| Popis: |
Hydrological changes in many watersheds worldwide have been attributed to land use change. In the River Njoro watershed, vast forested land has been replaced by other land uses including agriculture and grazing. This has led to decrease in infiltration in many parts of the watershed. The study was aimed at establishing the effects of land use• change on infiltration in the watershed. The study was done on runoff plots, which was used to assess infiltration in the watershed. There was a randomized block design with fi\c land use treatments and three replicates (sites) per treatment. The site plots were mapped using Global positioning System (GIS) and plotted in a Geographical Information System (GIS) environment. A rainfall simulator having dimensions of 0.4m by 0.25m was used to simulate rainfall on plot size of 0.1 m2. In every site rainfall was applied at an average rate of 10mm/h on three plots using a rainfall simulator. Infiltration, the difference between applied rainfall and runoff, generated from three sites in each land use was measured. The soil properties including bulk density, texture, organic matter content and pH were measured in every site. The highest infiltration was on indigenous forest and decreased in the order of plantation forest, deforested area, agricultural and grazing land. The mean infiltration rates for each land use were 43.5, 37, 26.2, 25.4 and 20.2 mm/hr. Statistical analysis (P< 0.05) showed that their were significant differences in infiltration between forested areas and all other land use areas. The land under forested cover registered high infiltration whereas areas of the watershed characterized by intensive interference of land cover and soil surface conditions experienced low infiltration. It is evident from the results that afforestation needs to be encouraged in the watershed. Published |
