Comparison of Hydrological Models (Hbv and Landpine) for Inflow Computation in the Modi River, Nepal

Master's Thesis from the year 2009 in the subject Energy Sciences, Norwegian University of Science and Technology, course: M Sc Hydropower Development, language: English, abstract: A Hydrological system is a very complex process that plays a great role in controlling the water balance in the world. The hydrological cycle is a major part of the hydrological system and its components are precipitation, evaporation, snow melt, infiltration, run off, ground water movement etc. The hydrological modeling is a system concept comprising the effects of all the components involving in the hydrological cycle.

In this study, a comparison of hydrological models for inflow computation in the Modi river, a tributary of Kali Gandaki river, has been carried out by using HBV a lumped and LANDPINE a distributed model although, at first both models were developed for Scandinavian catchments. The HBV model is a conceptual precipitation run off model which is used to simulate the run off process in a catchment based on observed data of precipitation, air temperature and potential evapotranspiration. LANDPINE is a distributed hydrological rainfall runoff model to study the effects of land use changes in runoff from catchment. It operates in integration with a geological information system, usually used for preparation of input data and analysis and presentation of simulation results.

The hydro meteorological data from stations Lumle, Ghandruk and Baglung with daily discharge data at Nayapool, have been used for the study of the catchment. The two stations, Lumle and Ghandruk lie within the catchment in its southern part and the Baglung lies about 12 km outside in south west direction from the boarder of the catchment.

Available precipitation data from stations within the region are examined to determine the trend of precipitation with respect to elevation. The long term average annual precipitations for all the stations from DHM have been used. The precipitation records show that the precipitation gradient is not only dependent on the elevation and seems to be difficult to define only as a single function of the elevation. It is observed that the precipitation increases up to certain elevation and decreases thereafter.

Because of the complex nature of precipitation distributions and limited number of gauging stations, the areal precipitation distribution for this study in the case of HBV model is calculated by the combination of different weightage for different precipitation stations according to the best result obtained among them. [...]