IRRIGATION SYSTEM PERFORMANCE AND ITS IMPACT ON CROP PRODUCTIVITY IN SRI LANKA (pp. 226-234)
Fuard Marikar, John Wilkin-Wells, Susan Smolnik and R.K. Sampath
Abstract: This article analyses the performance of two irrigation systems in Sri Lanka, using performance measures adapted from Theil’s mean-square forecast error concept. The performance is measured in terms of defined objectives that are decomposed into three components measuring adequacy, equity or dependability of water deliveries, and management capability. The relationship between the level of performance, as estimated by the above measures, and crop productivity is determined using regression analysis. The study demonstrates that input and institutional variables such as fertilizer, labour and power concentration have a positive impact on yields while poor irrigation management performance has a negative effect.
RIVER CHANNEL CHANGES IN THE LOWER MBOKODWENI RIVER: A CASE STUDY OF THE 1987 FLOOD (pp. 235-243)
G. du T. de Villiers and P.M.U. Schmitz
Abstract: This article deals with river channel conditions before and after a rare flood event. The characteristics of five cross-sections before the flood are described and compared with post-flood conditions. Hydraulic and flow data for the pre- and postflood channel are presented. It is maintained that the land adjoining the new channel can be developed if certain precautionary measures are taken.
CULTURE OF WATER CONSERVATION FOR PROGRESS (pp. 244-247)
Abstract: Water is a vital element for the plant and animal environment, and especially for human beings. Water is also an economic asset because of its importance and scarcity, and a social asset with respect to the quality of life. The conservation of water is thus an essential factor in development. The question then arises: what type of development? The one known as ‘growth’ or the one called ‘progress’? Water and its many uses represent not only growth, but progress. Water conservancy is, therefore, action for progress. Water conservation means using it in the right way: the right kind of works, correct management and accurate control. The techniques for management and control must be consistent with the proper use of water. The controversy of small versus big is meaningless where the size of the works is concerned: each situation calls for its own appropriate solution.
A SELF‐CORRECTION TECHNIQUE FOR REAL‐TIME SIMULATION OF REGULATED RIVERS (pp. 248-256)
Olcay I. Unver
Abstract: An automatic self-correction scheme is presented for online adjustment of streamflow forecasts during simulation of river systems with regulating structures, when actual flow data for interior points are available in real time. Another scheme is presented which allows for the modelling of channel losses due to physical effects such as evapotranspiration, bank storage and diversions. A previously developed river simulation/reservoir management model has been modified to include both schemes. The model is particularly useful for real-time, short-term flood forecasting and reservoir operation. The model application is made to the Lower Colorado River in Texas.
GROUNDWATER INVESTIGATIONS IN PAKISTAN: AN EMPHASIS ON DESERT AREAS (pp. 257-269)
L. A. Khan
Abstract: The desert regions of Pakistan are located in all the four provinces and occupy a large area. The climate in deserts is very hot and dry. The annual rainfall is scanty (100-150 mm) and uncertain. The water-table varies from over 10 m in Cholistan to more than 100 m in Tharparkar. A programme for groundwater exploration in the desert areas of Pakistan was initiated in 1986. The exploration was carried out in selected parts of Cholistan (Punjab), Tharparkar and Nara (Sindh) and Winder in Balochistan Province. In the Cholistan desert (Punjab) a fresh groundwater body containing less than 1000 ppm of total dissolved solids in an area of about 1500 km2 has been discovered. The values of the coefficient of transmissivity and storage range from 120 to 1200 m2/day and 3.0 × 10-4 to 2.1 × 10-3 respectively. In the Tharparkar desert (Sindh), an acceptable quality of groundwater containing up to 2500 ppm of total dissolved solids has been discovered in sandstone formation.
THE GREAT MANMADE RIVER PROJECT: A PARTIAL SOLUTION TO LIBYA’S FUTURE WATER SUPPLY (pp. 270-278)
Omar M. Salem
Abstract: The southern part of Libya is a desert area of negligible population density overlying two of the largest ground-water basins in the world: the Murzuk basin in the south-west and Kufra-Sarir basin in the south-east. In situ utilization of these huge groundwater reserves is uneconomical due to poor soils and unsuitable climatic conditions. Extensive hydrogeological studies conducted during the last two decades have indicated the possibility of transferring over 6 million m3 per day to the coastal zones in the north. The Great Manmade River Project was launched in 1983 aiming at a rational utilization of the transported water for agricultural and urban developments, along with restoration of the affected aquifers. The project consists of five phases and is planned to be completed before the turn of the century. This article highlights the technical aspects of this major project in terms of water availability, water quality, future drawdowns, cost of water, well-field design and other hydrogeological parameters. An analysis of the critical water supply conditions of Libya which necessitated the creation of this project as the most economically feasible solution is also provided.
OCCURRENCE AND DISTRIBUTION OF LEACHATE IN A SOLID WASTE LANDFILL: A FIELD-SCALE STUDY (pp. 279-285)
Reza M. Khanbilvardi, Shabbir Ahmed and Phillip J. Gleason
Abstract: A field-scale analysis for leachate flow was done for Sections 1/9 and 6/7 of the Fresh Kills landfill at Staten Island, New York. The leachate monitoring programme included field data collection of the leachate mound level for a six-month period. The monitoring points consisted of discretely screened piezometers and wells set at various depths down to the bottom of the landfill. The position of the iso-leachate mound head lines, derived from the field data, represented and delineated the shape of the leachate mound inside the landfill. The field data of the leachate mound head were used in the analysis of the hydraulic properties of the refuse and leachate flow rates through Sections 1/9 and 6/7 of the landfill. Piezometers and wells installed near the existing leachate collection line in Section 1/9 helped establish the gradients from which a refined estimate of the hydraulic conductivity was made. From the leachate mound head contours and flow gradients, contributions of flow from different sections of the mound were identified. Finally, the leachate flow rates were computed using Darcy’s law.
ENVIRONMENTAL CONSEQUENCES OF MENIK GANGA DIVERSION (pp. 286-291)
Abstract: Kirindi Oya Irrigation and Settlement Project is one of the main activities of the Southern Development Programme in Sri Lanka. The project has been in operation for the past five years though the reservoir constructed has not filled to the expected level. During this period it has met with a number of problems due to shortage of water. In an attempt to obtain sufficient water, a new proposal is being considered to divert water from another river, the Menik Ganga, into this reservoir. A feasibility study funded by ADB has recently been completed but does not include an environmental impact assessment. However, because of increasing public involvement it has been decided to do a socio-economic study with an environmental component. This article attempts to deliberate the environmental consequences of the proposed project.
Climatic Fluctuations and Water Management, by M.A. Abu-Zeid and A.K. Biswas, Buttenvorth Heinemann, Oxford, 1992
Developing an integrated approach, International Symposium on Transboundary River Basin Management and Sustainable Development, The Netherlands, 18—22 May 1992