variação da biomassa e produtividade ao longo de dois ciclos hidrológicos. Foram realizadas 21 visitas de campo durante as fases de reinundação, 576 PEDRO, F., MALTCHIk, L. and BIANCHINI JR., I.

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“…1). The Avelós stream is an ephemeral river of 2 nd order (Graff, 1987), ca. 8 km extension, medium steepness of 9.7 m/km and a drainage area of 42 km 2 .…”

Section: Study Areamentioning

confidence: 99%

“…The Taperoá river is a temporary river of the 6th order (Graff, 1987), whose water remains for several months throughout the year. Its source is at 720 m above sea level; it runs eastwards with a medium steepness of 2.2 m/km discharging its water into the Boqueirão dam.…”

Section: Study Areamentioning

confidence: 99%

Hydrologic cycle and dynamics of aquatic macrophytes in two intermittent rivers of the semi-arid region of Brazil

2006

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“…Indeed, in Mediterranean ephemeral streams, water remains in the channel for too short a time for evaporation to be an important Ž . factor Graf, 1988 . It must therefore be infiltration and transmission losses that reduce Ž .…”

Section: Hydrological Lossesmentioning

confidence: 99%

Flood events in Mediterranean ephemeral streams (ramblas) in Valencia region, Spain

Belmonte

Beltrán

2001

CATENA

143

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This article deals with flood events in Mediterranean ephemeral streams typical of the Valencia Ž region. The combination of the basin physical characteristics steep slopes, sparse vegetation, thin . soils and permeable rock and intense, heavy and irregularly distributed rain, generates flash floods. Runoff generation is sudden, giving rise to flash floods with sharp, narrow hydrographs with short time lags. The high amount of runoff is, nevertheless, only a small fraction of the total rainfall, since the characteristics of the river basins are such that infiltration of large amounts of water occurs. Using daily hydrological data from the Rambla de la Viuda basin and 5-min data from both the Barranc del Carraixet and the Rambla de Poyo basins, the rainfall-runoff processes have been analysed during flood events in these ephemeral streams. q

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“…The curve number (CN) method (USDA 1986) allows surface runoff volumes of individual storm events to be estimated; it is widely used because of its simplicity and the limited number of parameters required for runoff prediction (e.g., Graf 1988;Ponce and Hawkins 1996;Bhuyan et al 2003). It is used in a wide range of design situations and has been integrated into many hydrologic, erosion, and water-quality models such as CREAMS (Knisel 1980), SWRRB (Williams et al 1985;Arnold et al 1990), AGNPS (Young et al 1989), EPIC (Sharpley and Williams 1990), PERFECT (Littleboy et al 1992), WEPP (Risse et al 1994) and SWAT.…”

Section: Cn Runoff Estimationmentioning

confidence: 99%

A Simplified Hydrological Method for Flood Risk Assessment at Sub-basin Level in Niger

Fiorillo

Tarchiani

2017

Renewing Local Planning to Face Climate Change in the Tropics

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Flood events are increasing year by year in the Sahel, mainly caused by climate and land use changes. New strategies and tools are necessary to optimize flooding risk reduction plans. This paper presents a new hydrological method (FREM, Flooding Risk Evaluation Method), based on the curve number runoff estimation. The method can be adopted for small-medium basins and is based on the integration of remote sensing techniques with field surveys and participatory mapping. It consists of preliminary identification of the areas and sub-basins that most contribute to the flood risk; scenarios can then be developed in order to: (i) optimize the placement of traditional water retention structures in the elementary sub-basins that contribute most to the overall risk, (ii) assess the contribution of each hydraulic structure to reduce the total risk, (iii) give a priority ranking to these structures identifying those most urgent. The main advantages of this method are that it is easy to use and can be implemented using free available land cover, soil and morphology data and open-source GIS (Geographic Information System) software. A case study for the Ouro Gueladjo basin (Tillabery Region, Niger) is presented.

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Fluvial Processes in Dryland Rivers

Cited by 393 publications

References 0 publications

Hydrologic cycle and dynamics of aquatic macrophytes in two intermittent rivers of the semi-arid region of Brazil

Hydrologic cycle and dynamics of aquatic macrophytes in two intermittent rivers of the semi-arid region of Brazil

Flood events in Mediterranean ephemeral streams (ramblas) in Valencia region, Spain

A Simplified Hydrological Method for Flood Risk Assessment at Sub-basin Level in Niger

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