The Unit Hydrograph (UH) and Soil Conservation Service Curve Number (SCS-CN) are prevalent methods for estimating peak flow and peak time within the hydrological river basins. Different types of data, such as gauging data, morphometric analysis, and Land Use-Land Cover (LULC), are used to derive UH for the Kanarwe River Basin (KRB), which is an off-the-Lesser Zab River Basin (LZRB). Different hydrograph models, including HEC-1 (Hydrological Engineering Centre), TR55 (Technical release 55), HEC-HMS (Hydrological Engineering Centre-Hydrological Modeling System), Rational method, and Snyder unit hydrograph, have been applied and correlated with field data. Metrological data, geological setting, and land cover were integrated into the Geographic Information Systems (GIS) and Watershed Modelling System (WMS 11.1). The peak time (Tp) and peak flow (Qp) were estimated based on the five applied models. The results for models are (Qp = 739.93 m3/sec, Tp = 20 hr), (Qp 181.4 m3/sec, Tp = 14 hr), (Qp = 800 m3/sec, Tp = 12 hr, (Qp = 341.13 m3/sec, Tp = 11.65 hr), (Qp = 443 m3/sec, Tp = 19.9 hr), (Qp = 243 m3/sec) for HEC-1, TR55, HEC-HMS, Rational method, Synder unit hydrograph, and observed data respectively. The observed model (field data) peak time and peak flow value best agreed with the peak time and peak flow value of TR55, Snyder, and Rational models. Our finding confirmed that the geomorphoclimatic unit hydrograph, such as (Snyder) is highly efficient and more realistic for estimating peak time and peak flow for large basins than other models because it relates to basin characteristics.
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