SPATIOTEMPORAL VARIATION OF LAND-USE AND LAND-COVER IN THE NAIROBI RIVER WATERSHED, AND ITS EFFECTS ON THE INORGANIC GEOCHEMISTRY OF NAIROBI RIVER

Determining the effects of LULC and development on natural resources is necessary for sustainability. This study focused on LULC changes in NRW over the past 3 decades and the effects it had on the geochemistry of NR channel’s sediment. Impervious surfaces increased from 2.5% to 11.9%. Samples from the urban class had elevated levels of contaminants than other classes. The concentrations of major inorganic elements were normal compared to the juvenile UCC except MnO and P2O5 that were heterogeneously distributed and significantly enriched. Heavy metals exhibited high DR than USEPA SSL in urban. Pb, Ce and Sb had the highest concentration of 3400, 769 and 187.5 ppm respectively in the urban class. Heterogeneously distributed and enriched elements like Pb, Y, Yb, Zr, Er,Ce, Zn, Lu, Sm, Th, Nd etc., were attributed to humans’ input. Minerals identified were smectite, kaolinite, quartz, anorthoclase and critobalite? Sediments’ alteration decreased down the river gradient