Browsing by Author "Wambua, Raphael M"

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Drought Forecasting Using Indices and Artificial Neural Networks for Upper Tana River Basin, Kenya-A Review Concept
(Journal of Civil & Environmental Engineering, 2014-06) Wambua, Raphael M; Mutua, Benedict M; Raude, James M
Due to increased impact of drought on water availability at different scales there is need to understand droughts especially in upper Tana River basin which is a critical and largest water system in Kenya. There is need to correlate trends of drought as influenced by the climate variability of the present times. Drought frequency, duration and intensity in the basin have been increasing. The influencing hydro-meteorological parameters and their interaction are necessary in developing measures for mitigating impacts of droughts. It is important to have a timely review of drought definitions and fundamental concepts of droughts, classification of droughts, types of drought indices, historical droughts and artificial neural networks with special focus of Kenyan a basin. Out of the review, this paper draws conclusions where gaps for more focused research especially for a typical river basin in Kenya exist. By developing effective drought forecasting tool for on-set detection and drought classification and drought forecasting, information on decision making on matters of drought preparedness and mitigation programmes will be available for proper water resources management.
Yield Response, Water Use and Water Productivity of Tomato under Deficit Sub-Surface Drip Irrigation and Mulching
(Journal of Sustainable Research in Engineering, 2019) Sang, Hellen J.; Wambua, Raphael M; Raude, James M.
The greatest challenge in the agricultural sector is to produce more food with less water. The problem facing tomato growers in Njoro Sub County is the unfavourable conditions for tomato growth which includes very low rainfall during the dry periods. This requires maximizing yield per unit of water used. However, there is limited information on water management strategies, or deficit irrigation that would maximize tomato crop yield and additionally improve on the quality of fruit when drip irrigation is used. The objective of this study was to evaluate the effect of deficit sub – surface drip irrigation and mulching systems on water productivity of tomato (Lycopersicon esculentum mill) crop in Njoro Sub County. The study was carried out on experimental plots measuring 4 m2 in a shade at Egerton University’s Tatton farm. Factorial experimental design was used in this study where the treatments were three water levels (100 % ETC. 80% ETC and 60 % ETC) and four grass mulch densities (0, 0.5, 1 and 1.5 kg/m2 ) replicated three times. The sub – surface drip lines were laid at a depth of 5 cm below the ground surface. An estimated crop water requirement was applied to the respective plots based on various irrigation levels guided by the four main tomato crop development stages. The agronomic parameters and yield was monitored on weekly basis over a period of twenty weeks. The tomato water productivity under the interactive effect of deficit sub – surface drip irrigation and grass mulch densities was determined to be highest at 60 % ETC and 1 kg/m2 of grass mulch and lowest at 100 % ETC and 1.5 kg/m2. The study provides information on optimum application rates that can be adopted for production of more tomato yields by farmers with less water thus leading to poverty reduction by improving the agri-business in Njoro Sub County.