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447 KiB

Open AccessArticle

Best Fit and Selection of Theoretical Flood Frequency Distributions Based on Different Runoff Generation Mechanisms

by Vito Iacobellis, Mauro Fiorentino, Andrea Gioia and Salvatore Manfreda

Water 2010, 2(2), 239-256; https://doi.org/10.3390/w2020239 - 28 May 2010

Cited by 21 | Viewed by 10419

Theoretically derived distributions allow the detection of dominant runoff generation mechanisms as key signatures of hydrologic similarity. We used two theoretically derived distributions of flood peak annual maxima: the first is the “IF” distribution, which exploits the variable source area concept, coupled with [...] Read more.

Theoretically derived distributions allow the detection of dominant runoff generation mechanisms as key signatures of hydrologic similarity. We used two theoretically derived distributions of flood peak annual maxima: the first is the “IF” distribution, which exploits the variable source area concept, coupled with a runoff threshold having scaling properties; the second is the Two Component-IF (TCIF) distribution, which generalizes the IF distribution, and is based on two different threshold mechanisms, associated with ordinary and extraordinary events, respectively. By focusing on the application of both models to two river basins, of sub-humid and semi-arid climate in Southern Italy, we present an ad hoc procedure for the estimation of parameters and we discuss the use of appropriate techniques for model selection, in the case of nested distributions. Full article

(This article belongs to the Special Issue Feature Papers)

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1157 KiB

Open AccessArticle

Increasing River Flows in the Sahel?

by Okechukwu Amogu, Luc Descroix, Kadidiatou Souley Yéro, Eric Le Breton, Ibrahim Mamadou, Abdou Ali, Théo Vischel, Jean-Claude Bader, Ibrahim Bouzou Moussa, Emmanuèle Gautier, Stéphane Boubkraoui and Philippe Belleudy

Water 2010, 2(2), 170-199; https://doi.org/10.3390/w2020170 - 07 May 2010

Cited by 91 | Viewed by 16564

Abstract

Despite the drought observed since 1968 in most of the West African Sahel, runoff and rivers discharges have been increasing in the same region. This trend is related with land use change rather than climate change. This paper aims to describe the regional [...] Read more.

Despite the drought observed since 1968 in most of the West African Sahel, runoff and rivers discharges have been increasing in the same region. This trend is related with land use change rather than climate change. This paper aims to describe the regional extension of such a phenomenon and to demonstrate that the increase in runoff is observed from the point scale up to the regional scale. It highlights the opposition of functioning between a Sahelian zone, where the Sahel’s paradox applies, and the Sudanian and Guinean areas, where runoff has been logically decreasing with the rainfall. The current trend is evidenced using experimental runoff plots and discharge data from the local to the regional scales. Full article

(This article belongs to the Special Issue Feature Papers)

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474 KiB

Open AccessArticle

The Socio-Technical Aspects of Water Management: Emerging Trends at Grass Roots Level in Uzbekistan

by Iskandar Abdullaev and Peter P. Mollinga

Water 2010, 2(1), 85-100; https://doi.org/10.3390/w2010085 - 24 Feb 2010

Cited by 31 | Viewed by 13466

Abstract

In Soviet times, water management was presented generally as a technical issue to be taken care of by the state water bureaucracy. Due to structural changes in agriculture in the two decades post-independence, irrigation water management has become an explicitly political and social [...] Read more.

In Soviet times, water management was presented generally as a technical issue to be taken care of by the state water bureaucracy. Due to structural changes in agriculture in the two decades post-independence, irrigation water management has become an explicitly political and social issue in Central Asia. With the state still heavily present in the regulation of agricultural production, the situation in Uzbekistan differs from other post-communist states. Water management strategies are still strongly ‘Soviet’ in approach, regarded by state actors as purely ‘technical’, because other dimensions – economic, social and political – are ‘fixed’ through strong state regulation. However, new mechanisms are appearing in this authoritarian and technocratic framework. The application of a framework for socio-technical analysis in some selected Water Users’ Associations (WUAs) in northwest Uzbekistan’s Khorezm region shows that the WUAs are becoming arenas of interaction for different interest groups involved in water management. The socio-technical analysis of Khorezm’s water management highlights growing social differences at grass root level in the study of WUAs. The process of social differentiation is in its early phases, but is still able to express itself fully due to the strict state control of agriculture and social life in general. Full article

(This article belongs to the Special Issue Feature Papers)

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1727 KiB

Open AccessArticle

Estimating the Ground Water Resources of Atoll Islands

by Ryan T. Bailey, John W. Jenson and Arne E. Olsen

Water 2010, 2(1), 1-27; https://doi.org/10.3390/w2010001 - 14 Jan 2010

Cited by 37 | Viewed by 14605

Abstract

Ground water resources of atolls, already minimal due to the small surface area and low elevation of the islands, are also subject to recurring, and sometimes devastating, droughts. As ground water resources become the sole fresh water source when rain catchment supplies are [...] Read more.

Ground water resources of atolls, already minimal due to the small surface area and low elevation of the islands, are also subject to recurring, and sometimes devastating, droughts. As ground water resources become the sole fresh water source when rain catchment supplies are exhausted, it is critical to assess current groundwater resources and predict their depletion during drought conditions. Several published models, both analytical and empirical, are available to estimate the steady-state freshwater lens thickness of small oceanic islands. None fully incorporates unique shallow geologic characteristics of atoll islands, and none incorporates time-dependent processes. In this paper, we provide a review of these models, and then present a simple algebraic model, derived from results of a comprehensive numerical modeling study of steady-state atoll island aquifer dynamics, to predict the ground water response to changes in recharge on atoll islands. The model provides an estimate thickness of the freshwater lens as a function of annual rainfall rate, island width, Thurber Discontinuity depth, upper aquifer hydraulic conductivity, presence or absence of a confining reef flat plate, and in the case of drought, time. Results compare favorably with published atoll island lens thickness observations. The algebraic model is incorporated into a spreadsheet interface for use by island water resources managers. Full article

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795 KiB

Open AccessArticle

A Water Balance Budget for Bung Boraphet—A Flood Plain Wetland-Reservoir Complex in Thailand

by Nutchanart Sriwongsitanon, Kritsanat Surakit and Peter R. Hawkins

Water 2009, 1(1), 54-79; https://doi.org/10.3390/w1010054 - 30 Nov 2009

Cited by 6 | Viewed by 12147

Abstract

A water balance model was developed for Bung Boraphet reservoir, a large flood plain lake in Thailand, from daily measurements over three inflow outflow cycles between 2003 and 2006. Measurement error was 10% (as one standard deviation) of the total measured volume. The [...] Read more.

A water balance model was developed for Bung Boraphet reservoir, a large flood plain lake in Thailand, from daily measurements over three inflow outflow cycles between 2003 and 2006. Measurement error was 10% (as one standard deviation) of the total measured volume. The specific yield from the Bung Boraphet catchment was 3.9 m³/ha/yr and surface water inflow from the local catchment was the largest gain term and evaporation was the largest loss term in the water budget. Irrigation was the second largest loss term and dry season demand exceeded the storage supply. Uncontrolled extraction of water for irrigation is regarded as a threat to the reservoir fishery, although the increasing drawdown range may benefit wetland biodiversity. Sustainable management of the Bung Boraphet wetland will depend on careful management based on an informed understanding of the ecohydrological requirements of all wetland uses. Water balance models like this one are recommended as a tool to allocate water equitably and in ways which can be integrated across the Chao Phraya basin. Full article

(This article belongs to the Special Issue Feature Papers)

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Review

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200 KiB

Open AccessReview

Hydrologic Restoration in the Urban Environment Using Green Roofs

by Anna Palla, Ilaria Gnecco and Luca G. Lanza

Water 2010, 2(2), 140-154; https://doi.org/10.3390/w2020140 - 09 Apr 2010

Cited by 96 | Viewed by 16237

Abstract

Loss of natural soil and vegetation within the urban environment can significantly affect the hydrologic cycle by increasing storm water runoff rates and volumes. In order to mitigate these modifications in urban areas engineered systems are developed, such as green roofs, to mimic [...] Read more.

Loss of natural soil and vegetation within the urban environment can significantly affect the hydrologic cycle by increasing storm water runoff rates and volumes. In order to mitigate these modifications in urban areas engineered systems are developed, such as green roofs, to mimic and replace functions (evapo-transpiration, infiltration, percolation) which have been altered due to the impact of human development. Green roofs, also known as vegetated roof covers, eco-roofs or nature roofs, are composite complex layered structures with specific environmental benefits. They are increasingly being used as a source control measure for urban storm water management. Indeed, they are able to re-establish the natural water cycle processes and to operate hydrologic control over storm water runoff with a derived peak flow attenuation, runoff volume reduction and increase of the time of concentration. Furthermore green roofs exhibit the capacity to reduce storm water pollution; they generally act as a storage device, consequently pollutants are accumulated in the substrate layer and released when intensive rainwater washes them out. In order to investigate the hydrologic response of a green roof, the University of Genova recently developed a joint laboratory and full-scale monitoring programme by installing a “controlled” laboratory test-bed with known rainfall input and a companion green roof experimental site (40 cm depth) in the town of Genoa. In the paper, data collected during the monitoring programme are presented and compared with literature data. Full article

(This article belongs to the Special Issue Feature Papers)

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439 KiB

Open AccessReview

Sonochemical Treatment of Water Polluted by Chlorinated Organocompounds. A Review

by José González-García, Verónica Sáez, Ignacio Tudela, María Isabel Díez-Garcia, María Deseada Esclapez and Olivier Louisnard

Water 2010, 2(1), 28-74; https://doi.org/10.3390/w2010028 - 02 Feb 2010

Cited by 92 | Viewed by 20651

Abstract

As one of several types of pollutants in water, chlorinated compounds have been routinely subjected to sonochemical analysis to check the environmental applications of this technology. In this review, an extensive study of the influence of the initial concentration, ultrasonic intensity and frequency [...] Read more.

As one of several types of pollutants in water, chlorinated compounds have been routinely subjected to sonochemical analysis to check the environmental applications of this technology. In this review, an extensive study of the influence of the initial concentration, ultrasonic intensity and frequency on the kinetics, degradation efficiency and mechanism has been analyzed. The sonochemical degradation follows a radical mechanism which yields a very wide range of chlorinated compounds in very low concentrations. Special attention has been paid to the mass balance comparing the results from several analytical techniques. As a conclusion, sonochemical degradation alone is not an efficient treatment to reduce the organic pollutant level in waste water. Full article

(This article belongs to the Special Issue Feature Papers)

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56 KiB

Open AccessReview

Market-Driven Solutions to Economic, Environmental, and Social Issues Related to Water Management in the Western USA

by Jordan A. Clayton

Water 2009, 1(1), 19-31; https://doi.org/10.3390/w1010019 - 09 Oct 2009

Cited by 15 | Viewed by 11428

Abstract

Water management issues continue to plague the western United States, including rapid population growth, degraded aquatic ecosystems, unfulfilled claims to American Indian users, the threat of global warming, an economic recession, and many other issues. This essay outlines some advantages of market-driven reforms [...] Read more.

Water management issues continue to plague the western United States, including rapid population growth, degraded aquatic ecosystems, unfulfilled claims to American Indian users, the threat of global warming, an economic recession, and many other issues. This essay outlines some advantages of market-driven reforms to the management of water resources in the western USA. Historical and contemporary western water resource issues are examined from economic, environmental, and social viewpoints. In all such contexts, it is argued that regulated water markets provide flexible and just solutions to western water dilemmas, and reallocations may provide much-needed additional water supply. Full article

(This article belongs to the Special Issue Feature Papers)

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