Research
Effect of Different Bed Configuration on Flow Resistance under Different Flow Regimes in an Open Channel
This study was conducted to evaluate the effect of different bed configuration/bed-forms on flow resistance for different flow conditions in an open channel. The study was limited to investigate whether the flow resistance increases or decreases. The inter-relationship of flow discharge on the friction factor (f) and their quantitative relationship was also determined. A physical model was constructed in the Model Tray Hall of Centre of Excellence in Water Resource Engineering (CEWRE), University of Engineering & Technology Lahore, Pakistan. The sediment commonly available in rivers of Pakistan was used in the channel as bed load under different scenarios. The sediments as bed load were used having the size ranging from 0.5 to 1.2 mm. The bed-forms were predicted using the Athaullah, Simons, Richardson and Van Rijn’s Approach. Darcy–Weisbach equation was used to compute the friction factor (f). The results showed that the friction factor (f) in clear water decreased with increase of discharge upto 18 liter per second and a plane bed type was formed. For flow of 18 to 25 liter per second, a ripple bed type was formed due to increase in friction factor. For flow rate of 25 to 40 liter per second the friction factor decreased and dune bed type was formed.
Appraisal of Sediment Load in Rainfed Areas of Pothwar Region in Pakistan
Inadequate watershed management, natural, and man induced erosion of soils in the barani areas have threatened the sustainability of soil and water resources. In this study, sediment loads in the main streams passing through rainfed areas of the Pothwar region has been estimated for verifying the impacts of projects being implemented for agricultural development in the regions, especially the construction of small dams. The study has been carried out in three major basins namely Soan, Kanshi and Haro of Pothwar region. The daily discharge, sediment and rainfall data for the period 1982-2004 were analyzed and correlated accordingly. The sediment load has increased with the increase of river flow and vice versa. The unit rate of sediment yield decreased as the drainage area increased. Moreover, the observed sediment concentrations were low in low rainfall areas (Dhok Pathan) and high in areas fall under high rainfall zone (Chirah and Rawalpindi). Generally, the sediment concentration waslow during January to June (low rainfall) and high during months of October to December (high rainfall). The study concluded that sediment load beyond sustainable limits can affect the land and water resources negatively which can be identified by exploring basin hydrology and predicting sediment load as well as mitigating potential threats through application of computer simulation model.
