Runoff Generation I Flashcards
what is subsurface flow?
water reaching the stream through shallow soil and underlying rock layers (includes shallow subsurface flow and groundwater flow)
when does Hortonian overland flow occur?
when precipitation rate exceeds the soil infiltration rate
what is excess rainfall?
rainfall that is neither retained on the land surface nor infiltrated into the soil
excess rainfall= observed rainfall - hydrologic abstrations (mostly infiltration)
what is a hyetograph?
graph of excess rainfall vs time
where does Hortonian overland flow occur?
- impermeable or compacted areas (roads, bedrock outcrops, lawns, trails, city parks)
- hydrophobic soils
- on tramped and crusted soils
- on frozen ground
- on low-permeability soils (silt-clay soils without macropores)
when does saturation-excess overland flow occur?
when the soil if fully saturated and there is no space for additional water to infiltrate
what is return flow?
when subsurface water from saturated areas is pushed towards the surface
where does SOF occur?
in topographic lows and near stream channel
