Daulat Khan

Sustainable groundwater – a need of sustainable agriculture

Globally, irrigated agriculture is the largest extractor and the most frequent consumer of groundwater resources, with important groundwater-dependent and largely spread agro-economies. Quality of irrigation water is one of the key factors which have either direct or indirect impact on plant growth, soil and water management practices and plant yields. This work aims at highlighting the importance of periodic assessment of groundwater quality for irrigation, impact of different chemical parameters on plant yield and agriculture and water management practices needed in adverse irrigation water conditions. This study was conducted in semi-arid area where salinity and alkalinity are considered the main threats to the sustainable irrigation agriculture. Thirty representative samples were collected for chemical analyses from various sources of groundwater, within an area of 36 km 2 , lying in the north-east of the Lakki Marwat district Pakistan. The standard values suggested by WAPDA, FAO and USDA Handbook 60 were used as benchmark for comparison. The electrical conductivity and pH values together classify groundwater as saline-alkaline. It is revealed that none of the water samples has an adverse impact on the yield of barley, sorghum and wheat while 7% and 17% of this water respectively reduce the yield of corn and onion by 50%. Besides, 7% of this water reduces the yield of alfalfa by 25%. This work recommends management practices such as deep ploughing, provision of adequate drainage and crop rotation for improving the use of such water.

Withdrawn: Dissolved oxygen model for a river with extreme flow variations

This paper has been withdrawn by the authors due to errors in the results. A dissolved oxygen (DO) model is calibrated under low and medium flow conditions, while verification of the model is done under low flow condition, for a heavily polluted river. The Soan River is located in Pakistan, with large flow variations. The biokinetic rate coefficients for nitrogenous biochemical oxygen demand and carbonaceous biochemical oxygen demand (CBOD) are determined through ammonia river profiles and measured CBOD. A close agreement between the DO model results and the field values shows that the verified model can be used to develop DO management strategies for the Soan River. The biokinetic coefficient is known to vary with the degree of treatment (DOT) and needs to be adjusted for a rational water quality management model. The effect of this variation on the level of treatment has been evaluated by using the verified model to attain a DO standard of 4 mg/l in the river using the biokinetic rate coefficient. The r...

FACTORS AFFECTING FUEL EFFICIENCIES OF COMMERCIAL TRUCKS

Poor maintenance practices of commercial trucks, apart from a host of environmental problems, are leading to major fuel inefficiencies in the road transport sector of Pakistan. One hundred and fifty diesel operated commercial trucks were selected nationally for identification of the factors and their quantitative contribution to the fuel losses. Truck vintage caused up to 40.6% reduction in fuel efficiency, whereas the practice of keeping original motors on vehicles for 10-15 years further decreased the efficiency by 49.9%. Similarly, state of engine, road condition, speed of operation and type of steering significantly contributed to the fuel efficiency. Proper tune-up of vehicles, on the average, lowered the fuel expenses by 18 percent. This amounts to a saving of seven litres of diesel for a 100kW truck moving through i00km. All this suggested promotional activities for adoption of Original Equipment Manufacturers (OEM) schedules for vehicles maintenance.

DETERMINATION OF ROUGHNESS COEFFICIENT FOR WATERCOURSE DESIGN

Mannings roughness coefficient was evaluated for three water courses two lined (trapezoidal and rectangular concrete) and one in unlined condition. The derive values tended to be somewhat higher than those listed in available literature, because of small size of water courses and the tropical vegetation involved. A large variation of the coefficient depending on the channel conditions was evident. The results pointed out that moderate vegetation growth in earthen channels can increase the roughness coefficient causing increase in the depth of flow and thus increase the losses by 2 to 3 times. The study concluded that by cleaning water courses, roughness can be reduced and as a result the conveyance losses can be reduced significantly. Design roughness coefficient for concrete lined and earthen water courses are recommended as 0.014 and 0.035 respectively.

THE EFFECT OF LATERAL MOVEMENT OF WATER ON THE INFILTRATION RATE OF SOIL

Lateral movement of water causes significant loss during the infiltration process. To determine the effect of lateral movement on the infiltration rate, five different sites were selected randomly. Soil at each site was analyzed and preinfiltration soil moisture was measured. Both single and double infiltrometers on each site were installed to measure the infiltration rate. The results from these experiments are presented. Parameters of the Kostiakov equation were determined from regression analysis. The results of sites 2,3, and 5 show significant variation between the infiltration rate from single and double ring infiltrometers, while those of site 1 show a minor change. From the experimental results it is clear that significant loss of water occurs in the dense tillage operated field, which has a major role in the infiltration process.