22-27 September 2019
Trade Fairs and Congress Center (FYCMA)
Europe/Madrid timezone

The impact of land use cover change (1988-2018) on aquifer recharge capacity across Bogota river basin, Colombia

23 Sep 2019, 16:00
1h
Trade Fairs and Congress Center (FYCMA)

Trade Fairs and Congress Center (FYCMA)

Av. de José Ortega y Gasset, 201 29006 Malaga, Spain
Poster Topic 1 - Groundwater assessment and management Poster with refreshments

Speaker

Dr Fabio Iwashita (Los Andes University)

Description

Groundwater represents an important natural resource that must be managed in an adequate manner for its sustainable continuous use. The Teusacá River, tributary of the Bogotá River, is located in an area with aquifers of primary and secondary porosity. They represent an important water supply for municipalities of La Calera, Guasca, Sopó and Bogotá, the Colombian capital. The recharges of these reservoirs are vital for the preservation of their service, and the land use and cover change (LUCC) could be the most impacting factor to infiltration and runoff. This study has the objective of quantifying the impact of the LUCC between 1988 and 2018 in the groundwater recharge of the Teusacá catchment, heavily impacted by urbanization, deforestation and proliferation of weekend leisure ranches. To accomplish the abovementioned, we estimate the loss of recharge volume through a GIS based model that integrates physical variables that influence the runoff rate and a 30 year time series of river flow, precipitation and air temperature to obtain a groundwater recharge map. Additionally, a statistical analysis of the time series of the flow water and precipitation was performed to detect any inset trends on the river flow throughout the 30 year period. First, a land use map is obtained for 1988 and for 2018. Subsequently, the maps of soil permeability, infiltration capacity and slope of the land are combined in order to produce a final potential percolation map corresponding to each year. Next, a water balance calculated using the 30 year time series to find the approximate percolation annual volumes, and finally, these values are associated with their respective spatial locations using the potential percolation map. The statistical analysis includes Mann-Kendall nonparametric test to detect trends in the historical data and analysis of hydrographs. The results show a significant loss of Paramo ecosystem and an increase of the urban/bare soil, crops and greenhouses area. The loss of covers with high infiltration rate lead to an annual decrease of approximately 8.5% of total the volume infiltrated in 1988. The statistical analysis of the shows a positive trend (p-value < 0.0001) of the surface runoff across the 30 year period, whereas the hydrographs, for similar volumes of precipitation, also shows drastic increases in the river flow volume for each precipitation event.

Primary authors

Angelica Maria Moreno Rojas (Los Andes University) Dr Fabio Iwashita (Los Andes University)

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