Transport of solutes in streams with transient storage and hyporheic exchange

摘要: Environmental quality and health safety assessment often requires modeling of solute transport in rivers. Conceptually, a stream can be divided into distinct compartments mutually interacting through bidirectional exchanges mass momentum. A distinction generally drawn between main channel, where the velocities are relatively high, different types storage domains, average velocity is sensibly lower. The downstream propagation dissolved substances streams influenced by channel surrounding retention zones, typically vegetated pockets, pools recirculating or stagnant water, permeable subsurface. Submerged vegetation and, at small spatial scale, microbial biofilms also constitute additional domains which significantly contribute to determining fate transported substances. A one-dimensional model for rivers (STIR) with transient presented within this thesis. based on stochastic approach allows express concentration as function residence time distributions (RTDs) domains. As general RTD model, STIR used either calibration predictive tool. When form assumed relevant parameters determined fitting simulated breakthrough curves data from tracer tests. On other hand, if enough information available about properties system, specific closures incorporated represent individual exchange processes separately. In work applications field cases calibrated test data. Distinct forms zones assess capability reproduce observed curves. Results show that, when represented weighted two exponential distributions, provides an excellent approximation experimental all study reaches examined useful conceptual separation timescales retention. However, since result complex interaction uncertainty arise interpretation parameters. particular distribution determines both surface storage. This limitation cannot overcome traditional tests, unless complementing accurate hydrodynamic flow channel. In flume experiments hydraulic conditions strictly controlled, effect isolated, under proper assumptions, comparison those relative reference configuration system consideration not present. methodology illustrated application biofilms. Another important required water assessments in-channel subsurface near-stream region porous bed affected solutes known hyporheic zone, recognized extremely evolution riverine ecosystem. Exchange underlying zone primarily driven advective develop several scales because separate mechanisms such over forms, around obstacles bars meanders. Specific form-induced thesis case homogeneous stratified beds, extending previous works subject. These estimate manner or, least potentially, inverse approach.