This volume gives results of a semi-detailed soil survey carried out over a total gross area of 9,559 ha of the Mogambo irrigation project area. The report aims to extend the results of earlier studies on soils in the area . This is achieved by a more detailed observation network of survey sites in the area in particular within the Juba alluvial sails (five sites/km2). It also provides more quantitative data on the soil chemical and physical properties as an additional aid in soil classification for planning the development of irrigation in the area. Soil units identified are described in terms of modal characteristics and the variation found within the unit with profile descriptions for a11 pits and selected auger holes included in Appendices II and III. The nature of the mapped boundaries is fully described. The land was classified making use of the United States Bureau of Reclamation (USBR) methods, modified to suit the conditions found in the area. Suitability for rice and for field crops other than rice were considered separately and special use Class 4 was used to indicate areas more suitable for sprinkler development. Limitations affecting land suitability are denoted by the use of suitable land class suffix letters.

The principal tasks included in the terms of reference for the supplementary study are summarised below: ol; liUndertake a topographical survey of the whole project area and beyond its boundary, by up to 500 m where necessary. /li; liCarry out a semi-detailed soil survey of the project area including comprehensive in situ and laboratory analyses of soil and water samples./li; li Review the hydrology of the Juba river with particular regard to' the low flow periods and project flooding and the influence of Bardheere dam on the project. /li; liCarry out a preliminary design of the irrigation and drainage system including layout drawings, canal and drain longitudinal and cross-sections, flood protection details, pump station design, typical structure drawings and preliminary details of project infrastructure./li; /ol

In this report, written after a visit to Somalia to evaluate irrigation potential, the hydrometric data base is questioned as regards both its validity and its representativity. Steps to improve the basic data are proposed which include technical assistance to check and re-establish station ratings over a period of one year. The design plan of the juba high dam is discussed and attention drawn to the necessity of seeking the best professional advice to determine this parameter which has a direct bearing upon the safety and the cost of the dam. Present and proposed irrigation in the Shebelle and Juba valleys are examined.

The terms of reference for this Additional Study called for two alternatives (A and B) to be investigated. The development for alternative A has been based on the proposals of the Supplementary Study and allows for future expansion to the full area. The development for alternative B has been chosen as the beat area to be implemented independently of any future expansion. Alternative A identifies 2 052 ha net of surface irrigation and 163 ha net of overhead irrigation, and alternative B Identifies 1,809 ha net of surface irrigation end 122 ha net of overhead irrigation.

The goal of the project is to strengthen the capability of the water Development Agency of the Government of Somalia to design and implement a national water resource development program. The Project will assist in the collection of adequate national hydrogeologic, economic and social data and will provide technical assistance and commodities for a production drilling program. Data collected under the will enable the National Water Cormnittee (NWC) to establish priorities for a rational approach to national water resource development

(Extract from the introduction)brThe main objective of the hydrogeological appraisal was to determine whether the potable water demand of the proposed settlements could be supplied from groundwater sources. Further objectives were to determine the best methods of groundwater abstraction and evaluate the costs of any necessary installations. The main problem with attaining these objectives has been the weakness of the existing data base. Thus, though some work relevant to the hydrogeology of the region had been done in the past, much of the data appears to have been lost. Particular examples of this are the boreholes drilled by the Russians, for which all records seem untraceable. Further, even such scant data as exists has never been systematically analysed and compiled. The approach of this study has been to collect all the published informationparticularly the various development reports, to interview the personnel of various agencies concerned with groundwater work in Somalia and to conduct a field survey to collect geological and hydrogeological data. All this information has been carefully processed and compiled to obtain a regional picture of the groundwater systems. The Project Area itself, for which basically no subsurface data exists, was then viewed within that regional context. The results obtained are not fully conclusive but they are strongly indicative.