Net Gains from Conjunctive Use of Surface and Ground Water

Pakistan is fortunate enough because its soils, topography and climate are generally suitable for farming but its agriculture sector faces the problem of scarcity of the irrigation water. This paucity of irrigation supplies has forced the farmers to use the ground water to augment their surface supplies. The quality of ground water in Pakistan varies from fit for irrigation to moderately saline to sodic. Thus the tubewell owners in the marginal quality ground water areas are bound to use the tubewell water in conjunction with the surface water on their farms. Currently the farmers are using about 65.75 BCM of ground water in Pakistan [Halcrow (2002)]. The international literature is filled with the studies on conjunctive water management and its impact on crop productivity and related issues [Gangwar and Toorn (1987); Bredehoeft and Young (1983); Gorelick (1988); Lingen (1988); O’Mara (1988); Shah (1988); Brewer and Sharma (2000); Datta and Dayal (2000); Raju and Brewer (2000); Sakhtivadivel and Chawala (2002) and Chaudhary and Shah (2003)]. In Pakistan, the review of literature shows that all of the previous studies conducted in the arena of water management reported the management problems leading to the inefficiencies in irrigation application and reduction in crop productivity, [Kijne and Velde (1991); Mustafa (1991) and Siddiq (1994)]. Few of the studies took into consideration the impact of waterlogging and salinity on productivity at farm level [Meyer, et al. (1996); Prathaper, et al. (1997) and O’Connell and Khan (1999)]. None of these studies have taken into consideration the trade-offs between gross farm income, ground water and salinity at irrigation subdivision level. To answer the issues of spatial differences in the trade offs between gross farm income, ground water and salinity at irrigation Subdivision level, this paper presents the results of the optimisation modeling at the Subdivisional level

Efficiency Improvement of Fault-Tolerant Three-Level Power Converters

Fault-tolerant power converters play a critical role in the transportation electrification. However, fault-tolerant operation, high efficiency, and low cost usually result in design criteria that have conflicting constraints and goals. The majority of the fault-tolerant power converter topologies presented in the literature confirm these conflicts. In this paper, three types of fault-tolerant neutral-point clamped (NPC) converters are investigated. Various modulation strategies are explored to reduce the losses of the redundant phase leg. The simulation and experimental results show that the Switching Frequency Optimal Phase opposition Disposition modulation strategy is the most effective approach in minimizing the losses in the redundant phase leg

Participatory Irrigation Management and its Financial Viability: A Case Study

Water is a key input of agriculture. In the past, the area under cultivation was small and there was less stress on farmers to grow more and more of each crop. Water was considered a free good. The situation has changed since. The increase in cropping intensity has led to a rise in the demand for irrigation water. Water is not a free good any more. The provision of irrigation water to the farmer’s fields is going to be costlier. The Government of Pakistan is spending heavily on the operation and maintenance of the irrigation system yet shortage of funds is a major reason for deferred maintenance, which threatens the operational integrity of the irrigation system [World Bank (1988) and Haq (1995)]. The shortfall in O&M funding was estimated to be more than 24 percent in 1993 [World Bank (1994)]. As poor O&M has direct effect on the productivity of agriculture, indirectly it affects the whole economy [Carruthers (1981)]. The allocation of funds for the increasing O&M costs is becoming a problem for the Government of Pakistan with every successive year. One logical answer to this problem is to increase abiana1 fees from the users of irrigation water supplies. The revenue collected through abiana may be used for O&M purposes, but it has been reported that the revenue collection is far less than the expenditures incurred. Resultantly the gap has been increasing every year [Chaudhry (1989)]. This situation demands investigation of abiana recovery and increasing O&M costs to know the real situation which in turn will help in deciding whether it is feasible to divert the financing of O&M activities towards farmer organisations (completely or partially). This paper aims at estimating the present level of operation and maintenance expenditures of the H-4-R Distributary and the present situation of the abiana collection and the extent of its leakage through different means.

Genetic Markers and Duodenal Ulcer

Serum pepsinogen, ui-antitrypsin (ui-AT) and blood groups were studied as genetic markets in 32 patients with endoscopically proven duodenal ulcer and 44 control subjects with no family history of ulcer disease. Serum pepsinogen was detennined by the modified method of Edward et al7, a1-AT by single radial hnmunodiffusion8 (RID) and phenotyping was carried out by isoelectric focusing (IEF)9. Duodenal ulcer patients with hyper- pepsinogenemia (28%) and low serum ui-AT (35%) had a dominant blood group 0, lower mean age, an early onset of disease, a higher frequency of gastrointestinal (CI) bleeding and ulcer perforation. These parameters were found considerably different in patients with normal serum pepsi­nogen and ui-AT. Phenotype analysis of a1-AT revealed that four duodenal ulcer patients had partial deficiency of the protease inhibitor and none of the normal exhibited the deficiency pattern. The etiology of the disease appears to be genetic anomaly in 28% of patients while the rest (72%) had ulcers as a result of neuroendocrinological or environmental factors (JPMA 47:135,1997)

Trade Liberalisation Policies, Intra-regional Trade and Opportunities for Sustainable Agricultural Development

Many of the Near East (NE) countries are currently opening their agricultural markets at three distinct but interacting levels: unilateral liberalisation, regional integration schemes and multilateral trade liberalisation. These changes hold important implications for intra- and extra-regional trade, use of agricultural resources and sustainability of agricultural development in the NE countries. Unilaterally, and since the late 1980s, most countries of the region have liberalised their agriculture sectors by eliminating or reducing input subsidies, removing or reducing guaranteed producer prices, reducing the number of subsidised commodities and liberalising the exchange rate and the trade regime. Most of the implicit and explicit subsidies for agricultural inputs and outputs were withdrawn. However, some of the NE countries were able to continue supporting agriculture mainly for food security reasons. Experiences showed that domestic reform is necessary but not sufficient condition for economic growth.

Flowfield-dependent variant method for moving-boundary problems

A novel numerical scheme using the combination of flowfield-dependent variation method and arbitrary Lagrangian–Eulerian method is developed. This method is a mixed explicit–implicit numerical scheme, and its implicitness is dependent on the physical properties of the flowfield. The scheme is discretized using the finite-volume method to give flexibility in dealing with complicated geometries. The formulation itself yields a sparse matrix, which can be solved by using any iterative algorithm. Several benchmark problems in two-dimensional inviscid and viscous flow have been selected to validate the method. Good agreement with available experimental and numerical data in the literature has been obtained, thus showing its promising application in complex fluid–structure interaction problems

Estimating the Production Potential of Major Crops in Pakistan’s Irrigated Agriculture during the 21st Century

Land and irrigation are the basic resources in agriculture. The role and importance of these resources and their contribution towards productivity, in the context of the country’s increasing population, can hardly be exaggerated. Pakistani agriculture is set in a very distinctive situation of an increasing population on the one hand and diminishing resources on the other. The population of Pakistan was reported to be 131.63 million in 1996 and is projected to be 207 million in 2013 [Pakistan (1996) and WSIP (1990)]. The agriculture sector has to face the difficult task of doubling the existing food production by the turn of this century. The situation demands horizontal and vertical growth in the productivity, either by bringing more land under cultivation, or by increasing the cropping intensity of the existing land resources. This can also be accomplished by bringing more land under cultivation from the cultivable uncultivated area (a large proportion of which exists on medium and large farms under waterlogged or saline conditions). In this context, it becomes important to identify the nature of the relationship that exists between farm size and unculturable wastelands and the kinds of changes the green revolution/SCARPs projects introduced to this relationship.

Exact and Heuristic Algorithms for Runway Scheduling

This paper explores the Single Runway Scheduling (SRS) problem with arrivals, departures, and crossing aircraft on the airport surface. Constraints for wake vortex separations, departure area navigation separations and departure time window restrictions are explicitly considered. The main objective of this research is to develop exact and heuristic based algorithms that can be used in real-time decision support tools for Air Traffic Control Tower (ATCT) controllers. The paper provides a multi-objective dynamic programming (DP) based algorithm that finds the exact solution to the SRS problem, but may prove unusable for application in real-time environment due to large computation times for moderate sized problems. We next propose a second algorithm that uses heuristics to restrict the search space for the DP based algorithm. A third algorithm based on a combination of insertion and local search (ILS) heuristics is then presented. Simulation conducted for the east side of Dallas/Fort Worth International Airport allows comparison of the three proposed algorithms and indicates that the ILS algorithm performs favorably in its ability to find efficient solutions and its computation times