Submit Manuscript | http://medcraveonline.com Introduction A key parameter in designing reservoirs for water supply is the safe (or frm) yield, the maximum quantity of water that can be assured with some identifed degree of confdence during a critical period. For example, the assured volume of water available to domestic users during low summer fows is considered frm yield. Determining the frm yield required to meet water supply objectives at a particular level of confdence depends upon the volume and timing of supply and demand. It is imperative to note that varying, hydro- meteorological dynamics leads to variation in key reservoir variables like the infow, storage and outfow; because of this water managers face the challenge of making available adequate quantities of water for drinking, agricultural and others vis-a-vis the geometrically increasing population pressure and socio-economic development, increase the needs and demands for particular water fows. 1 The role of water-storage reservoirs, therefore, is to impound water during periods of higher fows, thus preventing food disasters, and then permit gradual release of water during periods of lower fows. According to Jose 2 the reservoir yield, denoted by Y, is the amount of water to be released whenever there is availability. The reservoir release at time t (Dt) is the volume effectivelyliberated from the reservoir to meet the demand. It is less than or equal to the yield (Y) and depends on the reservoir content. When the reservoir contents exceed the reservoir capacity, there is uncontrolled outfow, or spill. The outfow is the summation of all water that leaves the reservoir as release, evaporation or spill. Yield is used to characterise the capacity of a water resource to serve as a long-term water supply. It is a fundamental water-supply planning concept, and an understanding of its attributes is critical for those who participate in water-supply issues. In the context of surface-water resources, yield is often synonymous with safe yield or frm yield. Safe yield or frm yield in the context of water reservoirs is defned as the maximum quantity of water which can be guaranteed during a critical dry period. 3 Surface-water yield depends primarily on infows and storage. In the case of an unregulated stream, the frm yield is often conceptualised as the minimum historical fow during a specifed time period. It is important that yield analyses consider normal seasonal demand patterns; how demand varies during periods of drought in response to the drought itself and to applicable conservation measures; and that each drought has an individual signature defning the onset, critical period, duration, and precipitation/runoff variables, which may vary signifcantly among different drought events. Drought and shortage of fresh water is currently an important limitation of water resources development. While in last decades a great deal of effort is increasingly diverted towards the use of poor quality water, the issues related to the storage and management of fresh water have not yet been properly addressed. The regulation of stochastically fuctuating fows of a natural stream by the conservation storage of a reservoir is a classical problem, known for thousands of years. Many studies have been performed with many different methods and different results for the relationship between storage capacity and target draft, which is defned as frm yield for a failure- free operation over a fxed service period. Int J Hydro. 2020;4(3):100‒104. 100 ©2020 Mamman et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and build upon your work non-commercially. Application of multi yield analysis approaches to reservoir system Volume 4 Issue 3 - 2020 Mohammed Jiya Mamman, 1 Otache Y Matins 2 1 Department of Agricultural Technology, Niger State College of Agriculture Mokwa, Nigeria 2 Department of Agricultural and Bio- resource Engineering, Federal University of Technology Minna, Niger State, Nigeria Correspondence: Mohammed Jiya Mamman, Department of Agricultural Technology, Niger State College of Agriculture Mokwa, Niger State, Nigeria, Email Received: April 20, 2020 | Published: May 25, 2020 Abstract Yield is used to characterise the capacity of a water resource. It is a fundamental water- supply planning concept, and an understanding of its attributes is critical for those who participate in water-supply issues. This study tends to carry out frm yield analysis by employing both the accumulated difference method (ADM) and reverse chronology method (RCM) in order to ascertain the minimum storage capacity required to sustain the required yield of kainji reservoir system without interruption. In applying (ADM), the infows were accumulated and the difference calculated. The minimum infow within the year of record was determined to be the frm yield. The yield of 30x109m 3 was hypothetically chosen to determine the minimum capacity to sustain it without interruption during the period under record. Similarly the frm yield analysis was also done by employing the method of reverse chronology (RCM) to confrm the result in the accumulated difference method. This method is based on the premise that what is the minimum volume that has to be in storage at the end of the previous year plus the infow can meet the demand during the current year. This was carried out by starting with the last year of the record and working back to the frst year and the difference between the infow and the required yield was determined. The shortages were then observed form the difference obtained; the maximum shortage was then selected as the required capacity.The frm yield was determined to be 22.7283×109m 3 . The minimum capacity required to sustain a yield of 30×109m 3 per annum (the average annual demand) without interruption during the period under record was determined to be 7.3431×109m 3 . The interaction between the reservoir elements were signifcant considering the correlation matrix applied. Keywords: reservoir capacity, frm yield, infow, accumulated, chronology, storage International Journal of Hydrology Research Article Open Access