http://hdl.handle.net/123456789/572 2026-05-14T14:32:40Z 2026-05-14T14:32:40Z SESAY, M. J http://hdl.handle.net/123456789/4631 2026-05-07T14:21:00Z 2026-01-01T00:00:00Z

Title: MODELLING THE EFFECTS OF IRRIGATION DEPTHS AND DRAINAGE SYSTEMS ON RICE PERFORMANCE IN THE GUINEA SAVANNAH AGRO ECOLOGICAL ZONE OF GHANA Authors: SESAY, M. J Abstract: The study modelled the effects of irrigation depths and drainage systems on the performance of rice in the Guinea Savannah agro-ecological zone of Ghana. The study specifically evaluated the effect of different irrigation application depths and drainage systems on growth and yield of rice, assessed the effects of irrigation application depths and drainage systems on changes in soil electrical conductivity, soil temperature and nitrogen balance in irrigated ecology, estimated Crop Water Stress Index (CWSI) for rice culture in an irrigated ecology and modelled the effects of irrigation application depths and drainage systems on LAI and yield of rice. The irrigation application depths were continuous flooding at 5 cm, 10 cm and 15 cm and alternate wetting and drying (AWD) at – 5 cm, - 10 cm and – 15 cm while the drainage systems were no drainage as control, surface drainage and sub-surface drainage systems. Micro plots with concrete blocks were constructed measuring 1 m × 1 m × 1 m and laid in a Randomized Complete Block Design in a 6 × 3 factorial treatment arrangement replicated three (3) times in 2023 and 2024 growing seasons. Soil electrical conductivity (EC) was used to determine the salinity index of the soil. Monitoring of temperature within the root zone of the crop was done throughout the crop growth cycle depicting each of the six stages in the paddy rice. To compute the baselines, the air temperature, leaf canopy temperature and the vapour pressure deficit (VPD) were used. Results indicated that sub-surface drainage with 5 cm irrigation depth produced the tallest plants (80 – 94 cm), high LAI (2.39 – 3.89), high leaf chlorophyll content (16.24 – 19.93 CCI) and a high yield (6.77 – 9.55 t/ha). No drainage under AWD 15 recorded the shortest plant (65 – 79 cm), lower LAI (0.85 – 2.16), lower Leaf Chlorophyll Content (LCC) (5.37 – 9.50) and lower yield (0.41 – 1.27 t/ha) in both seasons. The salinity level of the soil was high (347.8 µS/cm) in treatments with no drainage and low (186 µS/cm) in sub-surface drainage. Soil temperature results indicated that surface drainage under AWD 15 recorded the highest (37 – 43 oC) while the lowest (20 – 26 0C) was recorded in treatments with no drainage under continuous flooding. AWD with sub-surface drainage resulted in higher nitrogen content (0.064 – 0.095 %) while the lowest was recorded in continuous flooding with no drainage (0.038 %) and continuous flooding with surface drainage (0.031 %). Results indicated that CWSI was lower (0.075) in CF 5-10 in 2023 and 0.143 in 2024 due to temperature differences while the highest CWSI (0.831 and 0.857) were recorded in AWD – 15. In 2023, CWSI gave a regression model of y = - 0.1191x + 0.7587 and a coefficient of determination (R2) value of 0.987 while in 2024, a regression model of y = - 0.0969x + 0.8673 where (x) represents the irrigation application depths. Observed simulation showed more accurate results for CF 5 with no drainage (d-stat = 0.92 and R2 = 0.93). The regression analysis of the yield produced a regression equation y = - 0.242x + 6182.2 with a coefficient of determination (R2) value of 0.654. During the evaluation, R2 for no-drainage condition ranged from 0.81 – 0.97, RMSE ranged from 0.11 – 1.72 and D-index ranged from 0.31 – 0.98. The continuous flooding at irrigation water depth of 5 cm (CF 5) gave the highest Willmot’s d-index of agreement of 0.98 while the lowest d-index was recorded on treatment AWD -15. In conclusion, sub-surface drainage system under 5 cm irrigation depth proved to be more efficient in terms improving the growth and yield parameters of rice while at the same time conserving water. The values derived for CWSI in this study can be used to understand the stress dynamics of rice in various stages of growth under different irrigation depths and drainage systems. The performance of rice can be increased greatly by adopting irrigation application depth of 5 cm with drainage management being put in place. CWSI estimation offers a practical tool for drought mitigation and irrigation scheduling in both irrigated and rainfed rice systems. Description: REQUIREMENTS FOR THE AWARD OF DOCTOR OF PHILOSOPHY IN IRRIGATION AND DRAINAGE ENGINEERING

2026-01-01T00:00:00Z UMUKIZA, E. http://hdl.handle.net/123456789/4628 2026-05-07T14:17:01Z 2026-01-01T00:00:00Z

Title: EVALUATION AND OPTIMISATION OF SITING OF SMALL DAMS AND RESERVOIRS IN NORTHERN GHANA Authors: UMUKIZA, E. Abstract: Water shortage is a significant challenge in developing countries, particularly in semi-arid and arid regions, posing obstacles to irrigation and human survival. Northern Ghana experiences a rainy season with occasional floods, water shortages, and dry spells. To address this recurring issue, a study on optimization of small dams and reservoirs was necessary. This study focused on sixteen (16) selected sub-catchments in three (3) northern Ghana regions where small dams and reservoirs were developed for domestic and agricultural purposes. On-site investigation of current status of reservoirs, engineering and structural conditions were conducted. Hydraulic conductivity and soils of embankment were analysed. Upstream simulation of spatio-temporal land use/landcover dynamics impacts on runoff generation was analysed using geographic information system, remote sensing techniques and curve number model. Additionally, the suitability assessment of the constructed small dams and reservoir locations was conducted using an analytic hierarchy process. Scenarios of optimal storage capacity of suitable dam locations were determined using 2D and Civil 3D. The results of the study highlighted the multifaceted challenges associated with small dam failures, emphasizing the need for a holistic approach that integrates engineering solutions and improved design. The comprehensive assessment highlighted variability in hydraulic conductivity ranging from 0.742 × 10-6 to 12.7 ×10-6 cm/s indicating lower and higher permeability and potential seepage, respectively. Spatial-temporal analysis of landuse and landcover from 1995 to 2023 revealed upstream anthropogenic activities, such as the conversion of grassland to agricultural/arable lands and built-up areas, indicating historical landuse and landcover changes and their impact on hydrological mechanisms, and the increase in impervious surfaces resulting in enhanced surface runoff. Findings on suitability assessment of the small dam locations revealed that ten (10) of the dams were located away but less than 100 m from major streamflow networks, posing potential challenges in optimal surface runoff collection. An overall analysis of suitable locations of dams and their optimal storage capacity identified potential relocations for six (6) dams. The proposed new dam locations and their storage capacities were deemed crucial for addressing water scarcity while balancing conflicting needs of various water users. The study findings underscored the significance of research-based decision-making in addressing water shortages and maintaining a balance between agricultural, domestic, and environmental water needs. Regular inspection programmes are recommended to identify and address problems early, preventing complex and costly issues. Assessment of challenges and opportunities in water infrastructure development under changing climatic conditions, and evaluation of socioeconomic impacts and involving communities for sustainability and resilience of small dams were suggested for future research. Description: REQUIREMENTS FOR THE AWARD OF DOCTOR OF PHILOSOPHY IN IRRIGATION AND DRAINAGE ENGINEERING

2026-01-01T00:00:00Z MAJEWEN, I. B. http://hdl.handle.net/123456789/4623 2026-04-28T10:13:54Z 2026-01-01T00:00:00Z

Title: EVALUATION OF WATER PRODUCTIVITY FOR VINE PRODUCTION OF ORANGE-FLESHED SWEET POTATO (Ipomoea batatas (L.) Lam.) UNDER DIFFERENT SUPPLEMENTARY IRRIGATION TECHNIQUES AND FERTILIZER APPLICATION IN EAST MAMPRUSI DISTRICT Authors: MAJEWEN, I. B. Abstract: Orange-Fleshed Sweet Potato (Ipomoea batatas (L.) Lam.) is a climate-resilient crop with significant potential for improving food security and livelihoods in semi-arid regions. However, its productivity is often limited by water scarcity and soil nutrient deficiencies. Despite its importance, limited research has been conducted on the combined effects of supplementary irrigation techniques and fertilizer application on vine production and water productivity. This study evaluated the performance of orange-fleshed sweet potato under three supplementary irrigation techniques-drip, rain tube, and furrow irrigation -combined with fertilizer application in the East Mamprusi District. A split-plot experimental design was used, with irrigation technique as the main plot factor and fertilizer application (with and without) as the subplot factor. The experiment consisted of six treatment combinations, replicated three times, making a total of eighteen experimental units. Each plot measured 5 m × 10 m, with a planting density of 33,333 plants per hectare. Supplementary irrigation was applied based on the estimated crop water requirement of 412 mm for the growing season. The hydraulic performance of the irrigation systems showed emitter flow variations of 58.2 % and 61.5 % for drip and rain tube, respectively, indicating poor performance. However, the uniformity coefficients were rated as good, at 82.4% for drip and 78.6% for rain tube. In evaluating the performance of the drip and rain tube irrigation system used on the study site, the ratings were assigned according to ASAE (1999). The emitter flow variation for drip and rain tube irrigation systems was 23.6 % and 30.8 %, respectively, both classified as poor. The uniformity coefficient was 90.45% for drip and 89.76 % for rain tube, rated as very good. Field emission uniformity was 85 % for drip and 81% for rain tube, both rated as good. The coefficient variation was 0.11 for drip (fair) and 0.15 for rain tube (poor), indicating moderate variability in water distribution. The highest vine yield (1.36 ton/ha) and dry above ground biomass (5.51 ton/ha) were recorded under drip irrigation with fertilizer, whereas the lowest yield (0.73 ton/ha) and above- ground biomass (3.12 ton/ha) was observed under rainfed conditions without fertilizer. Water productivity (WPET) followed a similar trend, with drip irrigation and fertilizer yielding 1.49 kg/m³, while rainfed conditions without fertilizer recorded 0.81 kg/m³. Canopy cover varied significantly, with the highest observed cover (90%) under drip and rain tube irrigation with fertilizer, while rainfed conditions without fertilizer had the lowest (56%). Water use efficiency (WUE) was highest under drip irrigation (2.22 kg/ha/mm), followed by rain tube (1.92 kg/ha/mm), furrow (1.75 kg/ha/mm), and rainfed conditions (1.53 kg/ha/mm). Findings indicate that supplementary irrigation, particularly drip irrigation with fertilizer, enhances vine yield and water productivity. However, rain tube irrigation presents a viable alternative due to its relatively lower cost. This study provides insights for optimizing irrigation strategies in semi-arid environments and serves as a valuable reference for policymakers, researchers, and extension officers promoting climate-smart agricultural practices. The adoption of climate-smart supplementary irrigation techniques with fertilizer support is recommended to improve water productivity and ensure sustainable orange-fleshed sweet potato production. Description: REQUIREMENTS FOR THE AWARD OF MASTER OF PHILOSOPHY IN IRRIGATION AND DRAINAGE ENGINEERING

2026-01-01T00:00:00Z ABDALLHA, E. I. N. http://hdl.handle.net/123456789/4570 2026-02-04T10:49:53Z 2025-01-01T00:00:00Z

Title: GROUNDWATER MINERALIZATION AND ITS IMPLICATIONS FOR DOMESTIC AND IRRIGATION PURPOSES IN TOLON DISTRICT, GHANA Authors: ABDALLHA, E. I. N. Abstract: Groundwater resources play a crucial role in sustaining the livelihoods of inhabitants in the semi arid Tolon District of the Northern Region of Ghana. This study assessed access to drinking water resources in relation to socioeconomic and geographical factors, investigated the sources and mechanisms of groundwater mineralization, evaluated groundwater quality for domestic and irrigation purposes, and assessed the associated human health risks. Ninety-seven (97) groundwater samples were analyzed using a combination of multivariate statistical, geostatistical, and geochemical techniques. Irrigation Water Quality Indices (IWQIs) were applied to determine groundwater suitability for irrigation. The results showed that only 40% of households had access to improved drinking water sources, with about 85% of the population consuming less than 15 liters of water per person per day. Access to drinking water varied significantly across socioeconomic groups and geographical locations. Hydrochemical analysis identified EC, TDS, Na⁺, Mg²⁺, HCO₃⁻, and Cl⁻ as the major contributors to groundwater mineralization, with dominant water types being Na–HCO₃, Na–Cl, Ca–HCO₃, and Mg–HCO₃. Evaporation and anthropogenic activities, particularly agriculture, were found to be the main sources of groundwater contamination. Water quality assessment revealed that several parameters, including turbidity, EC, Ca²⁺, F⁻, NO₃⁻, As, Cd, faecal coliforms (FC), and total coliforms (TC), exceeded the WHO recommended limits. The Water Quality Index (WQI) indicated that 1.82% and 2.38% of groundwater samples were unsuitable for drinking during the rainy and dry seasons, respectively. Health risk assessment identified non-carcinogenic risks associated with NO₃⁻, F⁻, As, and Cd, while carcinogenic risks from As and Cd were notably higher among children. Groundwater suitability for irrigation varied spatially and seasonally, with the southeastern parts of the district exhibiting higher mineralization and generally poorer water quality. In conclusion, the study highlights significant challenges in ensuring groundwater safety for both domestic and agricultural uses. The findings underscore the urgent need for continuous monitoring, improved groundwater management, and the implementation of mitigation measures to safeguard public health and promote sustainable water use in the Tolon District. Description: DOCTOR OF PHILOSOPHY IN IRRIGATION AND DRAINAGE ENGINEERING

2025-01-01T00:00:00Z