{"title":"How do different runoff generation mechanisms drive stream network dynamics? Insights from physics-based modelling","authors":"Francesca Zanetti, Matteo Camporese, Gianluca Botter","doi":"10.1002/hyp.15234","DOIUrl":null,"url":null,"abstract":"<p>Non-perennial river catchments are characterized by an ever-changing spatial configuration of their flowing streams. A combination of empirical data and simplified analytical frameworks has been frequently used in the literature to analyse the co-evolution of the total active stream length (<span></span><math>\n <semantics>\n <mrow>\n <mi>L</mi>\n </mrow>\n <annotation>$$ L $$</annotation>\n </semantics></math>) and the catchment discharge at the outlet (<span></span><math>\n <semantics>\n <mrow>\n <mi>Q</mi>\n </mrow>\n <annotation>$$ Q $$</annotation>\n </semantics></math>). However, despite the increasing availability of field data, understanding how runoff generation processes drive the spatio-temporal dynamics of non-perennial river reaches remains challenging. In this paper we use CATHY, an integrated surface–subsurface hydrological model (ISSHM), to investigate the impact of saturation-excess (Dunnian) and infiltration-excess (Hortonian) runoff generation on the stream network dynamics of two virtual catchments with spatially homogeneous subsurface properties but different morphology. The numerical simulations show that when surface runoff is triggered by saturation-excess mechanisms, the subsurface domain is slowly saturated, and the stream network gradually expands upstream from the outlet towards the catchment divides. In these conditions, the specific inflow per unit contributing area is relatively uniform along the network, thereby implying that <span></span><math>\n <semantics>\n <mrow>\n <mi>L</mi>\n </mrow>\n <annotation>$$ L $$</annotation>\n </semantics></math> and <span></span><math>\n <semantics>\n <mrow>\n <mi>Q</mi>\n </mrow>\n <annotation>$$ Q $$</annotation>\n </semantics></math> display a monotonically increasing one-to-one relationship. On the other hand, infiltration-excess mechanisms lead to more heterogeneous saturation patterns in the subsurface domain. In particular, during the wetting phase, Hortonian processes originate highly transient conditions and a non-uniform spatial distribution of the specific inflow along the stream network. This is reflected by a hysteretic <span></span><math>\n <semantics>\n <mrow>\n <mi>L</mi>\n <mfenced>\n <mi>Q</mi>\n </mfenced>\n </mrow>\n <annotation>$$ L(Q) $$</annotation>\n </semantics></math> relation and a marked asymmetry between the wetting and drying phases of the event. The application of an ISSHM proved to be a useful tool to elucidate the processes that drive stream network expansion and retraction in non-perennial rivers.</p>","PeriodicalId":13189,"journal":{"name":"Hydrological Processes","volume":null,"pages":null},"PeriodicalIF":3.2000,"publicationDate":"2024-07-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/hyp.15234","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Hydrological Processes","FirstCategoryId":"89","ListUrlMain":"https://onlinelibrary.wiley.com/doi/10.1002/hyp.15234","RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"Environmental Science","Score":null,"Total":0}
引用次数: 0
Abstract
Non-perennial river catchments are characterized by an ever-changing spatial configuration of their flowing streams. A combination of empirical data and simplified analytical frameworks has been frequently used in the literature to analyse the co-evolution of the total active stream length () and the catchment discharge at the outlet (). However, despite the increasing availability of field data, understanding how runoff generation processes drive the spatio-temporal dynamics of non-perennial river reaches remains challenging. In this paper we use CATHY, an integrated surface–subsurface hydrological model (ISSHM), to investigate the impact of saturation-excess (Dunnian) and infiltration-excess (Hortonian) runoff generation on the stream network dynamics of two virtual catchments with spatially homogeneous subsurface properties but different morphology. The numerical simulations show that when surface runoff is triggered by saturation-excess mechanisms, the subsurface domain is slowly saturated, and the stream network gradually expands upstream from the outlet towards the catchment divides. In these conditions, the specific inflow per unit contributing area is relatively uniform along the network, thereby implying that and display a monotonically increasing one-to-one relationship. On the other hand, infiltration-excess mechanisms lead to more heterogeneous saturation patterns in the subsurface domain. In particular, during the wetting phase, Hortonian processes originate highly transient conditions and a non-uniform spatial distribution of the specific inflow along the stream network. This is reflected by a hysteretic relation and a marked asymmetry between the wetting and drying phases of the event. The application of an ISSHM proved to be a useful tool to elucidate the processes that drive stream network expansion and retraction in non-perennial rivers.
期刊介绍:
Hydrological Processes is an international journal that publishes original scientific papers advancing understanding of the mechanisms underlying the movement and storage of water in the environment, and the interaction of water with geological, biogeochemical, atmospheric and ecological systems. Not all papers related to water resources are appropriate for submission to this journal; rather we seek papers that clearly articulate the role(s) of hydrological processes.