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Hydrologic processes and their principles are universal. However, the magnitude and impact of hydrological parameters influencing these processes vary along with space and time. Researchers since several decades are in the process of understanding and simulating them. One of such simulation is through the Hydrologiska Byrans Vattenbalansavedlning (HBV) model developed at the Swedish Meteorological and Hydrological Institute (SMHI) Stuttgart, Germany. This work explains how this model will perform in semi-arid conditions to understand the most sensitive parameter influencing soil moisture, among all and calibrate their optimum values. The watershed chosen is small agricultural watershed in a semi-arid region with fertile soil and limiting water. The study revealed that the “LP” a soil moisture value above which the evapotranspiration reaches its peak is the most sensitive. Thereafter parameters “fc”, “athron”, “ ” “cflux”, “pcalt”, “perc”, and “khq” follow suit. These parameters are sensitive within -10% and β +10% of their optimum values. Other parameters as prec”, “cevpl”, “alfa”, “hq”, “recstep”, “soilstep”, “stf, “uzlo” have new values that are not similar to the original values as recommended. All values have been tested for their one at a 2 time sensitivity using the objective functions values of the root mean square error , BIAS, Relative error, R and Nash Sutcliffe efficiency coefficient. This indicates that the model does perform well in semi-arid conditions to simulate the Soil Moisture Routine of an agricultural watershed. It is recommended that the HVB can be used in semi-arid conditions for successfully simulating the Soil Moisture processes. |
