Fig. 5: Trends in normalized baseflows in relation to cropland percentage.
From: Impacts of agriculture and snow dynamics on catchment water balance in the U.S. and Great Britain
Analysis of change in the normalized baseflows for the catchments in the US and GB, which contain at least 1% of cropland as a percentage of the total basin area shown in (a, b), respectively. The dashed lines demonstrate the significance level (i.e., the threshold for regression trend) for p-value = 0.05. The significance threshold is defined to detect instances of significant negative trends in baseflows. The y-axis is the linear regression trend of the normalized baseflow, and the x-axis is the percentage of catchment covered by crops. In the US, the regression trend of the baseflow is highly correlated with CL% (Spearman \(\rho\) = −0.45), with 7.1% of catchments showing significantly negative trends. In GB, however, the linear regression trend in the baseflow is barely correlated with CL% (Spearman \(\rho\) = −0.16), with only 2.3% of catchments showing significantly negative trends. To account for the sensitivity of the results to the cropland percentage, we repeat the analysis for the catchments with a 5% cropland percentage—See Supplementary Fig. 11.
