| Distributed hydrological models provide powerful tools for exploring the mechanism of basin hydrologic cycle, evaluating the dynamic variation of basin water resource and governing the basin water resource. For the upper and middle reaches of Huai River basin which is of large scale and complicated regional climatic conditions, systematic researches are conducted for the application of hydrological processes simulation of Huai River basin and the feasibility of driving ESSI distributed hydrological model with TRMM satellite precipitation data with the ESSI distributed hydrological model developed by Wanchang Zhang and Dong Zhang, precipitation data source and its spatial-temporal characteristics are the most important factors affecting the simulation result of distributed hydrological model. TRMM satellite data not only offers more convenient source for precipitation data, but also fixes the problems of low spatial-temporal resolution and discontinuity of traditional hydro-meteorological monitoring data. useing the TRMM satellite data to improve the precision of distributed hydrological model has drawn intense research interests recently. The study firstly test the application of ESSI distributed hydrological model for hydrological spatial-temporal simulation of Huai River basin which has complicated hydro-meteorological and underlying surface conditions, then explore the feasibility of driving this model with TRMM satellite data to simulate the basin hydrological spatial-temporal process, that provide scientific support for further studies.Huai River is located at the transitional zone of the north-south climate; climatic and underlying conditions are complicated, and problems related to water resource are prominent. In order to improve the simulation precision of hydrological processes, provide accurate description of basin hydrological cycling processes and characterize the spatial distribution of water resource, the upper and middle reaches of Huai River basin is selected as the study object, the TRMM satellite precipitation data with high spatial-temporal resolution are coupled into the ESSI model, and then compared and evaluated the efficiency of ESSI model before and after coupling the TRMM data. Several conclusions are drawn:(1) With GIS technology, TRMM 3h original products are disposed to daily rainfall raster data. Then TRMM daily rainfall data are disposed by the traditional interpolation methods. After that, the paper compares the results in spatial analyses surface precipitation and rainfall frequency distribution. The results show that the TRMM satellite data have good applicability in Huai River basin. Compared with IDW, Tyson polygons, IDW Based Markove random field, TRMM shows higher precision, but slightly lower than the Kriging interpolation. In different rainfall levels, TRMM rainfall distribution is consistent with the actually measured values, but TRMM has a low frequency when rainfall is smaller than O.Olmm/d. In daily surface precipitation, correlation coefficient between TRMM and measured data achieves 0.74; in the spatial distribution of annual rainfall, TRMM decreases from south to north, from east to west, which accurately describes the changing trend of the river basin.(2) ESSI distributed hydrological model is applied in Huai River basin. Combining GIS and remote sensing technology, we obtain the DEM, meteorology, soil, land use (LULC), drainage basin and basin outlet parameters. Selected suitable model parameters, ESSI model is applied to calibrate from year 2001-2004 and verify from year 2006-2010 respectively. The results show the parameters of ESSI model perform well in areas studied and accurately describe the hydrological processes. The daily runoff simulation is consistent with the measured runoff curve. The simulated results present seasonal rule:with the measured data, they are similar in water period (11-2 months), bigger in the water phase (3-6 months) and lower in the plentiful (7-10 months). With the increase of time scales, deterministic coefficient and correlation coefficient increase. The negative relative error indicates that simulated value is less than the measured. Simulation of the spatial distribution is consistent with the objective laws of Huai River basin including the simulated evaporation, canopy interception, runoff distribution, soil water content and variable space distribution.(3) TRMM satellite precipitation data is coupled and applied in ESSI distributed hydrological models. With Visual C++6.0, TRMM satellite data converted to the corresponding grid form are integrated into ESSI model, and compared with original results. In the daily runoff simulation, the simulation of runoff curve is consistent and the accuracy of the evaluation index is quite with the original results. In the monthly runoff simulation, TRMM is significantly better than the latter. The deterministic coefficient can reach 0.8 and the relative error percentage of TRMM data is less than 8%. In seasonal distribution, the simulated results of TRMM are ideal. The deterministic coefficient, correlation coefficient and the relative error percentage all substantially increase, especially in the summer, the relative error drops from-45.78% to 3.56%. In production flow type, surface runoff, soil and underground runoff hydrological processes, TRMM data presents grid shape, which is mainly related to its data source in grid form. |
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