A distributed hydrology‐vegetation model for complex terrain

TLDR

The study presents a distributed hydrology‑vegetation model that incorporates canopy interception, evaporation, transpiration, snow accumulation and melt, and saturation‑excess runoff generation. The model employs digital elevation data to parameterize topographic effects on radiation, temperature, precipitation, and water routing, uses a two‑layer Penman‑Monteith scheme for canopy evapotranspiration, an energy‑balance approach for snow dynamics, and a quasi‑three‑dimensional routing scheme for saturated subsurface flow, and was calibrated and verified with multi‑year precipitation, streamflow, and remote‑sensing snow cover data at 180‑m resolution in the Middle Fork Flathead River basin. Simulations showed discharge that agreed acceptably with observations, and snow‑cover patterns that matched remote‑sensing data overall but lagged slightly in timing.

Abstract

A distributed hydrology‐vegetation model is described that includes canopy interception, evaporation, transpiration, and snow accumulation and melt, as well as runoff generation via the saturation excess mechanisms. Digital elevation data are used to model topographic controls on incoming solar radiation, air temperature, precipitation, and downslope water movement. Canopy evapotranspiration is represented via a two‐layer Penman‐Monteith formulation that incorporates local net solar radiation, surface meteorology, soil characteristics and moisture status, and species‐dependent leaf area index and stomatal resistance. Snow accumulation and ablation are modeled using an energy balance approach that includes the effects of local topography and vegetation cover. Saturated subsurface flow is modeled using a quasi three‐dimensional routing scheme. The model was applied at a 180‐m scale to the Middle Fork Flathead River basin in northwestern Montana. This 2900‐km 2 , snowmelt‐dominated watershed ranges in elevation from 900 to over 3000 m. The model was calibrated using 2 years of recorded precipitation and streamflow. The model was verified against 2 additional years of runoff and against advanced very high resolution radiometer based spatial snow cover data at the 1‐km 2 scale. Simulated discharge showed acceptable agreement with observations. The simulated areal patterns of snow cover were in general agreement with the remote sensing observations, but were lagged slightly in time.