Transport at basin scales: 1. Theoretical framework

摘要

The paper describes the theoretical framework for aclass of general continuous models of the hydrologic responseincluding both flow and transport of reactive solutes. Theapproach orders theoretical results appeared in disparate fieldsinto a coherent theoretical framework for both hydrologic flow andtransport. In this paper we focus on the Lagrangian description ofthe carrier hydrologic runoff and of the processes embeddingcatchment-scale generation and transport of matter carried byrunoff. The former defines travel time distributions, while thelatter defines lifetime distributions, here thought of as contacttimes between mobile and immobile phases. Contact times areassumed to control mass transfer in a well-mixed approximation,appropriate in cases, like in basin-scale transport phenomena,where the characteristic size of the injection areas is muchlarger than that of heterogeneous features. As a result, we definegeneral mass-response functions of catchments which extend totransport of matter geomorphologic theories of the hydrologicresponse. A set of examples is provided to clarify the theoreticalresults towards a computational framework for generalizedapplications, described in a companion paper.