Thesis (MSc)--Stellenbosch University, 2015 / ENGLISH ABSTRACT : In this study we look at the syndemic of substance abuse and drug-related crime in the Western Cape province of South Africa. The intent of this study is to provoke critical thinking about the possibilities systems thinking and system dynamics posses for social and health challenges in a diverse and complex environment like that of South Africa, especially the Western Cape. This study ventures into cross-discipline work between Epidemiology, Biomathematics and System Dynamics, with the hope of encouraging researchers from different fields to collaborate in order to curb the scourge of substance abuse and drug-related crime in South Africa. Substance abuse and the associated health and social hazards such as drug-related crime is a major problem in the Western Cape. Drug-related crime cases reported by the South African Police Services (SAPS) for the Western Cape exhibited a 311.5% growth in the past decade. This highlights how the reduction of substance abuse and drug-related crime within theWestern Cape province, will be an elixir for the safety and development of the communities. The fight against substance abuse has been driven by a multi-sectorial approach involving several government departments, non-governmental organisations and communities. With systems thinking the assumption is that the world is systemic, which means that phenomena is understood to be an emergent property of the interrelated whole. Firstly, using non-linear ordinary differential equations, we formulate a deterministic mathematical model for the substance abuse and drug-related crime syndemic, evaluate the threshold number and use sensitivity analysis to analyze the model. Secondly, a dynamic system, called the Substance Abuse and Drug-related Crime in theWestern Cape (SADC-WC) system is constructed using the STELLA in order to explore and classify the underlying relationships and structures within the substance abuse and drug-related crime system. Both the sensitivity analysis, and the simulations of the SADC-WC system indicate that an increase of successful convictions will have a significant influence on the syndemic, and promise to reduce drug-related crime cases. / AFRIKAANSE OPSOMMING : In hierdie studie ondersoek on die syndemie (‘syndemic’) van dwelmmisbruik en dwelmverwante misdaad in die Wes-Kaap provinsie, in Suid-Afrika. Die moontlikhede wat sistemiese denke en dinamiese sisteme inhou vir sosiale en gesondheid kwale in ’n diverse en komplekse omgewing soos Suid-Afrika, word ondersoek. Hierdie studie waag interdisiplinêre werk tussen Epidemiologie, Biowiskunde en Dinamiese sisteme, met die hoop om navorsers van verskillende velde aan te moedig om saam te werk om die plaag van dwelmmisbruik en dwelm-verwante misdaad in Suid-Afrika te bekamp. Dwelmmisbruik en die gepaardgaande gesondheid en maatskaplike gevare soos dwelmverwante misdaad is ’n groot probleem in dieWes-Kaap. Die SAPD se vermelde dwelmverwante midaad het ’n groei van 311,5% ondergaan in die afgelope dekade, en is aanduidend vir hoe die beheer en beperking van dwelmmisbruik en dwelm-verwante misdaad in die Wes-Kaap provinsie bevordering van beide die veiligheid en ontwikkeling van die gemeenskap sal verseker. Dit beklemtoon hoe die vermindering van dwelmmisbruik en dwelm-verwante misdaad in dieWes-Kaapland, sal ’n elikser vir die veiligheid en ontwikkeling van die gemeenskappe. Die stryd teen dwelmmisbruik is gedryf deur ’n multi-sektorale benadering waarby verskeie regeringsdepartemente, nie-regerings organisasies en gemeenskappe. Stelsels denke en dinamiese sisteme is gebasseur op die aanname, dat die wÃłreld is sistemiese en dat verskynsels verstaan word ten opsigte van die ontluikende eienskap van die omvattende geheel. Eerstens stel ons ’n kompartementele model op wat deur nie-liniêre gewone differensiële vergelykings beskryf kan word vir die dwelmmisbruik en dwelm-verwante misdaad epidemies. Ons evalueer die drumpel getal en gebruik sensitiwiteitsanalise om die parameters van die model te analiseer. Tweedens, is ’n dinamiese sisteem genaamd die Middelmisbruik en dwelmverwante misdaad in dieWes-Kaap (SADC-WC) stelsel gebou met behulp van die STELLA platform om te verken en klassifiseer die onderliggende verhoudings en strukture binne die dwelmmisbruik en dwelm-verwante misdaad stelsel. Beide die sensitiwiteitsanalise, en die simulasies van die SADC-WC stelsel dui aan dat ’n toename in suksesvolle vonisse ’n beduidende invloed op die epidemies sal hê; en beloof om sake van dwelmverwante misdaad te verminder.