Modeling the Water and Energy Balance of Vegetated Areas with Snow Accumulation

Abstract

The ability to quantify soil-atmosphere water and energy exchange is important in understanding agricultural and natural ecosystems, as well as the earth\u27s climate. We developed a one-dimensional vertical model that calculates solar radiation, canopy energy balance, surface energy balance, snowpack dynamics, soil water flow, and snow–soil–bedrock heat exchange, including soil water freezing. The processes are loosely coupled (solved sequentially) to limit the computational burden. The model was applied to describe water and energy dynamics for a northeast-facing mountain slope in the Dry Creek Experimental Watershed near Boise, ID. Calibration was achieved by optimizing the saturated soil hydraulic conductivity. Validation results showed that the model can successfully calculate seasonal dynamics in snow height, soil water content, and soil temperature. Both the calibration and validation years confirmed earlier results that evapotranspiration on the northeast-facing slope consumes approximately 60% of yearly precipitation, while deep percolation from the soil profile constitutes about 40% of yearly precipitation

Bedrock infiltration and mountain block recharge accounting using chloride mass balance

“…In the small TL headwater catchment, NR/ P was greatest at 0·34 (0·17–0·44). This high rate agrees with independently modeled estimates by Kelleners et al (2009; 2010). In contrast, NR/ P in headwater catchment BG was 0·22 (0·03–0·42).…”

“…These studies imply that upland catchment must lose water to underlying bedrock. Indeed, by calibrating a physically based hydrology model with bedrock permeability as a parameter, Kelleners et al (2009; 2010) concluded that up to 35% of annual precipitation must recharge deep groundwater in small upland catchment in the Boise Front. Because of the small scale of that study, it was unknown if NR in the small catchment re‐emerged within the mountain block or migrated through deep flow paths to valley aquifers.…”

The impact of Saharan dust and black carbon on albedo and long-term mass balance of an Alpine glacier

“…If the liquid water content, θ , is larger than the residual water content, θ r , then the outflow O is obtained as O = cρ w θ h d w with c and d as constants and ρ w as the density of water. The residual water content is computed as θ r = F c ρ d /ρ w with F c = 0.02 (Tarboton and Luce, 1996;Kelleners et al, 2009) the mass of water retained per mass of dry snow. The exponent d is set to d = 1.25 as proposed by Nomura (1994) and the sitespecific coefficient c is assumed to be equal to 1 m −1 h −(d−1) (De Michele et al, 2013).…”

Investigating the dynamics of bulk snow density in dry and wet conditions using a one-dimensional model

“…In particular we assume that O = cρ W θ h d W for θ > θ r , otherwise 0, where c (m −1 h −(d−1) ) and d are two constants, and θ r is the residual water content (value under which the residual amount of liquid water is retained into the ice matrix and only vapour exchanges occur). The residual water content is calculated as θ r = F C ρ D /ρ W where F C is the mass of water that can be retained per mass of dry snow, assumed equal to 0.02, according to Tarboton and Luce (1996) and Kelleners et al (2009). The coefficient c is a site-specific parameter depending on factors like slope and altitude of the site.…”

“…Tarboton and Luce, 1996;Jansson and Karlberg, 2004;Ohara and Kavvas, 2006), (2) two-layer models (Marks et al, 1998;Koivusalo et al, 2001), and (3) multi-layer models (see e.g. Anderson, 1976;Jordan, 1991;Bartelt and Lehning, 2002;Zhang et al, 2008;Rutter et al, 2008;Kelleners et al, 2009). The choice of a singlelayer, rather than a multi-layer, model is dependent on the specific problem one wants to address.…”