10 results for Arias, M.E.

  • Assessment of flow changes from hydropower development and operations in Sekong, Sesan and Srepok Rivers of the Mekong Basin

    Piman, T.; Cochrane, T.A.; Arias, M.E.; Green, A.; Dat, N.D. (2013)

    Journal Articles
    University of Canterbury Library

    The Mekong River supports unique biodiversity and provides food security for over sixty million people in the Indo-Burma region, but potential changes to natural flow patterns from hydropower development are a major risk to the wellbeing of this system. Of particular concern is the ongoing and future development of 42 dams in the transboundary Srepok, Sesan and Sekong (3S) Basin which contributes up to 20% of the Mekong's annual flows and provides critical ecosystem services to the downstream Tonle Sap Lake and the Mekong Delta. To assess the magnitude of potential changes, daily flows were simulated over 20 years using the HEC ResSim and SWAT models for a range of dam operations and development scenarios. A 63% increase in dry season flows and a 22% decrease in wet season flows at the outlet of the 3S Basin can result from the potential development of new dams in the main 3S Rivers under an operation scheme to maximize electricity production. Water level changes in the Mekong River from this scenario are comparable to changes induced by the current development of Chinese dams in the Upper Mekong Basin and are significantly higher than potential flow changes from the proposed 11 mainstream dams in the Lower Mekong Basin. Dams on the upper sub tributaries of the 3S Basin have very low impacts on seasonal flow regimes because most of those projects are run-of-river dams and have small reservoir storages. Impacts on hourly flow changes due to intra daily reservoir operations, sediment movement, water quality and ecology need further study. Strategic site selection and coordinated reservoir operations between countries are necessary to achieve an acceptable level of development in the basin and mitigate negative impacts to seasonal flow patterns which sustain downstream ecosystem productivity and livelihoods.

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  • Modelling the Impact of Large Dams on Flows and Hydropower Production of the Sekong, Sesan, and Srepok Rivers in the Mekong Basin

    Cochrane, T.A.; Piman, T.; Arias, M.E. (2013)

    Conference Contributions - Other
    University of Canterbury Library

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  • Analysis of water level changes in the Mekong Floodplain impacted by flood prevention systems and upstream dams

    Dang, D.T.; Arias, M.E.; Van, P.D.T,; Vries, T.T.; Cochrane, T.A. (2015)

    Conference Contributions - Published
    University of Canterbury Library

    The rapid construction of water infrastructure in the Mekong Basin, including upstream dams and delta-based flood prevention systems, is raising public concerns due to potential impacts on ecosystems and agricultural productivity. Sixty eight multi-purpose dams, accounting for 71 billion m3 of active volume in total, had been built since the 1960s. It is estimated that an additional sixty seven dams with 68 billion m3 of active volume will be operational in the next ten years, resulting in highly regulated downstream flows. The Normalized Difference Vegetation Index (NDVI) was analyzed based on the MODIS satellite sensor images (temporal solution of 16-days), which indicates that the flood protected areas had increased nearly 3 times in the past 14 years (from 2000 to 2014) in the upper part of the Vietnam Mekong Delta. Flood prevention systems were built to increase rice production from two to three crops a year and to protect residential areas in the floodplain. This development has caused a significant reduction in water retention capacity of the floodplain and higher water levels in adjacent floodplain areas. Changes in historical water levels along the lower Mekong River ranging from the most upstream (Kratie) to the middle (Kampong Cham, Phnom Penh, Tan Chau, Chau Doc and Can Tho) and the coast station (Vam Kenh) were also analyzed. Historical alterations in water level patterns (maximum, minimum, rise rate, fall rate and fluctuations) over time were then associated with the development of either dams or flood prevention systems. Rise rates at the Kratie station in the upper part of the floodplain gradually decreased by 25% between 1960 and 2013, but remained rather constant at Phnom Penh, the middle of the floodplain. In the lower part of the floodplain, alterations to water levels, rise rates and fall rates have been higher since 2006, and this corresponds to the operation of flood prevention projects in the Vietnam Mekong Delta. The impact of existing upstream dams on the Vietnam Mekong Delta is currently buffered by the Tonle Sap Lake and Cambodian floodplains. Overall, the conclusion is that the development of flood prevention systems is currently a key driver of water level changes in the delta.

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  • The current and future impact of water resources development on flows and livelhoods of the Mekong River

    Cochrane, T.A.; Arias, M.E.; Piman, T. (2014)

    Conference Contributions - Other
    University of Canterbury Library

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  • Modelling future changes of habitat and fauna in the Tonle Sap wetland of the Mekong

    Arias, M.E.; Cochrane, T.A.; Elliott, V. (2014)

    Journal Articles
    University of Canterbury Library

    The Tonle Sap is the largest wetland in Southeast Asia and the heart of the largest inland fishery in the world. Its unique flood pulse system and annual flow reversal is a hotspot for biodiversity and productivity, as well as an essential habitat for many endangered fishes and birds. Despite predicted changes to the wetland’s hydrology due to climate change and hydropower development in the Mekong, the consequent impacts on the fauna of the lake are poorly understood. A spatial modelling framework was developed to simulate the impact of potential scenarios of change using relationships between fauna and biophysical characteristics. Potential impacts on 61 animal species with documented nutritional, conservation or ecological value were examined. A large number of species rely on gallery forest to provide important habitats for their life history, yet this area is likely to be highly impacted by permanent inundation.There is a strong synchronicity between life histories and the flood pulse; consequently continued hydrological disruptions will have a significant impact on ecosystem dynamics, imposing further challenges to conservation. Protecting areas that may become suitable for gallery forests and shrublands under a modified flood regime will be crucial to management planning and the maintenance of a diverse and healthy ecosystem.

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  • Paying the forest for electricity: A modelling framework to market forest conservation as payment for ecosystem services benefiting hydropower generation

    Arias, M.E.; Cochrane, T.A.; Lawrence, K.; Killeen, T.J.; Farrell, T.A. (2011)

    Journal Articles
    University of Canterbury Library

    Published in PESC Special issue: Payments for ecosystem services in conservation: performance and prospects

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  • Impacts of Hydrological Alterations to the Tonle Sap Ecosystem of the Mekong River Basin

    Arias, M.E.; Cochrane, T.A. (2013)

    Conference Contributions - Other
    University of Canterbury Library

    • The Tonle Sap is the largest wetland and fishery in the Mekong but it is expected to be affected by hydropower and climate change • Landscape-scale spatial distribution of habitats were found to be largely driven by flood duration patterns. • The flood-pulse hydrology could explain most of the underlying variability in soil and vegetation field-scale characteristics. • Hydropower could cause distinct seasonal changes, while climate change could increase inter-annual uncertainty. • Fauna species richness was found to be greatest in natural habitats likely to experience the most significant disruptions

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  • A landscape approach to assess impacts of hydrological changes to vegetation communities of the Tonle Sap Floodplain

    Arias, M.E.; Cochrane, T.A.; Caruso, B.; Killeen, T.; Kummu, M. (2011)

    Conference Contributions - Published
    University of Canterbury Library

    The Tonle Sap is South East Asia’s largest lake and Cambodia’s most important fishery. The hydrology of the Tonle Sap is directly linked to water levels of the Mekong River, which will experience major alterations as a response to hydropower development, irrigation, and climate change. This paper proposes a landscape approach to understand the impacts of hydrological alteration on the floodplain’s terrestrial vegetation. A land cover map, a digital elevation map and historical water records were used to create histograms of water depth for key vegetation communities. These histograms were used to create maps of vegetation coverage probability for future scenarios of hydrological changes. Selected scenarios of water resources development and climate change were used to demonstrate how vegetation could shift within the floodplain. This approach generated satisfactory results for land cover classes that extend over large portions of the floodplain such as wet season rice, abandoned fields, flooded shrubland and open lake.

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  • Simulated changes in water flows of the Mekong River from potential dam development and operations on the Se San and Sre Pok tributaries

    Cochrane, T.A.; Arias, M.E.; Teasley, R.L.; Killeen, T.J. (2010)

    Conference Contributions - Published
    University of Canterbury Library

    Rapid regional growth and energy demands have driven plans to build numerous dams along the Mekong’s mainstem and its tributaries prompting significant concern for potential changes in seasonal flow regimes and subsequent impacts on fisheries and biodiversity. In this paper, we demonstrate how multiple dam development and operation in the Se San and Sre Pok tributaries can affect flows in the mainstem of the Mekong. The Se San and Sre Pok tributaries were chosen because they are undergoing rapid dam development, are close to key wetlands, and because they contribute substantial flows to the Mekong. Dam operations along the Se San and Sre Pok Rivers were modelled with the HEC-HMS (Hydrological Modelling System) and HEC-ResSim (Reservoir Simulation) models. Two levels of dam development and three reservoir operation scenarios were modelled. For all operation scenarios of existing and high priority dams, daily changes in water flows and levels occur, but overall seasonal effects are low. However, substantial changes in discharge flows result when large medium priority dams are included and operated to maximize electricity generation. Dry season flows nearly double and wet season peak flows are significantly reduced, translating to changes in the order of 8% of water flows in the receiving Mekong River at Stung Treng. Changes in flows are clearly dependent on the number, size, and operation of reservoirs in the basin. However, simulation results imply that a coordinated management of dams operated under a wider set of rules to minimize changes to natural flow pulses can be a key to maximize total economic return by including the value of downstream ecosystem services. This analysis provides a methodology and basis for future work on studying changes in water levels from dam operations by which strategic options for dam development in the Mekong can be considered.

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  • Critical Basin at Risk: Assessing and managing ecosystem pressures from development and climate change in the 3S basin

    Cochrane, T.A.; Arias, M.E.; Piman, T.; Shrestha, B.; Oeurng, C. (2014)

    Conference Contributions - Other
    University of Canterbury Library

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