Population growth is one of the major socio-economic trends exerting direct pressure on the state of urban environment, a report by Rwanda Environment Management Authority (Rema) says.With population on a rapid increase, the City of Kigali is fast becoming one of the most densely populated cities in Africa.The city has a total area of 730 square kilometres with the average population density at 1556 persons per Square kilometre.Last year’s population census put Kigali’s population at 1.135 million, making it home to 16 per cent of the country’s population.The same census projected that with all factors constant, at the current growth rate of 4 per cent a year, the city’s population could clock three million in the next six years. Of the city’s three districts, Nyarugenge is the densest at 2,127 persons per square kilometre, with Gitega sector topping the list as the densest sector in the country, at 24, 603 persons per square kilometre. Other than a high birth rate, a 2012 research paper by Vincent Manirakiza, titled "Urbanisation issue in the Era of Globalisation; Perspectives for urban planning in Kigali,” pointed that migration is a leading cause of population growth in the city. A research paper presented at a conference in the University of Cape Town, South Africa, in March by Eugene Rurangwa, "Land Tenure Reform: Case study of Rwanda,” explained that after the 1994 Genocide against the Tutsi, some of the Rwandans living in neighbouring countries who had left in the 1950s and 60s began returning home but faced difficulties related to land rights and had lost social bonds needed to settle in the countryside and ended up in the city."Others returning to Rwanda were attracted to Kigali because it offered more opportunities and security than the rural areas some of them had previously left,” the paper reads.Rurangwa is the executive director of the Great Lakes Initiative against HIV/Aids.Refugees and urban migrationAs of December 2012, the United Nations High Commission for Refugees was supporting more than 60,000 refugees in four refugee camps across the country. This number has since increased by at least 10,000. Rural-urban migration has also accounted for the population increase, with 57.6 per cent being to Kigali. With the current population having visible impacts on the environment  it is  highly likely that if nothing much is done, the environment will be under more pressure in turn resulting into changes in water quality and quantity, soil fertility and the quality of life in general. Dr Rose Mukankomeje, the Rema director-general, said population growth should not be viewed as the main problem but rather lack of proper planning."Population growth is not the problem itself. The real issue is the lack of proper planning in order to accommodate people migrating from rural areas to cities. Infrastructure development like alternative sources of energy, waste management, affordable houses and, of course, creating farming activities are the way out,” she said. Dr Mukankomeje added that the Kigali city master plan, if adhered to, will help address challenges arising from population growth. "The City of Kigali master plan factor all this, but it has to be followed to avoid negative responses from environmental overwhelming. City dwellers also need to be informed on the importance of following the plan,” she said.Previously, the City administration accommodated growing population by expanding boundaries to include rural and agricultural zones where there was no urban infrastructure and services.Feasible city master planThe Permanent Secretary in the Ministry of Natural Resource, Caroline Kayonga, said being aware of the situation and potential problems that could arise were a step in the right direction. "Sustainable developments such as the one outlined in the city master plan, EDPRS2 and Green Urbanisation, also put environment into consideration. We are currently aware of the situation at hand and are at policy making process to come up with practical steps on how as the city develops the environment will not be victim,” Kayonga said.She added that it will require financial and technical resources to achieve this vision, but that "the cost of not acting is greater than the cost of acting.”Kayonga said they are also charting ways to include sectors in Green Urbanisation."The government or the City Of Kigali cannot do everything alone; we are coming up with ways to showcase the economic opportunities the private sector can tap into through initiatives like funding,” she said.The City of Kigali master plan, she added, was developed to rhyme with Vision 2020, which considers the projected population and environment consequences if proper planning is not factored. It addresses the factors and gives guidelines and focus on salient factors.