Seite - 20 - in options, Band winter 2021

As in many low-income settings, the lack of proper solid waste management is a critical problem in Kisumu County, Kenya. Most of the 500 tonnes of waste that is generated here every day ends up in open dumpsites or scattered alongside roads posing an environmental and health hazard. Open burning of the waste is common, releasing toxic air pollutants that cause respiratory and cardiovascular diseases. With urbanization, growing population, and projected economic growth, this issue is likely to worsen in the coming years. To avert the looming waste crisis, IIASA researchers Adriana Gómez-Sanabria and Gregor Kiesewetter participated in a study analyzing different waste management scenarios as part of a multi-partner effort to reduce air-pollution in Kisumu. Using a systems-dynamics approach, they modeled how the amount of waste, greenhouse gas, PM2.5 (fine particulate matter) emissions, and the number of life years saved changed based on two different waste management interventions: converting solid waste into biogas and banning open burning in landfills. The researchers found that combining the two interventions would save over 1.1 million tonnes of CO2 emissions, 1,150 cumulative life years, and reduce air pollution compared to baseline projections by 2035. “Waste is not just waste, it is also a material — by turning it into clean fuel we not only improve waste management, but also reduce greenhouse gas emissions and improve air quality,” says Gomez Sanabria. Sustainable agriculture is a challenge for much of the world. Nowhere is this challenge more pressing than in South Africa. In fact, growing water scarcity, coupled with rising fertilizer (Nitrogen) prices, are causing new complications for this already fraught situation. The most realistic solution to this problem is better management of both fertilizer and water usage. A study by IIASA researchers Stephan Pietsch from the Advancing Systems Analysis Program and Juraj Balkovic from the Biodiversity and Natural Resources Program, set out to help address this problem by exploring models for potential improvements. The researchers used a calibrated and validated Environmental Policy Integrated Climate (EPIC) model to simulate a range of Nitrogen and irrigation water levels on maize yield in South Africa’s Eastern Cape. Their results show that the highest average maize yield was produced by utilizing 155 kg of nitrogen and 600 mm of water. This number represents a 69% increase over the average farmer’s maize yield. The results confirm the importance of proper management practices. “If the goal is sustainable agricultural intensification, then the solution must involve developing effective, location-specific agricultural land management strategies,” explains Pietsch. “We must balance increased crop productivity with minimal negative environmental impact. The EPIC model can be used as a valuable tool in identifying optimal, site-specific irrigation water and proper application levels of Nitrogen fertilizer. This will not only increase maize crop productivity, but also maximize water use.” 0 100,000 200,000 300,000 400,000 2021 2024 2027 2030 2033 A) Landfill Food Waste Baseline Biogas 0 100,000 200,000 300,000 400,000 2021 2024 2027 2030 2033 B) Landfill Non- food Waste Baseline Biogas 0 50,000 100,000 150,000 200,000 2021 2024 2027 2030 2033 C) Scattered Food Waste Baseline Biogas 0 50,000 100,000 150,000 200,000 2021 2024 2027 2030 2033 D) Scattered Non- food Waste Baseline Biogas Figure: Stocks of waste, Baseline vs. Biogas scenario. Improving fertilizer and water management practices in South Africa A FR I C A Tackling solid waste management in Kenya Regional impacts Gregor Kiesewetter: kiesewet@iiasa.ac.at Adriana Gomez Sanabria: gomezsa@iiasa.ac.at Juraj Balkovic: balkovic@iiasa.ac.at Stephan Pietsch: pietsch@iiasa.ac.at Further info: pure.iiasa.ac.at/17224 Further info: pure.iiasa.ac.at/17073 By Jeremy Summers By Fanni-Daniela Szakal 20 Options www.iiasa.ac.atWinter 2021