Determining ammonia nitrogen decay rate of Malaysian river water in a laboratory flume

There is lack of information regarding ammonia nitrogen (AN), (i.e. NH₃-N) decay rate of river water in tropical regions like Malaysia. AN decay rate is a very important kinetic parameter to estimate NH₃-N, nitrate nitrogen (NO₃-N) and dissolved oxygen concentrations of river water by using computer models. This study presents determination of ammonia nitrogen decay rate of river water in the tropical environment of Malaysia. A laboratory flume was used to conduct twelve experiments. The flume was used to represent the turbulent condition of a typical river. Ammonia nitrogen decay rate for the tropical environment of Malaysia was observed to be between 0.194 and 0.554 per day. Median value of AN decay rate was 0.26 per day, which is slightly lower than the global median value of 0.295 per day. To check the accuracy of flume experiments, the AN decay rate of Pusu River obtained from the flume experiment was used to calibrate and validate ammonia nitrogen concentration of the river by using water quality analysis and simulation program (WASP). Very good calibration and validation results were achieved, which substantiated the accuracy of the flume experiments.     

Quantification of urban expansion in Siliguri urban agglomeration (UA): a model-based approach

In the study of new towns and cities, spatial assimilation and the complex nature of urban development hold issues of special importance. At present, in developing countries like India, rapid development as well as urbanization in medium sized cities is a noticeable phenomenon. However,researchers in the field of urban study,lay emphasis on larger cities in our country. Therefore,more studies are essential to identify the problem and future prospect and also to suggest satisfactory policies for the betterment of medium sized cities.The current paper assesses the spatial expansion of the Siliguri (a fast growing medium sized city of Eastern India) designed for the year 1990, 2000, 2010 as well as 2019 using satellite imagery and field investigation.The research quantifies the urban growth and sprawling pattern in the study area using statistical techniques and spatial matrices.The other objectives of this study are to predict and analyze the urban growth of Siliguri Urban Agglomeration (UA) of 2030 with the help of a Future Land Use Simulation (FLUS) model. This simulation model was chosen by using a technique to evaluate the classified images in three maps: a time 1 reference map, a time 2 reference map and a simulation map of time 3. Spatial metrics and Shannon entropy results revealed that Siliguri (UA) is experiencing rapid sprawl. In contrast, the degree of freedom results revealed a significant gulf between the observed and planned urban development.The simulation model also showed that the unsustainable trend will likely to remain intact in the future, with the built-up area rising to 78.496 km² by 2030, potentially resulting in loss of major cultivated land, fallow land and flora.