Land use and influence on the water quality index: The case of trussu river valley

Abstract

In order to evaluate the influence of land use and occupation on surface and groundwater levels in Trussu river perennial valley, Ceará, Brazil, we aimed at investigating data of the water quality in two distinct years. The first one was from Sep / 2002 to Feb / 2004 and the second from Apr/2013 to Jul/2015. Twenty-two water samples were collected in 9 sampling stations, 5 from surface and 4 from underground. The same stations were considered in the two periods, monitoring 6 attributes of water quality, totaling 2376 analyzes. The water quality assessment was performed using the water quality index (IQA, in Portuguese) and cash flow diagram. The changes in land use and occupation were sharp, with the dense tropical dry forests (Caatinga) moving from 38.7% occupancy of the study area in 2003 to 11.2% in 2013. There was no significant difference (P <0.05) in surface and groundwater quality over time. However, groundwater differed statistically in the two points. The IQA of surface waters was classified as good, and of groundwater as regular and bad. These results show the growth of agricultural practices in the region, with significant advance of the anthropized area on natural resources.