A calculation method of gas emission zone in a coal mine considering main controlling factors

The gas emission zone is an important parameter for the space–time effect of coal excavation and gas emission. In this paper, according to the effect of roadway excavation, a numerical model of gas emission zone based on the evolution of stress and permeability was established to obtain the width of gas emission zone with different pressure and permeability coefficient. Then the numerical simulation results were verified by measuring the gas content at different depths. Through numerical simulation and field measured data, the theoretical calculation formula is established on the basis of comprehensive consideration of the influencing factors of gas emission zone. The results showed that the gas emission zone increases with the increase of coal seam gas pressure and permeability coefficient when the roadway section and exposure time are the same. The measured gas emission zone, when taking gas content as the index with the same logistic function growth curve, matches the measured results with a relative error of 1.3 to 6%. The validity of the model is also verified by field experiments. The results can provide guidance for mine gas emission and gas drainage design.

Behavioural Dumping and Drainage Channels

Dumping is one of the inevitable societal behaviours because waste can only be controlled but not eliminated completely. The rapidly growing developing countries have cities, towns and trading centres emerging daily coupled with increasing populations can be well related to poor drainage and irresponsible dumping in water channels. The aim of this study was to scrutinize drainage dumping behaviours in relation to water channels in some selected cities in Uganda. In this study, observational and analytical experiments on dumping were done in selected towns and cities, along some major highways connecting them. The findings showed that a lot of illegal dumping is happening at a rate of 63% on average on roads and even near the legal dumping places. Most of the refuse that is erroneously dumped ends up in drainage channels leading to serious flooding and other environmental consequences. The study recommends other better models in addition to improving drainage design, construction and maintenance patterns. Strict laws and sensitization are crucial in this regard and can help in saving and improving the lives of the people by at least 11%

Analisis Tren Perubahan Intensitas Hujan (Studi Kasus: Jakarta dan Bogor)

Rainfall intensity and drainage channel capacity are the main inputs in flood management infrastructure planning. The Intensity-Duration-Frequency (IDF) curve in a region has a different pattern from other regions. This study examines the temporal distribution pattern of rain and the IDF curve with case studies of the Jakarta and Bogor, represented by Kemayoran Rainfall Station and Citeko Rainfall Station, respectively. This study compared data analysis from the above stations with the ABM Method, Modified Mononobe, Indonesian National Standard for Calculating Flood Discharge, and Indonesian National Standard for Road Surface Drainage Design. The analysis results showed that the rainfall event in the Jakarta and Bogor areas was dominated by events of ≤ 4 hours with the highest percentage of rainfall volume at the beginning of the event (at the first two hours of the event). The observed hourly rainfall data has a significant difference pattern with the rainfall distribution calculated using the ABM and Modified Mononobe methods. The IDF curve obtained from the Base Curve on the Indonesian National Standard for Road Surface Drainage Design gives higher results than the IDF curve of the observation data. Meanwhile, the IDF curve calculated using the Mononobe Equation gives lower results than the IDF curve of the observation data. This study shows that standard design of rainfall duration and rainfall intensity for drainage infrastructure planning and flood management need to be continuously developed based on the latest observational data with better temporal and spatial resolution. Continuous effort in improving codes and design standard needs to be conducted to respond to climate change challenges, dynamic regional developments, and the increasing trend of flood events in Indonesia.