Spatial-Temporal Sediment Hydrodynamics and Nutrient Loads in Nyanza Gulf, Characterizing Variation in Water Quality

• 作者: Angalika W. S. Misigo Seiji Suzuki
• 来源期刊: 世界工程和技术(英文)
• 学科: 医学
• 关键词: Micro-Basin Spatial SEDIMENT NUTRIENT SWAT ANTHROPOGENIC
• 年，卷（期）: 2018,（2）
• 页码范围: 98-115
• 页数: 18页
• 分类号: R73

摘要

Accelerated aging and eutrophication of water resources is a world menace attributed to influx of nutrient rich sediment from its catchment, resulting in poor water quality and shifts in ecological dynamism. Nyanza Gulf is a paramount source of livelihood, portable water, and of service to the rich biodiversity making it indispensable to the entire Lake Victoria watershed ecosystem. This water resource has been deteriorating over the past decades as a consequent of anthropogenic socio-economical activities. This has effectuated an increase in phytoplankton and hydrophyte colonies. The objective of this study was to track the quality and quantity of sediment inundation into the gulf considering the catchment micro-basins processes and influence of human socio-economical activities. Using Quantum Geographic Information System (QGIS) as an interface to Soil and Water Assessment Tool (SWAT) with input of satellite digital elevation model (DEM), local rainfall, soil and land use data sets were utilized to determine the daily variability in sediment and nutrient loads from five major river basins. The SWAT model was successfully calibrated, and the performance validated with observed hydrological and water quality data. The model achieved identification of seasonal water quality budget filling in knowledge gaps about the catchment. River Nyando, Sondu-Miriu, Awach-Kibuon, Awach-Tende and Kibos discharge sediment loads of 3.91, 1.6, 1.18, 1.06 and 0.78 tons/ha respectively. Total suspended solids (TSS) concentration of up to 578mg/L on average daily is discharged by River Awach-Kibuon. This was associated with intense agricultural activities (>54% of the entire basin) on steep slopes (average 12.97) with Acrisols (15%of the basin) soils that is prone erosion. Poorly managed range-bush land that covers about 10% of this basin also contribute significantly to the TSS yield. River Kibos discharge least TSS concentration of 144.43 mg/L in comparison with other rivers mainly due gentle slope falling into a plain, low erodibl