The importance of base flow in sustaining surface water flow in the Upper Colorado River Basin

Abstract

The Colorado River has been identified as the most overallocated river in the world. Considering predicted future imbalances between water supply and demand and the growing recognition that base flow (a proxy for groundwater discharge to streams) is critical for sustaining flow in streams and rivers, there is a need to develop methods to better quantify present-day base flow across large regions. We adapted and applied the spatially referenced regression on watershed attributes (SPARROW) water quality model to assess the spatial distribution of base flow, the fraction of streamflow supported by base flow, and estimates of and potential processes contributing to the amount of base flow that is lost during in-stream transport in the Upper Colorado River Basin (UCRB). On average, 56% of the streamflow in the UCRB originated as base flow, and precipitation was identified as the dominant driver of spatial variability in base flow at the scale of the UCRB, with the majority of base flow discharge to streams occurring in upper elevation watersheds. The model estimates an average of 1.8 3 10 10 m 3 /yr of base flow in the UCRB; greater than 80% of which is lost during in-stream transport to the Lower Colorado River Basin via processes including evapotranspiration and water diversion for irrigation. Our results indicate that surface waters in the Colorado River Basin are dependent on base flow, and that management approaches that consider groundwater and surface water as a joint resource will be needed to effectively manage current and future water resources in the Basin.

The role of baseflow in dissolved solids delivery to streams in the Upper Colorado River Basin

“…Interestingly, in many subbasins draining the Colorado Rocky Mountains (e.g., the San Juan and White‐Yampa subbasins), baseflow dissolved solids yields were low in the upper elevations, increased at mid‐elevations, and then decreased longitudinally downstream in lower elevation areas of the UCRB. The majority of baseflow discharge to streams in the UCRB occurs in high elevation areas of the watershed, where there is the greatest precipitation (Miller et al, ; Rumsey et al, ; Figure S3). These mountainous areas are dominated by relatively insoluble igneous and metamorphic rocks, typically generating dissolved solids concentrations of less than 100 mg/L in streams (Anning et al, ; Warner et al, ).…”

Slower Snowmelt in Spring Along With Climate Warming Across the Northern Hemisphere

“…On the other hand, slow snowmelt rates may influence the runoff formation, especially reduce the spring runoff. Earlier and slower snowmelt over the NH may threaten both the timing and the amount of snowmelt that infiltrate into soil aquifers, rivers (Miller et al, 2016), and reservoirs (Barnhart et al, 2017;Stewart et al, 2010) and consequently impact regional groundwater (Jasechko et al, 2015). Earlier and slower snowmelt over the NH may threaten both the timing and the amount of snowmelt that infiltrate into soil aquifers, rivers (Miller et al, 2016), and reservoirs (Barnhart et al, 2017;Stewart et al, 2010) and consequently impact regional groundwater (Jasechko et al, 2015).…”

Historical changes in fish communities in urban streams of the south‐eastern United States and the relative importance of water‐quality stressors

“…Stream base flow is critically important to sustaining stream discharge (Miller, Buto, Susong, & Rumsey, 2016). Stream base flow is critically important to sustaining stream discharge (Miller, Buto, Susong, & Rumsey, 2016).…”