Publications

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2013
2008
Ngigi SN, Savenije HHG, Gichuki FN. "Hydrological impacts of flood storage and management on irrigation water abstraction in Upper Ewaso Ng'iro river basin, Kenya.". 2008. AbstractWebsite

The upper Ewaso Ng’iro basin, which starts from the central highlands of Kenya and stretches northwards transcending different climatic zones, has experienced decreasing river flows for the last two decades. The Naro Moru sub-basin is used to demonstrate the looming water crisis in this water scarce river basin. The objective of the study was to show the extent of dry seasons’ irrigation water abstractions on river flows, and to assess the hydrological impact of flood storage on temporal water distribution and irrigation water management. Decreasing river flows are attributed to over-abstraction mainly for irrigating horticultural crops. The number of abstractors has increased four times over a period of 10 years. The amount of water abstracted has also increased by 64% over the last 5 years. Moreover, the proportion of unauthorized abstractions has been increasing over the years, currently at about 80% and 95% during high and low flows respectively. This has resulted in alarming conflicts among various water users. The situation is aggravated by low irrigation efficiency (25–40%) and inadequate flood storage facilities. The paper analyzes over 40 years’ observed river flow data and 5-year interval water abstraction monitoring records for 15 years. It assesses whether flood storage and management, can reduce dry seasons’ irrigation water abstractions without significantly reducing river flows to affect the sustenance of natural ecosystems downstream. The results demonstrate that flood storage and management can reduce water abstraction and increase river flows during the dry seasons, without significantly reducing high flows to affect the downstream water users. However, socio-economic, hydrological and environmental implications should be considered if a sustainable river basin water resources management strategy is to be developed and implemented. The case study of Naro Moru sub-basin is representative of the situation in the other sub-basins, and hence can be taken as a pilot basin for developing an integrated water resources management strategy that will foster socio-economic development with minimal negative hydrological impacts in the water scarce upper Ewaso Ng’iro river basin.

2006
NJUGUNA DRNGIGISTEPHEN. "Ngigi, S.N, H.H.G. Savenije and F.N. Gichuki. 2006. Hydrological impacts of rainwater harvesting and management on dry seasons' irrigation water abstraction in upper Ewaso Ng'iro river basin, Kenya. Paper submitted to Agriculture, Ecosystems and Environme.". In: Proceedings of 3rd Int. Conf. On bearing capacity of roads and airfields PP 743-756, Trondeihm, Norway. Longhorn; 2006. Abstract
 Journal of Civil Engineering, Jomo Kenyatta University of Agriculture and Technology Vol.7 PP
NJUGUNA DRNGIGISTEPHEN. "Ngigi, S.N, H.H.G. Savenije and F.N. Gichuki. 2006. Land use changes and hydrological impacts related to up-scaling of rainwater harvesting and management in upper Ewaso Ng 'iro river basin, Kenya. Land Use Policy (in press).". In: Proceedings of 3rd Int. Conf. On bearing capacity of roads and airfields PP 743-756, Trondeihm, Norway. Longhorn; 2006. Abstract
 Journal of Civil Engineering, Jomo Kenyatta University of Agriculture and Technology Vol.7 PP
NJUGUNA DRNGIGISTEPHEN. "Ngigi, S.N. 2006. Hydrological impacts of land use changes on water resources management and socio-economic development of upper Ewaso Ng'iro river basin in Kenya. Ph.D. dissertation, UNESCO-IHE/Technical University of Delft, Netherlands. A. A. Balkema Pu.". In: Proceedings of 3rd Int. Conf. On bearing capacity of roads and airfields PP 743-756, Trondeihm, Norway. Longhorn; 2006. Abstract
 Journal of Civil Engineering, Jomo Kenyatta University of Agriculture and Technology Vol.7 PP
NJUGUNA DRNGIGISTEPHEN. "Ngigi, S.N., J. Rockstrb'm and H.H.G. Savenije 2006. Assessment of rainwater retention in croplands due to conservation tillage and hydrological impacts in Ewaso Ng'iro river basin, Kenya. Physics & Chemistry of the Earth (in press).". In: Proceedings of 3rd Int. Conf. On bearing capacity of roads and airfields PP 743-756, Trondeihm, Norway. Longhorn; 2006. Abstract
 Journal of Civil Engineering, Jomo Kenyatta University of Agriculture and Technology Vol.7 PP
NJUGUNA DRNGIGISTEPHEN. "Ngigi, S.N., J.N. Thome and R.K. Muni. 2006. Rainwater harvesting and management systems and complementary technologies: Multi-sectoral approach towards sustainable livelihoods of pastoral and agro-pastoral communities in semi-arid districts of Kenya. GHA.". In: Proceedings of 3rd Int. Conf. On bearing capacity of roads and airfields PP 743-756, Trondeihm, Norway. Longhorn; 2006. Abstract
 Journal of Civil Engineering, Jomo Kenyatta University of Agriculture and Technology Vol.7 PP
2005
NJUGUNA DRNGIGISTEPHEN. "Ngigi, S.N., J. Rockstrom and C.K.K. Gachene. 2005. Hydro-economic evaluation of rainwater harvesting and management technologies: Fanners' investment options and risks in semi-arid Laikipia district of Kenya. Physics & Chemistry of the Earth, 30:772-782.". In: Proceedings of 3rd Int. Conf. On bearing capacity of roads and airfields PP 743-756, Trondeihm, Norway. Longhorn; 2005. Abstract
 Journal of Civil Engineering, Jomo Kenyatta University of Agriculture and Technology Vol.7 PP
NJUGUNA DRNGIGISTEPHEN. "Ngigi, S.N., J.N. Thome, J. Rockstrom, F.W.T. Penning de Vries, and H.H.G. Savenije 2005. Agro-hydrological evaluation of on-farm rainwater storage systems for supplemental irrigation in Laikipia district, Kenya. Agricultural Water Management, 73(1): 21-4.". In: Proceedings of 3rd Int. Conf. On bearing capacity of roads and airfields PP 743-756, Trondeihm, Norway. Longhorn; 2005. Abstract
 Journal of Civil Engineering, Jomo Kenyatta University of Agriculture and Technology Vol.7 PP
2003
NJUGUNA DRNGIGISTEPHEN. "Ngigi, S.N. 2003. Rainwater harvesting for improved food security: Promising technologies in the Greater Horn of Africa. Greater Horn of Africa Rainwater Partnership (GHARP), Kenya Rainwater Association (KRA), Nairobi, Kenya./) 266.". In: Proceedings of 3rd Int. Conf. On bearing capacity of roads and airfields PP 743-756, Trondeihm, Norway. Longhorn; 2003. Abstract
 Journal of Civil Engineering, Jomo Kenyatta University of Agriculture and Technology Vol.7 PP
NJUGUNA DRNGIGISTEPHEN. "Ngigi, S.N. 2003. What is the limit of up-scaling rainwater harvesting in a river basin? Physics & Chemistry of the Earth, 28:943-956.". In: Proceedings of 3rd Int. Conf. On bearing capacity of roads and airfields PP 743-756, Trondeihm, Norway. Longhorn; 2003. Abstract
 Journal of Civil Engineering, Jomo Kenyatta University of Agriculture and Technology Vol.7 PP
2002
1999
1994
NJUGUNA DRNGIGISTEPHEN. "Ngigi, S.N. 1994. The environmental impacts of irrigation development. Term paper adopted as Chapter 8: Ecology and Irrigation Development, in 'Social and Physical Ecology' M.Sc. lecture textbook edited by Prof. D.B. Thomas, Dept. of Agricultural Engineer.". In: Proceedings of 3rd Int. Conf. On bearing capacity of roads and airfields PP 743-756, Trondeihm, Norway. Longhorn; 1994. Abstract
 Journal of Civil Engineering, Jomo Kenyatta University of Agriculture and Technology Vol.7 PP
1979

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