Future land cover and climate may drive decreases in snow wind‐scour and transpiration, increasing streamflow at a Colorado, USA headwater catchment. Issue 11 (18th November 2021)

• Record Type: Journal Article
• Authors: Barnhart, Theodore B.; Vukomanovic, Jelena; Bourgeron, Patrick; Molotch, Noah P.
• Is Part Of: Hydrological processes. Volume 35:Issue 11(2021)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2021-11-18
• Subjects: Colorado -- future climate -- land cover -- snow -- streamflow -- evapotranspiration; Hydrology -- Periodicals; Hydrology -- Research -- Periodicals; Hydrologic models -- Periodicals; Hydrological forecasting -- Periodicals; 631.432
• DOI: 10.1002/hyp.14416
• Languages: English
• ISSNs: 0885-6087

Abstract

Abstract: Understanding how land cover change will impact water resources in snow‐dominated regions is of critical importance as these locations produce disproportionate runoff relative to their land area. We coupled a land cover evolution model with a spatially explicit, physics‐based, watershed process model to simulate land cover change and its impact on the water balance in a 5.0 km 2 headwater catchment spanning the alpine–subalpine transition on the Colorado Front Range. We simulated two potential futures both with greater air temperature (+4°C/century) and more precipitation (+15%/century, MP) or less precipitation (−15%/century, LP) from 2000 to 2100. Forest cover in the catchment increased from 72% in 2000 to 84% and 83% in 2050 and to 95% and 92% in 2100 for MP and LP, respectively. Surprisingly, increases in forest cover led to mean increases in annual streamflow production of 12 mm (6%) and 2 mm (1%) for MP and LP in 2050 with an annual control streamflow of 208 mm. In 2100, mean streamflow production increased by 91 mm (44%) and 61 mm (29%) for MP and LP. This result counters previous work as runoff production increased with forested area due to decreases in snow wind‐scour and increases in drifting leeward of vegetation, highlighting the need to better understand the impacts of forest expansion on the spatial pattern of snow scour, deposition and catchment effective precipitation. Identifying the hydrologic response of mountainous areas to climate warming induced land cover change is critically important due to the potential water resources impacts on downstream regions. Abstract : Using a hydrologic model and a land cover evolution model in a Colorado, USA headwater catchment under future climate, streamflow increased by 91 and 61 mm for more and less precipitation scenarios, respectively. These changes were driven by increases in snow drifting, reductions in snow scour as catchment forest cover increased and earlier snowmelt and streamflow due to warmer future air temperature.