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NIGERIAN TRANSBOUNDARY AQUIFERS: PHYSICAL AND MANAGEMENT ISSUES

IWRA World Water Congress 2003 Madrid Spain
IWRA WWC2003 - default topic
Author(s): ADENLE Depo

ADENLE Depo

Box 20077, UIPO, Ibadan, Nigeria


Article:

Abstract

The surface water resources of Nigeria is dominated by two main transboundary drainage basins – the Niger, with its main tributary the Benue that drains about 60% of the country, and the Lake Chad drainage basin which drains about 20% and into which a significant part of the rivers of the northeastern part of Nigeria drains.

Current water challenges in this part of West Africa are due to the rapidly increasing demand as a result of high population growth rate (>2.8%), increased urbanization, increase in irrigation farming and industrialization. These challenges have been exacerbated by persistent drought and have resulted in greater dependence on groundwater resources with its attendant adverse impacts. It has also awakened the riparians to manage the resource cooperatively on an integrated basis by entering into multilateral and bilateral agreements – the Niger Basin Authority, the Lake Chad Basin Commission and the Nigeria–Niger Joint Commission.

The framework document on “International Shared (Transboundary) Aquifer Management” noted that in transboundary aquifer, recharge may be received on one side while natural discharges are across the border. The Chad Formation and the Iullemeden main aquifers are examples of such. The Iullemeden aquifers consist of Mesozoic continental deposits outcropping along northern and eastern periphery of the basin. Recharge almost entirely occurs in the southeastern outcrops in Nigeria where rainfall exceeds 500mm per year. A significant part of the discharge is in Niger and in the River Niger itself. The Chad Formation consists of three zones – the upper, middle and lower zone aquifers. It has been widely reported that the phreatic aquifer in the Chad Basin receives most of its recharge in Nigeria along the Komadugu-Yobe drainage system and from the bottom of Lake Chad.

In 1995, the Japanese International Cooperation Agency observed that water crisis in northeastern Nigeria resulted in increased groundwater abstraction to such a level that it caused land subsidence around Maiduguri, a town in northeastern Nigeria. The little attention paid to the hydrologic inter-relatedness of the KomaduguYobe, Hadejia-Nguru Wetlands, the Lake Chad and the shared aquifer in this area has been a source of international concern. The concern centers on the gradual loss of the wetlands, the virtual disappearance of Lake Chad and the reduction in recharge to the phreactic aquifer on which the Republic of Niger and other down gradient users depend. It has also resulted in a reduction in recharge via the bottom of Lake Chad.

The impact of poor land use on the Nigerian side of the Iullemeden Basin as well as overexploitation of groundwater in this area could have untold impacts across the Nigerian border.

The paper proposes how a framework can be developed to avoid conflict in the management of these two transboundary aquifers that Nigeria shares with her neighbours. Specifically the paper explores the feasibility of evolving the kind of management structure and instruments in existence between Israel and Palestine.

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