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This book presents a comprehensive and up-to-date overview of the soils of Sri Lanka. Including sections on the soil research history, climate, geology, geomorphology, major soil types, soil maps, soil properties, soil classification, soil fertility, land use and vegetation, soil management, soils and humans, soils and industry, and future soil issues, the book summarizes the current state of knowledge in a concise and highly reader-friendly way.
The tropics provide the key to understanding much biological and Earth science. This is particularly true for the study of landforms, which in higher latitudes suffer great seasonal contrasts in process intensity and type, and which often in the past underwent the dramatic changes of glaciation and periglaciation. Yet studies in the tropics have shown that the legacy of past climate changes is much more dramatic than was formerly believed. This book, first published in 1985, brings together the variety of evidence about such environmental changes, over a variety of timescales, and sets it against the current knowledge of the nature of geomorphic processes in the tropics.
Agriculture is one of the most important economic sectors of Sri Lanka and is key to the livelihoodof its population. As agriculture is one of the sectors most vulnerable to climate change, a thorough understanding of its impact is critical for formulating informed and effective adaptation strategies. Climate change challenges agriculture in many ways and affects – directly or indirectly – the economy, productivity, employment and food security. Assessing the impacts of climate change on crops is fundamental for elaborating evidence-based adaptation policies and strategies, guaranteeing sustainable pathways towards intensification and adopting climate-smart agricultural practices. This report presents insights about future climate change impacts on six crops (rice, maize, green gram, big onion, chilli and potato), selected according to a wide range of criteria: contribution to gross domestic product, relevance to food security and role as staple food, importance for farming systems, social impact, effect on employment, role as animal feed, consumer preferences, contribution to the export market, climatic vulnerability/resilience, market prices and price fluctuations, and farming input requirements.
The core of this study involved an examination and analysis of certain key features of the traditional small tank cascade systems: a) the location and design of the systems in the past b) the hydro-system which considers the overall hydrological balance and groundwater conditions c) maintenance and tank use d) tank management and integration with local farming systems.
Chapter 1: Rice and its environment. Chapter 2: The geography of rice (oryza sativa L.). Chapter 3: The hidrology of rice-lands. Chapter 4: Classification of soils on which rice is Grown. Chapter 5: Soil-forming process in aquatic rice lands. Chapter 6: Soil and land properties that affect the growth of rice. Chapter 7: Elements for evaluation of land for rice growing.
This work is intended for advanced readers interested in methods of sustainable land management - the prevention and control of land degradation. It offers a coherent view of the situation concerning land degradation and the human response to the problem. It is generally recognized that technological solutions alone cannot solve the problems of land degradation. This book discusses the role of land use and land management policies, programmes, insitutional innovations, and economic incentives for the control and prevention of land degradation. Special attention is given to legal issues at the international level and in individual countries.
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.