ABSTRACT
Among other African cities, in terms of solid waste management (SWM), Harare has been ranked as one of the poorest. The municipality struggles to efficiently provide SWM services to its residents. Considering that SWM systems are complex, the individual behaviour of its components (waste generation, collection, and disposal) determines the overall performance of the system. This mini-review thus aims to understand the management system of the urban city's biggest source of solid waste which is household solid waste (HSW). The systematic literature review methodology using NVIVO was used to analyse the literature. Out of a selected sample size of 500 journal articles, 26 were selected based on their relevance to the study. The uncertainty of the data provided by the Harare City Council (HCC) and of HSW generation data harvested in the literature was calculated. According to the HCC data records, Harare has an average daily waste generation per capita of on average 0.38±0.1 kg producing about 207, 635, 294±56, 027, 040 kg of HSW generated annually. With the waste collection efficiency in Harare at about 72.4%±7.5%, the city collects approximately 170, 385, 600±33 384 209 kg of HSW annually. All the collected HSW is disposed of in the city's major MSW dumpsite called Pomona and only about 23, 498, 400±3, 988, 817 kg MSW is recovered annually with the average recovery efficiency at around 9.5%±2.8%, where most of the waste recovery is done by the waste pickers.
Subject(s)
Refuse Disposal , Waste Management , Cities , Developing Countries , Recycling , Solid Waste/analysis , ZimbabweABSTRACT
The loss of peri-urban wetlands is a major side effect of urbanization in India in recent days. Timely and proper assessment of wetland area change is essential for the conservation of wetlands. This study follows the integrated way of the peri-urban wetland degradation assessment in the case of medium and small-size urban agglomerations with a special focus on Chatra Wetland. Analysis of land-use and land cover (LULC) maps of the past 28 years shows a decrease of 60% area of the wetland including marshy land. This has reduced the ecosystem services value by about 71.90% over the period 1991-2018. From this end, The Land Change Modeler of IDRISI TerrSet using the combination of MLPNN and Markov Chain has been used to predict the LULC map of this region. The scenario-based modeling following the LULC conversion and nine explanatory variables suggests the complete loss of this wetland by 2045. However, the authors have also tried to present a future LULC pattern of this region based on an environmental perspective. This proposed map suggests possible areas for built-up expansion on the western side of the city without significantly affecting the environment.
ABSTRACT
The coupled regional simulation model, and the transport and reaction simulation engine were recently adapted to simulate ecology, specifically Typha domingensis (Cattail) dynamics in the Everglades. While Cattail is a native Everglades species, it has become invasive over the years due to an altered habitat over the last few decades, taking over historically Cladium jamaicense (Sawgrass) areas. Two models of different levels of algorithmic complexity were developed in previous studies, and are used here to determine the impact of various management decisions on the average Cattail density within Water Conservation Area 2A in the Everglades. A Global Uncertainty and Sensitivity Analysis was conducted to test the importance of these management scenarios, as well as the effectiveness of using zonal statistics. Management scenarios included high, medium and low initial water depths, soil phosphorus concentrations, initial Cattail and Sawgrass densities, as well as annually alternating water depths and soil phosphorus concentrations, and a steadily decreasing soil phosphorus concentration. Analysis suggests that zonal statistics are good indicators of regional trends, and that high soil phosphorus concentration is a pre-requisite for expansive Cattail growth. It is a complex task to manage Cattail expansion in this region, requiring the close management and monitoring of water depth and soil phosphorus concentration, and possibly other factors not considered in the model complexities. However, this modeling framework with user-definable complexities and management scenarios, can be considered a useful tool in analyzing many more alternatives, which could be used to aid management decisions in the future.
