KIGALI INSTITUTE OF SCIENCE AND TECHNOLOGY institut des Sciences et de Technologie de Kigali Avenue de l'Arme, B.P. 3900 Kigali, Rwanda

PROJECT TITLE COMPARATIVE STUDY OF VARIOUS PROTECTION MEASURES TO NZOVE WATER WELLS AGAINST NYABARONGO RIVER MEANDERING ACTION

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Done by : BAGARAGAZA Romuald (M2014028)

WATER CONSERVANCY AND HYDROPOWER ENGINEERING

COLLEGE OF INTERNATIONAL STUDENTS

ART OF ENGLISH WRITING AND PRESENTATION

5/26/2015

1 2.Problem statementErosion of river bankLoss of land around the wells areas.Loss of valuable land in general.Disappearances of Nzove water wellsDecrease of Nzove WTP capacity.

25/26/201523.DISAPPEARANCES OF NZOVE WATER WELLS

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4.objectives Main objectiveTo study how Nzove water wells can be protected against river meandering action, Specific objectivesTo illustrate the current and actual state of NZOVE water wells to NYABARONGO river valley. To produce the assessment report of various causes and effects of NYABARONGO river meandering on NZOVE water wells. To produce inventory and comparative study of various riverbank protection measures.To design and to layout of the best solution from the study.To deals with cost estimation of the project.

45/26/201545.Research methodology Site visit interviews

Total sediment load test

River bank soil test

Questionnaires

Documentation

55/26/201556.Study area Location of NWW on ground water mapSite description The NZOVE WTP is located in Kigali city, Nyarugenge District, Kanyinya sector, NZOVE cell to almost 12 km from Kigali downtown.

NWTP is located to almost 3km from Giticyinyoni road to Ruhengeri.

The NWW are located to almost 1.1 km toward nzove WTP.5/26/20156

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7.Comparison between: gabion wall, groins and RCC

S\NPARAMETERSGABION WALL

GROINS

RCC LONG WALL

1Flexibility highly flexiblehighly flexibleRigid2Permeabilityhighly permeablehighly permeabledeep hole required3Simplicity Simplesimple skilled work4Cost30-50 % saving20-35 % savingExpensive75/26/201578.Selection criteria Effectiveness and stability: (height and flow condition)Construction materials availability: (extraction of stones and reinforcement)Cost estimation,7. Causes of NYABARONGO river meandering on NZOVE water wells.silt deposited in the inner edge of the curve.river has a very higher slope (gradient).Flow variation (eg: flooding).85/26/201589.Typical Layout of Gabion Wall

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911.RESULTS AND DISCUSSIONSChecking sliding Soil classification 5/26/201510

1012.BENEFIT OF PROJECT 1. IN COST OF CONSTRUCTION

The project shows that to protect one water wells among the three is about 310,080,500 (three hundred billion )2.In general the project has many advantages such as:

Ecofriendly: A gabion wall will permit the growth of vegetation which will contribute to the integrity of structure and maintaining a natural appearance.Durability: The design life of a gabion structure constructed with suitable stone fill will be excess of the 60 years.Economy&Speedy Constructions: local material is used and non skilled laborers are required.Permeable & Self Supporting Structures

115/26/20151113.ConclusionBy concluding that gabion wall is cost effective ,and

Efficiency to protect river bank for the flow in motion.Eg: rivers ,turbitaires etc

125/26/20151214.Recommendation To avoid problems of foundation failures, we recommend the use of gabions or baskets filled with rocks .To limit the excavation of soil (clays)for brick making.To minimize the human interferences in the route of river flow, its flood plains, and river banks to decrease water erosion.To plant the bamboo or other vegetal all along Nyabarongo river.Other recommendation is to limit the owner land use as agriculture of sugar cane in Nyabarongo valley.135/26/201513 15.Bibliography- Abbas, A. Ibrahim 1995 Groynes in River Training, Ph.D. dissertation, Khartoum University Sudan Library.

- Breusers, H.N.C. and Raudkivi, A.J. 1991. Scouring. IAHR Hydraulic Structures Design Manual 2. A.A.Balkema, Rotterdam and Brookfield.

Chinese Standards, 1992: Standard for Measurement of Suspended Sediment in Rivers. GB 50159-92, Ministry of Construction.

- Li, M. H., and K. E. Eddleman. 2002. Biotechnical engineering as an alternative to traditional engineering methods: A biotechnical streambank stabilization design approach. Landscape and Urban Planning 60:225-242.

- NRI-NWRC, 1989 River Bank Erosion and Protection Methods. Working paper 200-7, NRI, Delta Barrage, Egypt.

- NRI-NWRC, 1992 River Nile Bank Protection, Egypt

NZOVE WTP Archives (2010).

Standards Australia 2002, Australian standard: earth retaining structures, (AS4678-2002), Standards Australia, Sydney, NSW.

Modular Gabion Systems 2004, Gabion Walls Design, Rev. 11/04, Modular Gabion Systems, Houston, Texas, USA.

Maynord, S., Ruff, J.F. and Abt, S.R. 1989. Riprap design. Journal of Hydraulic Engineering (ASCE), vol 115, no 7, 937-949

Fischenich, C. 2001. Impacts of Stabilization Measures. ERDC TN-EMRRP-SR-32. U.S. Army Corps of Engineers, Research and Development Center, Environmental Laboratory, Vicksburg, MS.5/26/20151414THANK YOU FOR YOUR KIND ATTENTION.

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