Evaluation of Urban Growth Using Remote Sensing and GIS Tools Case Study on Thanjavur City, Tamil Nadu, India

Evaluation of urban expansion and its use play a vital role in effective urban management in terms of providing water supply, storm water drainage, sewerage and solid waste collection. In recent years, the significance of spatial data technologies, especially the application of remotely sensed data, has increased and geographical information systems (GIS) have been widely used. This study investigates the urbanization process in terms of land use, built up density and sprawl using remotely sensed images of Thanjavur City, located in Tamil Nadu State of India, as a case study and (GIS). The changes in the land use were analyzed from a topographical map of 1970, images from a ETM+ EarthSat 1999 and IRS P6, 2006. The results revealed significant changes in land use and proportion of high, medium and low density built up area. Further, it has been identified that in the study area dominates the leapfrog sprawl rather than low density and ribbon sprawl

Estimation of Surface Run-off for Urban Area Using Integrated Remote Sensing and GIS Approach

Urban run-off increases significantly due to increased impervious area and reduced drainage network. Evaluation of land use in urban area plays a vital role as input to the estimation of runoff. The hydrological design standard for urban water resources planning and management is commonly based on the frequency of occurrence of heavy rainfall events. In the present study, the occurrence of most frequent heavy rainfall event is investigated for Thanjavur town, located in the State of Tamilnadu, India and used for estimation of run-off depth. The Soil Conservation Service Curve Number (SCS-CN) is used for evaluating run-off depth value for event rainfall starting from 10 mm to 400 mm. The land use detail for the study area was obtained by integration of GIS and remote sensing. The spatial variation of event rainfall is considered with certain percentage of deviation from base rainfall for each triangle area that contributes to the run-off. The results of the analysis indicate that the study area can produce the run-off volume more than that required for urban water management at an average seasonal rainfall

Optimisation procedure for pipe-sizing with break-repair and replacement economics

The importance of incorporating break-repair costs and pipe-replacement costs in optimal design of a water distribution network is highlighted and demonstrated with a hypothetical network. Deterioration due to ageing of pipes requires expensive maintenance and causes inconvenience. The number of breaks generally increases exponentially with pipe age and smalldiameter pipes are more likely to break than large-diameter pipes. After a certain age, it would be more cost-effective to replace the pipes than to repair them. The optimisation models which do not consider the maintenance costs tend to result in smaller pipe sizes. The proposed model incorporates both the repair cost and the replacement cost in addition to initial cost. The proposed model is demonstrated by applying it to a 2-loop network. Incorporating pipe-break and replacement economics into optimisation leads to slightly larger diameter pipes. The analysis also reveals that consideration of repair/replacement is essential if the pipe breaks cause high economic impact, the pipe-break growth rate increases fast and discount rate is low. For the example network considered, for a typical set of values, the cost benefit is as much as 12.92%. For cases with low breakage rates, incorporating repair/replacement has been found to make no practical difference. The results show that considering pipe break and pipe replacement in optimisation is important as this could save considerable amounts of money over the lifetime.Keywords: water distribution network, pipe-break analysis, optimisation, network design, economic