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    • Software maintenance and updating DWAF br

    2018-11-05

    Software maintenance and updating (DWAF, 2009).
    Hydrological analyses Detailed hydrological analyses provide the foundation of any assessment aimed at determining the capability of a water resource system and the level of confidence that can be placed on the results of such assessments is largely dependent on the quality of the data available. Typical hydrological analyses consist of a number of aspects and these are summarised below: a) Rainfall data Rainfall data are used for calculating, on a monthly basis the: b) Evaporation data Evaporation data are used for calculating, on a monthly basis the: c) Stream flow data Streamflow data are used in the WRSM as a basis for: The name of each incremental sub-catchment in the system is defined in the statistical parameter file, PARAM.DAT. For example, if an analysis of the uMgeni River system is being undertaken, incremental sub-catchments may be defined for the Midmar, Albert Falls, Nagle and Inanda Dam catchments, in which case the corresponding catchment names in the PARAM.DAT-file may be MID, ALB, NAG and INA. Furthermore, the total catchment area each incremental sub-catchment in the system (in units of km2) is also defined in the PARAM.DAT-file. This variable is used internally by the model for the purpose of calculating natural runoffs from the natural portion of each sub-catchment after having accounted for the combined extent of areas under irrigation, stream flow proton pump inhibitors catchment portion areas and coal mining activities.
    Creation of reservoirs Reservoirs have the capability of retaining water over time and are modelled in the WRSM using a special reservoir node-type. Variables used to define a reservoir include those relating to its physical characteristics, storage zones, rule curves and penalty structures (which are used to control the way in which a reservoir is operated) and these are discussed in the following sections. The simulation of reservoir behaviour in the WRSM involves a simple calculation relating to the volume of stored water in the reservoir at the end of each month in the simulation. If the storage volume in the reservoir is known at the beginning of the simulation period, then the storage at the end of the first month is calculated based on the change in storage that occurred. The latter is calculated based on a simple mass balance principle, which can be represented as follows: A second principle is applied in order to provide a link between the state of storage in the first and second months. The principle states that the storage in the reservoir at the beginning of any month must be equal to the storage in the reservoir at the end of the preceding month. This is shown below. By applying this principle, the start storage for the second month is determined.
    Planning analysis results Planning analysis results are generally presented in the form of “box-and-whisker”-plots and these are used to depict the projected probabilistic behaviour of a specific system element. The most important box-plots from a planning analysis are listed below, together with information on how the plots in question are generated:
    Discussion As shown in Figs. 4–6, the storage system stores the spills from storages if capacity permits, while in the real system, some of these spills cannot be stored. Similarly, the evaporation losses cannot be explicitly modelled because of the relationship between surface area and storage volume cannot be satisfactorily defined for the lumped storage to simulate the evaporation losses of individual storages. They are lost as wastage or unused water in the real system. The wastage or unused water comprises of water that cannot be used by demand zones and courted from the bottom ends of the catchments. Furthermore, the capacity constraints of carriers are not considered in the system. This is particularly important in some cases when the restricted demand cannot be supplied because of the problem in the carriers (such as capacity is insufficient), causing drought in some reservoirs. Shortfalls also could occur due to non-availability of water resources at certain reservoirs. If these effects are ignored in the derivation of restriction rules, the analysis has provided an erroneous solution.