An assessment of hydrology and environmental flows in the Walawe River Basin, Sri Lanka PDF Download

Author: Smakhtin, Vladimir
Publisher: IWMI
ISBN: 9290906197
Category : Hydrology
Languages : en
Pages : 19

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Book Description
Quantification of hydrological processes and water requirements of aquatic ecosystems is required for many projects related to environmental security and efficient water use in agriculture. This also applies to the Asian monsoon region. This paper focuses on the Walawe River basin, located in a semi-arid zone of southern Sri Lanka. The two major reservoirs in the upstream and middle reaches of the river with a total capacity of 486 million cubic meters (MCM) have significantly affected the hydrology of the river, with associated adverse environmental and social consequences.

Author: Rafik Hirji
Publisher: World Bank Publications
ISBN: 0821380125
Category : Nature
Languages : en
Pages : 212

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Book Description
This book advances the understanding and integration in operational terms of environmental flows (water allocation) into integrated water resources management (IWRM). Based on an in-depth analysis of 17 global water policy, plan, and project case studies, it addresses the highly contested complexities of environmentally responsible water resources development, broadens the global perspectives on "equitable sharing" and "sustainable use" of water resources, and expands the definitions of "benefits sharing" in high-risk water resources development. The book fills a major gap in knowledge on IWRM and forms an important contribution to the ongoing discourse on climate change adaptation in the water sector.

Author: Alexandra Evans
Publisher: IWMI
ISBN: 9290907223
Category : Agricultural productivity
Languages : en
Pages : 190

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Book Description
Contributed papers presented at the conference organized by International Water Management Institute, Irrigation Dept., Dept. of Agriculture, and Hector Kobbekaduwa Agrarian Research and Training Institute.

Author: Assefa M. Melesse
Publisher: Springer Science & Business Media
ISBN: 9400706898
Category : Science
Languages : en
Pages : 431

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Book Description
This book presents results of scientific studies ranging from hydrological modelling to water management and policy issues in the Nile River basin. It examines the physical, hydrometeorological and hydrogeological description of the basin along with analysis in understanding the hydrological processes of the basin under the changing land-use stemming from population pressure and increased natural resources tapping. The book discusses the increased impact of climate change on the river flows, and such issues as water availability and demand, management and policy to offset the imbalance between demand and available resources. This book will be of interest to researchers, practitioners, water resources mangers, policy makers as well as graduate and undergraduate students. It is a useful reference text for ecohydrology, arid zone hydrology, hydrology of transboundary rivers and similar courses.

Author: Robert C. Brears
Publisher: Springer Nature
ISBN: 3030877450
Category : Social Science
Languages : en
Pages : 2334

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Book Description
While urban settlements are the drivers of the global economy and centres of learning, culture, and innovation and nations rely on competitive dynamic regions for their economic, social, and environmental objectives, urban centres and regions face a myriad of challenges that impact the ways in which people live and work, create wealth, and interact and connect with places. Rapid urbanisation is resulting in urban sprawl, rising emissions, urban poverty and high unemployment rates, housing affordability issues, lack of urban investment, low urban financial and governance capacities, rising inequality and urban crimes, environmental degradation, increasing vulnerability to natural disasters and so forth. At the regional level, low employment, low wage growth, scarce financial resources, climate change, waste and pollution, and rising urban peri-urban competition etc. are impacting the ability of regions to meet socio-economic development goals while protecting biodiversity. The response to these challenges has typically been the application of inadequate or piecemeal solutions, often as a result of fragmented decision-making and competing priorities, with numerous economic, environmental, and social consequences. In response, there is a growing movement towards viewing cities and regions as complex and sociotechnical in nature with people and communities interacting with one another and with objects, such as roads, buildings, transport links etc., within a range of urban and regional settings or contexts. This comprehensive MRW will provide readers with expert interdisciplinary knowledge on how urban centres and regions in locations of varying climates, lifestyles, income levels, and stages development are creating synergies and reducing trade-offs in the development of resilient, resource-efficient, environmentally friendly, liveable, socially equitable, integrated, and technology-enabled centres and regions.

Author: Priyanka Dissanayake
Publisher: IWMI
ISBN: 929090674X
Category : Rivers
Languages : en
Pages : 21

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Book Description
Many decisions on water allocation in river basins are made on economic grounds. Environmental and social benefits of water should also be considered in river basin management, and attempts should be made to value them similarly. This is not a straightforward task and very few studies have directly addressed this issue to date. In this paper, the Menik Ganga (River) in southern Sri Lanka is used as a case study to attempt and evaluate the costs and benefits of environmental water allocations, referred to as ‘environmental flows™ (EF). In this study, a broad definition of EF is used: the components of EF evaluated include the requirements of the religious festival, the requirements of the Yala National Park, the requirements of the Pilinnawa Coastal Wetland and the requirements of the Yala Fishery Management Area, off the coast. Almost all estimates are based on use values of EF such as marketed goods and recreation. For some components multiple estimates have been attempted. The religious EF requirement is estimated using the cost of alternative water supplies. The benefits of the EF requirement for the Yala National Park are estimated using the forgone value of tourism in the dry season and the benefits of avoiding the Human-Elephant Conflict. The Additional expenditure for the park in the dry season is also presented as another proxy estimate of the benefits of EF. The Benefit Transfer method was used for the Pilinnawa Wetland and grassland due to data constraints. The market prices of lobster and income of chank divers are used as proxies for the economic benefits of EF to the Yala Fishery Management Area. Finally, the cumulative value of the individual components is presented and discussed. The paper intends to stimulate discussion and further research on the complex subject of valuing the social and environmental benefits of water whether it is in the Menik Ganga, elsewhere in Sri Lanka or elsewhere in the world.

Author: P. G. Somaratne
Publisher: IWMI
ISBN: 9290905921
Category : Tanks
Languages : en
Pages : 48

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Book Description
This report on small tank cascade systems is based on a study conducted on seven tank cascades of the Walawe river basin, one of the three main river basins in the Ruhuna benchmark basins selected by the International Water Management Institute (IWMI) for its benchmark basin study.The overall objective of this study is to document the situation of small tank cascade systems in the basin, paying special attention to their evolution under agro-ecological, socio-economic and institutional changes on an unprecedented scale in the country after the introduction of open market economic policies in the 1970s, and thereby to contribute to the existing knowledge on small tank cascades, a key feature of water resources in the Dry zone regions2 of Sri Lanka since time immemorial.

Author: Silva, E. I. L.
Publisher: IWMI
ISBN: 9290907789
Category : Nature
Languages : en
Pages : 126

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Book Description
Sri Lanka, an island in the Indian Ocean, has lagoons along 1,338 km of its coastline. They experience low-energy oceanic waves and semidiurnal microtidal currents. The Sri Lankan coastal lagoons are not numerous but they are diverse in size, shape, configuration, ecohydrology, and ecosystem values and services. The heterogeneous nature, in general, and specific complexities, to a certain extent, exhibited by coastal lagoons in Sri Lanka are fundamentally determined by coastal and adjoining hinterland geomorphology, tidal fluxes and fluvial inputs, monsoonal-driven climate and weather, morphoedaphic attributes, and cohesive interactions with human interventions.Most coastal lagoons in Sri Lanka are an outcome of mid-Holocene marine transgression and subsequent barrier formation and spit development enclosing the water body between the land and the sea. This process has varied from one coastal stretch to another due to wave-derived littoral drift, sediment transport by tidal fluxes, fluvial inputs and wave action or, in other words, sea-level history, shore-face dynamics and tidal range as the three major factors that control the origin and maintenance of the sandy barrier, the most important features for the formation and evolution of coastal lagoons with their landward water mass. In certain stretches of Sri Lanka’s coastline, formation of the barrier spit was very active due to shore-face dynamics that resulted in chains of shore parallel, elongated lagoons. They are among the most productive in terms of ecosystem yield and show some similarities to large tropical lagoons with respect to sea entrance, zonation, biodiversity and ecosystem services. However, some of them become seasonally hypersaline due to lack of freshwater input and high evaporation. Functions and processes of some of these water bodies are fairly known. There are a fair number of small back-barrier lagoons of different shapes and sizes whose origin goes back to sea-level history. They are located on low-energy coasts with prominent beach ridges and restricted hinterland geomorphology. Mixing processes of these landward indentations are hindered by elevated sand dunes, and their salinity increases due to poor freshwater input and high evaporation leading to seasonally hypersaline conditions. These sedimented lagoons, primarily confined to the southeastern coast of the island, are biologically the least productive, with limited ecosystem values and services. Another group of moderately elongated semicircular, slightly large lagoons in the same coast, formed exclusively by submergence due to mid-Holocene sea-level rises, do not receive sufficient freshwater input leading to seasonally hypersaline conditions. They are also biologically unproductive but some are ecologically important since they provide habitats conducive to migratory birds. In contrast, some lagoons on the southern coast receive sufficient freshwater via streams draining the wet zone, maintain more estuarine salinities, exhibit rich biodiversity and serve as functional resource units. Lagoons formed by mid-Holocene submergence and recession of water level with simultaneous chain barrier formation on the high energy southwest coast, which includes cliffs, small bays and headlands, show peculiar configurations and link channel characteristics. Some of these irregular water bodies have clusters of small isles and luxuriant mangrove swamps with high biodiversity but not very rich in catadromous finfish and shellfish species due to the restricted nature of the entrance channel and nondistinct salinity gradients. The barrier-built, seasonally hypersaline lagoon complex in the Jaffna Peninsula, the largest lagoon system in the country with multiple perennial entrances show extremely narrow salinity ranges towards the upper limit of salinity. The main lagoon is elongated and the shore parallel to eastward and southward extensions is connected by narrow channels. The other lagoon in the Jaffna Peninsula is elongated, shore parallel and ribbon-shaped and receives tidal water throughout the year but freshwater is received only from precipitation and surface runoff. Even though the lagoons in the peninsula are extremely rich in ecosystem heterogeneity their hydrology and hydrodynamics have been severely disturbed by infrastructural development for transportation and by attempts to create a freshwater river for Jaffna. There are a few virgin lagoons of moderate size also on the northern coast, south of the Jaffna Peninsula on both the east and west sides. They look very typical tropical lagoons rich in biodiversity and biological production but their structure, functions and values are virtually unknown in scientific or socioeconomic terms. The lagoons located on the east coast are not numerous but relatively large in extent. They are also an outcome not only of mid-Holocene sea-level rises but of submerged multi-delta valleys or abandoned paleo estuaries. When inundated, the multi-delta valley configuration became elongated and is shore parallel with a smooth seaward shoreline; both shorelines become irregular when coastal waves are weak, and internal waves are created by the action of local winds. Configuration of a lagoon formed by inundation of an abandoned river valley is irregular with a long entrance channel extended landward. These lagoons are highly productive with a variety of associated ecosystems, large open water areas and wide perennial sea entrances. When the lagoon is too much elongated, zonation is prominent due to fewer entrance effects. Lagoons form a particular type of natural capital which generates use values (fish, shrimp, fuelwood, salt, fodder, ecotourism, anchorage, recreation, etc.) and nonuse values (habitat preservation, biodiversity, ecosystem linkages, etc.) contributing positively towards improving the human well-being. Of many values of lagoons in Sri Lanka, only the extractive values are generally utilized at present, by way of fish and shrimp catches, salt production and use of mangrove for various purposes. Besides, coastal lagoons generate a range of nonextractive use values and nonuse values, which could add towards the total economic value. Misuse has taken place at several instances when “use” adversely affects the status of the resources or the health of the ecosystem due to vulnerability and poverty, population pressure, urbanization, development activities and multi-stakeholder issues. The status of lagoon resources shows that the resources in the majority of Sri Lankan lagoons still remain satisfactory, somewhat good or very good. Nevertheless, concerns for management of lagoons in Sri Lanka exist only where “use values” (extractive values, such as fish and shrimp) exist. There is no evidence of resources management in lagoons for inspirational, scholarly values or tacit knowledge of the same. Management for use values exhibits several stages from zero management to comanagement via community management and state intervention. Most of Sri Lanka’s lagoons have the potential for generating high extractive and nonextractive use values which could improve the human well-being, while maintaining resources sustainability. Unfortunately, these potentials have not been understood or “seen” yet by the relevant authorities, although a few instances of exploring this potential were noticed.

Author: Eriyagama, N.
Publisher: IWMI
ISBN: 9290907274
Category :
Languages : en
Pages : 56

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Book Description
There is ample evidence to suggest that Sri Lanka’s climate has already changed. However, the bigger question of national importance is what Sri Lanka’s climate will look like in 50 or 100 years and how prepared the country is to face such changes. This report reviews the status of climate change (CC) research/activities in Sri Lanka in terms of observed and projected climatic changes, their impacts on water resources and agriculture, CC mitigation and adaptation, and research needs. The study also developed a pilot level CC Vulnerability Index, which was subsequently mapped at district level. The maps indicate that typical farming districts such as Nuwara Eliya, Badulla, Moneragala, Ratnapura and Anuradhapura are the most vulnerable to CC due to their heavy reliance on primary agriculture.

Author: Intergovernmental Panel on Climate Change / Working Group Technical Support Unit
Publisher:
ISBN: 9789291691234
Category : Climatic changes
Languages : en
Pages : 200

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Book Description
The Technical Paper addresses the issue of freshwater. Sealevel rise is dealt with only insofar as it can lead to impacts on freshwater in coastal areas and beyond. Climate, freshwater, biophysical and socio-economic systems are interconnected in complex ways. Hence, a change in any one of these can induce a change in any other. Freshwater-related issues are critical in determining key regional and sectoral vulnerabilities. Therefore, the relationship between climate change and freshwater resources is of primary concern to human society and also has implications for all living species. -- page vii.