Journal of Applied Sciences Research, 7(3): 309-313, 2011 ISSN 1819-544X This is a refereed journal and all articles are professionally screened and reviewed ORIGINAL ARTICLES 309 Corresponding Author: Lily Montarcih, Department of Water Resources, Faculty of Engineering, Brawijaya University, Malang. E-mail: lilymont2001@yahoo.com Analysis of Average Rainfall Using Kagan-Rodda Hari Prasetijo, Lily Montarcih and Linda Prasetyorini Department of Water Resources, Faculty of Engineering, Brawijaya University, Malang 65145. (INDONESIA). ABSTRACT This paper studied the analysis of rainfall data using Kagan-Rodda method. Analysis was carried out at Duwet sub-watershed, Madiun Regency, Indonesia. The methodology was consisted of selecting available rainfall stations at location due to Kagan-Rodda method and then analysis average rainfall based on selected rainfall station. Result could be used to analyze design flood for planning some structures in water resources system. Key words: average rainfall, Kagan-Rodda. Introduction The main meteorological characteristics that have a direct effect on water balance formation on land surface general and groundwater infiltration recharge in particular are those that determine moisture input to the surface (total precipitation), its phase state (air temperature), and evaporation conditions (air temperature and humidity and solar radiation, which taken together, characterize the radiation, which taken together, characterize the radiation-heat balance of land surface (Grinevskil, 2010). Many systems dynamics studies on water resource management focus on the global policy results of large- scale systems. These studies use system dynamics to study long-term water resource planning and policy analysis. However, the tendency of current research is to model systems in detail, with more emphasis on quantitative results (Liang, 2011). Some researchers formulated an appropriate strategy that strikes a balance between mitigating water shortages and limit total financial costs. Drought is conceived as a multidimensional phenomenon which is difficult to model. Drought events are characterized by their severity, duration and areal extent. Several propositions have been made recently for limiting the dimensions of drought from the above three dimensions to one. The simplifications proposed are to replace duration and areal extent variables by two predetermined constant quantities so that the uni- dimensional frequency analysis of severity could lead to meaningful and practical results (Vangelis, 2011). No certain conclusions can be made regarding the changes in the variance, which characterizes the variation amplitude in meteorological elements around their mean values. Fisher’s test suggests a reliable decrease in the variance and accordingly the amplitude of amount variations only in one case for air temperature series and a reliable increase in the temperature for the warm period also in one case (Dzhamalov, 2010). A continuing problem in hydrology is the estimation of discharge for design purpose on watersheds with only limited available data. The rainfall model differentiates between high and low intensity events. The resulting rainfall statistics were checked by comparisons with measured data (Nandakumar, 1997). Physically based rainfall-runoff models are used in hydrology for a wide range of application such as the extension of stream flow records, estimation of flow for unmeasured watersheds, prediction of the effects of land use change and examination of the effects of climate change (Hoybye, 1999). Rainfall analysis was very important for designing hydraulic structure. Representative rainfall was analysis by selecting available scheme pattern of rainfall station. There were two problems which had to consider for determining area rainfall. The two problems were the number and distribution pattern of rainfall stations.