Water and Environment
http://repository.pauwes-cop.net/handle/1/291
2024-03-28T15:31:56ZModelling the Impacts of Structural Conservation Measures on Sediment and Water Yield in Thika-Chania Catchment, Kenya
http://repository.pauwes-cop.net/handle/1/182
Modelling the Impacts of Structural Conservation Measures on Sediment and Water Yield in Thika-Chania Catchment, Kenya
Gathagu, John Ng’ang’a; Sang, Joseph K.; Maina, Caroline W.
Recently, there have been a growing need to implement soil and water conservation measures in order to control sediment and water yield from agricultural areas. The objective of this study was to use a modelling approach to evaluate the impacts of structural conservation measures on water and sediment yield from Thika-Chania catchment in Central Kenya. SWAT model was calibrated and validated for stream flow and sediment yield at selected gauging station in the catchment. The calibrated model was run to create a base scenario for the simulation structural conservation methods i.e. terraces and grassed waterways. Model simulation results indicated that terraces and grassed waterways would significantly impact on water and sediment yield at the catchment outlet. Terraces were found to provide the greatest reduction in sediment yield by 80.7% from the baseline scenario while grassed waterways reduced sediment yield by 53.90%. Terraces indicated a reduction in surface runoff by 30.25% from the base annual average value of 202.28 mm. This was attributed to the increased infiltration that was indicated by increase in base flow by 8.35%. However, grassed waterways did not indicate any significant reduction in water yield. The results of this study show that structural conservation measures could reduce sediment yield from cultivated areas by more than 50% at the sub-catchment level. Results also indicated that the effectiveness of structural conservation measures can be increased by implementing more than one method. Structural conservation measures studied in the current study were found to have a positive impact in controlling water and sediment yield in the catchment. However, further studies need to be conducted to evaluate the costs and benefits of implementing them at small scale level.
2017-12-27T00:00:00ZSoil and Water Conservation in Thika-Chania Catchment, Kenya
http://repository.pauwes-cop.net/handle/1/178
Soil and Water Conservation in Thika-Chania Catchment, Kenya
Gathagu, John Ng’ang’a; Mainya, Johnstone Isiah; Oduor, Brian Omondi; Mourad, Khaldoon A.
Soil and water conservation measures are widely practiced in Kenya to tackle the degradation of the ecosystems and to improve land productivity. Local government and NGOs have developed programs and campaigns about soil and water conservation measures. The aim of this study is to assess the need for soil and water conservation measures in Thika-Chania catchment by conducting a household survey using QuickTap Survey software. A total of 200 respondents were successfully interviewed and results analyzed in SPSS program. GIS tools were also used to do a classification of slopes in the study area. Results indicate that more than 90% of the people in the catchment area are farmers. In the recent years, 50% of the respondents have noted a decline in the vegetation. During the rain seasons, the intensity of color in the local rivers due to sediments have been observed to increase by 75% of the respondent while 9% said there was no change. More than 70% of the respondents indicated that the water levels have been on the declining trend especially during the low flows. Terraces and grass strips were the common soil and water conservation measures although some of them were severely degraded. We concluded that there is an immediate need to implement soil and water conservation measures in the catchment to enhance and restore the optimum functioning of the ecosystems. Capacity building and frequent extension services are needed to increase awareness on the impacts of the respective conservation methods. Incentives programs need to be established to encourage more farmers to participate in conserving and protecting their lands from degradation.
2017-09-20T00:00:00ZAssessing the Sustainability of Decentralized Wastewater Treatment Systems in Rwanda
http://repository.pauwes-cop.net/handle/1/176
Assessing the Sustainability of Decentralized Wastewater Treatment Systems in Rwanda
Kazora, Amos Shyaka; Mourad, Khaldoon A.
Kigali city, the capital of Rwanda, relies on decentralized, on-site, wastewater systems due to the absence of central sewerage systems and the limited finances to construct sustainable sanitation infrastructures. However, the city has increasingly shown failures in managing these on-site systems either at individual or collective levels. This study aims at assessing the sustainability of the operated collective public semicentralized sewage systems in Kigali city. To fully cover the sustainability assessment of such collective systems, the methods used were field observation, questionnaires, interviews, and laboratory tests. The study also reviewed the influence of national ruling sanitation legal instruments in addressing development, operation and management of such decentralized wastewater systems. The results showed that the sustainability levels of these systems were low in the technical, socioeconomic status, institutional, and legal dimensions. While the sustainability level was fair for the environmental quality. In conclusion, the research highlighted that the improved sanitation coverage does not mean coverage in terms of sewerage connection proportions for wastewater collection as these connections do not imply safe and sustainable treatment before being discharged into the environment.
2018-12-05T00:00:00Z