Climate Change: Vulnerability Assessmenthttp://repository.pauwes-cop.net/handle/1/1602024-03-29T08:04:27Z2024-03-29T08:04:27ZGroundwater Vulnerability Mapping in the Karstic System of Ghar Boumaza, Using the C.O.P. MethodBouabdallah, Mohammed El Hadihttp://repository.pauwes-cop.net/handle/1/2002020-01-28T13:13:15Z2018-01-01T00:00:00ZGroundwater Vulnerability Mapping in the Karstic System of Ghar Boumaza, Using the C.O.P. Method
Bouabdallah, Mohammed El Hadi
After an extensive literature review on the methods of vulnerability mapping, analysis of the European project COST action 620, a geological and hydrological study of Merchich watershed, we saw the possibility of the application of COP method. It has been selected to assess the value of intrinsic vulnerability of groundwater resources in the watershed, with varying degrees of karstification.
The cartography of the intrinsic groundwater vulnerability of this system was realized by applying the COP method (Concentration of flow, overlying and precipitation).The resulting map has shown that more than 38% of the surface of the system is in high vulnerability area,more than 18% in low vulnerability,44% with moderate vulnerabilit.
The superposition of the map of intrinsic groundwater vulnerability with the map of polluting sources established for Ghar Boumâaza system helped to develop a map of pollution risks in which the areas that are most threatened by the pollution of the surrounding area A.Taga are highlighted.Indeed a bacteriological analysis campaign of water of this system performed recently allowed to see that some water sources are contaminated and therefore undrinkable.
The water analyses of the fourth points assessed showed the real pollution of the groundwater which should be controlled and protected.
2018-01-01T00:00:00ZSoil Loss In A Catchment And Change Of Storage Volume In A Hydropower Reservoir Case Study: Lom Pangar Hydroelectric Dam, East Region CameroonNjoya, Ousmanouhttp://repository.pauwes-cop.net/handle/1/1452020-01-28T13:13:15Z2017-01-01T00:00:00ZSoil Loss In A Catchment And Change Of Storage Volume In A Hydropower Reservoir Case Study: Lom Pangar Hydroelectric Dam, East Region Cameroon
Njoya, Ousmanou
For many purposes such as water supply, irrigation flood control and hydropower production, many reservoirs are built throughout the planet. However, because of the processes of erosion and sedimentation, these infrastructures are facing a big problem of progressive reduction of their storage capacity. Consequently, a good knowledge of the change of storage for proper planning and management is very important. The wellknown Universal Soil Loss Equation (USLE) was used to evaluate the gross erosion in Lom Pangar catchment and the sediment delivery ratio relation used to evaluate the quantity of sediment that effectively reach the outlet of the catchment. To evaluate the soil loss from the watershed using USLE model, the topographic map of 30 m x30m resolution was used in ArcGIS software to generate the LS factor which average was 3.64. To determine the erodibility factor, the FAO map was used to generate different soil type, present in the catchment and come up with different mineral component. The average erodibility was evaluated to be 0.024 t. ha.h (ha MJ mm). The roose (1980) equation and the average annual rainfall were used to generate the erosivity factor which average for the watershed was 14 509.55 MJ?mm?ha?1 h?1 yr?1. Concerning the cover factor, the MODIS table and the classified map were used to come up with an average C factor of 0.08. In order to avoid underestimating the soil loss, the practice factor was considered to be one. Following the determination of different factors, the gross erosion was developed to be 202.8 million ton of soil per year with an average of 28.392 million ton per year that effectively reach the outlet. On the quantity that reach the outlet, the Brune (1953) Sediment trap efficiency was applied and 50.7% of the storage volume is filled after 140 years. The impact of land use change on erosion was studied too. That for the year 2015 and 2017, and main result was 101.4 t/ha/year of soil lost in 2017 instead of 28.4 t/ha/year in 2015. Based on the construction design parameter, the useful life of reservoir is generally 100 years; per consequent, it can be retained from our result that the sediment is not a major problem in Lom Pangar reservoir.
2017-01-01T00:00:00ZModelling Runoff, Soil Erosion And Sediment Yield In Sosiani Catchment In Kenya Using ArcswatMainya, Johnstone Isiahhttp://repository.pauwes-cop.net/handle/1/1392020-01-28T13:13:15Z2017-01-01T00:00:00ZModelling Runoff, Soil Erosion And Sediment Yield In Sosiani Catchment In Kenya Using Arcswat
Mainya, Johnstone Isiah
Sosiani catchment hosts Eldoret Town, a major agricultural, education and medical center in the Rift valley region of Kenya. Recent research has established that the quality of water in Sosiani River is rapidly deteriorating because of catchment erosion and wastes from industries. However, even though there have been efforts to control the pollution, non-point sources of pollution have not been characterized. The aim of this study was to simulate effect of rainfall magnitude on soil erosion, runoff and sediment yield in Sosiani catchment using ArcSWAT. The soil dataset used was obtained from Digital World Soil Map, weather datasets were obtained from Climate Forecast System Reanalysis (CFSR), DEM dataset was obtained from Open Topography, landuse/land cover dataset was obtained from USGS and river flow dataset was obtained from Water Resources Authority Kenya. The period of study was 1984-2012. Flow Calibration period was 1986-1990 while the validation period was 2008-2012. Sediment and soil erosion were not calibrated for lack of observed data. Flow calibration and validation results returned an R2 value of 0.90 and 0.60 and NS value of -19.92 and -14.90. The study observed that increase in rainfall magnitude increased runoff, soil erosion and sediment yield except under conditions of increasing vegetative land cover. The study concludes that the model did not simulate the catchment correctly because it oversimulated both low and high flows. It recommends that datasets for the catchment (observed rainfall and river flows) need to be thoroughly checked for integrity before attempting to use them for hydrologic modelling. It further notes that agricultural land is the main contributor of sediment into river Sosiani and therefore remedial measures such as agroforestry and cover cropping would be appropriate immediate actions to control soil erosion.
2017-01-01T00:00:00ZA Modeling Approach to Soil Erosion Control and Management Using PAP/RAC Model and GIS: A Case Study of Boufekrane Watershed, MoroccoKone, Gninwokan Eden Josiashttp://repository.pauwes-cop.net/handle/1/1402020-01-28T13:13:15Z2017-01-01T00:00:00ZA Modeling Approach to Soil Erosion Control and Management Using PAP/RAC Model and GIS: A Case Study of Boufekrane Watershed, Morocco
Kone, Gninwokan Eden Josias
Erosion by water remains the predominant form of land degradation in the world and accounts for 84% of affected areas. More particularly, the Mediterranean costal region is recognized to be of extreme fragility to erosion. Studies estimated that Morocco agriculture represents almost 20% of its annual GDP, which makes it more concerned with the issue of soil erosion which is recognized to significantly affect crop productivity. The area under study, Boufekrane, is an agricultural area where cultivations (including cereals and tree crops) and other activities such as grazing and livestock account for more than 80% of the total watershed area. The overall purpose of this study was to evaluate soil erosion in Boufekrane watershed located in the eastern part of the plain of Sais (Morocco). Prioritization of the watershed in terms of erosion risk magnitude and expansion trends was made using ArcGIS and qualitative approach called PAP / RAC. It consisted to integrate major causative factors recognized to influence water erosion. In this study, slope, lithology, pedology, vegetation cover and land use were used to assess soil erosion risks. Mapping and overlaying of thematic maps were performed by using ArcGIS software. The assessment of water erosion in this study was carried out in three phases based on PAP/RAC guidelines. The first approach called predictive was aimed at providing preliminary hypotheses for development of erosion risk. It consisted of analysis of natural factors influencing water erosion. The second phase called descriptive consisted to identify current on-site erosion forms that develop in Boufekrane. The consolidation phase, which was the last step, exhibited spatial distribution of erosion risk in Boufekrane by integration and combination of results obtained from the two previous phases. Results indicated that 55.61% of the watershed is affected by sheet erosion, 12.42% is affected by solifluction /sheet erosion. Gully and rills only accounts for 17% of the total surface area of the watershed and are found in areas where slopes and soils are highly sensitive to erosion. The results also showed that cultivation practices, crop types and vegetation cover are found to influence erosion processes in Boufekrane. Effects of slope in water-induced erosion process were found to be of minor degree. The final output map provides a valuable insight for soil conservation planning in Boufekrane and contributes to a more standardized framework of soil erosion control by making findings more applicable and comparable to other watersheds where decision to address soil erosion has been made based on PAP/RAC. In addition, the study can enable the local authorities to prevent from a premature and quick sedimentation of El Gaada dam. However, the model did not consider important data such as rainfall and other climatic data which taints its accuracy in evaluating soil erosion water. Therefore, there is a high recognition to improve PAP/RAC model if one wants it to be an efficient and effective tool for decision-making in soil erosion control and management projects.
2017-01-01T00:00:00Z