This solution addresses the increasing uncertainty regarding the availability of water resources in the Tota Lake basin, Colombia. It aims to strengthen the resilience of productive systems through rainwater harvesting system.
The effects of climate change, and particularly climate variability during the dry season or days without rain, have been prolonged, resulting in greater uncertainty regarding the availability of water resources. The climate change scenarios for the Lake Tota basin, Colombia, show that for the 2026-2050 period, rainfall could increase by 15-40% in the wet scenario, and decrease by 10-20% in the dry scenario. Regarding average, maximum and minimum temperatures, it was found that all of them could increase in the range of 0.5 to 1°C. Meanwhile, with respect to climate variability, it can be seen that the changes would be increasingly greater: in the projected period, there would be increases of more than 100% in precipitation or reductions of 80% (Armenta Porras, 2019).
Additionally, it is estimated that the agricultural demand of the sub-basins with a very high climate risk oscillates between 37.7 L/s in Quebrada Aguablanca, 33.0 in L/s, Quebrada la Mugre, and 90.5 L/s in the Tobal River (Peña, 2020), all considerably high values when compared to other sub-basins. This situation causes greater uncertainty about the availability of water resources, generating pressure and conflicts for the community to secure it.
These projected intense climate variations, added to the overuse of water, could cause water deficit events, loss of crops, detriment to livelihoods, shortages, economic losses, among others. This implies important challenges in the management and practices of water use, both for productive activities and for domestic use.
Rainwater harvesting is a practice that seeks to collect excess water derived from precipitation and conduct it through channels for its subsequent use (Hirozumi, 2015). To intercept rainwater, available surfaces within a property or farm such as roofs, tiles, sheets and plastic surfaces are usually used. It is estimated that to guarantee the operation of the system, a single or gable roof structure is necessary, with a minimum slope of approximately 3% (Paredes & Sindy, 2019).
Rainwater harvesting systems are mainly made up of the following elements:
- Catchment surface;
- Conduction system;
- Storage tank; and
- Water filter.
These systems vary according to the storage capacity for rainwater harvesting and the needed demand to supply the different activities of the producers or families (Sánchez Rodríguez, 2020). This practice provides water for different uses such as domestic, agricultural and animal consumption, among others. Consequently, the community incurs lower costs for both the collection and transportation of this important resource. Finally, through the implementation of this measure, resilience is generated for families that do not have constant access to water during variability and climate change phenomena, such as droughts or prolonged summer seasons.
In this sense, considering climate change scenarios, an increase in temperature ranging from (0.85 to 0.88 °C) has been identified as a threat in the area where the measure will be implemented, which may eventually cause changes in water availability. Added to this is the fact that in times of drought, various livelihoods of the community of the Tota Lake basin are affected, therefore, rainwater harvesting would increase the adaptive capacity of the community and improve the resilience of agricultural systems since it provides an alternative source of water. The above aims to contribute to reducing the impacts of water shortages, a fundamental resource for the agricultural activity that predominates in the basin.
The objective of this adaptation measure is to strengthen the resilience of productive systems in the Tota Lake basin through rainwater harvesting systems in areas with climatic risks related to changes in water availability.
Additionally, the implementation of the measure is expected to increase the adaptive capacity of communities through capacity building processes for the proper use and management of water, focusing on the response to hydro-meteorological phenomena derived from climate variability and change.