Field validation of two river morphological models on the Pasak River, Thailand

Abstract

A comparison is made of the quasi-two-dimensional GSTARS2.1 mathematical model, which can analyse lateral erosion, and the well-known one-dimensional HEC-6 model. Also, both models are validated by means of comparison with observations. The study emphasizes the differences in principle, concept, results and efficiency of the two models. The morphological processes over the 56-km reach of the Pasak River, downstream of Pasakjolasid Dam in Thailand, are considered. The analysis was carried out on a 14-year continuous period (1990–2004). The computational results are compared with the observed data, collected from six river cross-sections in 1990 and 2004. Compared with the observed bed level data, the results computed by using HEC-6 and GSTARS2.1 are similar for one-dimensional simulation without the consideration of lateral change of bed elevation. However, when both bed change and lateral erosion were considered, the GSTARS2.1 model gave better agreement to the measured river cross-sections than the HEC-6 model, due to the advantage of the stream tube technique.