A split between Spain and Catalonia would cause a major political shake-up in the country but would also have significant consequences for the economy of both sides, experts have told CNBC. Police fired rubber bullets, wrestled protesters, smashed doorways and carted off ballot boxes in several parts of Barcelona on Sunday , as long lines of people voted in an independence referendum that could radically reshape politics across a divided region. Pro-independence lawmakers hope the northeastern region will gain complete political and economic autonomy from Spain despite the referendum putting Catalonia in open defiance of central authorities in Madrid. As the most prosperous of Spain's 17 regions, Catalonia houses roughly 19 percent of Spain's economy, benefiting from tourism, exports, manufacturing, and industry. Catalonia has talked of separation from Spain since the founding of Estat Català – a political movement which began in 1922 - and throughout the 36-year dictatorship of Franco, however, the resurgence of the pro-secession movement over the past few years is due primarily to Spain's economic woes, a 2010 constitutional court decision to lessen Catalonia's sovereignty, and a distrust of Madrid or the centralized Spanish government. Amid discussions of Scotland's own relationship to the European Union after Brexit, questions have arisen on the economic implications of a Catalonia-Spain split. Here, CNBC investigates the implications if the two areas divide.

Immediate impacts of the separation The short-term outcomes of separation would be negative for both parties, according to Alain Cuenca, an economics professor at the University of Zaragoza in Spain. "The establishment of a border would result in a loss of jobs, income and wealth for everybody, whether they live in Catalonia or in the rest of Spain," Cuenca told CNBC via email. "Those losses would be provoked by the obstacles to trade, by financial problems, by the spending needs of the new state." While Catalans only account for about 16 percent of the Spanish population, Catalonia makes a hefty contribution to the overall Spanish economy, making 223.6 billion euros ($262.96 billion) a year, according to the regional government. This is around 20 percent of its total gross domestic product (GDP). Larger than the contribution that California makes to the whole United States. Using figures from official European and Catalonian organizations, Business Insider claimed earlier this year that the region would quickly gain about 16 billion euros yearly in the case of a split, as they would no longer have to pay taxes to Spain. This would then result in a loss of about 2 percent to the Spanish GDP (gross domestic product ) yearly. At the same time, Catalonia could take a potential hit, as 35.5 percent of Catalan exports are to the Spanish market. Catalonia would also have pay to create new state structures (embassies, central banks, etc.) which carry a large price tag. Earlier this month, Spanish Economy Minister Luis de Guindos claimed that Catalonia could see its economy shrink by 25 to 30 percent and its unemployment double if it splits to form a separate state. Regardless, the fate of both nations would ultimately come down to the decisions made in post-separation negotiations on debt and the European Union. The debt issue Spain's national public debt in 2016 was priced at roughly $1.18 trillion, according to central bank statistics. Meanwhile, Catalonia has amassed one of the largest public debts of Spain's regions, at roughly 72.2 billion euros ($86.9 billion) in 2016. Around 6 billion euros of this is for long-term securities that have been issued and the rest being various loans from different institutions. Therefore, Catalonia accounts for 16.34 percent of Spain's debt, which is not a small price tag. This aspect, combined with the loss of Catalonia's tax revenues, would be a hit to the Spanish economy. While many believe that the public debt of the new nation "would inevitably be assumed by the Kingdom of Spain," Cuenca explains that the direct separation impact to the debt is impossible to predict. "The problem, again, is transition: For how many years would financial trouble last? How many jobs, how many investments, how many commercial operations would be lost during transition? No one knows precisely," Cuenca said. The success of Catalonia is determined heavily on whether or not they would assume a percentage of the Spanish debt and if they would be required to pay off their own debt. Either situation could prove to be detrimental to a new Catalan nation and would damage the potential for economic expansion.