Browsing by Author "Mahoo, H. F."

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Application of self-organizing-maps technique in downscaling GCMs climate change projections for Same, Tanzania
Tumbo, S. D.; Mpeta, E.; Mbillinyi, B. P.; Kahimba, F. C.; Mahoo, H. F.; Tadross, M.
Application of self-organizing-maps technique in downscaling GCMs climate change projections for Same, Tanzania
(2010) Tumbo, S. D.; Mpeta, E.; Mbillinyi, B. P.; Kahimba, F. C.; Mahoo, H. F.; Tadross, M.
High resolution surface climate variables are required for end-users in climate change impact studies; however, information provided by Global Climate Models (GCMs) has a coarser resolution. Downscaling techniques such as that developed at the University of Cape Town, which is based on Self-Organizing Maps (SOMs) technique, can be used to downscale the coarse-scale GCM climate change projections into finer spatial resolutions; but that must be combined with verification. The SOM downscaling technique was employed to project rainfall and temperature changes for 2046-2065 and 2080-2100 periods for Same, Tanzania. This model was initially verified using downscaled NCEP reanalysis and observed climate data set between 1979 and 2004, and between NCEP reanalysis and GCM controls (1979 - 2000). After verification, the model was then used to downscale climate change projections of four GCMs for 2046-2065 (future-A) and 2080-2100 (future-B) periods. These projections were then used to compute changes in the climate variables by comparing future-A and B to the control period (1961-2000). Verification results indicated that the NCEP downscaled climate data compared well with the observed data. Also, comparison between NCEP downscaled and GCM downscaled showed that all the four GCM models (CGCM, CNRM, IPSL, and ECHAM) compared well with the NCEP downscaled temperature and rainfall data. Future projections (2046-2065) indicated 56 mm and 42 mm increase in seasonal total rainfall amounts for March-April-May (MAM) and October-November-December (OND) (23% and 26% increase), respectively; and a temperature increase of about 2°C for both seasons. Furthermore, it was found that during MAM there will be a decrease in dry spells by 2 days, and an increase in seasonal length by 8 days, while for OND, there will be also 2 days decrease in dry spells, and 40 days increase in the seasonal length. The results for future-B shows a 4°C rise in temperature, and 46.5% and 35.8% increase in rainfall for MAM and OND, respectively. The results imply a better climatic future for the area because of the increase in the amount of rainfall and decrease in dry spells. However, it is suggested that further investigations are required to see if the projected changes will have real positive effects in agricultural production and also identify better agronomic practices that will take advantage of the opportunities.
Comparative assessment of soil and nutrient losses from three land uses in the central highlands of Ethiopia
(Academic journals) Jaleta, D.; Mbilinyi, B. P.; Mahoo, H. F.; Lemenih, M.
Comparative assessment of soil and nutrient losses from three land uses in the central highlands of Ethiopia
(Academic journals, 2017) Jaleta, D.; Mbilinyi, B. P.; Mahoo, H. F.; Lemenih, M.
Land use/land cover change drive changes in several ecosystem processes over short and long terms. In Ethiopia, the main land use/land cover change involves conversion of natural ecosystem into cultivated land. However, a recent change also involves conversion of cultivated and gra zing land into Eucalyptus woodlots. This study was conducted to analyse the effects of such land use/land cover change on soil and nutrient losses. Three land use/ land cove r types (cultivated land, grassland and Eucalyptus woodlot) were selected for a comparative assessment. A total of twelve runoff plots, each with 43.3 m2 area and with four replications, were installed. Rainfall depth, runoff volume and sediment samples (500 ml) were collected from each plots every morning and evening for 91 days (from 4th July to 2nd October, 2015) in the main rainy season. The sediment samples for ten consecutive days were stored in separate containers and composite sediment concentration samples were weighed after being filtered and oven dried for 24 hours at 105o c. From the samples taken at the end of the rainy season, separate composite a sample before filtration of one litre was analysed in the laboratory for nutrient losses. The effect of land use/land cover on soil and nutrients losses was statistically tested using analysis of variance. The study found that soil loss significantly differed between the land use /land cover types. Soil loss from cultivated land (16.8 ton/ha) was significantly higher than loss from grassland (7 ton/ha) and Eucalyptus stand (8.1 ton/ha). The soil and nutrient losses were positively correlated with runoff volume. There was higher nutrient (N and P) loss from cultivated land than grassland and Eucalyptus. From the results, it can be concluded that soil and nutrients losses are above tolerable limit, and perennial land covers including Eucalyptus stand reduce soil and nutrient losses significantly. This re-affirms the multi-purpose nature of Eucalyptus not only for socioeconomic benefit but also for soil erosion control when planted in appropriate locations
Comparison of silicon status in rice grown under the system of rice intensification and flooding regime in Mkindo Irrigation Scheme, Morogoro, Tanzania
(TAJAS) Gowele, G. E.; Mahoo, H. F.; Kahimba, Frederick C.
Determination of suitability levels for important factors for identification of potential sites for rainwater harvesting
Tumbo, S. D.; Mbillinyi, B. P.; Mahoo, H. F.; Mkiramwinyi, F. O.
Determination of suitability levels for important factors for identification of potential sites for rainwater harvesting
(2016) Tumbo, S. D.; Mbillinyi, B. P.; Mahoo, H. F.; Mkiramwinyi, F. O.
Indigenous and scientific knowledge for locating potential sites for water harvesting technologies do exists, however, a simple and integrated tool to assist farmers’ support agencies, is missing. A geographic information system (GIS)-based decision support system (DSS) can be a valuable tool for such a task. However, pre-requisite for such DSS are the factors and their suitability levels, which are not well developed. This paper focused on development of suitability levels for most important factors/parameters for identification of such sites, which are soil texture, soil depth, drainage, topography and land use or cover. Specific suitability levels were obtained using both the analysis of existing RWH technology at Makanya river catchment and through literature review. Results of field survey together with literature review showed that suitability levels of factors differ with different RWH technologies. For example, suitable levels/areas for water reservoirs (ndiva) are steep slopes (>30o) with clay soils whereas suitable sites for stone terraces are moderately steep slopes (18o – 30o) with sandy loam soils. It was also found that most RWH technologies are located at a distance between 0 and 125m from cropland.
Economics of Rainwater Harvesting for Crop Enterprises in Semi-Arid Areas: The Case of Makanya Watershed in Pangani River Basin, Tanzania
(Sokoine University of Agriculture) Mutabazi, K.D.; Senkondo, E. E.; Mbilinyi, B.P.; Tumbo, D.S.; Mahoo, H. F.
Effect of Eucalyptus expansion on surface runoff in the central highlands of Ethiopia
(SpringerOpen.) Jaleta, D.; Mbilinyi., B. P.; Mahoo, H. F.; Lemenih, M.
Enhancing response farming for strategic and tactical management of risks of seasonal rainfall variability
Admassu, H.; Mahoo, H. F.; Rwehumbiza, F. B. R.; Tumbo, S. D.; Mogaka, H.
Estimation of environmental flows in the Great Ruaha River Catchment, Tanzania: use of the desktop reserve model
(WATERNET/WARFSA/GWP-SA) Kashaigili, J. J.; Mccartney, M.; Mahoo, H. F.
GIS-based decision support system for identifying potential sites for rainwater harvesting
(Physics and Chemistry of the Earth) Mbilinyi, B. P.; Tumbo, S. D.; Mahoo, H. F.; Mkiramwinyi, F. O.
GIS-based decision support system for identifying potential sites for rainwater harvesting
(Physics and Chemistry of the Earth, 2007) Mbilinyi, B. P.; Tumbo, S. D.; Mahoo, H. F.; Mkiramwinyi, F. O.
Identification of potential sites for rainwater harvesting (RWH) is an important step towards maximizing water availability and land productivity in the semi-arid areas. However, selection of appropriate sites for different RWH technologies on a large scale presents a great challenge, since the necessary biophysical data and infrastructure are often lacking. This paper presents a geographic information system (GIS)-based decision support system (DSS) that uses remote sensing (RS), limited field survey to identify potential sites for RWH technologies. The input into the DSS include maps of rainfall, slope, soil texture, soil depth, drainage and land use/cover and the outputs are maps showing potential sites of water storage systems (ndiva), stone terraces, bench terraces and borders. The Model Builder in the Arc View GIS was used as a platform for the DSS. Two sites in the Makanya watershed, in Kilimanjaro Region, Tanzania, were used for testing and validation of the DSS. The results reflect specific suitability levels of parameters and weight of factors; for example, near streams (drainage) with slope ranges from moderately steep to steep (10 –30 ) are potential sites for ndiva locations whereas moderately undulating to steep slopes (5 –30 ) with unstable soils are potential sites for stone terraces. Moderately undulating slopes (5 –10 ) with clay, silt clay and sandy clay soils are potential sites for bench terrace and gently undulating slopes (2 –5 ) with clay, silt clay and sandy clay soils are potential sites for borders. The results from testing and validation of the developed DSS indicated that the tool can be used reliably to predict potential sites for RWH technologies in semi-arid areas. Most of predicted RWH technologies during testing were found within very highly and highly suitable locations (41.4% and 40%, respectively) also in validation 36.9% of RWH technologies were found within the moderately suitable followed by very highly suitable and highly suitable both with 23.6%. Despite the good results, it is recommended that more work be carried out to refine the model and to include other pertinent ancillary data like socio-economic factors to increase its usefulness.
Hydrological modelling to assist water management in the Usangu wetlands, Tanzania
(JRBM) McCartney, M.P.; Kashaigili, J.J.; Lankford, B.A.; Mahoo, H. F.
Identification of suitable indices for identification of potential sites for rainwater harvesting
(Tanzania Journal of Agricultural Sciences) Tumbo, S. D.; Mbillinyi, B. P.; Mahoo, H. F.; Mkilamwinyi, F. O.
Identification of suitable indices for identification of potential sites for rainwater harvesting
Tumbo, S.D.; Mbilinyi, B. P.; Mahoo, H. F.; Mkilamwinyi, F.O.
Identification of suitable indices for identification of potential sites for rainwater harvesting
(Tanzania Journal of Agricultural Sciences, 2014) Tumbo, S. D.; Mbillinyi, B. P.; Mahoo, H. F.; Mkilamwinyi, F. O.
Although indigenous and scientific knowledge for locating potential sites for water harvesting technologies do exist, a simple and integrated tool to assist farmers’ support agencies, is missing. A geographic information system (GIS)-based decision support system (DSS) can be a valuable tool for such a task. However, key to such DSS are the factors and their suitability levels, which are not well developed. This study therefore focused on the development of suitability levels for most important factors/parameters for identification of such sites. The factors included rainfall, soil texture, soil depth, drainage, topography and land use or cover. Specific suitability levels were derived from analysis of existing RWH technologies in Makanya river catchment. Results showed that suitability levels of factors differ with different RWH technologies. Suitable areas for ndiva is on steep slopes (18o-30o) with clay soils, stone terraces is on moderately steep slopes (10o – 18o) with sandy clay loam soils, bench terraces (5o-18o slopes, clay or silt clay soils) and “boda” (2o-5o slopes, slit clay or clay soils). It was also found that ndiva, “boda”, stone terrace and bench terrace are located at a distance within 125m from cropland. Testing of the developed parameters using ArcView-based DSS framework showed that 81.4% RWH technologies were located in the very high and high suitability levels, indicating the usefulness of the developed parameters and their suitability levels.
Impact of projected climate change on agricultural production in semi-arid areas of Tanzania: A case of Same district
Tumbo, S. D.; Kahimba, F. C.; Mbilinyi, B. P.; Rwehumbiza, F. B.; Mahoo, H. F.; Mbungu, W. B.; Enfors, E.
Integrated catchment characteristics, runoffwater reservoir capacities and irrigation - requirement for bean productivity
Singa, D. D.; Tumbo, S. D.; Mahoo, H. F.; Rwehumbiza, F. B. R.; Lowole, M. W.
Integrated catchment characteristics, runoffwater reservoir capacities and irrigation - requirement for bean productivity
(2013) Singa, D. D.; Tumbo, S. D.; Mahoo, H. F.; Rwehumbiza, F. B. R.; Lowole, M. W.
Crop production in semi-arid Sub-Saharan Africa (SSA) is limited by over-reliance on rainfall, which is erratic and inadequate. Rainwater conservation and irrigation are needed to avert drought effects and dry spells, and extend crop production activities to dry seasons. A study was conducted from 2011 to 2013 at Ukwe area in Malawi, to determine the size of seasonal open surface reservoir and crop field in relation to catchment characteristics among smallholder farming communities, using beans as a case study crop. There is positive linear relationship between seasonal harvested watershed runoff and rainfall (over 75%). Based on the catchment characteristics and crop water requirement, catchment/cultivated area ratio was 2.1. Harvested runoff water is linearly related to seasonal rainfall amount. About 6000 m3 of water was required to irrigate a hectare of beans. Total volume harvested was estimated to support six-fold the current field area at bean water productivity of 0.7 g L-1. It is possible to determine dry season bean water productivity based on integrated effects of catchment characteristics, runoff water reservoir capacities and irrigation water requirement.