Relating land use and land cover to surface water quality in the Densu River basin, Ghana

摘要

The Densu River basin is one of Ghana's most reliable freshwater sources, though greatly stressed through pervasive land-use activities. This warrants that water quality variability be understood in relation to land use and land cover (LULC) processes in the basin. In this paper, water quality variables and LULC attributes were evaluated using multivariate techniques such as Pearson's correlation and linear regression to decipher the relationship between them. The study found water quality variability to be influenced by both seasonality and geographical location. While water quality variables such as pH, turbidity, DO, total suspended solids, Ca~(2+), K~+ and NO_3~- -N relatively were increasing during the rains, T, electrical conductivity, TDS, Cl~-and PO_4~(3-)-P were conversely higher in the dry season. Consistent with other studies, spatial differences observed for water quality variables probably reflect local variability in land use, geology, lithology and soil properties across the basin. Adequately vegetated sub-basins experienced minimal load of nutrients compared with other land cover types. Temperature, pH, turbidity, dissolved oxygen, phosphate-phosphorus and nitrate-nitrogen in surface water could be estimated from multiple regression analyses, using land cover information. We recommend that riparian vegetation of the basin is conserved while urban effluent discharges into running water are minimized, under an integrated water management programme.