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Irrigation Projects (irrigation + project)

Distribution by Scientific Domains

Engineering	66%

Selected Abstracts

Application of a checklisting technique for the assessment of impacts of the Chashma Right Bank Canal on land use and cropping pattern of D.I.Khan District, Pakistan,

IRRIGATION AND DRAINAGE, Issue 2 2008
Atta-ur-Rahman
utilisation des terres; assolements; impacts Abstract This paper attempts to discover the ex post impact of the Chashma Right Bank Canal (CRBC) on the land use and cropping pattern of D.I.Khan district. The CRBC commands 250,000,ha and is spread over two provinces. The CRBC project was completed in three stages. Stage I was commissioned in 1987,88, and stages II and III in 1989 and 2001, respectively. The CRBC brought radical changes in the land use and cropping pattern of D.I.Khan district. For this study, three variables were selected including land use, cropping pattern and land values. To discover these changes at micro-level, five sample villages were randomly selected, four from within the CRBC command area and one outside. The analysis found that after commissioning of the CRBC, prime cultivable land was brought under non-agricultural use. The net sown area was also enhanced. Dry farming crops were replaced by water-intensive cash crops, which in effect caused the twin problem of waterlogging and salinity, particularly in stage I. Likewise, land values increased considerably. This study is a sort of ex post evaluation of the CRBC and provides policy guidelines for decision makers and for the proposed Chashma Right Bank 1st Lift Irrigation Project not to repeat the weaknesses of Chashma Right Bank Irrigation Project. Copyright © 2008 John Wiley & Sons, Ltd. Cet article essaie de mesurer l'impact à postériori du canal de rive droite de la Chashma (CRBC) sur l'utilisation des terres et les assolements du District de D.I.Khan. Le CRBC dessert 250,000,ha, répartis sur deux provinces. Le projet du CRBC a été mené à bien en trois étapes. L'étape I a été réalisée en 1987,1988, et les étapes II et III en 1989 et 2001, respectivement. Le CRBC a apporté des changements radicaux à l'utilisation des terres et aux assolements du District de D.I.Khan. Pour cette étude, les trois variables retenues ont été l'utilisation des terres, les assolements et le prix des terres. Pour mettre en évidence ces changements au niveau micro, cinq villages témoin ont été choisis au hasard, quatre dans la zone de desserte du CRBC et un en dehors. L'analyse a montré qu'après la mise en route du CRBC, les meilleures terres cultivables ont cessé d'être utilisées pour l'agriculture. La surface nette emblavée a également augmenté. Les cultures en sec ont été remplacées par des cultures commerciales fortement consommatrices d'eau, ce qui a en fait créé les problèmes jumeaux de l'engorgement et de la salinité, en particulier au cours de l'étape I. De même, les prix des terres se sont considérablement accrus. Cette étude est une sorte d'évaluation à postériori du CRBC, permettant de fournir des directives aux décideurs et de ne pas répéter pour le projet envisagé d'irrigation haut-service en rive droite de la Chashma les faiblesses du premier projet. Copyright © 2008 John Wiley & Sons, Ltd. [source]

RESERVOIR OPERATION ANI EVALUATION OF DOWNSTREAM FLOW AUGMENTATION,

JOURNAL OF THE AMERICAN WATER RESOURCES ASSOCIATION, Issue 3 2001
Mahesh Kumar Sahu
ABSTRACT: Operation of a storage-based reservoir modifies the downstream flow usually to a value higher than that of natural flow in dry season. This could be important for irrigation, water supply, or power production as it is like an additional downstream benefit without any additional investment. This study addresses the operation of two proposed reservoirs and the downstream flow augmentation at an irrigation project located at the outlet of the Gandaki River basin in Nepal. The optimal operating policies of the reservoirs were determined using a Stochastic Dynamic Programming (SDP) model considering the maximization of power production. The modified flows downstream of the reservoirs were simulated by a simulation model using the optimal operating policy (for power maximization) and a synthetic long-term inflow series. Comparing the existing flow (flow in river without reservoir operation) and the modified flow (flow after reservoir operation) at the irrigation project, the additional amount of flow was calculated. The reliability analysis indicated that the supply of irrigation could be increased by 25 to 100 percent of the existing supply over the dry season (January to April) with a reliability of more than 80 percent. [source]

Stabilization of soft clay in irrigation projects,

IRRIGATION AND DRAINAGE, Issue 2 2005
M. M. Mubeen
stabilisation de chaux; utilisation d'argile molle; déchet de pierre pulvérisée; ouvrage d'irrigation Abstract Clay,lime improvement is an effective means to improve soft clay soil. Lime stabilization especially improves the strength and the workability of the clay soil. In addition, lime improvement provides more resistance to the soil structure and to the effect of weather on the soil structure. This study has investigated lime stabilization of soft clay and the possibility of utilizing waste rock powder produced in crusher plants as a supplemental material for lime stabilization in order to increase the strength of the soil structure. The purpose of the study was to apply the results especially in irrigation projects in order to avoid the problems of soft clay on irrigation structures in Sri Lanka. However, the results and conclusions can be considered for other regions, where the same type of soft clay problems exists. The Dutch Oostvaardersplassen (OVP) soft clay, which has a high plasticity, low shear strength and high natural water content, was chosen for the investigations. The results of unconfined compressive strength for different water contents of clay and also for different lime and waste rock powder contents show an excellent increase in strength and workability. The waste rock powder proved to increase the effect of lime stabilization. The strength improvement caused by waste rock powder is more significant for those soils which have a low clay content. Since in irrigation projects a wide range of clay soils exist, this investigation may be useful to utilize waste rock powder in order to improve the quality and the durability of the foundation of irrigation structures in the long run. Therefore the application of lime and rock material improvement on soft clay in irrigation projects may be a useful approach to stabilize soft soils and improve medium-scale shallow foundation irrigation structures and road and canal embankments, including repairing canal leaks. It has also been found that by applying this method in irrigation projects in Sri Lanka, the stabilization cost for structures on soft clay can be significantly reduced compared to other methods. Copyright © 2005 John Wiley & Sons, Ltd. L'amélioration de l'argile avec de la chaux est une moyenne effective pour améliorer la terre de l'argile molle. Spécialement la stabilisation de chaux améliore la force et la maniabilité de la terre argileuse. De plus l'amélioration de chaux fournit plus de résistance à la structure de la terre avec l'effet du temps sur la structure de la terre pendant les conditions atmosphériques différentes. Dans cette étude on a examiné la stabilisation de chaux dans l'argile molle et la possibilité de utiliser des déchets de pierre pulvérisée, obtenus par pulvériser des usines, comme une matérielle supplémentaire pour la stabilisation de chaux afin que la force de la structure de la terre s'améliore. L'objective de cette étude était d'appliquer les résultats spécialement dans des projets d'irrigation pour éviter des problèmes de l'argile molle dans des structures d'irrigation en Sri Lanka. Les résultats et les conclusions peuvent être considérés pour d'autres régions, ayant le même problème de l'argile molle. Les Oostvaarderplassen (OVP) en Hollande ont de l'argile molle ayant une plasticité haute, une résistance au cisaillement basse et un haut pourcentage de l'eau naturelle. C'est pour ça les Oostvaardersplassen ont été choisis pour accomplir la recherche. Les résultats de la force de pression indéfinie pour des teneurs en eau différents dans l'argile, aussi pour les teneurs en chaux différents et des déchets de pierres pulvérisées montrent une augmentation excellente de la force et de la maniabilité. Les déchets de pierre pulvérisée se révèlent d'augmenter l'effet de la stabilisation de chaux. L'amélioration de la force, causée par les déchets de pierre pulvérisée, est plus significative pour ces terres ayant un teneur d'argile bas. Parce que les projets d'irrigation ont beaucoup de la terre d'argile cette recherche peut être utile pour user des déchets de pierre pulvérisée pour améliorer la qualité et la durabilité de la fondation des structures d'irrigation à long terme. C'est pourquoi l'application du matériel de chaux et de pierre sur de l'argile molle dans des projets d'irrigation peut être une approche utile pour stabiliser des terres molles et peut améliorer des structures de fondations d'irrigation dans des eaux pas profondes, dans des remblais de chemins et de canaux, inclus dans des réparations des fuites de canaux. Aussi on a révélé qu'en appliquant ce méthode dans des projets d'irrigation en Sri Lanka les coûts de la stabilisation des structures sur de l'argile molle peuvent être réduits d'une manière importante comparée avec d'autres méthodes. Copyright © 2005 John Wiley & Sons, Ltd. [source]

Policies, plans, practice, and prospects: irrigation in northeastern Syria

LAND DEGRADATION AND DEVELOPMENT, Issue 2 2007
F. Hole
Abstract Over the past half-century the agricultural landscape of northeastern Syria has been transformed, due in large part to the introduction of significant irrigation to the steppe. At the beginning of this period, irrigation was confined almost entirely to river floodplains and natural depressions. The steppe was dominated by wintertime rain-fed agriculture and year-round grazing. The introduction of diesel-powered wells and, subsequently, state-operated dam and canal systems, has led to the expansion of both wintertime and summertime irrigation on the steppe away from the floodplain. The sustainability of these irrigation projects has always been suspect. Even as technologies for water extraction have allowed for previously impossible patterns of cultivation, the combination of declining water quality, a deepening water-table, and degradation-prone soils have limited crop yields and led to the rapid abandonment of many steppe farms. The actual trajectory of land-use in the region is determined by social and political forces as well as by hydrology and surficial geology. In this paper we examine recent land-use history in the watersheds of two tributaries of the Euphrates River, the Balikh and Khabur. A review of historical drivers of development in the region is combined with satellite analyses to provide an overview of the structure and dynamics of land-use in this water-limited region. Copyright © 2006 John Wiley & Sons, Ltd. [source]

Impact of irrigation on malaria in Africa: paddies paradox

MEDICAL AND VETERINARY ENTOMOLOGY, Issue 1 2001
J. N. Ijumba
Summary The high population growth rate of the African continent has led to an increased demand for food and is in danger of outstripping agricultural production. In order to meet this need, many governments have sought ways of improving food production by initiating large-scale irrigation projects, involving reclamation of arid and semi-arid areas for the cultivation of crops. Although crop irrigation promises one solution to alleviating hunger and encourages economic growth, irrigation has often been blamed for aggravating disease in local communities. Malaria is one of the major tropical diseases associated with irrigation schemes, and changes in the transmission pattern of this disease following irrigation development have been a perennial subject of debate. It has often been assumed that high numbers of malaria vector Anopheles mosquitoes (Diptera: Culicidae) resulting from irrigation schemes lead inevitably to increased malaria in local communities. However, recent studies in Africa have revealed a more complex picture. Increased numbers of vectors following irrigation can lead to increased malaria in areas of unstable transmission, where people have little or no immunity to malaria parasites, such as the African highlands and desert fringes. But for most of sub-Saharan Africa, where malaria is stable, the introduction of crop irrigation has little impact on malaria transmission. Indeed, there is growing evidence that for many sites there is less malaria in irrigated communities than surrounding areas. The explanation for this finding is still unresolved but, in some cases at least, can be attributed to displacement of the most endophilic and anthropophilic malaria vector Anopheles funestus Giles by An. arabiensis Patton with lower vectorial capacity, as the latter thrives more than the former in ricefields. Similarly, among members of the An. gambiae complex, some cytotypes of An. gambiae sensu stricto are more vectorial than others. For example, the Mopti form has high vectorial capacity and breeds perennially in irrigated sites, whereas the savanna form is often sympatric but more seasonal. Also we suggest that many communities near irrigation schemes benefit from the greater wealth created by these schemes. Consequently irrigation communities often have greater use of bednets, better access to improved healthcare and receive fewer infective bites compared with those outside such development schemes. Thus, in most cases, irrigation schemes in Africa do not appear to increase malaria risk, except in areas of unstable transmission. However, developers should take the opportunity to improve health-care facilities for local communities when planning irrigation schemes wherever they occur. [source]