Climate Change and Land Use - Batch 3

Carbon Stock Potential of Agroforestry Systems in Savannah West Africa: A Case Study of Agroforestry Parkland in Burkina Faso.

2019-02-01T00:00:00Z

Carbon Stock Potential of Agroforestry Systems in Savannah West Africa: A Case Study of Agroforestry Parkland in Burkina Faso. Neya, Tiga Agroforestry plays an important role in food security and farmer‘s resilience to climate change and variability in West Africa. However, the link between agroforestry parkland profiles and the capability of these parklands to sequester carbon are not well known. Therefore, agroforestry parkland profiles in three climatic zones of Burkina Faso were studied. Thirty (30) farmlands in each of the climatic zones representing about 35 ha were randomly selected and systematic woody species inventory and dendrometry data were collected. Diameter classes‘ distribution and agroforestry parkland typologies using Importance Value Index analysis were done for agroforestry parkland profiling purpose. The mean tree canopy cover and tree cover in the farms were calculated and three principal crops (millet, red sorghum and white sorghum) yield were used to estimate the trade-off using the mean tree canopy cover as the potential for no cropping area. Non-destructive method of fitted allometrics equations were used to compute carbon stock and to estimate equivalent dioxide carbon. Sustainability analysis of carbon sequestration potential was done using ]0-10], ] 10-40] and ]40-110 cm] diameter classes as long , medium and short term capability of agroforestry parklands to sequester the carbon respectively. The balance between marketable carbon value and the trade-off resulting from tree conservation and the major crops (millet, red sorghum and white sorghum) value were also analysed. The results showed 42 woody species in Sudanian, 31 Sudan-Sahel and 34 Sahel strict zones with corresponding density of 37, 30 and 35 trees/ha respectively. Agroforestry parklands in Sudan-Sahel zone appeared to be unstable compared to the two others climatic zones. Mono-woody species parkland of Vitellaria paradoxa was observed in the Sudanian zone while multi-woody species parklands were observed in the Sudan-Sahel and Sahel strict zones. Moreover, mean tree canopy cover observed was 66.25 m2 in Bouroum-Bourom, 59.92 m2 in Sapouy and 42.1 m2 in Ouahigouya . The average tree cover was 23.99% in Bouroum-Bouroum, 18.23% in Sapouy and 14.88% ix in Ouahigouya. This represents a loss in grain production of 109.5 kg/ha in Bouroum-Bouroum, 247.6 kg/ha in Sapouy and 252.8kg/ha in Ouahigouya. Carbon stock analysis revealed 24.71± 5.84 tCO2ha-1, 28.35± 5.84 tCO2ha-1 and 33.86±5.84 tCO2ha-1 in Ouahigouya, Sapouy and Bouroum-Bouroum respectively. Ouahigouya earned the first place for long term carbon sequestration potential with 1.82% of total amount of carbon. The medium term analysis gave the first place to Sapouy with 71.71% of total amount of carbon and the short-term analysis gave the first place to Ouahigouya with 68.03%. The marketable carbon value was less than the trade-off value resulting from tree keeping and crop production value. The balance analysis revealed that carbon payment system promoted by REDD+ initiative will be profitable and compensable to smallholder farmers effort to keep tree when the tCO2 ha-1 price will be around US$ 4. Both the density of tree (trees/ha) and the number of species constituting the agroforestry parklands have a direct impact of carbon stock potential. A higher tree cover implies a higher trade-off in the agroforestry parkland and suggests reduction in tree density. When considering farmers‘, interest, profitability on carbon market will be the most relevant incentive method to enhance carbon sequestration in agroforestry parkland in order to meet Paris agreement (2015) goals. A Thesis submitted to the West African Science Service Centre on Climate Change and Adapted Land Use and the Kwame Nkrumah University of Science and Technology, Kumasi, Ghana, in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Climate Change and Land Use

Vulnerability of Rice and Maize Yields to Climate Variability in the Sudano-Sahelian Zone of The Gambia: Drivers and Adaptation Options

2019-06-01T00:00:00Z

Vulnerability of Rice and Maize Yields to Climate Variability in the Sudano-Sahelian Zone of The Gambia: Drivers and Adaptation Options Sonko, Ebrima Staple food crops are considered as the driving force for household food security and source of livelihood activities for many developing nations. Farming practices face many challenges due to the adverse impacts of climate change and variability in the 21st century. This study assessed the extent to which maize (Zea mays L.) and rice (Oryza sativa L.) yields are vulnerable to climate variability in the Lower River Region of The Gambia. The influence of climate variability was assessed using the ordinary least square regression and heteroscedasticity methods. The potential soil physical and chemical properties were estimated using diagnostic soil survey of simple random sampling approach. Data were collected from 30 upland maize fields and 30 swamp rice fields. Crop yields were projected using two Global Circulation Model (GCM) models that performed best in the study area: CSIRO-RCP4.5 and NOAA-RCP4.5. Climate change adaptation options were assessed through semi-structured questionnaires with 180 selected households in eighteen communities using multistage sampling techniques. The results of climate influence on crop yields showed that CO2 and rainfall unfavourably affect rice yield and were statistically significant. Maximum and minimum temperature negatively affect yield but not statistically significant at (P < 0.05). The results further revealed that CO2, maximum temperature and sunshine duration adversely affect maize yield and statistically significant whilst rainfall and minimum temperature negatively affect maize yield but not significant at (P < 0.05). Soil survey results indicated that swamp rice ecologies had high percentage of NPK (N 0.07 %, P 0.0184 % and K 0.04 %) than percentage NPK contents in the maize fields (N 0.06 %, P 0.018 % and K 0.01 %). Soil pH is generally low and ranges from (4.6 to 4.7). The electrical conductivity of the soils for rice and maize fields are generally high (4.8 dS/m) indicating salt-affected soils. It is projected that, crop yields showed the percentage mean yield gain for maize iv under NOAA-RCP4.5 by 12 % and 41 % but most importantly CSIRO-RCP4.5 by 17 %, 31 %, and 48 % respectively, as the period gets close to mid-century compared to mean rice yield losses of -19 % and -23 % under NOAA-RCP4.5 scenario. The results showed that the majority (72 %) of farmers’ use drought-tolerant crop varieties with 67 % adapting to changing planting date. Majority (64 %) of farmers were forced to fallow their lands with 40 % of farmers practising petty trading and 47 % depending on temporal migration as a coping mechanism. It is concluded that rice and maize yield were vulnerable to climate variability coupled with fragile soil conditions. The future projection of yields will be inadequate to feed the growing population in the Lower River Region of The Gambia. There is a need for more adaptation strategies that are compatible with the local condition that can strengthen the resilience of households to cope with climate variability. Therefore, climate change adaptation policy should include local knowledge as a bottom-up approach to enhance their sustainability at the local level. A Thesis submitted to the West African Science Service Centre on Climate Change and Adapted Land Use and the Kwame Nkrumah University of Science and Technology, Kumasi, Ghana, in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Climate Change and Land Use

Land Use and Climate Change Impacts on Water Resources and Water-Related Ecosystem Services Using a Multi-Model Approach in the Ouriyori Catchment (Benin)

2019-06-01T00:00:00Z

Land Use and Climate Change Impacts on Water Resources and Water-Related Ecosystem Services Using a Multi-Model Approach in the Ouriyori Catchment (Benin) Togbevi Honfin, Quentin Fiacre Predicting and supplying freshwater resources in West Africa remain major concerns and challenges, basically due to factors such as lack of operational governance frameworks, socio-economic factors, poor resources at political/decision-making levels, and scarcity of reliable hydro-meteorological observations and related factors. This study investigated the impacts of climate change and land use on water availability in the Ouriyori catchment. The catchment is a meso-based headwater catchment and covers an area of about 14.51 km2 of the sudanian north-eastern Volta basin of Benin. The annual growth rate of the population over the study area was about 2.54 % (2002-2013). First, land use/land cover (LULC) change was assessed using Landsat images over the period 1988-2016. Next, soil infiltration measurement was carried out over the catchment considering the major LULC (cropland and fallow) using the hood infiltrometer along the transect lines. Afterwards, based on field investigations and spatio-temporal LULC, field measurements on soil hydraulic properties and the daily climatic and hydrological observed data, two distributed and physically based hydrological models, the Water Simulation Model (WaSiM) and the Soil and Water Assessment Tool (SWAT) were successfully calibrated, validated and used to evaluate the catchment water balance for the study area. From the models’ outputs and demographic data, some Hydrological Ecosystem Services (HES) were assessed in line with the ecosystem accounting framework to identify changes in the capacity of the catchment to provide services such as crop water and household water supply. Finally, five climate model datasets of the Coordinated Regional Climate Downscaling Experiment project using the Representative Concentration Pathways 4.5, were used to analyze the projected climate change signal in the catchment. In addition, the climate models’ ensemble was applied in WaSiM and SWAT to determine the ability of the climate models to reproduce the catchment discharge. LULC in the catchment showed an increase in cropland of about 42 % and decreased inversely with natural vegetation. These changes were attributed to the population growth and the conversion of natural vegetation to agricultural land and the environmental conditions. The good performance between observed and simulated daily discharge of both models was indicated by the goodness of fit coefficients (R2, NSE and KGE) with values ranging between 0.75 and 0.89. Both models were found suitable for discharge modelling exercises. Added to that, the HES-service capacity was found to be in general higher than the HES-service flow for crop water supply, surface water supply (SW) and groundwater (GW) supply with a general annual decrease in service capacity of both SW and GW. Results of the climate signal indicated that rainfall will increase by about 3.5 % to 5 % for CNRM-CERFACS and ICHEC-HIRHAM whereas a decrease of 1.5 % to 3 % is shown by ICHEC-REMO, MPI-REMO and MPI-RCA. The mean temperature will increase by 2 ˚C under RCP4.5. However, the individual models showed a mixed trend in discharge change. In addition, due to the large associated uncertainty, the results of the ensemble RCMs-GCMs do not give a clear path of the future hydrological behavior. For the development of suitable adaptation strategies, a mixed trend may be considered. Despite these findings, this study has demonstrated that more appropriate strategies would have to be implemented for the adequate and sustainable management of land and water resources of the catchment. A Thesis submitted to the West African Science Service Centre on Climate Change and Adapted Land Use and the Kwame Nkrumah University of Science and Technology, Kumasi, Ghana, in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Climate Change and Land Use

Modeling the Hydrological Response of the Dano Catchment, in the Volta Basin to Landuse Landcover Change and Climate Change

2019-06-01T00:00:00Z

Modeling the Hydrological Response of the Dano Catchment, in the Volta Basin to Landuse Landcover Change and Climate Change Okafor, Gloria Chinwendu This study investigated the scenario-based impacts of land-use landcover change and climate change on water resources of the Dano Catchment, in the Volta basin. Combining remote sensing images, field investigation, and historical climate variables, a scenario analysis was complemented by a spatially-distributed and physically process-based modeling approach to simulate the impact of LULCC and climate change on the catchment governing hydrological processes. First, CORDEX-Africa framework RCMs outputs were thoroughly investigated to gain knowledge on patterns and spatial variations in precipitation and temperature of the Volta basin and determine the model that best replicates the climate of the Volta Basin. Subsequently, climatic scenarios were constructed from these set of Regional Climate Models (RCMs) outputs. Representative concentration pathways (RCP) 4.5 and 8.5 ensemble of four datasets of the CORDEX-Africa project were then used to study the future change in temperature and precipitation. The predicted climate change signal was investigated in detail by comparing the future period 2020 – 2049 with the historical period 1971 – 2005. With regard to the future climate, the used climate models’ ensemble projected a clear trend of reduced rainfall over the catchment and consistent increase of temperature between 1.5°C and 1.7°C. The past LULC change was studied based on classified land use maps of the years 1990, 2000, 2010 and 2016 produced using supervised Maximum Likelihood Algorithm. Based on these maps two future LULC scenarios, viz, Business-as-usual and Afforestation were developed for the year 2050. The LULCC investigation from 1990 to 2016 suggests a decrease of savanna at annual rates of 2.53% while cropland and settlement areas have increased. However, the study noted about 5.3% forest recovery and grassland increased between 2000 and 2010. Prior to impact assessment, data retrieved from CHIRPS and NASA-POWER for Precipitation and Temperature (after validation with station climate data), were used to set up and drive the hydrological model SWAT. The model correctly reproduces the observed runoff regime at the basin outlet. Statistical performance measures (R², NSE, KGE) range between 0.71 and 0.94 for the calibration and validation of surface runoff indicating satisfactory. The modeled future LULC maps and climate scenarios were used to feed SWAT. The isolated and combined influence of LULC and climate change is investigated. The simulations that assumed constant LULC and climate as changing factor indicated decreases in surface runoff of about 77% and 3.6% to 3.9% increase in potential evapotranspiration. The simulation that assumed a constant climate and a changing LULC showed increasing water yield between 0.18% – 0.28% and mainly increasing runoff (0.02 - 3.30%). Actual evapotranspiration was estimated to slightly increase by 0.21% from the baseline condition. The combined application of LULC change and climate change signals gave a clear potential evapotranspiration increase (3.2% to 3.7%) causing surface runoff reduction between 72% - 77% and other components. The application of the historical and future climate data to SWAT showed that future changes in surface runoff follow the predicted precipitation signal. SWAT tends to produce larger hydrological changes under climate change scenarios and runoff showed more sensitivity to changes in precipitation. In summary, there is a strong relationship between runoff, climate, and human factors in the catchment that could result to increase in drought and flood risks, signifying the vulnerability of the catchment to future water availability. Therefore, efforts should be geared towards strengthening the operation of existing soil-water conservation techniques to enhance water infiltration and aquifer recharge. A Thesis submitted to the West African Science Service Centre on Climate Change and Adapted Land Use and the Kwame Nkrumah University of Science and Technology, Kumasi, Ghana, in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Climate Change and Land Use