Site selection for combine hydro, irrigation and water supply in Malawi: assessment of water resource availablility

The provision of efficient, affordable, reliable and clean energy, drinking water and food to rural people is one key challenge facingMalawi to achieve theMillennium Development Goals, future sustainability and self reliance. However, the current forms of energy used in rural areas are unable to facilitate a wide range of services since the majority of the population still depends on biomass for their energy needs and rainfall for agricultural production.Multipurpose schemes for energy production, irrigation and water supply are known to provide all of these ranges of services. The choice of site for a multipurpose water resources project is based on the close interaction between the various demands within the catchment. It is therefore necessary to establish the inventory of the energy demand and water demand for other functions and the availability of the resources. This paper is focusing on assessment of the availability of water resource for multipurpose scheme development in the northern highlands of Malawi

Flood plain contribution to open channel flow structure

Enhanced understanding of the role of flood plains in dictating open-channel flow is essential for environmental and ecological management of fluvial systems. This paper presents the field measurements and primary analysis of flood flow across a compound channel in the River Severn, England. A three-dimensional acoustic Doppler velocimeter in combination with a directional current meter is deployed to measure the velocity. The statistical flow structure is compared with existing analytical formulations derived for single channel flows. The existence of a vertically double-layer structure around the interface between the main channel and the flood plain is demonstrated, indicating (a) a vertical shear-dominated flow zone near the bed; and (b) away from the bed a transverse shear-dominated flow zone with enhanced turbulent mixing. This feature necessitates concurrent consideration of both the transverse and the vertical resolution in mathematical modelling. The measured data can be utilized to assess the performance of mathematical river models

Velocity and turbulence measurements for two overbank flow events in River Severn

Field measurements of velocity and turbulence have been carried out in a study reach of the River Severn at Lower Farm near Shrewsbury during overbank flow. Acoustic Doppler velocity meters have been used for the field measurements of velocity and turbulence, particularly in the interface region between river channel and floodplain. The values of local shear velocity and roughness length for the reach under study were calculated using measured velocity data. The distributions of turbulent intensities, and the Reynolds stresses are also presented. The variation of horizontal shear stress in the vertical direction deviates from linear for the main channel/floodplain interaction region due to the existence of a lateral shear and momentum transfer from the floodplain towards the main channel. Comparisons are made between the field data and previous experimental data from the Flood Channel Facility