Blantyre City has experienced a wide range of changes in land use and land cover (LULC). This study used Remote Sensing (RS) to detect and quantify LULC changes that occurred in the city throughout a twenty-year study period, using Landsat 7 Enhanced Thematic Mapper (ETM+) images from 1999 and 2010 and Landsat 8 Operational Land Imager (OLI) images from 2019. A supervised classification method using an Artificial Neural Network (ANN) was used to classify and map LULC types. The kappa coefficient and the overall accuracy were used to ascertain the classification accuracy. Using the classified images, a postclassification comparison approach was used to detect LULC changes between 1999 and 2019. The study revealed that built-up land and agricultural land increased in their respective areas by 28.54 km2 (194.81%) and 35.80 km2 (27.16%) with corresponding annual change rates of 1.43 km·year−1 and 1.79 km·year−1. The area of bare land, forest land, herbaceous land, and waterbody, respectively, decreased by 0.05%, 90.52%, 71.67%, and 6.90%. The LULC changes in the study area were attributed to urbanization, population growth, social-economic growth, and climate change. The findings of this study provide information on the changes in LULC and driving factors, which Blantyre City authorities can utilize to develop sustainable development plans.

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This paper is to discuss the main factors leading to the air pressure fluctuations in appliance branch pipes and measures to control them. It has been established that the main factors characteristics of a good sanitary pipework system are that it must prevent the transmission of foul air into the building, minimize blockages, provide efficient conveyance of discharge from sanitary appliances and minimize the risk of flooding to any part of a building. However, due to the nature and properties of sanitary appliance discharge, the flow being a three-phase flow which is simplified to two-phase for design computations and discharge being probabilistic, air variations in the horizontal appliance pipe result in phenomenon in which the sanitary network fails to perform as designed and installed to prevent or minimize aforementioned circumstances. It has been established that the main factors to be discussed leading to air pressure fluctuations in the appliance branch pipe are water traps, bend structures, pipe diameter, pipe slope and length, angle and connection mode and ventilation conditions. These factors' associated control measures have also been presented. However, factors pertaining to concentration of appliance discharge have not been discussed. The result of this discussion will enable designers and installers of sanitary pipework to incorporate measures to control air pressure fluctuations in appliance branch pipes inside buildings.