Hydrological transport model

An hydrological transport model is a mathematical model used to simulate the flow of rivers, streams, groundwater movement or drainage front displacement, and calculate water quality parameters. These models generally came into use in the 1960s and 1970s when demand for numerical forecasting of water quality and drainage was driven by environmental legislation, and at a similar time widespread access to significant computer power became available. Much of the original model development took place in the United States and United Kingdom, but today these models are refined and used worldwide. There are dozens of different transport models that can be generally grouped by pollutants addressed, complexity of pollutant sources, whether the model is steady state or dynamic, and time period modeled. Another important designation is whether the model is distributed (i.e. capable of predicting multiple points within a river) or lumped. In a basic model, for example, only one pollutant might

Hydrology and Pesticide Transport Modelling in the Petite Chamberonne catchment

Pascal Stalder

This project studied hydrological models used in the catchment of the Petite Chamberonne north-west of Lausanne. In a first step, input data have been analysed and prepared for the spatially explicit, conceptual hydrological model SEHR-ECHO. It has been proved that rainfall data can be taken and homogeneously distributed over the catchment from a nearby rain gauge (Crissier). The 9 months of discharge data proved to be of good quality; 9 months of data however is rather short for automatic calibration. Unique annual events influence the calibration of the hydrological model strongly and had to be removed and tested manually. First results showed a mediocre performance of the standard version of SEHR-ECHO. In order to improve the results of the simulation, several adaptations of the model have been tested. The best variant showed to be SEHR-ECHO, using reservoirs in series (instead of parallel) and Horton’s mechanism for surface runoff production (instead of Dunne’s mechanism). A NSE of 0.77 has been achieved. Based on this hydrological model, two types of pesticide transport models have been developed and tested. Though not yet calibrated (due to the lack of data), it has been observed that the two models give results that are sensitive to the chemical properties of the simulated pesticide and that the results show similarities to what has been observed in previous studies (e.g. [Leu et al., 2004a]). A further effort in calibration using more date will have to be undertaken in order to improve and validate the hydrological simulations. At last, the pesticide transport model will have to be calibrated and its results interpreted once data is available.

2013

MODÉLISATION HYDROLOGIQUE DE LA BIRSE

Kévin André

The main objective of this research is to keep up existing work related to the hydrological modeling of the Birse River in Switzerland. The present studies were performed using the software package HydroRoute System, being developed by Richard Metzger. HydroRoute incorporates the mathematical model entitled GSM-Socont (Glacier and Snowmelt - SOIL CONTribution Model) developed by Schaefli et al. (2005). Although the efficiency of this model has been proved (Beck, 2006), these studies have not yielded satisfactory results for watersheds of small and medium size. Consequently, this study works on carrying out changes in the hydrological model built in HydroRoute System so that it delivers hydrological responses closer to observations. According to previous studies, the extreme flows during summer thunderstorms are undervalued by the model for small watersheds. Two source code adjustments were developped and tested during this work. The first was kept as simple as possible, and under the assumption that too much water infiltrates during these extreme rainfall events. Therefore the production function was adapted by inserting a rainfall threshold parameter. Beyond this threshold, it assigns any remaining water quantity to the runoff reservoir. This change requires an additional parameter to calibrate. Once the calibration performed, the simulations lead to satisfactory results for the extreme discharges generated values. However, the agreement between observed and simulated discharge values was deteriorated. The modification seems to be insufficient and inadequate to the purpose of improving the overall model performance at the study site. Hence a second and more significant change was tested. Based on the knowledge of other existing models, adding an additional reservoir could allow greater flexibility of the model to approximate the observed data. The results showed an improved agreement between simulated and observed discharges and extreme discharges. In addition, the model has given better results for simulated discharge values during extreme events. However, it has imposed the insertion of three additional parameters. A disadvantage of increasing the number of parameters lies in an increase in parameters combinations to calibration of the model and therefore a substantial computing time required for this phase.

2013

MODÉLISATION HYDROLOGIQUE DE LA BIRSE

Kévin André

2013

Hydrology and Pesticide Transport Modelling in the Petite Chamberonne catchment

Comment on "Pursuing the method of multiple working hypotheses for hydrological modeling" by P. Clark et al.

MODÉLISATION HYDROLOGIQUE DE LA BIRSE

MODÉLISATION HYDROLOGIQUE DE LA BIRSE

Hydrology and Pesticide Transport Modelling in the Petite Chamberonne catchment

Comment on "Pursuing the method of multiple working hypotheses for hydrological modeling" by P. Clark et al.